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- Boivie, Patrik, 1976-
(författare)
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Cerebrovascular accidents associated with aortic manipulation during cardiac surgery
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Despite the successful development in cardiac surgery, cerebrovascular accidents (CVA) remain a devastating complication. Aortic atherosclerosis has been identified as a major risk factor for CVA. The present thesis addresses this question in relation to aortic manipulation during cardiac surgery, being divided into a clinical (I-II) and an experimental part (III-V). Material and methods: Consecutive cardiac surgery cases (n=2641) were analyzed. Patients with CVA were extracted from a database designed to monitor clinical symptoms. Patient records were used to confirm clinical data and diagnosis. Subdivision was made into three groups: control subjects, immediate, and delayed CVA, being analyzed for neurological symptoms (I). Patients with CVA who also had been investigated with computer tomography (CT) (n=77) were further evaluated in terms of hemispheric and vascular distribution of lesions. The CT-findings were compared with CVA symptoms (II). An aortic perfusion model was developed using cadaver aorta onto which multiple cross-clamp manipulations were applied (III). Washout samples of perfusate were analyzed by computerized image processing and with subdivision into different particle spectra. The model was further developed with the introduction of intraluminal manipulation from cannula and intra-aortic filter (IV). A technique for macro-anatomic mapping of plaque distribution of cadaver thoracic aorta was developed (V). Variation in plaque density was analyzed in different anatomical segments, monitored by digital image analysis. Hazards associated with surgical manipulation were studied by superimposing cannulation and cross-clamp sites onto the aortic maps in a blinded fashion. Results: The incidence of immediate and delayed CVA was 3.0% and 0.9%, respectively. Aortic quality was a strongly associated with immediate but not delayed CVA. Left-sided symptoms of immediate CVA were significantly more frequent than of the contra-lateral side. Positive signs on CT were seen in 66% of the CVA patients. Right-hemispheric lesions were more frequent compared with the contra-lateral side and the middle-cerebral artery territory dominated. Aortic cross-clamping produced a substantial output of particulate matter. Manipulation by intra-aortic filter produced a significant washout of embolic particles that escaped the filter, although some particles were captured. Cannulation was an additional source of embolic material. In terms of plaque distribution was the anterior wall of the ascending part and arch of the aorta more affected than its posterior side. However, observing a plaque in the anterior wall of this aortic segment predicted to 83% a concomitant plaque in the posterior wall. Increased age correlated positively with plaque density. The theoretical chance of interfering with a plaque during cannulation and/or clamp positioning was 45.8%. Conclusions: Both CT scans and clinical symptoms confirmed that CVA after cardiac surgery had a right-hemispheric predominance. The perfusion model resulted in a profound output of material during cross-clamp maneuvers. The intra-aortic filter successfully collected particles but also generated embolic debris on its own. Aortic cannulation was an additional source of embolic debris. Plaques were frequently found in the cadaveric aorta, and there was a high risk of plaque interference during surgical manipulation. As expected, plaque density was age-dependent.
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| 5. |
- Fors, Carina, et al.
(författare)
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Analysis of breathing-related variations in ECG-triggered laser Doppler perfusion signals measured on the beating heart during surgery
- 2006
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Ingår i: Computers in cardiology. - 0276-6574. ; 33, s. 181-184
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Tidskriftsartikel (refereegranskat)abstract
- Laser Doppler perfusion monitoring (LDPM) is amethod to assess microvascular perfusion. A modified,ECG-triggered LDPM system has been developed tomeasure myocardial perfusion with minimum influencefrom heart motion. With this method, one systolic (PLS)and one diastolic (PLD) perfusion value is obtained.The aim of this study was to analyse breathing-relatedvariations in PLS and PLD measured during open-heartsurgery. The phase delays between PLS, PLD, meanarterial blood pressure (MAP), heart rate and, indirectly,the respiration were determined.MAP tended to be in phase with or precede thevariations in PLD, i.e., PLD was at a maximum at the endof inspiration or at the beginning of expiration. No clearrelation between PLS and any of the other signals couldbe found.
