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Biomedical subjects

A S Trimble

Publications and source records attributed to A S Trimble.

At least 19 recordsLinked to original sources
PubMed1976

Aortocoronary bypass graft in dogs: late histological changes.

Late histological changes occurring in aortocoronary bypass vein grafts were studied by lignt and electron microscopy in three dogs killed one, two and three years after grafting. The changes consisted of intimal thickening due to a proliferation of modified smooth muscle cells (myointimal hyperplasia) and replacement of most of the medial smooth muscle by fibrocytes. Serial angiography in the dogs did not reveal progression of the intimal thickening after one month.

Animals↗
PubMed1976

Aortocoronary bypass made possible by coronary endarterectomy.

Thirty bypass grafts to coronary arteries were made possible by manual core endarterectomy. The overall patency rate of the grafts was 57%, which is less than the patency rate of bypass grafts to nonendarterectomized vessels (75 to 80%). In the perioperative period and during follow-up to 29 months there was no increase in mortality or morbidity even when the endarterectomized vessel subsequently became occluded. These results represent early technical experience. Routine anticoagulant therapy in the postoperative period, to prevent early occlusion, was not used. The results of this and other studies suggest that coronary endarterectomy with bypass grafting is a useful procedure in situations where the coronary artery is so severely obstructed that standard saphenous vein bypass grafting cannot be performed; the procedure is superior to coronary endarterectomy alone.

Arterial Occlusive Diseases↗
PubMed1975

Myocardial infarction in coronary artery surgery.

Myocardial infarction has been noted as a frequent complication of coronary artery surgery in many review series, although its causes are uncertain. Follow-up of 100 patients at 19.7 months (mean) after coronary bypass surgery identified 15 patients with perioperative myocardial infarction as judged by new, significant Q waves after surgery. There were no significnat differences in age, preoperative anginal class, previous infarction, presence of hypertension, hyperlipidemia, or frank glucose intolerance compared with the 85 patients without infarction. Nor was there a significnat difference in coronary artery score, left ventricular end-diastolic pressure, cardiac index, or presence of collaterals. Cardiopulmonary bypass time, duration of anoxic arrest, and number of vessels grafted did not differ. Perioperative infarction always occurred in the territory of a grafted vessel and not in comparably compromised, nongrafted areas. In 13 cases new Q waves appeared in the first 24 hours, and myocardial infarction was not clinically suspected. Eight of the 15 grafts at risk were patent at late follow-up. Mean ejection fraction was not significantly changed postoperatively, but affected segmental wall motion declined in most cases. Five patients with perioperative infarction but no patent grafts improved by only 1 NYHA class (mean), but ten patients with infarction and one or more grafts patent improved by 2.9 NYHA classes (mean). Perioperative infarction could not be correlated with currently recognized patient and operative risk factors. The consistent anatomical relationship suggested that the grafting procedure itself was critical to the occurrence of distal segmental infarction.

Adult↗
PubMed1975

Saphenous vein bypass grafting. Changes in native circulation and collaterals.

One hundred patients were evaluated 12 to 43 months after saphenous vein bypass surgery. The rate of progression of obstructive disease in the native vessels and changes in collateral circulation were analyzed in detail. Fifty-five per cent of preoperatively patent vessels showed progression proximal to the site of graft insertion, 40% proximal to patent grafts; there was distal progression in only 7% of grafted vessels. The progression rate for nongrafted vessels was 14%. Patent grafts were associated with a high rate of disappearance of collaterals to the grafted vessels, while occluded grafts were associated with preservation of collaterals or appearance of new collaterals. Progression of obstructive disease in the native circulation and changes in collaterals did not prevent symptomatic improvement (93% of patients were symptomatically improved).

Adult↗
PubMed1975

Morphologic observations on heart valve prostheses made of fascia lata.

A cooperative, international study permitted morphologic observations on 58 fascia lata heart valve prosthese. Thirty-nine had been in position less than a year, the remainder for periods up to 50 months. The fascial cusps, no matter whether free or stent mounted, underwent changes that included death of the original fascia and vacuolar, degenerative changes if a valve had been in situ more than 3 years. Formation of a pseudointima on a cusp's surface caused it to shrink. The rate of progression and severity of the changes varied from prosthesis to prosthesis. Severe cusp shrinkage caused valve incompetence. That seemed particularly likely in mitral and tricuspid prostheses and explains why their use has been abandoned. Clinically, fascia lata aortic valves function satisfactorily for several years. However, their long-term value is still uncertain. Morphologically, the specter of late calcification and other degenerative changes haunt their use until more, from long-term survivors, are available for study.

Aortic Valve↗
PubMed1974

The late results of cardiac valve replacement using autologous fascia lata.

Over an eight-month period beginning in November 1969, 53 patients received 63 fascia lata heart valves at the Toronto General Hospital. The late results of this form of valve substitution are reviewed. The fascia used to fashion the tricuspid valve underwent progressive thickening and contracture and this process caused failure of the prosthesis within months of insertion. The mitral fascial prosthesis failed in a similar manner although the process took longer. The aortic fascia lata valve, however, has not shown progressive thickening after 3(1/2) years and it has so far retained its functional integrity. Indeed, we have been impressed by the excellent clinical results and absence of complications such as thromboembolism although anticoagulation has not been used. We therefore consider that fascia lata valves offer a suitable alternative to other forms of aortic valve substitution, but are unsatisfactory for tricuspid or mitral valve replacement.

Adult↗
PubMed1972

Saphenous vein bypass grafting for coronary atherosclerosis: clinical experience.

Saphenous vein bypass grafting is a recent and important procedure in the management of atherosclerotic coronary artery disease. A review of the first 150 patients operated on to July 1971 at the Toronto General Hospital is presented. Many had multiple bypass grafts and some had additional procedures including internal mammary artery implantation, valve replacement and scar tissue resection. There were five operative deaths (3%) and an additional five hospital deaths; the majority were related to myocardial infarction.A clinical review of the results six months to three years after operation indicates marked improvement in over 80% of the survivors. Postoperative hemodynamic studies were performed in many. It is suggested that patients with poor myocardial function presenting in failure may not benefit from the operation.

Adult↗
PubMed1971

The use of autologous fascia lata for cardiac valve replacement: preliminary results.

Since November 1969, 53 patients have been operated on at the Toronto General Hospital for cardiac valve replacement with valves fashioned from autologous fascia lata. Sixty-three such valves have been inserted, including single aortic and mitral, double and triple valve replacements. The preliminary results indicate that operative mortality, considering the status of the patient submitted to the procedure, is comparable to that of plastic prosthetic valve replacement at this centre. Early follow-up confirms that anticoagulation is unnecessary and thromboembolism can be avoided with this form of valve substitution.

Adult↗