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Sökning: WFRF:(Brodin Lars Åke)

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1.
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2.
  • Bratel, Tomas, et al. (författare)
  • Ventilation-perfusion relationships in pulmonary arterial hypertension : Effect of intravenous and inhaled prostacyclin treatment
  • 2007
  • Ingår i: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 158:1, s. 59-69
  • Tidskriftsartikel (refereegranskat)abstract
    • In seven patients with idiopathic or secondary pulmonary arterial hypertension (PAH), ventilation-perfusion (V-A/Q) relationships were measured during a right heart catheterization using the multiple inert-gas elimination technique before and during intravenous infusion with epoprostenol (EPO), and following 5 months of 20 mu g inhaled iloprost taken three times daily (ILO). Pre-treatment pulmonary vascular resistance (PVR) was 9.3 +/- 5.0 mmHg/l/min and the dispersion of perfusion and ventilation for V-A/Q-ratios was increased. EPO reduced PVR by 20%, and increased cardiac output, shunt, and mixed venous oxygenation (Sv(O2)) The arterial oxygen tension (Pa-O2) remained unchanged. Basal central haemodynamics did not change after 5 months of ILO. Fifteen minutes after ILO, PVR decreased by 20%, and the shunt, Sv(O2), and Pa-O2 remained unaltered. Conclusions: In secondary PAH with normal lung volumes, significant V-A/Q mismatching occurred. The PVR was reduced to a similar degree during EPO and after ILO, but only EPO increased the shunt and Sv(O2). EPO and ILO did not significantly affect the Pa-O2.
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4.
  • Carlsson, Lars, et al. (författare)
  • Enhanced systolic myocardial function in elite endurance athletes during combined arm-and-leg exercise
  • 2011
  • Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 111:6, s. 905-913
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim here was to employ color tissue velocity imaging (TVI), to test the hypothesis that highly trained endurance athletes exhibit enhanced systolic function of the left ventricular (LV) myocardium both at rest and during combined arm-and-leg exercise in comparison with untrained subjects. For each of the ten elite male (EG) and ten matched control participants (CG), LV dimensions and systolic function were assessed at rest using echocardiography. Subsequently, these subjects exercised continuously on a combined arm-and-leg cycle ergometer for 3 min each at 50, 60, 70, 80, 90 and 100% of VO2max. Oxygen uptake, heart rate, systolic blood pressure (SBP) and peak contraction systolic velocities of the LV myocardium (PSV) were recorded in the end of each level. At rest, the trained and untrained groups differed with respect to LV dimensions, but not systolic function. At 60–100% VO2max, the EG group demonstrated both higher PSV and SBP. The observation that the EG athletes had higher PSV than CG during exercise at 60–100% VO2max, but not at rest or at 50% of VO2max, suggested an enhanced systolic capacity. This improvement is likely to be due to an enhanced inotropic contractility, which only becomes apparent during exercise.
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6.
  • Linnersjö, Anette, et al. (författare)
  • Low mortality and myocardial infarction incidence among flying personnel during working career and beyond
  • 2011
  • Ingår i: Scandinavian Journal of Work, Environment and Health. - : Scandinavian Journal of Work, Environment and Health. - 0355-3140 .- 1795-990X. ; 37:3, s. 219-226
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective The aim of this study was to evaluate mortality and acute myocardial infarction (AM!) incidence among commercial and military flying personnel in Sweden. Methods Flying personnel, employed at the Swedish part of Scandinavian Airlines and/or the Swedish Armed Forces at some point between 1957-1994, were included. The cohort was followed regarding mortality and AMI incidence using national registers of hospital discharges and deaths. The observed mortality and AMI incidence was compared with the expected rate in the general Swedish population through standardized mortality ratios (SMR) and standardized incidence ratios (SIR) taking age, gender, and calendar year into account. Results Swedish flying personnel, except male cabin crew, had a lower-than-expected all-cause mortality (SMR ranging from 0.57 among female cabin crew to 0.79 among navigators and mechanics; male cabin crew 0.89) and cardiovascular mortality (SMR from 0.31 among female cabin crew to 0.79 among navigators and mechanics). We observed an elevated mortality in aircraft accidents (SMR ranging from 23.87 among commercial pilots to 165.68 among military pilots). Male cabin attendants had a higher-than-expected mortality for alcohol-related death causes and acquired immunodeficiency syndrome (AIDS). AMI incidence was reduced in all groups and across the lifespan (SIR between 0.13 among female cabin crew and 0.61 among navigators and mechanics). Conclusions Swedish flying personnel have a low all-cause mortality. This is mostly due to a reduced cardiovascular mortality reflecting a low AMI incidence during the working life as well as after retirement.
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8.
  • Andersson, Agneta, et al. (författare)
  • Domiciliary liquid oxygen versus concentrator treatment in chronic hypoxaemia: a cost-utility analysis
  • 1998
  • Ingår i: European Respiratory Journal. - 1399-3003. ; 12:6, s. 1284-1289
  • Tidskriftsartikel (refereegranskat)abstract
    • Whether long-term oxygen therapy (LTOT) improves quality of life in chronic hypoxaemia has been questioned. LTOT with an oxygen concentrator (C/C) and gas cylinders for ambulation is considered cumbersome compared to mobile liquid oxygen equipment (L). The hypothesis for this study was that LTOT with liquid oxygen treatment (L) improves patients' health-related quality of life, but that it is also more expensive compared to concentrator (C/C) treatment. A prospective, randomized multicentre trial comparing C/C with L for LTOT was conducted during a six-month period. Fifty-one patients (29 on L and 22 on C/C) with chronic hypoxaemia, regularly active outside the home, participated in the study initially. Costs for oxygen were obtained from the pharmacies. Patient diaries and telephone contacts with members of the healthcare sector were used to estimate costs. Health-related quality of life was measured by the Sickness Impact Profile (SIP) and the EuroQol, instruments at the start and after 6 months. The average total cost per patient for group C/C for the six-month period was US$1,310, and for group L it was US$4,950. Health-related quality of life measured by the SIP instrument showed significant differences in favour of group L in the categories/dimensions of physical function, body care, ambulation, social interaction and total SIP score. In conclusion, liquid-oxygen treatment was more expensive compared to concentrator treatment. However, treatment effects showed that liquid oxygen had a better impact on quality of life.
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9.
  • Andersson, L., et al. (författare)
  • Effect of CO2 pneumoperitoneum on ventilation-perfusion relationships during laparoscopic cholecystectomy
  • 2002
  • Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 46:5, s. 552-560
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Previous studies have shown that pneumoperitoneum transiently reduces venous admixture as assessed by a calculation based on the shunt formula, and increases arterial oxygen tension (PaO2) in patients without heart or lung disease. The aim of the present study was to further explore the relationship between ventilation-perfusion ((V) over dot (A)/(Q) over dot) before and during pneumoperitoneum by using the multiple inert gas technique. Methods: Nine patients without heart or lung disease (ASA I), with a mean age of 42 years, scheduled for laparoscopic cholecystectomy were included. After premedication and induction of anaesthesia, radial artery and pulmonary artery catheters were introduced percutaneously. The (V) over dot (A)/(Q) over dot relationships were evaluated by the multiple inert gas elimination technique before and during pneurnoperitoneum to obtain a direct measure of the pulmonary shunt. Results: Induction of pneumoperitoneum decreased the pulmonary shunt from 5.8 (4.5) to 4.1 (3.2)% (P<0.05) and increased PaO2 from 21.7 (5.9) to 24.7 (4.8) kPa (P<0.01). During surgery, the shunt increased from 3.2 (2.8) to 5.2 (3.4)% to the same level as before pneumoperitoneum induction. No area with low (V) over dot (A)/(Q) over dot was seen. Dead space ventilation amounted to 20.0 (1.2)% in the supine position and did not change during the investigation. Conclusions: In patients without heart or lung disease, pneumoperitoneum at an intra-abdominal pressure level of 11-13 mmHg- causes a transient reduction of the pulmonary shunt. The mechanisms underlying the present finding remain to be elucidated.
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10.
