Biomedical subjects

H T Tevaearai

Publications and source records attributed to H T Tevaearai.

At least 19 recordsLinked to original sources

PubMed2001

Ventricular dysfunction after cardioplegic arrest is improved after myocardial gene transfer of a beta-adrenergic receptor kinase inhibitor.

BACKGROUND: Acute cardiac contractile dysfunction is common after cardiopulmonary bypass (CPB). A potential molecular mechanism is enhanced beta-adrenergic receptor kinase (betaARK1) activity, because beta-adrenergic receptor (betaAR) signaling is altered in cardiomyocytes after cardioplegia. Therefore, we examined whether adenovirus-mediated intracoronary delivery of a betaARK1 inhibitor (Adv-betaARKct) could prevent post-CPB dysfunction. METHODS AND RESULTS: Rabbits were randomized to receive 5x10(11) total viral particles of Adv-betaARKct or PBS. After 5 days, hearts were arrested with University of Wisconsin solution, excised, and stored at 4 degrees C for 15 minutes or 4 hours before reperfusion on a Langendorff apparatus. Left ventricular (LV) function measured by end-diastolic pressure response to preload augmentation, contractility (LV dP/dt(max)), and relaxation (LV dP/dt(min)) was assessed by use of increasing doses of isoproterenol and compared with a control group of nonarrested hearts acutely perfused on the Langendorff apparatus. In the PBS-treated hearts, LV function decreased in a temporal manner and was significantly impaired compared with control hearts after 4 hours of cardioplegic arrest. LV function in Adv-betaARKct-treated hearts, however, was significantly enhanced compared with PBS treatment and was similar to control nonarrested hearts even after 4 hours of cardioplegia. Biochemically, several aspects of betaAR signaling were dysfunctional in PBS-treated hearts, whereas they were normalized in betaARKct-overexpressing hearts. CONCLUSIONS: Myocardial gene transfer of Adv-betaARKct stabilizes betaAR signaling and prevents LV dysfunction induced by prolonged cardioplegic arrest. Thus, betaARK1 inhibition may represent a novel target in limiting depressed ventricular function after CPB.

Adenoviridae↗

PubMed2001

Myocardial angiogenesis induction with bone protein derived growth factors (animal experiment).

Myocardial angiogenesis induction with vascular growth factors constitutes a potential strategy for patients whose coronary artery disease is refractory to conventional treatment. The importance of angiogenesis in bone formation has led to the development of growth factors derived from bovine bone protein. Twelve pigs (mean weight, 73 +/- 3 kg) were chosen for the study. In the first group (n = 6, growth factor group) five 100 micrograms boluses of growth factors derived from bovine bone protein, diluted in Povidone 5%, were injected in the lateral wall of the left ventricle. In the second group (n = 6, control group), the same operation was performed but only the diluting agent was injected. All the animals were sacrificed after 28 days and the vascular density of the left lateral wall (expressed as the number of vascular structures per mm2) as well as the area of blood vessel profiles per myocardial area analysed were determined histologically with a computerised system. The growth factor group had a capillary density which was significantly higher than that of the control group: 12.6 +/- 0.9/mm2 vs 4.8 +/- 0.5/mm2 (p < 0.01). The same holds true for the arteriolar density: 1 +/- 0.2/mm2 vs 0.3 +/- 0.1/mm2 (p < 0.01). The surface ratios of blood vessel profiles per myocardial area were 4900 +/- 800 micron 2/mm2 and 1550 +/- 400 micron 2/mm2 (p < 0.01) respectively. In this experimental model, bovine bone protein derived growth factors induce a significant neovascularisation in healthy myocardium, and appear therefore as promising candidates for therapeutic angiogenesis.

Animals↗

PubMed2001

Venous drainage with a single peripheral bicaval cannula for less invasive atrial septal defect repair.

New peripheral venous cannulae have recently been proposed for minimally invasive open cardiac surgery. We present a femoral venous cannula designed to simultaneously drain both superior and inferior vena cavae. Used in adult patients for atrial septal defect repair, the cannula allowed passive blood drainage of 70.6% +/- 11.7% of theoretical cardiac output. Drainage was augmented to 93.4% +/- 8.6% of theoretical cardiac output by means of a centrifugal pump.