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| 7. |
- Fors, Carina, 1978-
(författare)
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Evaluation of a Laser Doppler System for Myocardial Perfusion Monitoring
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Coronary artery bypass graft (CABG) surgery is a common treatment for patients with coronary artery disease. A potential complication of CABG is myocardial ischemia or infarction. In this thesis, a method - based on laser Doppler flowmetry (LDF) - for detection of intra- and postoperative ischemia by myocardial perfusion monitoring is evaluated.LDF is sensitive to motion artifacts. In previous studies, a method for reduction of motion artifacts when measuring on the beating heart has been developed. By using the ECG as a reference, the perfusion signal is measured in intervals during the cardiac cycle where the cardiac motion is at a minimum, thus minimizing the artifacts in the perfusion signal.The aim of this thesis was to investigate the possibilities to use the ECG-triggered laser Doppler system for continuous monitoring of myocardial perfusion in humans during and after CABG surgery. Two studies were performed. In the first study, changes in myocardial perfusion during CABG surgery were investigated (n = 13), while the second study focused on postoperative measurements (n = 13). In addition, an ECG-triggering method was implemented and evaluated.It was found that the large variations in myocardial perfusion during CABG surgery could be monitored with the ECG-triggered laser Doppler system. Furthermore, a perfusion signal of good quality could be registered postoperatively from the closed chest in ten out of thirteen patients. In eight out of ten patients, a proper signal was obtained also the following morning, i.e., about 20 hours after probe insertion. The results show that respiration and blood pressure can have an influence on the perfusion signal.In conclusion, the results indicate that the method is able to detect fluctuations in myocardial perfusion under favourable circumstances. However, high heart rate, abnormal cardiac motion, improper probe attachment and limitations in the ECG-triggering method may result in variations in the perfusion signal that are not related to tissue perfusion.
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| 9. |
- Fors, Carina, 1978-, et al.
(författare)
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Online Laser Doppler Measurements of Myocardial Perfusion
- 2008
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Ingår i: IFMBE Proceedings 22,2008. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783540892076 - 9783540892083 ; , s. 1718-1721
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Konferensbidrag (refereegranskat)abstract
- Laser Doppler perfusion monitoring is a suitable method for microvascular blood perfusion measurements. When used on a moving tissue or organ, the Doppler signal arising from the moving blood cells may be distorted. ECG triggering of the laser Doppler signal can be used for reducing the influence from movements during measurements on the beating heart. The aim of this study was to determine the most appropriate triggering intervals during the cardiac cycle for online measurements. Recordings from thirteen coronary artery bypass graft (CABG) patients were included in the study. During surgery, the fibre-optic probe was passed through the chest wall and sutured to the left anterior ventricular wall with the probe tip inserted 3–5 mm into the myocardium. After the patient arrived at the intensive care unit a second measurement was initiated and lasted for about two hours. Before the probe was removed a third measurement was performed for about 5 minutes the following morning. A total of 97 data sequences were analysed and the intervals of low and stable perfusion signal were compared to the positions of the T and P peaks in the ECG.It was found that the most appropriate time intervals were in late systole at the T peak [−3, 9] ms and just before the P peak [−28, -10] ms in late diastole. However, the position of these intervals may vary between individuals, because of e.g., abnormal cardiac motion. With the use of the appropriate interval online measurement of the myocardial perfusion on a beating heart appears possible.
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- Granfeldt, Hans, et al.
(författare)
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A single center experience with the HeartMate II (TM) Left Ventricular Assist Device (LVAD)
- 2009
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1401-7431 .- 1651-2006. ; 43:6, s. 360-365
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. Left ventricular assist devices (LVAD), used in the setting bridge-to-transplantation and destination therapy, for patients with deteriorating severe heart failure are continuously developing. The second generation, the axial flow pumps, have been introduced since some years. Design. Eleven consecutive patients, seven male, with severe heart failure due to ischemic cardiomyopathy (n = 5), dilated cardiomyopathy (n = 5) and cytotoxic ethiology (n = 1) were implanted with the HeartMate-II (TM). They were preoperatively treated with inotropic support (n = 9), ventricular assist device (n = 2) and mechanical ventilation (n = 4). Results. Eight patients were bridged to transplant after median 155 days (range, 65 to 316 days). One patient is ongoing for 748 days, intended for destination therapy. Ten of eleven patients were discharged after median 64 days (range, 40 to 105 days). Four patients were reoperated due to bleeding. Two embolic events were recorded. One perioperative death. Conclusion. Eleven HM-II (TM) LVADs have been implanted in our institution with good early results. Eight patients were successfully bridged to heart transplantation. One patient is intended for destination therapy and is ongoing since November 2006. In these severely ill patients, this technique offers a good chance surviving until heart transplantation. In selected cases the technique also offers the possibility of a permanent support and longevity.
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| 12. |
- Granfeldt, Hans, et al.