  • A'roch, Roman, 1959- (författare)
  • Left ventricular function's relation to load, experimental studies in a porcine model
  • 2011
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Background: Loading conditions are recognized to influence ventricular function according to the Starling relationship for length/stretch and force.  Many modern echocardiographic parameters which have been announced as describing ventricular function and contractile status, may be confounded by uncontrolled and unmeasured load.  These studies aimed to measure the relation between four differ­ent types of assessments of ventricular dysfunction and degrees of load.  Study examined the ‘myo­cardial performance index’ (MPI).  Study II examined long axis segmental mechanical dyssynchrony.  Study III examined tissue velocities, and Study IV examined ventricular twist.  All studies aimed to describe the relation of these parameters both to load and to inotropic changes. Methods:  In anesthetized juvenile pigs, left ventricular (LV) pressure and volume were measured continuously and their relationship (LVPVR) was analysed.  Preload alterations were brought about by inflation of a balloon tipped catheter in the inferior vena cava (IVCBO).  Inotropic interventions were brought about by either an overdose of anesthetic (combine intravenous pentobarbital and inhaled isoflurane, Study I), or beta blocker and calcium channel blocker given in combination (Stud­ies III and IV).  In one study (II), global myocardial injury and dysfunction was induced by endotoxin infusion.  MPI measurements were derived from LVPVR heart cycle intervals for isovolumic contrac­tion and relaxation as well as ejection time.  Long axis segmental dyssynchrony was derived by ana­lyzing for internal flow and time with segmental dyssynchronous segment volume change during systole, hourly before and during 3 hours of endotoxin infusion.  Myocardial tissue velocities were measured during IVCBO at control, during positive and then later negative inotropic interventions.  The same for apical and base circumferential rotational velocities by speckle tracking.  Load markers (including end-diastolic volume) were identified for each beat, and the test parameters were analysed together with load for a relation.  The test parameters were also tested during single apneic beats for a relation to inotropic interventions. Results: MPI demonstrated a strong and linear relationship to both preload and after-load, and this was due to changes in ejection time, and not the isovolumic intervals.  Long axis segmental dyssyn­chrony increased during each hour of endotoxin infusion and global myocardial injury.  This dysyn­chrony parameter was independent of load when tested by IVCBO. Peak systolic velocities were strongly load-independent, though not in all the inotropic situations and by all measurement axes.  Peak systolic strain was load-dependent, and not strongly related to inotropic conditions.  Peak sys­tolic LV twist and untwist were strongly load-dependent. Conclusions: MPI is strongly load-dependent, and can vary widely in value for the same contractile status if the load is varied.  Mechanical dyssynchrony measures are load-independen in health and also in early global endotoxin myocardial injury and dysfunction.  Peak sytole velocities are a clinically robust parameter of LV regional and global performance under changing load, though peak systolic strain seems to be load-dependent.  Left ventricular twist and untwist are load-dependent in this pig model.
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11.
  • Bajraktari, Gani, 1964- (författare)
  • The clinical value of total isovolumic time
  • 2014
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The objective of this thesis is to evaluate the use of Doppler echocardiography markers ofglobal dyssynchrony [total isovolumic time (t-IVT)] in the following 6 studies: 1) Its prognostic role in predicting cardiac events in patients undergoing CABG surgery,compared with conventional global systolic and diastolic measurements. 2) Its additional value in predicting six minute walk test (6-MWT) in patients with leftventricular (LV) ejection fraction (EF) <45%. 3) Its prognostic value in comparison with other clinical, biochemical and echocardiographicvariables in patients with chronic systolic heart failure (HF). 4) The relationship between 6-MWT and cardiac function measurements in a consecutivegroup of patients, irrespective of EF and to identify predictors of exercise capacity. 5) To investigate the effect of age on LV t-IVT and Tei index compared with conventionalsystolic and diastolic parameters. 6) To assess potential additional value of markers of global LV dyssynchrony in predictingcardiac resynchronization therapy (CRT) response in HF patients.Study IMethods: This study included 74 patients before routine CABG who were followed up for18±12 months. Results: At follow-up, 29 patients were hospitalized for a cardiac event or died. LV-ESD wasgreater (P=0.003), fractional shortening (FS) lower (p<0.001), E:A ratio and Tei index higher(all P<0.001), and t-IVT longer (P<0.001) in patients with events. Low FS [0.66 (0.50–0.87),P<0.001], high E:A ratio [l4.13 (1.17–14.60), P=0.028], large LV-ESD [0.19 (0.05–0.84),P=0.029], and long t-IVT [1.37 (1.02–1.84), P=0.035] predicted events and deaths. Conclusion: Despite satisfactory surgical revascularization, long t-IVT and systolicdysfunction suggest persistent ventricular dyssynchrony that contributes to post-CABGcardiac events.Study IIMethods: We studied 77 patients (60±12 year, and 33.3% females) with stable HF using 6-MWT.iii Results: E’ wave (r=0.61, p<0.001), E/e’ ratio (r=-0.49, p<0.001), t-IVT (r=-0.44, p<0.001),Tei index (r=-0.43, p<0.001) and NYHA class (r=-0.53, p<0.001) had the highest correlationwith the 6-MWT distance. In multivariate analysis, only E/e’ ratio [0.800 (0.665-0.961),p=0.017], and t-IVT [0.769 (0.619-0.955), p=0.018] independently predicted poor 6-MWTperformance (<300m). Conclusions: In HF, the higher the filling pressures and the more dyssynchronous the LV, thepoorer is the patient’s exercise capacity.Study IIIMethods: We studied 107 systolic HF patients; age 68±12 year, 25% females and measuredplasma NT-pro-BNP. Results: Over a follow-up period of 3718 months, t-IVT ≥12.3 sec/min, mean E/Em ratio≥10, log NT-pro-BNP levels ≥2.47 pg/ml and LV EF ≤32.5% predicted clinical events. Theaddition of t-IVT and NT-pro-BNP to conventional clinical and echocardiographic variablessignificantly improved the χ2 for the prediction of outcome from 33.1 to 38.0, (p<0.001). Conclusions: Prolonged t-IVT adds to the prognostic stratification of patients with systolicHF.Study IVMethods: We studied 147 HF patients (61±11 year, 50.3% male) with 6-MWT.Results: The 6-MWT correlated with t-IVT (r=-0.49, p<0.001) and Tei index (r=-0.43,p<0.001) but not with any of the other clinical or echocardiographic parameters. Group Ipatients (<300m) had lower Hb (p=0.02), lower EF (p=0.003), larger left atrium (p=0.02),thicker septum (p=0.02), lower A wave (p=0.01) and lateral wall a’ (p=0.047), longerisovolumic relaxation time (r=0.003) and longer t-IVT (p= 0.03), compared with Group II(>300m). Only t-IVT ratio [1.257 (1.071-1.476), p=0.005], LV EF [0.947 (0.903-0.993),p=0.02], and E/A ratio [0.553 (0.315-0.972), p=0.04] independently predicted poor 6-MWTperformance. Conclusion: In HF, the limited 6-MWT is related mostly to severity of global LVdyssynchrony, more than EF or raised filling pressures.Study VMethods: We studied 47 healthy individuals (age 62±12 year, 24 female), arbitrarilyclassified into: M (middle age), S (seniors), and E (elderly). Results: Age strongly correlated with t-IVT (r=0.8, p<0.001) and with Tei index (r=0.7,p<0.001), E/A ratio (r=-0.6, p<0.001), but not with global or segmental systolic function measurements or QRS duration. The normal upper limit of the t-IVT (95% CI) for the three groups was 8.3 s/min, 10.5 s/min and 14.5 s/min, respectively, being shorter in the S compared with the E group (p=0.001). T-IVT correlated with A wave (r=0.66, p<0.001), E/Aratio (r=-0.56, p<0.001), septal e’ (r=-0.49, p=0.001) and septal a’ (r=0.4, p=0.006), but notwith QRS. Conclusions: In normals, age is associated with exaggerated LV global dyssynchrony anddiastolic function disturbances, but systolic function remains unaffected.Study VIMethods: We studied 103 HF patients (67±12 year, 82.5% male) recruited for CRTtreatment. Results: Prolonged t-IVT [0.878 (0.802-0.962), p=0.005], long QRS duration [0.978 (0.960-0.996), p=0.02] and high tricuspid regurgitation pressure drop (TRPD) [1.047 (1.001-1.096),p=0.046] independently predicted response to CRT. A t-IVT ≥11.6 s/min was 67% sensitiveand 62% specific (AUC 0.69, p=0.001) in predicting CRT response. Respective values for aQRS ≥ 151ms were 66% and 62% (AUC 0.65, p=0.01). Combining the two variables had asensitivity of 67% but higher specificity of 88% in predicting CRT response. In atrialfibrillation (AF) patients, only prolonged t-IVT ≥11 s/min [0.690 (0.509-0.937), p=0.03]independently predicted CRT response with a sensitivity of 69% and specificity of 79% (AUC0.78, p=0.015). Conclusion: Combining prolonged t-IVT and broad QRS had higher specificity in predictingresponse to CRT, with the former the sole predictor of response in AF patients.
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12.
  • Bjällmark, Anna, et al. (författare)
  • A system to quantify and visualize ventricular rotation pattern of the heart
  • 2009
  • Patent (populärvet., debatt m.m.)abstract
    • Different modalities have been used to describe the rotational motion of the ventricles of the heart and studies have indicated LV twist to be an additional integral component in LV function. So far, only amplitudes and timings of rotation have been reported, whereas no method is available to fully describe the rotation pattern of the ventricles. The object of the present application is to achieve a system that presents a novel way to quantify and visualize the ventricular rotation pattern of the heart. We present a novel method that assesses and describes the rotation pattern by calculating the rotation axis of the ventricle. Non- invasive image acquisition is required to collect rotation values from different positions of the myocardium. Thereafter, a kinematic model of a ventricle is constructed to determine the rotation planes at different levels of the heart. The motion of the rotation planes are visualized by plotting the normal vectors of the planes over time, i.e. the rotation axis of the planes. This new method is different to all other methods used today for assessing cardiac function, as it does not describe the amplitude of a motion but the relationship in motion between different parts within a ventricle. Preliminary results indicate that the rotation axis is more sensitive to changes in the rotation pattern than conventional measurements of ventricular rotation. This new method could be used for early detection of cardiac diseases and for selection of patients for and optimization of cardiac resynchronization therapy.