Adult↗

PubMed2001

Smart suction device for less blood trauma: a comparison with Cell Saver.

OBJECTIVE: The major source of hemolysis during cardiopulmonary bypass remains the cardiotomy suction and is primarily due to the interaction between air and blood. The Smart suction system involves an automatically controlled aspiration designed to avoid the mixture of blood with air. This study was set-up to compare this recently designed suction system to a Cell Saver system in order to investigate their effects on blood elements during prolonged intrathoracic aspiration. METHODS: In a calf model (n=10; mean weight, 69.3+/-4.5 kg), a standardized hole was created in the right atrium allowing a blood loss of 100 ml/min, with a suction cannula placed into the chest cavity into a fixed position during 6 h. The blood was continuously aspirated either with the Smart suction system (five animals) or the Cell Saver system (five animals). Blood samples were taken hourly for blood cell counts and biochemistry. RESULTS: In the Smart suction group, red cell count, plasma protein and free hemoglobin levels remained stable, while platelet count exhibited a significant drop from the fifth hour onwards (prebypass: 683+/-201*10(9)/l, 5 h: 280+/-142*10(9)/l, P=0.046). In the Cell Saver group, there was a significant drop of the red cell count from the third hour onwards (prebypass: 8.6+/-0.9*10(12)/l, 6 h: 6.3+/-0.4*10(12)/l, P=0.02), of the platelet count from the first hour onwards (prebypass: 630+/-97*10(9)/l, 1 h: 224+/-75*10(9)/l, P<0.01), and of the plasma protein level from the first hour onwards (prebypass: 61.7+/-0.6 g/l, 1 h: 29.3+/-9.1 g/l, P<0.01). CONCLUSIONS: In this experimental set-up, the Smart suction system avoids damage to red cells and affects platelet count less than the Cell Saver system which induces important blood cell destruction, as any suction device mixing air and blood, as well as severe hypoproteinemia with its metabolic, clotting and hemodynamic consequences.

Animals↗

PubMed2001

Reshaping the remodelled left ventricle: a new concept.

OBJECTIVE: Based on the law of Laplace, transventricular tension members were designed to diminish wall stress by changing the left ventricle (LV) globular shape to a bilobular one, thus reducing the ventricular wall radius of curvature. This concept was tested in a model of congestive heart failure. METHODS: Seven calves were used for the study (74.3+/-4.2 kg). Treatment efficacy was assessed with sonomicrometric wall motion analysis coupled with intraventricular pressure measurement. Preload increase was applied stepwise with tension members in released and tightened position. RESULTS: Tightening of the tension members improved systolic function for CVP>10 mmHg (dP/dt: 828+/-122 vs. 895+/-112 mmHg/s, P=0.019, for baseline and 20% stress level reduction respectively; wall thickening: 11.6+/-1.5 vs. 13.3+/-1.7%, P<0.001) and diastolic function (LV end-diastolic pressure: 15.9+/-4.8 vs. 13.6+/-2.7 mmHg, P<0.001, for CVP>10 mmHg; peak rate of wall thinning: -12.2+/-2.2 vs. -14+/-2.3 cm(2)/s, P<0.001 and logistic time constant of isovolumic relaxation: 48.4 +/-10.9 vs. 39.8+/-9.6ms, P<0.001, for CVP>5 mmHg). CONCLUSIONS: This less aggressive LV reduction method significantly improves contractility and relaxation parameters in this model of congestive heart failure.

Animals↗

PubMed2001

[Coronary artery bypass by mini-thoracotomy: noticeable benefits with clinical experience of the treatment team].

