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Biomedical subjects

A Koshal

Publications and source records attributed to A Koshal.

At least 37 records · Page 2Linked to original sources
PubMed1991

Mechanical bridge to cardiac transplant: where do we stand in 1990?

Various mechanical devices have been used to support the circulation in patients requiring cardiac transplantation who are in cardiogenic shock. The devices produce either a pulsatile or nonpulsatile blood-flow pattern. Of the former, the intra-aortic balloon pump is the most frequently used. However, it augments but does not replace the function of the left ventricle. At the Ottawa Heart Institute, orthotopic replacement of both ventricles with a total artificial heart has proven a reliable and effective bridge to transplantation in selected patients. Heterotopic ventricles, known as ventricular assist devices, may also be used to replace the function of one or both ventricles and are increasingly being used to maintain the circulation. The future of nonpulsatile devices for mechanical support remains unclear because the long-term effects of this unphysiologic flow pattern are unknown. As refinements in circulatory support devices continue and as patient selection and timing of device insertion become more clearly defined, the results in these patients will likely approach those of elective cardiac transplantation.

Assisted Circulation↗
PubMed1991

Long-term clinical results with the Ionescu-Shiley pericardial xenograft.

From 1977 to 1987, 829 Ionescu-Shiley pericardial valves (Shiley, Inc., Irvine, Calif.) were implanted in 766 patients at the University of Ottawa Heart Institute. There were 476 patients who had aortic valve replacement, 234 who had mitral valve replacement, and 44 who had double valve replacement. The standard-profile design was used in 508 patients and the low-profile design in 321 patients. Follow-up was obtained for 97% of patients, with calculation of event-free probabilities. At 10 years the overall probability of freedom from structural failure was 48% +/- 7% after aortic valve replacement, 44% +/- 15% after mitral valve replacement, and 79% +/- 11% after double valve replacement. Although at 5 years the probability of failure was statistically lower with the low-profile design, this favorability was lost by 6 years. Freedom from structural failure was only 47% +/- 7% for the standard-profile valve at 10 years. Thus the probability of freedom from reoperation was only 46% +/- 7% after aortic valve replacement, 39% +/- 6% after mitral valve replacement, and 65% +/- 20% after double valve replacement at 10 years. Thromboembolism occurred in 69 patients, for a predicted freedom from this complication at 10 years of 79% +/- 3% after aortic, 73% +/- 7% after mitral, and 96% +/- 4% after double valve replacement. There were 31 cases of endocarditis. The 10-year predicted freedom from endocarditis, therefore, was 86% +/- 3% after aortic, 98% +/- 1% after mitral, and 97% +/- 1% after double valve replacement. A total of 221 operative and late deaths were recorded in this series. Prosthetic valve failure accounted for 27% of late deaths. The 10-year survival rates were estimated to be 56% +/- 5% (aortic valve replacement), 54% +/- 6% (mitral valve replacement), and 51% +/- 8% (double valve replacement). We concluded that the Ionescu-Shiley pericardial xenograft provides less than optimal clinical performance and its use has been discontinued.

Actuarial Analysis↗
PubMed1989

Are temperatures attained by donor hearts during transport too cold?

Excessive myocardial cooling may have detrimental effects on donor heart integrity. This study assessed the standard technique for donor myocardial preservation using hearts from seven mongrel dogs (mean weight 192.7 gm), which were arrested, excised, and placed in a cooler containing saline and ice. Temperature probes placed in both the left and right ventricular free walls and the septum revealed that, after cardioplegia, temperatures fell to 10.3 degrees, 7.5 degrees, and 7.6 degrees C, respectively. Temperature decreased to below 1 degree C after 75, 75, and 60 minutes for the left ventricle, right ventricle, and septum, respectively, independent of the size of the heart (range = 104 to 322 gm). After 4 hours of cooling, temperature was below 0 degrees C throughout the myocardium. Examination with an electron microscope showed similar serial changes over 4 hours in all hearts, including moderate-to-severe cytoplasmic and nuclear swelling and mitochondrial calcium deposits. Cell membranes remained intact, which suggests that the damage was not irreversible. We conclude that current donor heart preservation techniques may result in unacceptably low myocardial temperatures that cause reversible myocardial injury.

Animals↗
PubMed1988

Separate extraction of cardiac and pulmonary grafts from a single organ donor.

The scarcity of multiple-organ donors for perfused organ transplantation requires cooperation between various transplanting teams to maximize organ retrieval. We have developed a technique for the extraction of a cardiac and separate pulmonary graft from the same donor. These grafts can then be successfully implanted into two separate recipients. Our experience with 9 successful extractions and implantations is recorded.

Anastomosis, Surgical↗
PubMed1988

Coronary endarterectomy. An adjunct to coronary artery bypass grafting.