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13.
  • Bjällmark, Anna, et al. (författare)
  • Effects of hemodialysis on the cardiovascular system: Quantitative analysis using wave intensity wall analysis and tissue velocity imaging
  • 2010
  • Ingår i: Heart and Vessels. - : Springer Science and Business Media LLC. - 0910-8327 .- 1615-2573.
  • Tidskriftsartikel (refereegranskat)abstract
    • Cardiovascular disease is the leading cause of death in patients with end stage renal disease (ESRD). The aim of this study was to investigate the changes in cardiovascular function induced by a single session of hemodialysis (HD) by the analysis of cardiovascular dynamics using wave intensity wall analysis (WIWA) and of systolic and diastolic myocardial function using tissue velocity imaging (TVI). Grey-scale cine loops of the left common carotid artery, conventional echocardiography and TVI images of the left ventricle were acquired before and after HD in 45 patients (17 women, mean age 54) with ESRD. The WIWA indexes, W1 preload-adjusted W1, W2 and preload-adjusted W2, and the TVI variables, isovolumic contraction velocity (IVCV), isovolumic contraction time (IVCT), peak systolic velocity (PSV), displacement, isovolumic relaxation velocity (IVRV), isovolumic relaxation time (IVRT), peak early diastolic velocity (E’) and peak late diastolic velocity (A’), were compared before and after HD. The WIWA measurements showed significant increases in W1 (p < 0.05) and preload-adjusted W1 (p < 0.01) after HD. W2 was significantly decreased (p < 0.05) after HD, whereas the change in preload-adjusted W2 was not significant. Systolic velocities, IVCV (p < 0.001) and PSV (p < 0.01), were increased after HD, whereas the AV-plane displacement were decreased (p < 0.01). For the measured diastolic variables, E’ was significantly decreased (p < 0.01) and IVRT was significantly prolonged (p < 0.05), after HD. A few correlations were found between WIWA and TVI variables. The WIWA and TVI measurements indicate that a single session of HD improves systolic function. The load dependency of the diastolic variables seems to be more pronounced than for the systolic variables. Preload-adjusted wave intensity indexes may contribute in the assessment of true LV contractility and relaxation.
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14.
  • Bjällmark, Anna, 1980- (författare)
  • New ultrasonographic approaches to monitoring cardiac and vascular function
  • 2009
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Atherosclerotic cardiovascular disease is the leading cause of death worldwide. To decrease mortality and morbidity in cardiovascular disease, the development of accurate, non-invasive methods for early diagnosis of atherosclerotic cardiac and vascular engagement is of considerable clinical interest. Cardiovascular ultrasound imaging is today the cornerstone in the routine evaluation of cardiovascular function and recent development has resulted in two new techniques, tissue velocity imaging (TVI) and speckle tracking, which allow objective quantification of cardiovascular function. TVI and speckle tracking are the basis for three new approaches to cardiac and vascular monitoring presented in this thesis: wave intensity wall analysis (WIWA), two-dimensional strain imaging in the common carotid artery, and the state diagram of the heart.   WIWA uses longitudinal and radial strain rate as input for calculations of wave intensity in the arterial wall. In this thesis, WIWA was validated against a commercially available wave intensity system, showing that speckle tracking-derived strain variables can be useful in wave intensity analysis. WIWA was further tested in patients with end stage renal disease and documented high mortality in cardiovascular disease. The latter study evaluated the effects of a single session of hemodialysis using WIWA and TVI variables and showed improved systolic function after hemodialysis. The results also indicated that preload-adjusted early systolic wave intensity obtained by the WIWA system may contribute in the assessment of left ventricular contractility in this patient category. Two-dimensional strain imaging in the common carotid artery is a new approach showing great potential to detect age-dependent differences in mechanical properties of the common carotid artery. Among the measured strain variables, global circumferential strain had the best discriminating performance and appeared to be superior to conventional measures of arterial stiffness such as elastic modulus and β stiffness index. The state diagram is a visualisation tool that provides a quantitative overview of the temporal interrelationship of mechanical events in the left and right ventricles. Case examples and a small clinical study showed that state diagrams clearly visualize cardiac function and can be useful in the detection of non ST-elevation myocardial infarction (NSTEMI).   Even though WIWA, two-dimensional strain imaging in the common carotid artery and the state diagram show potential to be useful in the evaluation of cardiovascular function, there still remains a considerable amount of work to be done before they can be used in the daily clinical practice.
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15.
  • Bjällmark, Anna, et al. (författare)
  • Ultrasonographic strain imaging is superior to conventional non-invasive measures of vascular stiffness in the detection of age-dependent differences in the mechanical properties of the common carotid artery
  • 2010
  • Ingår i: European Journal of Echocardiography. - : Oxford University Press (OUP). - 1525-2167 .- 1532-2114. ; 11:7, s. 630-636
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims: Elastic properties of large arteries have been shown to deteriorate with age and in the presence of atherosclerotic vascular disease. In this study, the performance of ultrasonographic strain measurements was compared to conventional measures of vascular stiffness in the detection of age-dependent differences in the elastic properties of the common carotid artery.Methods and results: In 10 younger (25-28 years, 4 women) and 10 older (50-59 years, 4 women) healthy individuals, global and regional circumferential and radial strain variables were measured in the short-axis view of the right common carotid artery using ultrasonographic two-dimensional (2D) strain imaging with recently introduced speckle tracking technique. Conventional elasticity variables, elastic modulus (Ep) and β stiffness index, were calculated using M-mode sonography and non-invasive blood pressure measurements. Global and regional circumferential systolic strain and strain rate values were significantly higher (p < 0.001, p < 0.01 for regional late systolic strain rate) in the younger individuals, whereas the values of conventional elasticity variables in the same group were lower (p < 0.05). Among all strain and conventional elasticity variables, principal component analysis and its regression extension identified only circumferential systolic strain variables as contributing significantly to the observed discrimination between the younger and older age groups.Conclusion: Ultrasonographic 2D-strain imaging is a sensitive method for the assessment of elastic properties in the common carotid artery, being in this respect superior to conventional measures of vascular elasticity. The method has potential to become a valuable non-invasive tool in the detection of early atherosclerotic vascular changes.
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16.
  • Bjällmark, Anna, et al. (författare)
  • Velocity tracking - a novel method for quantitative analysis of longitudinal myocardial function
  • 2007
  • Ingår i: Journal of the American Society of Echocardiography. - : Elsevier. - 0894-7317 .- 1097-6795. ; 20:7, s. 847-856
  • Tidskriftsartikel (refereegranskat)abstract
    • Doppler tissue imaging is a method for quantitative analysis of longitudinal myocardial velocity. Commercially available ultrasound systems can only present velocity information using a color Dopplerbased overlapping continuous color scale. The analysis is time-consuming and does not allow for simultaneous analysis in different projections. We have developed a new method, velocity tracking, using a stepwise color coding of the regional longitudinal myocardial velocity. The velocity data from 3 apical projections are presented as static and dynamic bull's-eye plots to give a 3-dimensional understanding of the function of the left ventricle. The static bull's-eye plot can display peak systolic velocity, late diastofic tissue velocity, or the sum of peak systolic velocity and early diastolic tissue velocity. Conversely, the dynamic bull's-eye plot displays how the myocardial velocities change over one heart cycle. Velocity tracking allows for a fast, simple, and hituitive visual analysis of the regional longitudinal contraction pattern of the left ventricle with a great potential to identify characteristic pathologic patterns.
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17.
  • Blomstrand, Peter (författare)
  • Echocardiographic methods for assessment of coronary artery disease
  • 1995
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Upright bicycle exercise echocardiography with digital image acquisition in seated position during exercise and in recumbent position before and immediately after exercise was performed in 66 men, one month after an episode of unstable coronary arte1y disease. It was difficult to obtain images of adequate quality during exercise but new or worsening of wall motion abnormalities not seen in recumbent position after exercise were detected at peak-exercise in patients with good image quality. Therefore, image acquisition seated at peak bicycle exercise and in the recumbent position immediately after exercise are of complementary value.Bicycle exercise echocardiography and 201-Tl myocardial perfusion scintigraphy SPECT were compared in 65 men after an episode of unstable coronary artery disease. Reversible abnormalities were seen in 55 patients with cchocardiography and in 43 patients with 201-Tl scintigraphy {pThe hemodynamic alterations induced by dobutamine stress testing were investigated using Doppler-echocardiography and venous occlusion plethysmography in 11 healthy women and 18 female patients. The healthy subjects received a lower peak-dose of dobutamine, 22±7.5 j.lg kg-I miu-1 compared with 33±9.7 j.lg kg- I min-I administered to the patients (p10 mm Hg). One patient in the hypotension group developed a paradoxical vagal reaction with bradycardia at peak-dose and two patients had a very low increase in cardiac output (12%). The fomth patient with hypotension did not differ in change in cardiac output compared to the other patients. Despite a more pronounced decrease in total peripheral vascular resistance in these four patients compared with other patients, there was no difference in leg peripheral vascular resistance between the groups. The disparity between the pattern of total to legperipheral vascular resistance in patients with hypotension might reflect a baroreceptor mediated compensatmy increase in vasoconstrictor tone of muscle vessels not matched in other vascular territories.Echocardiographic M-mode recordings of mitral annulus motion were compared with Doppler registrations of mitral and pulmonary venous flow velocities in 38 patients with heart failure (NYHA ll-IU) after myocm·dial infarction. Patients with an increased atlial component of annulus motion in absolute (a :::::5.1 mm, n::::l9) or relative terms (a/T >57%, n::::l2) had a higher miti·allate to early flow velocity ratio and pulmonmy venoussystolic to diastolic filling ratio (p
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21.