AIM OF THE STUDY: Minimally invasive coronary artery bypass surgery is fundamentally different as compared to open sternal approach under cardiopulmonary bypass. Modifications of the surgical, anesthesiologic and post-operative techniques are necessary before evaluation of its real benefit. We analyze the potential effect of a learning period on the short term results of this technique. METHODS: From July 1997 to February 1999, 20 patients were operated using this method. We compare the results of the first 10 patients (group 1: 8M/2F, 59.6 +/- 13.8 years) to those of the last 10 patients (group 2: 8M/2F; age = 63.2 +/- 6.1 years). DISCUSSION: Progress between the two groups is striking. Left anterior descending coronary clamping time could be reduced from 28.5 +/- 2.4 min. in group 1 to 22.2 +/- 1.8 min. in group 2 (p < 0.05), and operative time was reduced from 125 +/- 4 min. to 97 +/- 5 min. (p < 0.005). The post-operative atrial fibrillation rate diminished from 4/10 in group 1 to 1/10 in group 2.3/10 patients in group 1 suffered a post-operative pneumonia whereas none in group 2 had pulmonary complication. The stay in the intensive care unit could be reduced from 2.3 +/- 0.3 days to 1.4 +/- 0.2 days (p < 0.05) and the total post-operative stay diminished from 8.5 +/- 0.9 days to 4.7 +/- 0.5 days (p < 0.005). CONCLUSION: There are evidence for a learning period in minimally invasive cardiac surgery. Short term benefits of this technique are then evident as demonstrated by a reduction in the ICU stay and the hospital stay.

Adult↗

PubMed2001

Intrachannel versus interchannel application of angiogenic factors in transmyocardial laser revascularization.

BACKGROUND AND OBJECTIVE: Theoretically myocardial angiogenesis of laser injury can be further enhanced by the addition of angiogenic growth factors. The influence of the way of administration of these factors on vascular growth around the channels is still unclear. MATERIALS AND METHODS: 18 pigs (mean weight 72 +/- 5.2 kg) were randomized to either triads of transmyocardial laser revascularization (TMLR) channels (group 1, n = 6) or isolated channels (group 2, n = 6), or a control group (n = 6). The animals had injections of bovine bone derived growth factor mixture either in the center of the triads in group 1 or within the channels themselves in group 2. Animals were sacrificed one month later for histological analysis. RESULTS: The vascular densities of myocardial areas within the triads of group 1 and around the channels in group 2 were significantly larger than in the control group: 15.2 +/- 3.7/mm2 and 14.2 +/- 3.5/mm2 respectively vs 5.3 +/- 1.6/mm2 (p < 0.001 for both differences). Differences of densities between group 1 and 2 were not statistically significant (p = 0.6). CONCLUSIONS: In this porcine model, the addition of a bovine bone derived growth factor mixture to TMLR significantly stimulates angiogenesis in the areas adjacent to the channels. The place of injection does not influence the angiogenesis intensity.

Angiogenesis Inducing Agents↗

PubMed2001

Are standard human coagulation tests suitable in pigs and calves during extracorporeal circulation?

The thrombogenicity of membrane oxygenators as well as clotting parameters profiles, using standard human clotting tests, was analyzed in calves and pigs during 6 h perfusion. Three calves and 3 pigs were connected to extracorporeal circulation with standard heparinization. Blood samples were taken for coagulation variables throughout perfusion, and oxygenators were examined for clot deposits at the end of the experiment. Two out of 3 oxygenators of the calf group presented clot deposits while none in the pig group did. Baseline coagulation variables of pigs showed values similar to those of humans while neither extrinsic nor intrinsic pathways could be activated in calves with standard human coagulation tests. The calf model, in conclusion, was confirmed to be a difficult model for the testing of extracorporeal circulation device resistance to thrombus formation, which is, however, not reflected by standard human coagulation tests. The pig model is a better model in which both coagulation pathways could be activated with standard human coagulation tests.

Adult↗

PubMed2001

Did the introduction of a minimally invasive technique change the incidence of atrial fibrillation after single internal thoracic artery-left anterior descending artery grafting?

OBJECTIVE: Atrial fibrillation after coronary artery bypass operations remains frequent and increases morbidity, as well as resource use. Its cause remains unclear. The introduction of a minimally invasive technique provides an opportunity to evaluate the effect of intraoperative factors, such as cardiopulmonary bypass, global myocardial ischemia, and myocardial protection technique, on the occurrence of this arrhythmia. METHODS: All the patients undergoing isolated left internal thoracic artery-left anterior descending artery grafting between January 1994 and December 1999 were reviewed. Twenty possible risk factors for postoperative atrial fibrillation, including the choice of operative technique--minimally invasive technique was introduced in January 1997--were entered into univariate and multivariable logistic regression analysis. RESULTS: Postoperative atrial fibrillation occurred in 36 (20%) of 183 patients. On univariate analysis, age (P <.001) and a history of supraventricular arrhythmia (P <.001) were found to be risk factors. In particular, 15 (22%) of 69 patients operated on with the minimally invasive technique had postoperative atrial fibrillation versus 21 (18%) of 114 in the standard group (P =.58). On multivariable analysis, including the operative technique, the same variables (P =.001 and.01, respectively) were identified as independent risk factors. CONCLUSIONS: The introduction of a minimally invasive technique for coronary artery bypass operations did not reduce the occurrence of postoperative atrial fibrillation in this study population. This suggests that prophylactic measures to reduce this arrhythmia should be focused on factors unrelated to cardiopulmonary bypass or myocardial preservation technique.

