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Biomedical subjects

C M Feindel

Publications and source records attributed to C M Feindel.

48 records · Page 3Linked to original sources
PubMed1989

Myocardial infarction determined by technetium-99m pyrophosphate single-photon tomography complicating elective coronary artery bypass grafting for angina pectoris.

The incidence of acute myocardial infarction (AMI) complicating coronary artery bypass grafting (CABG) has previously been based on concordance of electrocardiographic, enzymatic and scintigraphic criteria. Technetium-99m pyrophosphate (Tc-PPi) single-photon emission computed tomography now enables detection of AMI with high sensitivity and specificity. Using this technique, perioperative AMI was detected in 12 of 58 patients (21%) undergoing successful elective CABG for stable angina pectoris. Stepwise multivariate logistic regression analysis was performed to compare the predictive value of preoperative (New York Heart Association class, left ventricular ejection fraction and use of beta blockers) and intraoperative (number of grafts constructed, use of internal mammary anastomoses, use of sequential saphenous vein grafts, smallest grafted distal vessel lumen caliber and aortic cross-clamp time) variables. Preoperative New York Association class (p = 0.04) and smallest grafted distal vessel lumen caliber (p = 0.03) were significant multivariate predictors of perioperative AMI. Only 1 perioperative patient with AMI (and 1 pyrophosphate-negative patient) developed new Q waves. Serum creatine kinase-MB was higher in patients with AMI by repeated measures analysis of variance (p = 0.0003). Five AMIs occurred in myocardial segments revascularized using sequential saphenous vein grafts, and 7 in segments perfused by significantly stenosed epicardial vessels with distal lumen diameter and perfusion territory considered too small to warrant CABG. At 6-month follow-up, the mean left ventricular ejection fraction increased from 0.61 to 0.65 in Tc-PPI-negative patients (p = 0.01), but not in perioperative patients with AMI.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Postoperative myocardial infarction documented by technetium pyrophosphate scan using single-photon emission computed tomography: significance of intraoperative myocardial ischemia and hemodynamic control.

The aim of this prospective study was to document postoperative myocardial infarction (PMI) by technetium pyrophosphate scan using single-photon emission computed tomography (TcPPi-SPECT) in 28 patients undergoing elective coronary bypass grafting (CABG). The relationships of intraoperative electrocardiographic myocardial ischemia, hemodynamic responses, and pharmacological requirements to this incidence of PMI were correlated. Radionuclide cardioangiography and TcPPi-SPECT were performed 24 h preoperatively and 48 h postoperatively. A standard high-dose fentanyl anesthetic protocol was used. Twenty-five percent of elective CABG patients were complicated with PMI, as documented by TcPPi-SPECT with an infarcted mass of 38.0 +/- 5.5 g. No significant difference in demographic, preoperative right and left ventricular function, number of coronary vessels grafted, or aortic cross-clamp time was observed between the PMI and non-PMI groups. The distribution of patients using preoperative beta-adrenergic blocking drugs or calcium channel blocking drugs was found to have no correlation with the outcome of PMI. As well, no significant differences in hemodynamic changes or pharmacological requirements were observed in the PMI and non-PMI groups during prebypass or postbypass periods, indicating careful intraoperative control of hemodynamic indices did not prevent the outcome of PMI in these patients. However, the incidence of prebypass ischemia was 39.3% and significantly correlated with the outcome of positive TcPPi-SPECT, denoting a 3.9-fold increased risk of developing PMI. Prebypass ischemic changes in leads II and V5 were shown to correlate with increased CPK-MB release (P less than 0.05) and tends to occur more frequently with lateral myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Artery Bypass↗
PubMed1987

Reconstruction of the mitral anulus.

The mitral anulus was reconstructed with autologous pericardium in nine patients. Six patients had infective endocarditis with one or more abscesses in the anulus, and three had an iatrogenically damaged anulus. In patients with disruption of the mitral anulus limited to its posterior portion, a semicircular patch of pericardium was sutured directly to the endocardium of the left ventricle. In patients with multiple defects in the anulus, circumferential reconstruction of the mitral ring with pericardium was performed. In cases in which abscesses involved the central fibrous body, pericardium was used to reconstruct both the mitral anulus and the aortic root. Eight patients survived and have remained well for a mean of 8 months. There has been no prosthetic or patch dehiscence. All patients experienced substantial functional improvement. This experience indicates that the disrupted mitral anulus can be successfully reconstructed with autologous pericardium that is sutured directly to the endocardium of the left ventricle.