  • Brodin, Lars-Åke, et al. (författare)
  • Global and local detection of blood vessel elasticity
  • 2006
  • Patent (populärvet., debatt m.m.)abstract
    • The present invention is a non-invasive analysis system for detection of global and local blood vessel elasticity. The analysis system comprises two subsystems where subsystem 1 is data collecting unit and subsystem 2 is an analysis unit. The data collecting unit comprises one or many non-invasive image generating systems, or the data collecting system makes the registration possible of movement parameters that quantifies the dynamics of the blood vessel wall in longitudinal and radial directions. Subsystem 2 performs Wave Intensity Analysis which is an analysis method using co-related parts of the circulation system by measuring the intensity change (dl) of the blood vessel during a heart cycle. The intensity change is calculated as the product of the pressure derivate and the flow velocity derivate. In subsystem 2 the changes of pressure and flow are approximated by the deformation velocity or velocity of the radial and longitudinal direction, respectively. By calculating time constants and amplitudes of the intensity change graph a measure is obtained of the local and global elasticity of the blood vessel and atherosclerotic constrictions of arterial vessels may then be identified at an early stage.
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22.
  • Brodin, Lars-Åke (författare)
  • Tissue Doppler, a fundamental tool for parametric imaging
  • 2004
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 24:3, s. 147-155
  • Tidskriftsartikel (refereegranskat)abstract
    • Tissue Doppler has been used for clinical applications since 1989. It has been developed from a pulsed Doppler acquisition tool towards a method where extraction of velocities can be performed from colour-coded images. This has introduced a further development into different forms of parametric images describing different myocardial functions as colour-coded information, like deformation imaging, motion imaging and phase imaging. The technical requirements have been established with temporal requirements of frame rates in acquisition exceeding 100 frames s(-1). The most powerful application of the tissue Doppler technique today is perhaps to quantify the myocardial functional reserve, during stress echocardiography, making the method applicable to diagnose the presence of coronary disease with an accuracy exceeding that of nuclear and other non-invasive techniques. The method has also great potential for future developments with introduction of more regional measuring variables.
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23.
  • Burmeister, Jens, et al. (författare)
  • Contention-Based Wireless Sensor Networks : A case study for ambient assisted living
  • 2010
  • Ingår i: Active Ageing, Smart Solutions, New Markets.
  • Konferensbidrag (refereegranskat)abstract
    • Wireless personal area networks have emerged as an important communication infrastructure in areas such as at-home healthcare and home automation, independent living and assistive technology. Initiatives towards interoperability and standardization are taken by several players. Zigbee Alliance has launched a profile for “Zigbee wireless sensor applications for health, wellness and fitness” [1]. The Continua Health Alliance promotes “an interoperable personal healthcare ecosystem”. They have published “design guidelines for the telehealth ecosystem” including the interface to personal area network health devices and electronic health record devices ([2], [3]). These examples show that wireless personal area networks, including body sensor networks, are becoming more mature and are considered to be a realistic alternative as communication infrastructure for demanding services. However, to transmit vital sign parameters from ECGs, pulse-oximeters, EEGs etc in wireless networks is also a challenge, especially if multiple sensors compete for access. Contention-based access networks offer simplicity and utilization advantages, but the drawback is unpredictable performance due to loss of transmitted packets.We have used the SHIMMER wireless sensor platform developed at Intel [4] in the living lab at the Centre for Health and Building at KTH in a case study to identify and evaluate performance problems. The full-scale living lab consists of two apartments especially equipped with modern technique for healthcare at home and assisted living.Our paper focuses on continuous monitoring of the heart activity using a wireless ECG based on the wireless personal area network (WPAN) standard IEEE 802.15.4. Results from performance tests in the living lab will be presented e.g. influence of equipment such as micro wave ovens. Since contention-based wireless access has no guarantees for the quality of the delivered service it is interesting to determine to what extent the received ECG signal is sensitive to loss of information. We have recorded ECG signals as well as emulated packet loss in existing ECG records from official databases. The result of two cardiologists´ assessment of ECGs with different loss ratio levels and patterns will be reported in the paper. One interesting conclusion is that a diagnosis is fully possible for ECGs with packet loss ratio up to at least 5%. This project is part of research at the School of Technology and Health at KTH.
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24.
  • Carlsson, Camilla, et al. (författare)
  • Initial experience with a thin single segment pressure and conductance catheter for measurement of left ventricular volume
  • 2001
  • Ingår i: Annual Reports of the Research Reactor Institute, Kyoto University. ; , s. 103-106
  • Konferensbidrag (refereegranskat)abstract
    • Aims: To evaluate a thin and soft multifunctionalcatheter for the simultaneous real time monitoring of leftventricular volume and pressure with special consideration toside elTects such as interference with normal cardiacelectrophysiology.Methods and results: In four pigs, pressure and volumewere simultaneously recorded by using the thin single segmentpressure and conductance catheter. Measurements were doneunder varied cardiac conditions: at baseline, during preloadreduction and afterload Increase. Volumes were calibrated withintracardiac ultrasound measurements. During preloadreduction the pressure and volume decreased as expected. Acautious afterload increase resulted in a corresponding pressureand volume increase, the maximum of the pressure curvechanged from early to late. Both SV and EDV increased. Thevery few arrhythmias were mainly caused by surgicalinterference.Conclusion: The present study demonstrates that our thinsingle segment conductance catheter for the simultaneousmeasurement of LV volume and pressure has a performancethat warrants further development with the goal to make themethod available for human use. In particular, the catheter didnot cause any arrhythmias.
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25.
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26.
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27.
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28.
  • Dellgren, G., et al. (författare)
  • Eleven years' experience with the Biocor stentless aortic bioprosthesis : clinical and hemodynamic follow-up with long-term relative survival rate
  • 2002
  • Ingår i: European Journal of Cardio-Thoracic Surgery. - 1010-7940 .- 1873-734X. ; 22:6, s. 912-921
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective. The long-term durability and hemodynamics of stentless valves are largely unknown. Our aim was to prospectively investigate long-term hemodynamic function and clinical outcome after aortic valve replacement with the Biocor stentless aortic bioprosthesis. Patients and methods. Between October 1990 and November 2000 we inserted the Biocor stentless aortic valve in 112 patients (male/female: 38:74) with a mean age of 78.5 years (median 79.3, range 60-88). The predominant diagnosis was aortic stenosis in 86% of the patients. Concomitant coronary artery bypass surgery was performed in 31% of the patients. Average prosthetic valve size was 23.3 +/- 1.6 mm. All patients were followed in a prospective study with a mean follow-up of 66 +/- 33 months. The follow-up was 100% complete with a closing interval from October I to December 31, 2001. The observed actuarial survival of patients was compared to expected survival for an age- and gender-matched comparison population as calculated from Swedish life tables by Statistics Sweden. Relative survival rates were calculated annually for the patient population. Results. Early mortality was 7% (8/112). Late mortality was 38% (43/112). Actuarial survival at 5 and 9 years was 74 +/- 5% and 38 +/- 7%, respectively. Observed survival among patients was not different from the expected survival for the comparison population and calculation of relative survival rates indicates a 'normalized' survival pattern for the patient population. At 5 and 9 years the actuarial freedom from valve-related death was 94 +/- 3% and 86 +/- 6%; from cardiac death, 82 +/- 4% and 57 +/- 8%; from valve reoperation, 96 +/- 2% and 87 6%; from structural valve degeneration, 96 +/- 2% and 87 +/- 6%; from thromboembolism, 89 +/- 4% and 71 +/- 9%; and from endocarditis, 96 +/- 2% and 90 +/- 5%. At 9 years the transvalvular mean pressure difference for all valves was 7.3 +/- 1.3 mmHg (range 6-10 mmHg) measured with Doppler echocardiography. Aortic regurgitation progressed slowly over time in a few patients and necessitated reoperation in two patients. Conclusion. The Biocor stentless bioprosthesis has an excellent hemodynamic function and confers a good long-term outcome. This patient population could be regarded as 'cured' from valve disease since the observed survival did not differ from the expected survival for an age- and gender-matched Swedish comparison population, a conclusion that is also supported by a constant relative survival after the first postoperative year. However, despite excellent long-term hemodynamics, patients with stentless bioprostheses need to be evaluated with echocardiography at regular intervals to discover the rare cases of progressive aortic regurgitation.