Aged↗

PubMed2001

Does laser injury induce a different neovascularisation pattern from mechanical or ischaemic injuries?

AIM: To analyse the arteriolar pattern of laser induced channels and their surroundings compared with mechanical and ischaemic injury. METHODS: 24 pigs were randomised to a myocardial infarction group, a transmyocardial laser revascularisation group, a needle group, or a control group. In the laser revascularisation and needle groups, five channels were created either with a 1.75 mm probe holmium-YAG laser or a Tru-cut needle of the same size. Animals were killed 28 days later. Morphometric analysis of vascular density was expressed as the mean (SD) number of arteriolar structures/cm(2). RESULTS: Laser and needle channels were completely invaded by granulation tissue. Their surface areas did not differ significantly: 2.28 (0.7) mm(2) and 2.38 (1.1) mm(2), respectively (p = 0.82). Within both types of channel, arteriolar density was significantly increased in comparison with the myocardial infarction scar: 197 (52)/cm(2) and 190 (64)/cm(2), respectively (p = 0.8) versus 56 (20)/cm(2) (p < 0.001 for both comparisons). The area of 1 mm width immediately adjacent to the laser and needle channels showed a density of 25 (16)/cm(2) and 23 (18)/cm(2), respectively, which is similar to that of normal tissue (28 (10)/cm(2); p = 0.6 and p = 0.4, respectively). The mean arteriolar diameter was similar throughout all the regions analysed. CONCLUSIONS: Both laser and needle channels produce a similar increase in arteriolar structures, which is limited to the lesion itself. This suggests that laser injury is not more potent as an angiogenic stimulator than mechanical injury, which in turn is superior to infarction.

Animals↗

PubMed2001

Performance of a new implantable cardiac assist centrifugal pump.

The AB-180 is a new implantable centrifugal pump with a low volume dome (10 ml) and a local heparin delivery system which avoids systemic heparinization. This study focuses on its hemodynamic performance. We analyzed 3 anesthetized calves (71.0 +/- 2.5 kg), equipped with arterial pressure (AP), and Swan-Ganz and left atrial pressure (LAP) catheters. The AB-180 pump was installed through a left thoracotomy, with a transmitral left ventricular (LV) inflow cannula inserted via the left appendage and an outflow tract sutured to the descending aorta. LAP, AP, and blood flow across the pump were recorded for various pump speed and in different preload conditions (right atrial pressure = 4, 7, and 10 mm Hg, respectively). The pump significantly unloaded the left heart cavities and was able to increase the mean AP. For an RAP of 10 mm Hg, running the pump at 4,500 rpm decreased the LAP from 11.0 +/- 0.8 mm Hg to 3.0 +/- 0.8 mm Hg (p < 0.001) and augmented the mean AP from 48.2 +/- 6.4 mm Hg to 80.8 +/- 12.1 mm Hg (p < 0.001). A maximal pump flow of 5.6 +/- 0.2 L/min was obtained under these conditions. In addition to the advantage of its particular design, the AB-180 can be considered as an efficient left ventricular assist device (LVAD). It significantly unloads the left heart cavities and ensures efficient systemic AP and blood flow.

Animals↗

PubMed2001

Hemolysis and hematology profile during perfusion: inter-species comparison.