Adult↗
PubMed1987

Reconstruction of the left ventricle with autologous pericardium.

Autologous pericardium was used to reconstruct different parts of the left ventricle in 25 desperately ill patients. Fourteen patients had intractable sepsis resulting from infective endocarditis and myocardial abscess and 10 patients had noninfectious disorders. Of the patients with infections, 12 had valvular endocarditis with periannular abscess and three had interventricular septal abscess. The noninfected patients had acute rupture of the ventricular wall after mitral valve replacement (one patient) heavily calcified or surgically absent mitral anulus (three patients), or rupture of the interventricular septum after acute myocardial infarction (six patients). The interventricular septum, the posterior wall of the left ventricle, and the periannular areas were reconstructed by suturing appropriately tailored pericardial patches directly to the endocardium. In patients who also required valve replacement, the prosthetic valve was partially or completely secured to the pericardial patch. There were three operative deaths. All three patients were in either septic or cardiogenic shock before operation and in none of them was the death related to the pericardial patch. All 22 survivors have been observed from 3 to 34 months, an average of 14 months. There has been no case of patch dehiscence, patch aneurysm, prosthetic valve dehiscence, or recurrent endocarditis. Autologous pericardium appears to be safe for reconstruction of the left ventricle. It is easy to handle and problems with suture line bleeding are practically nonexistent.

Endocarditis, Bacterial↗
PubMed1984

Multidose blood versus crystalloid cardioplegia. Comparison by quantitative assessment of irreversible myocardial injury.

The relative efficacy and safety of blood-based potassium cardioplegic solutions compared to crystalloid arresting solutions has been a major controversy in the field of intraoperative myocardial protection for cardiac operations. In this study multidose potassium (K+ = 30 mEq/L) blood cardioplegia was compared to multidose potassium crystalloid cardioplegia in a dog model in which hearts were arrested for periods of 4 1/2 and 6 hours. The cardioplegic solution was given as an initial bolus of 500 ml and then as 250 ml doses every 30 minutes of arrest. In the 4 1/2 hour arrest group, six animals received blood cardioplegia, six received a low-sodium crystalloid cardioplegia (modified Roe's solution), and 10 received a high sodium crystalloid cardioplegic solution of our own design. In the 6 hour arrest group, four animals received blood cardioplegia, four received the low-sodium solution, and four received the high-sodium solution. Myocardial temperature was precisely controlled at 27 degrees +/- 1 degree C in all groups. The hearts were reperfused for periods of 2 to 4 hours after the arrest periods and then examined morphologically for injury. The extent of myocardial damage was quantified in 5 mm thick transverse sections through the ventricles by using a tetrazolium enzyme-mapping technique. In the crystalloid groups the hearts arrested for 4 1/2 hours were significantly injured. The percentage (+/- SEM) of necrosis was 12.3 % +/- 5.6% in the low-sodium cardioplegic (modified Roe's) group and 9.3% +/- 3.4% in the high-sodium group. In the 6 hour arrest group the hearts were severely injured, with contracture occurring in all cases. The percentage of necrosis was 56.5% +/- 13% in the low-sodium cardioplegic group and 71.3% +/- 12% in the high-sodium group. In striking contrast all hearts protected with blood cardioplegia failed to show any evidence of tissue damage either on tetrazolium staining or on electron microscopic examination. We conclude that blood cardioplegia offers superior protection to the arrested heart at moderate hypothermia compared to crystalloid cardioplegia.

Animals↗
PubMed1982

Immune response to transplanted pancreas in pigs.

Segmental allografts of the body and tail of the pancreas have been carried out in pigs using an open duct technique. Diabetes was induced by total pancreatectomy. Control animals on no immunosuppression survived an average of 17 days while animals receiving CyA survived 30 days. In the CyA group those with adequate serum levels of CyA survived 46 days while those with low levels survived 18 days. Once the animal became diabetic rejection was not reversible. In this model complement dependent cytotoxicity was more useful than lymphocyte mediated cytotoxicity in predicting rejection. However the rejected pancreas showed intensive mononuclear infiltration. Malabsorption resulting from total pancreatectomy used to induce diabetes may have contributed to the erratic CyA absorption. Prolonged and relatively normal pancreatic allograft function is possible, but adequate CyA levels must be achieved and maintained. Monitoring of serum levels is essential.