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29.
  • Ehrenberg, J., et al. (författare)
  • Retrograde crystalloid cardioplegia preserves left ventricular systolic function better than antegrade cardioplegia in patients with occluded coronary arteries
  • 2000
  • Ingår i: Journal of Cardiothoracic and Vascular Anesthesia. - : Elsevier BV. - 1053-0770 .- 1532-8422. ; 14:4, s. 383-387
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: To investigate retrograde and antegrade crystalloid cardioplegia in terms of cardiac cooling and postoperative cardiac function. Design: Prospective, randomized, and blinded. Setting: University hospital. Participants: Twenty male patients with triple-vessel disease and proximal occlusion of the circumflex or the left anterior descending coronary artery. Interventions: Left ventricular ejection fraction at rest and during exercise was evaluated by nuclear ventriculography the day before and 3 months after surgery. After induction of anesthesia and hourly for the first 5 postoperative hours, hemodynamic. echocardiographic, and electrocardiographic data were acquired. Myocardial temperature was measured with needle thermistors in 3 myocardial regions. Measurements and Main Results: Demographic and temperature data were analyzed by t-test. Hemodynamic and echocardiographic data were analyzed by analysis of variance. The groups were similar in baseline characteristics. Retrograde cardioplegia cooled the region distal to an occlusion better than antegrade cardioplegia (9.6 degrees C +/- 4.8 degrees C v 21.8 degrees C +/- 5.9 degrees C; p < 0.01). Hemodynamic, echocardiographic, and electrocardiographic data did not differ between the groups. Three months after surgery, the retrograde cardioplegia group showed a higher left ventricular ejection fraction at rest (58% +/- 10% v 47% +/- 10%; p < 0.02) and during exercise (58% +/- 13% v 47% +/- 10%; p < 0.05) compared with the antegrade cardioplegia group. Conclusions: Retrograde cardioplegia provides more homogenous myocardial cooling than antegrade cardioplegia in hearts with coronary artery occlusions. The use of retrograde cardioplegia seems to benefit long-term left ventricular function.
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30.
  • Elmstedt, Nina, et al. (författare)
  • Fetal cardiac muscle contractility decreases with gestational age : a color-coded tissue velocity imaging study
  • 2012
  • Ingår i: Cardiovascular Ultrasound. - : Springer Science and Business Media LLC. - 1476-7120. ; 10, s. 19-
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Present data regarding how the fetal heart works and develops throughout gestation is limited. However, the possibility to analyze the myocardial velocity profile provides new possibilities to gain further knowledge in this area. Thus, the objective of this study was to evaluate human fetal myocardial characteristics and deformation properties using color-coded tissue velocity imaging (TVI). Methods: TVI recordings from 55 healthy fetuses, at 18 to 42 weeks of gestation, were acquired at a frame rate of 201-273 frames/s for offline analysis using software enabling retrieval of the myocardial velocity curve and 2D anatomical information. The measurements were taken from an apical four-chamber view, and the acquired data was correlated using regression analysis. Results: Left ventricular length and width increased uniformly with gestational age. Atrioventricular plane displacement and the E'/A' ratio also increased with gestational age, while a longitudinal shortening was demonstrated. Conclusions: Fetal cardiac muscle contractility decreases with gestational age. As numerous fetal-and pregnancy-associated conditions directly influence the pumping function of the fetal heart, we believe that this new insight into the physiology of the human fetal cardiovascular system could contribute to make diagnosis and risk assessment easier and more accurate.
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31.
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32.
  • Elmstedt, Nina (författare)
  • Prenatal Tisse Velocity Imaging of the Heart : A new approach to assess fetal myocardial function
  • 2013
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The general aim of this thesis has been to evaluate color‐coded tissue velocity imaging (TVI) as an approach to developing a new, non‐invasive assessment method for fetal myocardial function. Such a method could hypothetically give early indications of fetal pathology, as myocardial dysfunction is often the consequence when the circulation tries to adapt to deteriorating situations. This would be beneficial in clinical decision making when evaluating fetal well‐being in a wide range of pregnancy associated conditions, to facilitate risk assessment and to monitor the benefit of therapeutic interventions.TVI is an ultrasound technique that enables quantification of longitudinal myocardial motion with high temporal resolution, which is essential in the identification of fetal myocardial movements of short duration. Furthermore, the longitudinal motion is mainly determined by subendocardial fibers that usually become abnormal in the very early stages of cardiac dysfunction as they are sensitive to milder degrees of hypoxia. Thus, TVI has the potential to give early indications of impaired fetal myocardial function and hypothetically facilitate the detection of intrauterine hypoxia. Hypoxia is a common phenomenon of many pathological conditions in pregnancy, from which a substantial number of children either die or acquire permanent brain injury during delivery every year.After having established optimal sampling requirements and ensured an acceptable reproducibility for TVI measurements of the fetal myocardium, normal reference values were determined feasible and sensitive enough to provide insight into maturational changes in myocardial function. This provided a foundation that should enable further investigations and was partly accomplished using the cardiac state diagram (CSD) to accurately time the myocardial events during a cardiac cycle according to the motion shifts of the atrioventricular plane.The demonstrated results are promising and the general conclusion of this thesis is that TVI contributes to increasing the knowledge and understanding of fetal myocardial function and dysfunction. Used together with CSD this technique has great potential as an assessment method. However, further testing of the clinical potential is needed in larger study populations concerning the pathological or physiological questions at issue, and additional development of the method is required to render the method simple enough to be of potential aid in clinical practice.
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33.
  • Elmstedt, Nina, et al. (författare)
  • Reference values for fetal tissue velocity imaging and a new approach to evaluate fetal myocardial function
  • 2013
  • Ingår i: Cardiovascular Ultrasound. - : Springer Science and Business Media LLC. - 1476-7120. ; 11:1, s. 29-
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives: Myocardial function can be evaluated using color-coded tissue velocity imaging (TVI) to analyze the longitudinal myocardial velocity profile, and by expressing the motion of the atrioventricular plane during a cardiac cycle as coordinated events in the cardiac state diagram (CSD). The objective of this study was to establish gestational age specific reference values for fetal TVI measurements and to introduce the CSD as a potential aid in fetal myocardial evaluation. Methods: TVI recordings from 125 healthy fetuses, at 18 to 42 weeks of gestation, were performed with the transducer perpendicular to the apex to provide a four-chamber view. The myocardial velocity data was extracted from the basal segment of septum as well as the left and right ventricular free wall for subsequent offline analysis. Results: During a cardiac cycle the longitudinal peak velocities of septum increased with gestational age, as did the peak velocities of the left and right ventricular free wall, except for the peak velocity of post ejection. The duration of rapid filling and atrial contraction increased during pregnancy while the duration of post ejection decreased. The duration of pre ejection and ventricular ejection did not change significantly with gestational age. Conclusion: Evaluating fetal systolic and diastolic performance using TVI together with CSD could contribute to increase the knowledge and understanding of fetal myocardial function and dysfunction. The pre and post ejection phases are the variables most likely to indicate fetuses with abnormal myocardial function.
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34.
  • Elmstedt, Nina, et al. (författare)
  • Reproducibility and variability in the assessment of color-coded tissue velocity imaging of the fetal myocardium
  • 2013
  • Ingår i: Journal of biomedical graphics and computing. - : Sciedu Press. - 1925-4008 .- 1925-4016. ; 3:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: The introduction of color-coded tissue velocity imaging (TVI) in fetal medicine is quite recent, and as this method is presently evaluated and developed in regard to diagnostic precision it is of outmost importance to evaluate the reproducibility for adequate clinical use. In this study, reproducibility and intra- and inter-observer variability was assessed for offline analysis as well as echocardiography investigations. Also, we evaluated the importance of exact placement of the region of interest (ROI).Methods: TVI recordings from 21 fetuses, at a gestational age of 27 to 41 weeks, were acquired at 208-239 frames/s for subsequent offline analysis. All recordings were performed with the transducer positioned to provide an apical four-chamber view and the myocardial velocity data was obtained from basal inferoseptum. The data set was analyzed according to Bland-Altman and reproducibility was expressed as the standard error of a single determination, estimated from duplicate determinations in percentage of the total.Results: The variation of reproducibility for the echocardiography investigation ranged from 2.0% to 9.8%. The duration of left ventricular ejection, and the peak velocities of early diastolic filling and atrial contraction being the most robust events measured. The variation of inter-observer variability for the echocardiography investigation ranged from 1.5% to 8.4%, and the variation of intra- and inter-observer variability for the offline analysis ranged from 1.2% to 10.4%. Least robust were the events of shortest duration, including isovolumetric contraction and relaxation.Conclusion: We believe that TVI measurements of the fetal myocardium could be performed in the clinical routine with acceptable reproducibility.
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35.