There is a wide variation in the reported results of endarterectomy in conjunction with coronary artery bypass grafting. Operative mortality ranges from 0 to 10 per cent, perioperative infarction ranges from 5 to 30 per cent, and patency rates range from 38 to 100 per cent, with 74 to 95 per cent being asymptomatic or improved. This wide discrepancy in clinical outcome occurs for a number of reasons. First, there is nonhomogeneity of patient populations resulting from a lack of standardized patient selection criteria. Second, the operative experience of most published reports spans a decade throughout which major advances in cardiac surgery have occurred. Finally, endarterectomy is a technically challenging procedure with its own learning curve. Differences in technique and expertise almost certainly contribute to the variability of results. Patients with diffuse coronary artery disease pose a challenge to the cardiac surgeon. Endarterectomy entails the risks of increased morbidity and mortality and therefore should be done only if conventional bypass grafting is precluded. However, the risks of these complications must always be weighed against the possible benefits. At the present time carefully selected patients can benefit from this procedure. Unfortunately, until such time as controlled randomized studies are carried out on a prospective basis, statistical support for this procedure will not be available. Given that such a study is questionable from an ethical point of view, clinical decisions for this select group of patients must be done on a case-by-case basis. The best that can currently be done is to carefully follow these patients and scrutinize existing data to ensure optimal clinical management.

Coronary Artery Bypass↗
PubMed1988

Urgent surgical reperfusion in acute evolving myocardial infarction. A randomized controlled study.

To assess the benefit of immediate surgical reperfusion over conventional medical treatment during the first acute evolving transmural myocardial infarction, 68 patients presenting within 4 hours of onset of chest pain were randomized into a medical group and a surgical group. Both groups were comparable for age, sex, coronary risk factors, location of infarct, and coronary anatomy. Radionuclide global ejection fraction at 48 hours after admission was 45 +/- 15% for the medical group versus 50 +/- 15% for the surgical group; at 3 months, ejection fraction values were 51 +/- 13% and 51 +/- 13%, respectively (p = NS). The average radionuclide wall-motion scores (normal, 3) at 3 months were 2 +/- 0.6 for the medical group and 2 +/- 0.7 for the surgical group. There were three (8.8%) early and four (11.7%) late deaths in the medical group and only one (2.9%) early death in the surgical group. Urgent surgical reperfusion in acute evolving myocardial infarction is a safe and effective procedure that appears to reduce early and late mortality but does not appear to improve left ventricular function.

Clinical Trials as Topic↗
PubMed1988

Ongoing role of pulmonary embolectomy.

Pulmonary embolism remains a frequent and often fatal disorder. For the majority of patients, anticoagulation with heparin followed by warfarin represents the primary mode of treatment. Thrombolytic therapy is recommended for the patient with massive pulmonary embolism that has produced hypotension. Embolectomy is reserved for the patient with post embolic systemic hypotension who has an absolute contraindication to thrombolysis or who deteriorates despite thrombolytic therapy. Following successful embolectomy the surgeon must treat the complications of the surgery and prevent recurrence. Complications include cerebral infarction, pulmonary infarction and endobronchial hemorrhage, right ventricular failure, local or systemic bleeding and venous stasis. A case of successful pulmonary embolectomy with a complicated postoperative course is presented and the pathophysiology and treatment of the complications are discussed.

Adrenal Gland Diseases↗
PubMed1986

Pros and cons of urgent exploratory sternotomy after open cardiac surgery.

To determine whether it is appropriate to perform urgent exploratory sternotomy for potentially life-threatening complications of open-heart procedures, the authors reviewed the charts of 100 such patients managed by exploratory sternotomy between December 1982 and December 1984. Group 1 comprised 32 patients who suffered cardiac arrest (8) or had acute profound hypotension (24). Group 2 included 68 patients with persistent excessive bleeding. Of group 1 patients operated because of acute profound hypotension, 50% had definite evidence of cardiac tamponade. In the remainder the cause was severe myocardial ischemia and left ventricular failure. In group 2 an identifiable correctable site of bleeding was found in 78%. Four of the 8 patients with cardiac arrest and 20 (83%) of the 24 patients with acute profound hypotension survived and left the hospital. In group 2, 58 (85%) of the 68 survived. The mean postoperative stay was higher in group 1 than group 2-20.3 +/- 3.08 days versus 14.2 +/- 1.23 days (p less than 0.1). The duration of ventilatory support in group 1 was also higher - 6.18 +/- 1.32 days versus 2.12 +/- 0.38 days. Postoperatively, sputum cultures gave positive results in 19% of the patients, all of whom had required prolonged ventilatory support. Minor sternal wound infections were present in two and major in four. There was no significant difference in morbidity of the survivors between those who underwent sternotomy in the recovery room or in the operating room.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Ionescu-Shiley pericardial xenografts: follow-up of up to 6 years.

