| 1. |
- Bratel, Tomas, et al.
(författare)
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Ventilation-perfusion relationships in pulmonary arterial hypertension : Effect of intravenous and inhaled prostacyclin treatment
- 2007
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Ingår i: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 158:1, s. 59-69
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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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| 2. |
- Bjällmark, Anna, et al.
(författare)
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Effects of hemodialysis on the cardiovascular system: Quantitative analysis using wave intensity wall analysis and tissue velocity imaging
- 2010
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Ingår i: Heart and Vessels. - : Springer Science and Business Media LLC. - 0910-8327 .- 1615-2573.
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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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| 3. |
- Bjällmark, Anna, et al.
(författare)
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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
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Ingår i: European Journal of Echocardiography. - : Oxford University Press (OUP). - 1525-2167 .- 1532-2114. ; 11:7, s. 630-636
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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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| 4. |
- Govind, Satish C., et al.
(författare)
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Quantification of low-dose dobutamine stress using speckle tracking echocardiography in coronary artery disease
- 2009
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Ingår i: European Journal of Echocardiography. - : Oxford University Press (OUP). - 1525-2167 .- 1532-2114. ; 10:5, s. 607-612
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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.
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| 5. |
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| 6. |
- Hayashi, Shirley Yumi, et al.
(författare)
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A single session of haemodialysis improves left ventricular synchronicity in patients with end-stage renal disease : A pilot tissue synchronization imaging study
- 2008
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Ingår i: Nephrology, Dialysis and Transplantation. - : Oxford University Press (OUP). - 0931-0509 .- 1460-2385. ; 23:11, s. 3622-3628
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Tidskriftsartikel (refereegranskat)abstract
- Background. Mechanical left ventricular (LV) dyssynchrony impairs cardiac function in patients with heart failure and LV hypertrophy (LVH) and may be a factor contributing to the high incidence of cardiac deaths in patients with end-stage renal disease (ESRD). Objectives. To evaluate the possible presence of LV dyssynchrony in ESRD patients, and acute effect of haemodialysis (HD) on LV synchronicity using a tailored echocardiographic modality, tissue synchronization imaging (TSI). Methods. In 13 clinically stable ESRD patients (7 men; 65 +/- 10 years) with LVH, echocardiography data were acquired before and after a single HD session for subsequent off-line TSI analysis enabling the retrieval of regional intraventricular systolic delay data. Six basal and six midventricular LV segments were evaluated. Dyssynchrony was defined as a regional difference in time to peak systolic velocity > 105 ms. Results. Before HD, all patients had at least one dyssynchronous LV segment. The percentage of delayed segments correlated positively to LV end-diastolic diameter (r = 0.68, P < 0.05). HD induced a substantial decrease in the percentage of delayed segments from 36 +/- 25% to 19 +/- 14% (P < 0.01), reduced average maximal mechanical systolic LV delay from 300 +/- 89 to 225 +/- 116 ms (P < 0.05) and completely normalized LV synchronicity in three patients (23%). Conclusions. LV dyssynchrony appears to be present frequently in ESRD patients with LVH. The severity of LV dyssynchrony correlates with LV end-diastolic diameter and decreases after a single session of HD suggesting a mechanistic relevance of volume overload and possibly other toxins accumulating in HD patients.
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| 7. |
- Hayashi, Shirley Yumi, et al.
(författare)
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Left ventricular mechanical dyssynchrony in patients with different stages of chronic kidney disease and the effects of hemodialysis
- 2013
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Ingår i: Hemodialysis International. - : Wiley-Blackwell. - 1492-7535 .- 1542-4758. ; 17:3, s. 346-358
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Tidskriftsartikel (refereegranskat)abstract
- Left ventricular (LV) dyssynchrony is a known cause of mortality in patients with heart failure and may possibly play a similar role in patients with chronic kidney disease (CKD) in whom sudden death is one of the most common and as yet not fully explained cause of death. LV synchronicity and its relationship with increased volume load and various biomarkers was analyzed in 145 patients including 53 patients with CKD stages 3 and 4 and in 92 CKD stage 5 patients undergoing hemodialysis (HD) or peritoneal dialysis (PD) using color tissue Doppler imaging and tissue synchronization imaging. The HD patients were evaluated both before and after a single HD session. LV dyssynchrony was defined as a regional difference in time to peak systolic myocardial velocity, between 12 LV segments>105milliseconds. LV dyssynchrony was present in 54% of the patients with no difference between CKD 3 and 4 (58%), HD (48%), and PD (51%). LV dyssynchrony was independently associated with LV mass index and increased estimation of LV end-diastolic pressure. A single HD session resulted in significant changes in LV synchronicity variableswith improvement in 50% of the patientsespecially in patients with higher myocardial systolic velocities and lower LV mass index. Abnormalities in LV synchronicity are highly prevalent in CKD patients already prior to dialysis treatment and are associated with LV hypertrophy, LV dysfunction and load conditions, underlining the importance of volume status for LV synchronicity in CKD patients.
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| 8. |
- Kronander, Håkan, et al.
(författare)
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Analysis of ST/HR hysteresis improves long-term prognostic value of exercise ECG test.