  • Elmstedt, Nina, et al. (författare)
  • Temporal frequency requirements for tissue velocity imaging of the fetal heart
  • 2011
  • Ingår i: Ultrasound in Obstetrics and Gynecology. - : Wiley. - 0960-7692 .- 1469-0705. ; 38:4, s. 413-417
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives The high velocity and short duration of myocardial motion requires a high sampling rate to obtain adequate temporal resolution; this issue becomes even more important when taking into consideration the high fetal heart rate. In this study we have established optimal sampling requirements for assessing the duration of various cardiac cycle events and myocardial velocities of the fetal heart using color-coded tissue velocity imaging (TVI). Methods Recordings from 30 fetuses were acquired at an initial frame rate of 180-273 frames/s. All TVI recordings were performed from an apical four-chamber view and stored as cineloops of five to 10 consecutive cardiac cycles for subsequent offline analysis using software enabling a reduction in frame rate. Different components of the myocardial velocity curve, obtained from the basal part of the ventricular septum, were measured at the initial frame rate and compared with their equivalents at gradually decreased frame rates. Results As acquisition frame rate was reduced, there was a marked increase in deviation from the initial values, resulting in an underestimation of all systolic and diastolic velocities. For the measured durations, there was a clear tendency to underestimate isovolumetric contraction and relaxation, and a clear tendency to overestimate ventricular ejection and diastolic E-wave and A-wave. An acceptable <= 5% deviation from the value obtained at the highest frame rate corresponded to measurements obtained at above 150-200 frames/s. Conclusions A high sampling rate of at least 200 frames/s is necessary for adequate reconstruction of TVI data for the fetal heart. Frame rates that are too low result in considerable loss of temporal and velocity information.
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36.
  • Ericsson, Anders B., et al. (författare)
  • Correlation between a Mid-ventricular Volume Segment and Global Left Ventricular Volume Measured by the Conductance Catheter
  • 2001
  • Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1401-7431 .- 1651-2006. ; 35:2, s. 129-135
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives-To investigate whether acute volume changes in single volume segments of the left ventricle can be correlated with global volume changes. If so, changes in global volume might be predicted from changes in segmental volumes. Design-Volume changes were recorded in six pigs in five intraventricular segments, from apex to heart base, using the conductance catheter (at baseline, after 60 min of apical ischaemia, during preload reduction and afterload increase). A computer algorithm was created to calculate the instantaneous absolute difference between the curve shape of global and normalized segmental volume as a percentage of global stroke volume. Results-For a mid-cardiac volume segment constituting 34 (14-39)% [median (range)] of global stroke volume, the mean difference over a cardiac cycle was 4 (1-8)% at baseline. Apical ischaemia resulted in apical dyskinesia, but did not influence the mid-cardiac segment. Conclusions-The volume curve from a segment at mid-cardiac level seems to be a good estimator of the global volume curve, thus giving a foundation for estimation of global volume changes from such a segment.
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37.
  • Erlandsson, Björn-Erik, et al. (författare)
  • Medicinsk säkerhet
  • 2016. - 3
  • Ingår i: Anestesi. - Stockholm : Liber AB. - 9789147100545 ; , s. 168-173
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)
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38.
  • Fraser, AG, et al. (författare)
  • Feasibility and reproducibility of off-line tissue Doppler measurement of regional myocardial function during dobutamine stress echocardiography
  • 2003
  • Ingår i: European Journal of Echocardiography. - 1525-2167 .- 1532-2114. ; 4:1, s. 43-53
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims: Off-line post-processing of colour tissue Doppler from digital loops may allow objective quantification of dobutamine stress echocardiography. We assessed the reproducibility of off-line measurements of regional myocardial velocities. Methods and Results: Nine observers analysed 10 studies, each making 2400 observations. Coefficients of variation in basal segments from apical windows, at rest and maximal stress, were 9-14% and 11-18% for peak systolic velocity, 16-18% and 17-19% for time-to-peak systolic velocity, 9-17% and 18-24% for systolic velocity time integral, and 18-23% and 21-27% for systolic acceleration. Coefficients of variation for diastolic velocities in basal segments at rest were 11-40%. Coefficients of variation for peak systolic velocity were 10-24% at rest and 14-28% at peak in mid segments, and 19-53% and 29-69% in apical segments. From parasternal windows coefficients of variation for peak systolic velocity were 14-16% in basal posterior, and 19-29% in mid-anterior segments. High variability makes measurement unreliable in apical and basal anterior septal segments. The feasibility of obtaining traces was tested in 92 subjects, and >90% in all basal and mid segments apart from the anterior septum. Conclusion: Quantification of myocardial functional reserve by off-line analysis of colour tissue Doppler acquired during dobutamine stress is feasible and reproducible in 11 segments of the left ventricle. The most reliable measurements are systolic velocities of longitudinal motion in basal segments.
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39.
  • Frånberg, Oskar, 1976- (författare)
  • Oxygen content in semi-closed rebreathing apparatuses for underwater use : Measurements and modeling
  • 2015
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The present series of unmanned hyperbaric tests were conducted in order to investigate the oxygen fraction variability in semi-closed underwater rebreathing apparatuses. The tested rebreathers were RB80 (Halcyon dive systems, High springs, FL, USA), IS-Mix (Interspiro AB, Stockholm, Sweden), CRABE (Aqua Lung, Carros Cedex, France), and Viper+ (Cobham plc, Davenport, IA, USA). The tests were conducted using a catalytically based propene combusting metabolic simulator. The metabolic simulator connected to a breathing simulator, both placed inside a hyperbaric pressure chamber, was first tested to demonstrate its usefulness to simulate human respiration in a hyperbaric situation. Following this the metabolic simulator was shown to be a useful tool in accident investigations as well as to assess the impact of different engineering designs and physiological variables on the oxygen content in the gas delivered to the diver by the rebreathing apparatuses. A multi-compartment model of the oxygen fractions was developed and compared to the previously published single-compartment models. The root mean squared error (RMSE) of the multi-compartment model was smaller than the RMSE for the single-compartment model, showing its usefulness to estimate the impact of different designs and physiological variables on the inspired oxygen fraction.
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40.
  • Gardeback, M., et al. (författare)
  • Splanchnic blood flow and oxygen uptake during cardiopulmonary bypass
  • 2002
  • Ingår i: Journal of Cardiothoracic and Vascular Anesthesia. - : Elsevier BV. - 1053-0770 .- 1532-8422. ; 16:3, s. 308-315
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: To measure splanchnic blood flow (SBF) with 2 indicator dilution techniques during and after cardiopulmonary bypass (CPB), to compare the results with transesophageal echocardiography Doppler-measured right hepatic vein (RHV) flow, and to study gastric tonometry data in the same patients. Design: Single-arm prospective study. Setting: University hospital operating room and intensive care unit. Participants: Ten adult patients undergoing cardiac surgery. Interventions: SBF was measured using constant rate in fusion of indocyanine green dye and low-dose ethanol from induction of anesthesia until end of hypothermic CPB. The infusion of ethanol was continued, and SBF was measured postoperatively at 2, 3, and 4 hours after CPB. Simultaneously, RHV flow, splanchnic oxygen delivery and uptake, and gastric mucosal pH were calculated. Measurements and Main Results: SBF, RHV flow, and gastric mucosal pH remained unchanged during the study period. SBF measured with indocyanine green was 765 +/- 88 (SEM) mL/min after induction of anesthesia. SBF before CPB measured with ethanol was 985 +/- 218 mL/min. There was no significant difference between the methods. RHV flow was 450 +/- 87 mL/min after induction of anesthesia. There was no correlation between individual values of RHV flow and SBF. Splanchnic oxygen uptake was 52 +/- 7.8 mL/min after induction of anesthesia and decreased to 28 +/- 2.6 mL/min during CPB. Gastric mucosal pH was 7.32 +/- 0.02 after induction of anesthesia and showed no correlation to SBF or to splanchnic oxygen uptake. Conclusion: SBT did-not decrease during CPB. SBF could be measured with ethanol with reasonable accuracy. Transesophageal echocardiography assessment of RHV flow was not suitable to quantify SBF in the individual patient, but could be used to follow relative changes.
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41.
  • Govind, Satish C., et al. (författare)
  • Acute administration of a single dose of valsartan improves left ventricular functions : a pilot study to assess the role of tissue velocity echocardiography in patients with systemic arterial hypertension in the TVE-valsartan study I
  • 2006
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 26:6, s. 351-356
  • Tidskriftsartikel (refereegranskat)abstract
    • Background The advent of colour-coded tissue velocity echocardiography (TVE) has now made it possible to quantify left ventricular (LV) functions in patients with systemic arterial hypertension (HTN). Hypothesis In this project, we have studied the cardiac effects of a single dose of orally administered valsartan in patients with known HTN. Methods Fifty-five patients with HTN with a mean age of 56 +/- 10 years were given an early morning dose of 80 mg valsartan withholding regular antihypertensive medications on the day of investigation. TVE images, acquired on VIVID systems were digitized for postprocessing of longitudinal and radial peak systolic velocities, strain rate, and systolic and diastolic time intervals before (pre) and 5 h after (post) administration of the drug. Results Blood pressure (mmHg) pre and post, respectively, were 147 +/- 15 versus 137 +/- 14 systolic and 90 +/- 7 versus 86 +/- 7 diastolic (all P < 0.01). LV longitudinal systolic velocities (cm s(-1)) were significantly higher post in LV septum (5.7 +/- 1.1 versus 6.4 +/- 1.6; P < 0.001) with similar results obtained in other LV walls. Radial strain rate (1 s(-1)) was significantly higher post compared with pre valsartan (2.1 +/- 0.6 versus 2.3 +/- 0.9; P < 0.01). Regional diastolic filling and ejection times (ms) were significantly shorter post (390 +/- 122 versus 370 +/- 120 and 275 +/- 32 versus 163 +/- 36 respectively; all P < 0.05). Conclusions Within 5 h after oral administration of valsartan, improvement in regional myocardial systolic functions could be registered. Although the changes could well be secondary to afterload reduction, additional effects of the drug, evidenced by improved strain rate that is relatively load-independent, may have contributed in this improvement.