Animals↗
PubMed1981

Tolerance of the liver to ischemia: an experimental study.

The experiments described in this study challenge the 20th century belief that the liver is particularly vulnerable to deprivation of its blood supply for appreciable periods of time. The authors studied the effects of 60 minutes of normothermic hepatic ischemia on 10 pigs. The hepatic artery and its collateral vessels were occluded and portal blood was diverted by a portojugular shunt. This produced a 90% reduction in liver blood flow as determined by xenon-127 washout. None of the animals died of liver failure. The ischemic insult did not produce jaundice in any of the animals and only minimal transient changes in liver enzymes occurred. The results suggest that the liver is capable of withstanding prolonged periods of ischemia.

Alanine Transaminase↗
PubMedDate not supplied

Mitral valve replacement in dogs. Surgical technique and postoperative management.

Although techniques for the perioperative management of patients undergoing mitral valve replacement have been well established in humans, the use of these techniques has not been widely accepted in veterinary practice. The purpose of this study is to demonstrate that low morbidity and mortality could be achieved in the dog undergoing mitral valve replacement. Nine mongrel dogs (25-45 kg body weight) were subject to left thoracotomy and mitral valve replacement using cardiopulmonary bypass (CPB). The average time on CPB was 1 hour with an aortic cross-clamping time of 40 minutes using chemically induced cardiac arrest. CPB was performed under conditions of moderate systemic hypothermia (28-30 degrees C) and hemodilution (hematocrit, 25-35%). Operative mortality was 22% (2/9) with one death from excessive bleeding and the other from cerebral air embolism. All other animals recovered and were clinically normal 3 weeks after surgery. The authors conclude that successful mitral valve replacement is possible in the large dog.

Animals↗
PubMedDate not supplied

Recycled heart valves from transplant patients.

Forty heart transplantations were performed at the Toronto Western Hospital, University of Toronto, from October 1987 to December 1989. Each heart extracted from a recipient was examined with the view of using the aortic valve as a homograft for another patient requiring aortic valve replacement. Of the 40 explanted hearts, 26 had normal aortic valves that were potentially suitable for homografting, and 14 had aortic valves judged as unsuitable. Of the potentially suitable valves, four were preserved for ex vivo arrhythmia studies requiring aortic root perfusion and four were damaged during harvesting. The remaining 18 usable valves were sized at the time of explantation and stored in an antibiotic solution at 4 degrees C. Thirteen valves were transplanted within 10 days of harvesting, and five were discarded because no suitable recipients were available within this period. There were no operative deaths or valve-related complications in the 13 homograft valve recipients. Mean follow-up was 13 months (range, 3 to 27 months). One patient required replacement of the homograft with a mechanical prosthesis because of insufficiency and stenosis. All patients are alive, are New York Heart Association functional class status I, and have insignificant valve gradients based on Doppler echocardiography. Although hearts removed from transplant recipients are severely diseased, the aortic valves are frequently normal and should be considered for use as homografts for other patients requiring aortic valve replacement.

Adult↗
PubMedDate not supplied

Relationship between preoperative pulmonary status and outcome after heart transplantation.

To determine whether routine preoperative pulmonary function tests provide useful prognostic information in orthotopic heart transplant candidates, we evaluated the pulmonary status of 33 patients who subsequently underwent transplantation. There was one perioperative death and five other fatalities within 9 months after operation. Mean age of the six patients who died (mean +/- SD 51.8 +/- 5.0 years) was significantly different (p less than 0.05) from that of the survivors (44.6 +/- 11.1 years). Mean preoperative pulmonary vascular resistance was significantly different (p less than 0.05) between those patients who had a fatal outcome (mean, 4.4 +/- 2.0 mm Hg/L/min) and those who survived (2.7 +/- 1.0 mm Hg/L/min). By contrast, we found that measures of forced vital capacity, forced expired volume in 1 second, diffusion capacity for carbon monoxide, and arterial blood gases bore no apparent relationship to outcome. We conclude that standard noninvasive measures of pulmonary function may be useful in preoperative preparation of heart transplant candidates, but they do not appear to be helpful in predicting eventual outcome.

Adult↗