(författare)
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Experience with the Impella (R) recovery axial-flow system for acute heart failure at three cardiothoracic centers in Sweden
- 2009
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1401-7431 .- 1651-2006. ; 43:4, s. 233-239
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. The Impella (R) recovery axial-flow system is a mechanical assist system for use in acute heart failure. This retrospective study reports the use of the device at three cardiothoracic units in Sweden. Design. Fifty patients (35 men, mean age 55.8 years, range 26 to 84 years) underwent implantation of 26 Impella (R) LP 2.5/5.0 (support-time 0.1 to 14 days), 16 Impella (R) LD (support-time 1 to 7 days) and 8 Impella (R) RD (support-time 0.1 to 8 days) between 2003 and 2007. Implantation was performed because of postcardiotomy heart failure (surgical group, n=33) or for various states of heart failure in cardiological patients (non-surgical group, n=17). The intention for the treatments was mainly to use the pump as a obridge-to-recoveryo. Results. Early mortality in the surgical and non-surgical groups was 45% and 23%, respectively. Complications included infection, 36% and right ventricular failure, 28%. Cardiac output and cardiac power output postoperatively were significantly higher among survivors than non-survivors. Conclusions. The Impella (R) recovery axial-flow system facilitates treatment in acute heart failure. Early intervention in patients with acute heart failure and optimized hemodynamics in the post-implantation period seem to be of importance for long-term survival. Insufficient early response to therapy should urge to consider further treatment options.
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| 13. |
- Hübbert, Laila, et al.
(författare)
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Axial flow pump treatment during myocardial depression in calves : an invasive hemodynamic and echocardiographic tissue Doppler study.
- 2008
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Ingår i: ASAIO journal (1992). - Philadelphia, PA USA : Lippincott Williams & Wilkins. - 1058-2916 .- 1538-943X. ; 54:4, s. 367-371
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate flow characteristics and myocardial function after implantation of an axial pump left ventricular assist device while varying afterload and during progressive myocardial depression. Ten calves were included, seven of which fulfilled the protocol. Invasive hemodynamic monitoring and echocardiography with color-coded systolic tissue Doppler velocity (TD velocity) were used during prepump conditions, at three different pump speeds, during modification of the systemic vascular resistance (SVR), and during increasing degrees of beta-blockade. The TD velocity decreased with the myocardial function whereas left ventricular size, fractional shortening, and pump speed did not correlate significantly with the TD velocity. The TD velocity correlated significantly with native stroke volume, heart rate, SVR and cardiac output but none of these alone could explain more than 20% of the changes in TD velocity. The axial flow pump studied is effective in unloading the severely depressed heart and has a high capacity for maintaining an adequate cardiac output, regardless of differing hemodynamic conditions, pump speed or decreasing LV function. Echocardiography with volumetric rendering and TD velocity imaging are valuable tools for monitoring and quantifying residual myocardial function during pump treatment.
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| 14. |
- Häggblad, Erik, et al.
(författare)
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Myocardial tissue oxygenation estimated with calibrated diffuse reflectance spectroscopy during coronary artery bypass grafting
- 2008
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Ingår i: Journal of Biomedical Optics. - : SPIE-Intl Soc Optical Eng. - 1083-3668 .- 1560-2281. ; 13:5, s. 054030-
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Tidskriftsartikel (refereegranskat)abstract
- We present a study using a method able to assess tissue oxygenation, taking into account the absorption and the level of scattering in myocardial tissue using a calibrated fiber optic probe. With this method, interindividual comparisons of oxygenation can be made despite varying tissue optical properties during coronary artery bypass grafting (CABG). During CABG, there are needs for methods allowing continuous monitoring and prediction of the metabolism in the myocardial tissue. 14 patients undergoing CABG are investigated for tissue oxygenation during different surgical phases using a handheld fiber optic spectroscopic probe with a source-detector distance of less than 1 mm. The probe is calibrated using a light transport model, relating the absorption and reduced scattering coefficients (mu(a) and mu()(s)) to the measured spectra. By solving the inverse problem, absolute measures of tissue oxygenation are evaluated by the sum of oxygenized hemoglobin and myoglobin. Agreement between the model and measurements is obtained with an average correlation coefficient R-2 of 0.96. Oxygenation is found to be significantly elevated after aorta cross-clamping and cardioplegic infusion, as well as after reperfusion, compared to a baseline (p < 0.05). Tissue oxygenation decreases during cardiac arrest and increases after reperfusion.
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| 16. |
- Karlsson, Daniel M. G., et al.