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42.
  • Govind, Satish C., et al. (författare)
  • Differing myocardial response to a single session of hemodialysis in end-stage renal disease with and without type 2 diabetes mellitus and coronary artery disease
  • 2006
  • Ingår i: Cardiovascular Ultrasound. - : Springer Science and Business Media LLC. - 1476-7120. ; 4:9
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Though hemodialysis (HD) acutely improves cardiac function, the impact of background diseases like coronary artery disease (CAD) and Type 2 diabetes (DM) in the setting of end-stage renal disease (ESRD) is not known. Tissue velocity echocardiography (TVE) offers a fast choice to follow changes in myocardial function after HD in ESRD with concomitant DM and/or CAD. Methods: 46 subjects (17 with ESRD, Group 1; 15 with DM, Group 2; 14 with DM+CAD, Group 3) underwent standard and TVE prior to and shortly after HD. Besides standard Doppler variables, regional myocardial systolic and diastolic velocities, as well as systolic strain rate were post processed. Results: Compared with pre-HD, post-HD body weight (kg) significantly decreased in all the three groups (51 ± 9 vs. 48 ± 8, 62 ± 10 vs.59 ± 10, and 61 ± 9 vs. 58 ± 9 respectively; all p < 0.01). Left ventricular end diastolic dimensions (mm) also decreased post- HD (46 ± 5 vs. 42 ± 7, 53 ± 7 vs. 50 ± 7, 51 ± 7 vs. 47 ± 8 respectively; all p < 0.01). Regional longitudinal peak systolic velocity in septum (cm/s) significantly increased post-HD in Group 1(5.7 ± 1.6 vs. 7.2 ± 2.3; p < 0.001) while remained unchanged in the other two groups. Similar trends were noted in other left ventricular walls. When the myocardial velocities (cm/s) were computed globally, the improvement was seen only in Group 1 (6.3 ± 1.5 vs. 7.9 ± 2.0; p < 0.001). Global early regional diastolic velocity (cm/s) improved in Group 1, remained unchanged in Group 2, while significantly decreased in Group 3(-5.9 ± 1.3 vs. -4.1 ± 1.8; p < 0.01). Global systolic strain rate (1/sec) increased in the first 2 Groups but remained unchanged (-0.87 ± 0.4 vs. -0.94 ± 0.3; p = ns) in Group 3. Conclusion: A single HD session improves LV function only in ESRD without coexistent DM and/or CAD. The present data suggest that not only dialysis-dependent changes in loading conditions but also co-existent background diseases determine the myocardial response to HD.
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43.
  • Govind, Satish C., et al. (författare)
  • Impaired Myocardial Functional Reserve in Hypertension and Diabetes Mellitus Without Coronary Artery Disease: Searching for the Possible Link With Congestive Heart Failure in the Myocardial Doppler in Diabetes (MYDID) Study II
  • 2006
  • Ingår i: American Journal of Hypertension. - : Oxford University Press (OUP). - 0895-7061 .- 1941-7225. ; 19:8, s. 851-857
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Although the impact of type 2 diabetes mellitus (DM) and hypertension (HTN) on myocardial function has recently been studied using tissue Doppler echocardiography (TDE), the independent role of both conditions, and the influence of other risk factors on myocardial function has not been completely defined, particularly in absence of coronary artery disease (CAD). The aim of this study was to assess the myocardial functional reserve in patients with DM or HTN with apparently normal left ventricular (LV) systolic function. Methods: Standard and dobutamine stress echocardiography using TDE was performed in 128 subjects: 59 had DM, 20 had HTN, 27 had both DM and HTN (HTN + DM), and 22 subjects were controls (C). Subjects with known CAD and depressed LV function were excluded. In addition, standard two-dimensional and Doppler measurements, LV regional peak systolic (PSV), early (E') and late (A') diastolic velocities, strain (S%) and strain rate (SR), were assessed at rest and peak stress. Results: The LV mass did not differ, although relative wall thickness was significantly higher in subjects with HTN + DM and HTN. The PSV did not differ at rest but was lowest in subjects with HTN + DM at peak stress. The E' wave velocity was significantly lower in subjects with HTN + DM both at rest and during peak stress, as were S% and SR. Conclusions: The addition of DM to HTN has a negative effect on LV systolic and diastolic functions. A depressed myocardial functional reserve might be postulated as one of the pathophysiologic mechanisms for the excessive occurrence of congestive heart failure in patients with DM or HTN.
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44.
  • Govind, Satish C., et al. (författare)
  • Isolated Type 2 Diabetes mellitus Causes Myocardial Dysfunction That Becomes Worse in the Presence of Cardiovascular Diseases : Results of the Myocardial Doppler in Diabetes (MYDID): Study 1
  • 2005
  • Ingår i: Cardiology. - : S. Karger AG. - 0008-6312 .- 1421-9751. ; 103:4, s. 189-195
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims: Patients with type 2 diabetes mellitus (DM) often suffer disproportionately and have a worse outcome when burdened with cardiovascular complications compared with those without DM. A specific heart muscle disease reportedly caused by DM per se may explain this. We sought to investigate whether an echo Doppler diagnosis of such a myocardial disease is clinically relevant in DM with or without coexistent coronary artery disease (CAD) and/or hypertension ( HTN). Subjects and Methods: Two hundred subjects (127 males, 73 females, 56 +/- 10 years) including controls (n=23), patients with HTN (n=20), CAD (n=35), uncomplicated DM (n=59), DM+HTN (n=27), DM+ CAD (n=16) and DM+CAD+HTN (n=20) underwent tissue Doppler-enhanced dobutamine stress echocardiography. Myocardial function was assessed by measuring left ventricular myocardial peak systolic velocity (PSV) and early diastolic velocity at rest and during peak stress, besides measurements of standard Doppler variables. Results: Average left ventricular PSV at rest was significantly lower in CAD (4.7 +/- 1.5) compared with controls (5.7 center dot +/- 1.2) and in DM+CAD+HTN (4.6 +/- 1.4) compared with DM (5.6 +/- 1.3; all p < 0.05). During peak stress, lower PSV persisted in CAD (9.5 +/- 3.1) and DM+CAD+HTN (8.1 +/- 2.7), while appearing de novo in DM (11.3 +/- 2.6) and HTN (11.0 +/- 2.3) unlike in the controls (12.5 +/- 2.5; all p < 0.001). When pooled together, DM subjects with CAD and/or HTN or both had significantly lower PSV (9.1 +/- 2.7) than those without (10.0 +/- 2.8; p < 0.001). Early diastolic velocity response was equally lower in both groups compared with the controls. Conclusion: The results suggest that dobutamine stress unmasks myocardial functional disturbances caused by uncomplicated DM. The discrete disturbances become quantitatively more pronounced in the presence of coexistent cardiovascular diseases.
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45.
  • Govind, Satish C., et al. (författare)
  • Microalbuminuria and Left Ventricular Functions in Type 2 Diabetes : A Quantitative Assessment by Stress Echocardiography in the Myocardial Doppler in Diabetes (MYDID) Study III
  • 2007
  • Ingår i: International Journal of Cardiology. - : Informa UK Limited. - 0167-5273 .- 1874-1754. ; 41:6, s. 363-369
  • Tidskriftsartikel (refereegranskat)abstract
    • Background. Left ventricular (LV) function might be altered in type 2 diabetes (DM) and microalbuminuria (MA) may accentuate the abnormalities. We sought to investigate whether additional LV dysfunction could be unmasked using tissue Doppler (TVE)-enhanced dobutamine stress echocardiography (TVE-DSE) in patients with DM+MA. Methods. Twenty seven DM subjects with MA, (DM+MA), 31 DM subjects without MA (DM-MA), and 13 Controls were evaluated using TVE-DSE. LV basal peak systolic (PSV), early (E') and late (A') diastolic velocities (cm/sec) at rest and peak stress were post-processed. LV filling pressure was assessed using E/E'ratio. Results. PSV and E'velocity at peak stress in the respective three groups were 13.7±1.0, 10.1±1.1, 10.0±1.2 for PSV; and 10.0±1.6, 5.0±1.4, 4.8±1.4 for E' (p < 0.001 for controls vs. both groups). E/E' at rest was 7.9±0.7 in the controls, 10.8±2.4 in DM-MA, and 11.0±2.2 in DM+MA (p < 0.01 Controls vs. both the DM groups). Conclusions. Patients with DM+MA do not have additional LV regional systolic and diastolic dysfunctions compared with DM-MA, as revealed by TVE-DSE, when controlled for glycemia levels, lipids, and treatment strategies.