INTRODUCTION: Cardiopulmonary bypass components need to be tested on an animal model before their clinical application. Because their weight is similar to that of man, the calf and pig are often used. This study compares the impact of prolonged perfusion on hemolysis and hematology profile in both species. METHODS: Three calves (mean bodyweight: 77.2+/-4.4 kg) and three pigs (80+/-5.3 kg) were connected to an extracorporeal circulation circuit by jugular venous and carotid arterial cannulation, with a mean flow rate of 3.5L/min for 6h. After 7 days, the animals were sacrificed. A standard battery of blood samples was taken before, throughout, and 24h, 48h and 7 days after bypass. ANOVA was used for repeated measurements. RESULTS: Absolute values of red cell count were higher in the calf (p<0.001), while normalized values were higher in the pig (p<0.001). Absolute values of white cell count were higher in the pig, while normalized values diverged toward the end of the perfusion with an increase in the calf and a decrease in the pig (p<0.001). Free plasma Hb and LDH exhibited similar profiles in both groups. CONCLUSIONS: In the setting of prolonged perfusion, species type--bovine or porcine--has an impact on hematology profile, but not on hemolytic parameters. These findings should be taken into account when cardiopulmonary bypass components are tested.

Analysis of Variance↗

PubMed2001

Tricuspid valve involvement in combined mitral and aortic valve surgery.

BACKGROUND: Combined mitral and aortic valve disease requiring surgery may involve the tricuspid valve as well. Our treatment policy is conservative especially for tricuspid regurgitation which is operated on when severe only. METHODS: A retrospective study was performed at a tertiary and secondary referral center for cardiovascular disease. Over a 15-year period, 65 consecutive patients underwent aortic and mitral surgery with concomitant tricuspid regurgitation and/or stenosis. Fifty-five/65 (85%) patients were in NYHA class III-IV. Fifty-eight/65 (89%) patients had tricuspid regurgitation secondary to right chamber dilatation and 7/65 (11%) had tricuspid stenosis and/or regurgitation because of previous endocarditis. Twenty-two/65 (34%) tricuspid valves were operated on: 18/22 (82%) de Vega annuloplasty, 2/22 (9%) commissurotomies and 2/22 (9%) prosthetic valves. Mortality and complications were recorded during a mean follow-up of 5.3 yrs (range, 6 months-15.3 yrs). Event-free survivals were determined using the Kaplan-Meier method. RESULTS: Hospital mortality was 6.2% (4/65) and the complication rate was 18.5% (12/65). The freedom from late valve related mortality and morbidity at 5, 10 and 15 years was 86+/-5.5%, 81.9+/-6.8%, and 81.9+/-6.8% respectively. One valve related complication was due to the tricuspid valve. At last follow-up, 87% (47/54) of the survivors were in NYHA class I-II. CONCLUSIONS: With a conservative policy of tricuspid valve intervention, functional results of this patient population are good and long-term valve related morbidity and mortality are mainly related to the mitral and aortic valve procedures.

Adult↗

PubMed2001

Gene-mediated inhibition of the b-adrenergic receptor kinase: a new therapeutic strategy for heart failure.

Molecular changes that take place during the evolution of heart failure (HF), especially the well characterized beta-adrenergic receptor (betaAR) signaling abnormalities, represent attractive targets for myocardial gene therapy. The beta-adrenergic receptor kinase (betaARK1 or GRK2) is a cytosolic enzyme that phosphorylates only agonist-occupied betaARs as well as other G protein-coupled receptors (GPCRs), leading to desensitization and functional uncoupling. betaARK1 levels and activity are elevated in the failing heart and therefore, it has recently been evaluated as a potential target for novel HF treatment. This review summarizes recent results obtained in transgenic mouse models as well as in animals where a betaARK1 inhibitor peptide (betaARKct) was delivered via the coronary arteries by exogenous gene transfer. These results strongly suggest that betaARK1 inhibition may represent a significant improvement in HF therapy.

Animals↗

PubMed2000

Pain pattern and left internal mammary artery grafting.

BACKGROUND: This study was designed to determine whether the pain pattern in patients with an internal mammary artery (IMA) harvest differs from that in other cardiac operations and whether these patients present specific characteristics with clinical implications. METHODS: One hundred patients with left IMA grafting (IMA group) were compared prospectively with 100 patients who had a heart operation without IMA harvest (non-IMA group). Pain assessment was performed on postoperative days (POD) 1, 2, 3, and 7, and included pain intensity (10-point scale) and pain localization. RESULTS: In the IMA group, pain intensity was higher on POD 2 (4.2 +/- 2.4 versus 3.2 +/- 2.3, p < 0.01), and there were more patients without pain on POD 7 (32 versus 19, p = 0.03). In the IMA group, more patients had left basal thoracic pain throughout the entire study period and had sternal pain on POD 7, whereas more patients in the non-IMA group complained about back pain during the early postoperative period. CONCLUSIONS: The impact of IMA harvest on pain intensity is moderate, but the pain localization pattern of each group exhibits specific features that could help to better target pain management.