(författare)
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Myocardial perfusion monitoring during coronary artery bypass using an electrocardiogram-triggered laser Doppler technique
- 2005
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Ingår i: Medical and Biological Engineering and Computing. - : Springer. - 0140-0118 .- 1741-0444. ; 43:5, s. 582-588
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Tidskriftsartikel (refereegranskat)abstract
- Electrocardiogram (ECG)—triggered laser Doppler perfusion monitoring (LDPM) was used to assess myocardial perfusion, with minimum myocardial tissue motion influence, during coronary artery bypass grafting (CABG). Thirteen subjects were investigated at six phases: pre- and post-CABG; post aorta cross-clamping; pre and post left internal mammary artery (LIMA) graft declamping; and post aorta declamping. The perfusion signal was calculated in late systole and late diastole, with expected minimum tissue motion, and compared with arrested heart measurements. Patient conditions or artifacts caused by surgical activity made it impossible to perform and analyse data in all six phases for some patients. No significant (n=5) difference between perfusion signals pre- and post-CABG was found. Diastolic perfusion signal levels were significantly (p<0.02) lower compared with systolic levels. After aorta cross-clamping, the signal level was almost zero. A distinct perfusion signal increase after LIMA and aorta declamping, compared with pre-LIMA declamping, was found in ten cases out of 13. A significantly (p<0.04) lower perfusion signal in the arrested heart compared with in the beating heart was registered. Influence from mechanical ventilation was observed in 14 measurements out of 17. In conclusion, ECG-triggered LDPM can be used to assess myocardial perfusion during CABG. Perfusion signals were lower in the arrested heart compared with in the beating heart and in late diastole compared with late systole. No significant difference between pre- and post-CABG was found.
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- Lindbergh, Tobias
(författare)
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Quantitative diffuse reflectance spectroscopy : myocardial oxygen transport from vessel to mitochondria
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the field of biomedical optics, diffuse reflectance spectroscopy (DRS) is a frequently used technique for obtaining information about the optical properties of the medium under investigation. The method utilizes spectral difference between incident and backscattered light intensity for quantifying the underlying absorption and scattering processes that affects the light-medium interaction.In this thesis, diffuse reflectance spectroscopy (DRS) measurements have been combined with an empirical photon migration model in order to quantify myocardial tissue chromophore content and status. The term qDRS (quantitative DRS) is introduced in the thesis to emphasize the ability of absolute quantification of tissue chromophore content. To enable this, the photon migration models have been calibrated using liquid optical phantoms. Methods for phantom characterization in terms of scattering coefficient, absorption coefficient, and phase function determination are also presented and evaluated. In-vivo qDRS measurements were performed on both human subjects undergoing routine coronary artery bypass grafting (CABG), and on bovine heart during open-chest surgery involving hemodynamic and respiratory provocations. The application of a hand-held fiber-optic surface probe (human subjects) proved the clinical applicability of the technique as the results were in agreement with other studies. However, problems with non-physiological variations in detected intensity due to intermittent probe-tissue discontact were observed. Also, systematic deviations between modeled and measured spectra were found. By model inclusion of additional chromophores revealing the mitochondrial oxygen uptake ability, an improved model fit to measured data was achieved. Measurements performed with an intramuscular probe (animal subjects) diminished the influence of probe-tissue discontact on the detected intensity. It was demonstrated that qDRS could quantify variations in myocardial oxygenation induced by physiological provocations, and that absolute quantification of tissue chromophore content could be obtained.The suggested qDRS method has the potential of becoming a valuable tool in clinical practice, as it has the unique ability of monitoring both the coronary vessel oxygen delivery and the myocardial mitochondrial oxygen uptake ability. This makes qDRS suitable for directly measuring the result of different therapies, which can lead to a paradigm shift in the monitoring during cardiac anesthesia.
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| 22. |
- Olofsson, Pia, et al.
(författare)
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Gastrointestinal microcirculation and cardiopulmonary function during experimentally increased intra-abdominal pressure
- 2009
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Ingår i: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 37:1, s. 230-239
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim of this study was to assess gastric, intestinal, and renal cortex microcirculation parallel with central hemodynamics and respiratory function during stepwise increase of intra-abdominal pressure (IAP). Design: Prospective, controlled animal study. Setting: Research laboratory, University Hospital. Subjects: Twenty-six anesthetized and mechanically ventilated pigs. Interventions: Following baseline registrations, CO2 peritoneum was inflated (n = 20) and IAP increased stepwise by 10 mm Hg at 10 mins intervals up to 50 mm Hg and subsequently exsufflated. Control animals (n = 6) were not insufflated with CO2. Measurements and Main Results: The microcirculation of gastric mucosa, small bowel mucosa, small bowel seromuscular layer, colon mucosa, colon seromuscular layer, and renal cortex were selectively studied at all pressure levels and after exsufflation using a four-channel laser Doppler flowmeter (Periflex 5000, Perimed). Central hemodynamic and respiratory function data were registered at each level and after exsufflation. Cardiac output decreased significantly at IAP levels above 10 mm Hg. The microcirculation of gastric mucosa, renal cortex and the seromuscular layer of small bowel and colon was significantly reduced with each increase of IAP. The microcirculation of the small bowel mucosa and colon mucosa was significantly less affected compared with the serosa (p < 0.01). Conclusions: Our animal model of low and high IAP by intraperitoneal CO2-insufflation worked well for studies of microcirculation, hemodynamics, and pulmonary function. During stepwise increases of pressure there were marked effects on global hemodynamics, respiratory function, and microcirculation. The results indicate that intestinal mucosal flow, especially small bowel mucosal flow, although reduced, seems better preserved in response to intra-abdominal hypertension caused by CO2-insufflation than other intra-abdominal microvascular beds.