- 2011
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Ingår i: International Journal of Cardiology. - : Elsevier BV. - 0167-5273 .- 1874-1754. ; 148:1, s. 64-9
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: ST/HR hysteresis is one of the better diagnostic exercise ECG variables for coronary artery disease. This study evaluates the long-term prognostic value of ST/HR hysteresis in predicting acute myocardial infarction (AMI) and all-cause mortality in men and women. METHODS: The study population consisted of 8317 patients who had undergone routine exercise test on bicycle ergometer at one Swedish centre. Information on AMI and all-cause mortality was obtained from national Swedish registers covering a mean follow-up period of 9.5 years. RESULTS: The adjusted hazard ratio for AMI at a diagnostic cut point of ≤-20 µV for ST/HR hysteresis was 1.88 (95% CI, 1.62-2.17) in men and 2.31 (95% CI, 1.83-2.91) in women. For all-cause death the adjusted hazard ratio was 1.72 (95% CI, 1.52-1.96) in men and 1.90 (95% CI, 1.57-2.29) in women. The corresponding hazard ratios for ST-segment depression with horizontal or down-sloping ST-segment, ST-segment depression, ST/HR index, and ST/HR slope were lower. For comparison, the adjusted hazard ratio for AMI using maximal workload in percent of predicted was 2.02 (95% CI, 1.77-2.32) in men and 2.14 (95% CI, 1.71-2.67) in women. Area under the ROC curves for prediction of AMI was significantly larger using ST/HR hysteresis than using any of three other evaluated ECG indicators. CONCLUSIONS: ST/HR hysteresis appears to improve the prognostic ability of an exercise ECG test for AMI and all-cause mortality in a long-term perspective compared to conventional ST-segment and ST/HR indicators in both genders and clearly more markedly in women.
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| 9. |
- Kronander, Håkan, et al.
(författare)
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Diagnostic performance and partition values of exercise electrocardiographic variables in the detection of coronary artery disease - improved accuracy by using ST/HR hysteresis
- 2010
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Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 30:2, s. 98-106
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Tidskriftsartikel (refereegranskat)abstract
- P>Exercise electrocardiography is widely used for initial identification of patients with coronary artery disease (CAD). This study compares the measurements of ST-segment changes during exercise and during early postexercise recovery in terms of diagnostic discrimination capacity and optimal partition values. Data from 1876 patients undergoing a routine bicycle exercise test were analysed. CAD was angiographically verified in 668 patients, and excluded by angiography (n = 119), myocardial scintigraphy (n = 250), and on clinical grounds (n = 839) in 1208 patients. Postexercise ST/HR hysteresis was calculated as normalized for heart rate (HR) ST/HR loop area during the first 3 min of recovery. ST/HR index was obtained by dividing the overall ST amplitude change during exercise by exercise-induced HR change, and ST/HR slope was calculated using linear regression analysis of ST/HR data pairs during exercise. ST-segment depression was measured during, and for 3 min after the exercise. Discriminating capacity of the methods was evaluated in terms of receiver operating characteristic areas and optimal partition values providing the combination of the best sensitivity and specificity were established. The best diagnostic discrimination was provided by ST/HR hysteresis at optimal partition value of -15 mu V, followed by postexercise ST amplitude measurements at gender-specific partition values of -10 to -90 mu V, ST/HR slope [partition value 2 center dot 4 mu V (beats/min)-1], ST/HR index [partition value 1 center dot 6 mu V (beats/min)-1], and ST-segment depression during exercise (partition value 70 mu V in men and 90 mu V in women). The results demonstrate that analysis of postexercise ST/HR hysteresis offers the most accurate and gender indifferent identification of patients with CAD.
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| 10. |
- Larsson, Malin, et al.
(författare)
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Visualization of multimodal polymer-shelled contrast agents using ultrasound contrast sequences : an experimental study in a tissue mimicking flow phantom
- 2013
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Ingår i: Cardiovascular Ultrasound. - : Springer Science and Business Media LLC. - 1476-7120. ; 11, s. 33-
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Tidskriftsartikel (refereegranskat)abstract
- Background: A multimodal polymer-shelled contrast agent (CA) with target specific potential was recently developed and tested for its acoustic properties in a single element transducer setup. Since the developed polymeric CA has different chemical composition than the commercially available CAs, there is an interest to study its acoustic response when using clinical ultrasound systems. The aim of this study was therefore to investigate the acoustic response by studying the visualization capability and shadowing effect of three polymer-shelled CAs when using optimized sequences for contrast imaging. Methods: The acoustic response of three types of the multimodal CA was evaluated in a tissue mimicking flow phantom setup by measuring contrast to tissue ratio (CTR) and acoustic shadowing using five image sequences optimized for contrast imaging. The measurements were performed over a mechanical index (MI) range of 0.2-1.2 at three CA concentrations (10(6), 10(5), 10(4) microbubbles/ml). Results: The CTR-values were found to vary with the applied contrast sequence, MI and CA. The highest CTR-values were obtained when a contrast sequence optimized for higher MI imaging was used. At a CA concentration of 106 microbubbles/ml, acoustic shadowing was observed for all contrast sequences and CAs. Conclusions: The CAs showed the potential to enhance ultrasound images generated by available contrast sequences. A CA concentration of 106 MBs/ml implies a non-linear relation between MB concentration and image intensity.
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