Adult↗

PubMed2000

Impact of duration of chest tube drainage on pain after cardiac surgery.

OBJECTIVE: This study was designed to analyze the duration of chest tube drainage on pain intensity and distribution after cardiac surgery. METHODS: Two groups of 80 cardiac surgery adult patients, operated on in two different hospitals, by the same group of cardiac surgeons, and with similar postoperative strategies, were compared. However, in one hospital (long drainage group), a conservative policy was adopted with the removal the chest tubes by postoperative day (POD) 2 or 3, while in the second hospital (short drainage group), all the drains were usually removed on POD 1. RESULTS: There was a trend toward less pain in the short drainage group, with a statistically significant difference on POD 2 (P=0.047). There were less patients without pain on POD 3 in the long drainage group (P=0. 01). The areas corresponding to the tract of the pleural tube, namely the epigastric area, the left basis of the thorax, and the left shoulder were more often involved in the long drainage group. There were three pneumonias in each group and no patient required repeated drainage. CONCLUSIONS: A policy of early chest drain ablation limits pain sensation and simplifies nursing care, without increasing the need for repeated pleural puncture. Therefore, a policy of short drainage after cardiac surgery should be recommended.

Adult↗

PubMed2000

[Surgical repair of aortic coarctation in adults over 30 years of age].

Coarctation of the aorta is nowadays rarely observed among adult population, as it is usually detected and treated during infancy. The natural history of this disease however is known to lead to early death due to the consequences of severe arterial hypertension. We report on 3 patients older than 30 years, recently operated on in our cardiosurgical units. Two of them were foreigners recently arrived in Switzerland, of 46 and 32 years old respectively. The medical examination highlighted severe hypertension and bilateral absence of femoral pulses. The third patient was a Swiss citizen and had a similar examination. Chest X-rays clearly showed rib notching, and the suspected diagnosis was confirmed with angiography. Three different surgical techniques were chosen, according to the peroperative situation. In one case, the stenosis was resected and an end-to-end anastomosis could be performed. In another case, the occlusion was complete and extended over 3 centimeters. The resected segment was replaced by a prosthetic graft. In the third case, we performed a synthetic patch graft aortoplasty. Postoperative care were simple in every cases. Coarctation of the aorta must be evoked among the possible etiologies of severe hypertension, as the surgical treatment is of real benefit and with reduced morbidity.

Adult↗

PubMed2000

3-D vision improves performance in a pelvic trainer.

BACKGROUND AND STUDY AIMS: Experienced endoscopic surgeons have adapted to the absence of depth perception while using two-dimensional (2-D) visualization. However, three-dimensional (3-D) vision may prove useful at least at the beginning of the learning curve in celioscopic training. METHODS: In a pelvitrainer with a fixed camera, two skill tests were designed to assess the performance of three groups of operators: "non-surgeons", "non-celioscopist surgeons", and "trained celioscopists". In the first test, the candidate had to touch with a needle a sequence of dots distributed on a 7.1-cm2 area. In the second test, a 6-0 C-1 needle had to be passed consecutively through two 1-mm holes made in a thin vertical plastic wall. Each test was performed ten times, using either 2-D vision (five times) or 3-D vision (five times) interspersed in a random manner. RESULTS: In both tests and within each group, performance was related to the experience of the operator, with the trained celioscopists' group obtaining the best results and the non-surgeons the worst. In every situation, including the trained celioscopists' group, 3-D vision significantly improved performances. No significant difference was observed between the results of the non-celioscopist surgeons' group using 3-D vision and those of the trained celioscopists' group using 2-D vision. CONCLUSIONS: 3-D vision improves the performance and accuracy of endoscopic surgeons. It provides a visual perception "close to reality", and helps celioscopic beginners to accelerate their training.

Adult↗