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| 23. |
- Olofsson, Pia H., 1962-, et al.
(författare)
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Increased transmucosal uptake of E. coli K12 in porcine small bowel following experimental short term abdominal compartment syndrome
- 2009
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background: Abdominal compartment syndrome (ACS) may lead to bacterial translocation and possibly be of importance for development of multiorgan failure. However, the underlying mechanisms have not been fully elucidated. In a porcine model we recently demonstrated preserved intestinal mucosal blood flow during experimental short duration ACS. In the present study we used the same model to determine mucosal barrier function and morphology in the small bowel and colon of pigs before and after short term ACS. Methods: The study comprised 12 anaesthetized pigs exposed to experimental ACS and 6 control animals. Via laparotomy, samples of small bowel and colon were taken out for studies before short term ACS, where the abdomen was inflated with CO2 and IAP was increased stepwise by 10 mm Hg at 10-minute intervals up to 50 mm Hg, and again 10 minutes after exsufflation. Mucosal microcirculation was measured by laser Doppler flowmetry, and mucosal tissues were mounted in modified Ussing chambers for assessment of barrier function (E. coli K12 uptake and 51Cr-EDTA permeability). Specimens were also fixed in formaldehyde, stained with eosin-hematoxylin and evaluated blindly using an 8-grade scale for assessment of mucosal damage. Results: Transmucosal passage of E. coli was three-fold increased in the small bowel after ACS (22.6 [18.2 – 54.4] units) vs. baseline (8.1 [2.0 – 13.9]; P< 0.050) with a significant correlation to alterations of mucosal microcirculation. In the colon bacterial passage was unchanged, whereas 51Cr-EDTA permeability after ACS increased to 181% of baseline (P<0.05) and was correlated to significant mucosal histopathological changes (P<0.03). Conclusion: Short term ACS with reperfusion induced significant dysfunction of the intestinal mucosal barrier. The response patterns concerning barrier dysfunction differed between small bowel and colonic mucosa, with increased bacterial passage and paracellular permeability, respectively.
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| 24. |
- Strüber, Martin, et al.
(författare)
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HeartMate II left ventricular assist device, early European experience
- 2008
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Ingår i: European Journal of Cardio-Thoracic Surgery. - : Oxford University Press (OUP). - 1010-7940 .- 1873-734X. ; 34:2, s. 289-294
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The novel axial flow left ventricular assist device HeartMate II was introduced into clinical practice in Europe as part of the pilot study and after CE approval in November 2005. In order to get an overview of the use and performance of the device in Europe a group of investigators was founded to compare the initial results. Methods: In a retrospective analysis of the first 101 consecutive cases in Europe, data were collected with regard to postoperative outcome and severe adverse events and anticoagulation protocols. Results were stratified by intention to treat as a bridge to transplant or as chronic support therapy in heart failure (destination therapy). Results: In 70% of patients, the HeartMate II was intended as a bridge to transplant therapy, in 30%, it was used as a destination therapy device. The perioperative mortality post implant was 20% in the bridge to transplant patients and 7% in the destination therapy arm. However, after 1 year a comparable survival was observed in both groups (69% destination therapy, 63% bridge to transplant). Main causes of death were multiple organ failure (n = 12) and cerebrovascular accidents (n = 5). All, but one cerebrovascular accident occurred in the first 9 days after surgery. Only one other death was reported thereafter and there was no mechanical failure of the device. Conclusions: Even in the early experience the HeartMate II was used as a chronic support device in a substantial number of patients in Europe. Although the total experience is still limited, the incidence of cerebrovascular accidents is very low and the survival beyond the perioperative period is excellent. © 2008 European Association for Cardio-Thoracic Surgery.
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