The results of valve replacement with the Ionescu-Shiley pericardial xenograft compare favorably with results obtained with other bioprostheses. From March, 1977, to July, 1983, 497 Ionescu-Shiley pericardial valves were implanted in 463 patients at the University of Ottawa Heart Institute. There were 292 patients who had aortic valve replacement (AVR), 140 with mitral valve replacement (MVR), 28 with double valve replacement, and 3 with triple valve replacement. The survivors were followed regularly. Actuarial analysis of late results indicates an expected survival of 71% at 6 years for patients who underwent AVR and 72% at 3 years for patients who had MVR. The only valve-related deaths were due to endocarditis, which occurred at a rate of 3.9% per patient-year for aortic valves and 0.6% per patient-year for mitral valves. Despite a low usage of formal anticoagulation, embolic complications occurred at a rate of 1.4% per patient-year for aortic valves and 4.0% per patient-year for mitral valves. Five valves were removed for intrinsic failure after 36 to 72 months of follow-up. New York Heart Association Functional Class improved an average of 1.28 classes per patient.

Actuarial Analysis↗
PubMed1985

Should obese patients not undergo coronary artery surgery?

To assess the effect of obesity on the patient's recovery from coronary artery bypass surgery, a prospective study was performed on 200 patients. Group 1 comprised 101 nonobese patients and group 2, 99 obese patients. The mean percentage over the ideal weight was 8.2% in group 1 and 33.4% in group 2 (p less than 0.001). Preoperative assessment revealed no difference in age, sex, height, incidence of diabetes, family history or smoking habits between the two groups. Group 2 had a higher incidence of hypertension (p less than 0.01) and hyperlipidemia (p less than 0.02). The average number of grafts placed per patient was 3.4 +/- 0.8 in group 1 and 3.5 +/- 0.08 in group 2. Operative mortality was 2.9% and 2.0% in groups 1 and 2 respectively. Obesity was a predictive factor in postoperative hypertension (p less than 0.025), in the development of wound infection (p less than 0.01) and in an increased requirement of bronchodilators (p less than 0.01). The postoperative progression of physical activity and length of hospital stay was similar, being 10.9 +/- 5.8 days and 9.7 +/- 9.5 days in groups 1 and 2 respectively. The authors conclude that bypass grafting is an acceptable therapeutic option for obese patients with coronary artery disease.

Adult↗
PubMed1985

Mitral valve replacement with Hancock porcine bioprostheses: up to 7-year follow-up.

From February 1976 to May 1981 at the University of Ottawa Heart Institute, 137 mitral valves were replaced with the Hancock porcine bioprosthesis. This study concerns 111 patients (55 men, 56 women) who had single-valve replacement. The average age of the patients was 53.0 years. The predominant lesion in the 102 patients who were receiving their first substitute valve was stenosis in 46% and regurgitation in 42%. Preoperatively, 82% were New York Heart Association (NYHA) class III or IV. Additional procedures were performed in 44 patients (39.6%). The 26 patients who had multiple valves replaced were considered only for durability studies. Hospital mortality was 8.9% for isolated replacement and 22% for replacement associated with aortocoronary bypass grafting. At the time of discharge, 50% of patients were in atrial fibrillation, 14% were taking warfarin and 82% antiplatelet agents. Follow-up was available for a total of 374 patient-years (average of 5.4 years per patient). The mean symptomatic improvement was 1.6 NYHA classes per patient. Actuarial analysis indicated a survival rate of 70% at 8 years. Of the 18 late deaths, 4 (22%) were valve-related. The rates of endocarditis and thromboembolism were 1.1% and 5.8% patient-year respectively. In the 137 prostheses at risk, intrinsic failure occurred at the rate of 4.7% patient-year for a cumulative rate of 35% at 8 years. The authors conclude that the Hancock porcine bioprosthesis provides good relief of symptoms in the mitral position with an acceptable rate of thromboembolism even without anticoagulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Bioprosthesis↗
PubMed1981

Preservation of platelets and their function in prolonged cardiopulmonary bypass using prostacyclin.

The effects of prostacyclin (PGI2) with and without heparin were studied in 28 dogs that underwent 2 hours of cardiopulmonary bypass. Five groups were created: group I (six dogs) received heparin, 1.25 mg/kg; group II (six dogs) received low-dose heparin, 0.5 mg/kg, and PGI2, 500 ng/kg/min; group III (six dogs) received low-dose heparin alone; group IV (four dogs) received PGI2, 500--1000 ng/kg/min; and group V (six dogs) received ibuprofen, 12.5 mg/kg, dipyridamole, 1 mg/kg, PGI2, 20 ng/kg/min, and low-dose heparin. Significant clot deposition occurred in the oxygenators in groups III, IV and V. Platelet counts decreased to a mean of 36.8 +/- 5.7% (+/- SEM) of control in group I, which had normal clinical heparin dose for dogs, but to only 74 +/- 7% of control in group II. This improvement was significant (p less than 0.005). Platelet aggregation induced by adenosine diphosphate 60 minutes after CPB showed poor aggregation in group I but almost normal aggregation in group II. Protamine was unnecessary in groups that received PGI2. PGI2 in combination with low-dose heparin provides adequate anticoagulation during cardiopulmonary bypass in dogs, preserves platelet number and function and is associated with minimal postoperative bleeding.

Animals↗