  •  
46.
  • Govind, Satish C. (författare)
  • Myocardial Effects of Type 2 Diabetes, Co-morbidities, and Changing Loading Conditions : a Clinical Study by Tissue Velocity Echocardiography
  • 2007
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Ever since the validation of the tissue velocity echocardiography (TVE) technique more than a decade ago the modality has been used rather successfully in various clinical situations, at rest as well as during stress echocardiography. Hitherto, dobutamine stress echocardiography has been the hallmark of all forms of stress procedures, now with TVE, quantification of the longitudinal motions of the left ventricle shows far superiority, with improved sensitivity and specificity in the functional diagnosis of coronary artery disease. Morever there has been continued interest in this technique for even assessing subclinical myocardial systolic and diastolic function in clinical scenarios like diabetes, hypertension and chronic kidney disease. The aim of the present study was to evaluate left ventricular myocardial functions by applying TVE in human subjects having type 2 diabetes with or without co-morbidities and during changing loading conditions. The effects of changing loading conditions were analyzed during hemodialysis and following oral administration of an AT1 receptor blocker. The studied subjects included individuals with diabetes as well as those with associated hypertension, coronary artery disease, microalbuminuria and end-stage renal disease. All patients with type 2 diabetes and co-morbidities underwent TVE enhanced dobutamine stress echocardiography while load dependant left ventricular functions were analyzed at rest. There were 270 subjects in the study of type 2 diabetes and associated cardiovascular diseases and 101 subjects in the study of changing loading conditions. Patients with type 2 diabetes revealed subclinical left ventricular dysfunction characterized by reduced functional reserve. This influence becomes quantitatively more pronounced in the presence of coexistent coronary artery disease and hypertension. The coexistence of type 2 diabetes and hypertension appears to have additive negative effect on both systolic and diastolic left ventricular function, even in the absence of coronary artery disease. The presence of microalbuminuria in type 2 diabetes patients does not worsen diminished myocardial functional reserve. A single session of hemodialysis improves left ventricular function in patients with end-stage renal disease only in the absence of type 2 diabetes and co-morbidities, while a single dose of an AT1 receptor blocker valsartan results in reduction of afterload and, subsequently, in improvement of left ventricular function. TVE appears to be a sensitive tool for objective assessment of left ventricular function and can be successfully applied for the clinical evaluation of the effect of type 2 diabetes and co-morbidities on myocardial performance.
  •  
47.
  • Govind, Satish C., et al. (författare)
  • Quantification of low-dose dobutamine stress using speckle tracking echocardiography in coronary artery disease
  • 2009
  • Ingår i: European Journal of Echocardiography. - : Oxford University Press (OUP). - 1525-2167 .- 1532-2114. ; 10:5, s. 607-612
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims We sought to evaluate the utility of speckle tracking echocardiography (STE) for detecting left ventricular (LV) mechanical abnormalities during low-dose (20 mu g) dobutamine stress (DSE). Methods and results Twenty-nine patients (56 +/- 12 years) with a history of recent acute coronary events (ACE) underwent STE-DSE. Left ventricular images, sampled at frame rates 70-100 Hz, were analysed off-line (Echopac BT 6.0.0). Velocity, strain, and rotational imaging were performed. Twenty patients had LV ejection fraction (EF) >40% (Group 1) whereas nine patients had LVEF <40% (Group 2). Average heart and frame rates were identical during DSE in the two groups (P = ns). Global circumferential strain (%) was significantly lower in Group 2 compared with Group 1 (10.65 +/- 5.30 vs. 16.82 +/- 6.61; P < 0.05) at rest and during peak stress (14.72 +/- 6.51 vs. 21.13 +/- 7.2; P < 0.05). The global peak rotation rate (degree/s) was, however, higher at rest in Group 2 (70 +/- 97 vs. 19 +/- 67; P < 0.05) and 20 mu g stress. Peak systolic velocity increased in three of the four LV walls at 20 mu g ( in Groups 1 and 2). A global rotational rate increased significantly at 20 mu g during systole in both the groups, but was unchanged in Group 2 during diastole. Conclusions Speckle tracking echocardiography dobutamine stress appears to provide comprehensive information on LV mechanical status in the aftermath of ACE. The modality may help risk stratify such patients.
  •  
48.
  • Govind, Satish C, et al. (författare)
  • Role of N-terminal pro-brain natriuretic peptide in ST-segment elevation myocardial infarction : experience from a tertiary centre in India.
  • 2011
  • Ingår i: Critical Pathways in Cardiology. - 1535-282X .- 1535-2811. ; 10:4, s. 180-184
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Role of biomarkers in ST-segment elevation myocardial infarction (STEMI) is paramount, as they aid in diagnosis and gauge prognosis of the disease. In this project, we sought to study the short-term outcome and clinical associates of N-terminal pro-brain natriuretic peptide (NT-proBNP) in the setting of STEMI at a tertiary center in India. METHODS: In all, 173 STEMI patients (mean age: 57 ± 12 years, 38 women) had their NT-proBNP assayed in addition to troponins and high-sensitive C-reactive protein. Subjects were divided according to NT-proBNP levels into 2 groups: group 1 (NT-proBNP ≤100 pg/mL) and group 2 (NT-proBNP >100 pg/mL). RESULTS: NT-proBNP values (pg/mL) were elevated in group 2 (group 1: 61.7 ± 6.2; group 2: 1006.5 ± 990.6, P < 0.0001). Significantly greater number of females had elevated NT-proBNP (P < 0.05) that could be predicted by the duration of chest pain related to STEMI (area under the curve: 0.72), and age at presentation (area under the curve: 0.66). Multiple regression analysis showed a strong inverse association between NT-proBNP and left ventricular ejection fraction and a strong positive association between the peptide and high-sensitive C-reactive protein. A significant positive association was also noted between NT-proBNP and troponin I (all P < 0.05, Global R = 0.47). Diabetes mellitus and/or hypertension, and infarction localization showed no effect on NT-proBNP levels along with death, primary coronary intervention-related bleeding, and arrhythmias, (χ, P = ns). CONCLUSIONS: The data suggest that women are more likely to have increased NT-proBNP while presenting with STEMI. Duration of chest pain and age at presentation are the best predictors of elevated NT-proBNP, though without much bearing on short-term morbidity and mortality.
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49.
  •  
50.
  • Grishenkov, Dmitry, 1983-, et al. (författare)
  • In vitro contrast-enhanced ultrasound measurements of capillary microcirculation : Comparison between polymer- and phospholipid-shelled microbubbles
  • 2011
  • Ingår i: Ultrasonics. - : Elsevier BV. - 0041-624X .- 1874-9968. ; 51:1, s. 40-48
  • Tidskriftsartikel (refereegranskat)abstract
    • The focus of contrast-enhanced ultrasound research has developed beyond visualizing the blood pool and its flow to new areas such as perfusion imaging, drug and gene therapy, and targeted imaging. In this work comparison between the application of polymer- and phospholipid-shelled ultrasound contrast agents (UCAs) for characterization of the capillary microcirculation is reported. All experiments are carried out using a microtube as a vessel phantom. The first set of experiments evaluates the optimal concentration level where backscattered signal from microbubbles depends on concentration linearly. For the polymer-shelled UCAs the optimal concentration level is reached at a value of about 2 x 10(4) MB/ml, whereas for the phospholipid-shelled UCAs the optimal level is found at about 1 x 10(5) MB/ml.Despite the fact that the polymer shell occupies 30% of the radius of microbubble, compared to 0.2% of the phospholipid-shelled bubble, approximately 5-fold lower concentration of the polymer UCA is needed for investigation compared to phospholipid-shelled analogues. In the second set of experiments, destruction/replenishment method with varied time intervals ranging from 2 ms to 3 s between destructive and monitoring pulses is employed. The dependence of the peak-to-peak amplitude of backscattered wave versus pulse interval is fitted with an exponential function of the time gamma = A( 1 - exp(-beta t)) where A represents capillary volume and the time constant beta represents velocity of the flow. Taking into account that backscattered signal is linearly proportional to the microbubble concentration, for both types of the UCAs it is observed that capillary volume is linearly proportional to the concentration of the microbubbles, but the estimation of the flow velocity is not affected by the change of the concentration. Using the single capillary model, for the phospholipid-shelled UCA a delay of about 0.2-0.3 s in evaluation of the perfusion characteristics is found while polymer-shelled UCA provide response immediately. The latter at the concentration lower than 3.6 x 10(5) MB/ml have no statistically significant delay (p < 0.01), do not cause any attenuation of the backscattered signal or saturation of the receiving part of the system. In conclusion, these results suggest that the novel polymer-shelled microbubbles have a potential to be used for perfusion evaluation.
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