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Biomedical subjects

D H Tyras

Publications and source records attributed to D H Tyras.

At least 55 records · Page 3Linked to original sources
PubMed1978

Atypical mycobacteria and the xenograft valve.

During a 4 month interval, cultures taken at the time of porcine xenograft valve implantation grew a fastidious atypical mycobacterium, Mycobacterium chelonei (Runyon's groups IV), in eight of 20 patients. Initial growth occurred at 2 to 3 weeks in thioglycollate broth only; detailed biochemical and bacteriologic evaluation demonstrates altered catalase activity accounting for its initial slow growth. Only one patient has manifested clinical evidence of infection 5 months after mitral valve replacement. A large pericardial effusion required pericardiectomy. Pericardial tissue and fluid have grown M. chelonei with the same growth characteristics as the initial valve culture. It is recommended that manufacturers of xenograft valve bioprostheses maintain a quarantine of 6 weeks until cultures, smears of culture broth, and microscopic evaluation of aortic wall coupons are negative. Users of these prostheses should keep cultures for a minimum of 3 weeks. Should positive cultures result, antimicrobial therapy should be considered only with clinical evidence of infection.

Animals↗
PubMed1977

Coronary-subclavian steal.

Of 450 patients undergoing internal mammary artery grafts for coronary artery bypass, proximal subclavian artery stenosis with reversal of flow in the internal mammary and vertebral arteries ("coronary-subclavian steal") subsequently developed in two patients. Carotid-subclavian bypass successfully reestablished antegrade blood flow in the ipsilateral internal mammary and vertebral arteries in both patients. Arch aortography is indicated preoperatively in myocardial revascularization patients in the presence of cerebrovascular symptoms, upper extremity blood pressure gradients, and carotid or subclavian bruits. Should subclavian artery stenosis develop subsequent to myocardial revascularization, carotid-subclavian or acillary-axillary bypass can effectively restore antegrade blood flow and reverse the coronary-subclavian steal.

Adult↗
PubMed1977

Nonsyphilitic coronary ostial stenosis.

From October 1970 to June 1977, a total of 15 patients (12 women) were seen with atherosclerotic coronary ostial stenosis (14 left, one right). All patients had angina and two had aortic valve disease. Additional coronary arterial disease was present in nine. One patient declined surgery and died four months later after myocardial infarction. All patients had coronary bypass grafts and two had aortic valve replacement. One patient with valve replacement and one with preoperative cardiogenic shock died postoperatively. Angina recurred nine months postoperatively in one patient; the others (11) are free of angina. Postoperative catheterization from two weeks to 4.5 years in ten of 12 showed 11 of 13 vein grafts and eight of nine internal mammary artery grafts to be patent. In three patients, only a single left-sided coronary bypass was placed to the left anterior descending artery, because the circumflex branches were too small. Ideally, two left-sided bypass grafts should be placed for left ostial disease.

Adult↗
PubMed1975

Myocardial revascularization combined with intracoronary infusion of hyperosmolar solution in the early management of postinfarction ventricular septal defect. Report of a case.

A patients is described with postinfarction ventricular septal defect in whom the perforation was successfully closed within 24 hours of septal rupture. This presents the second such case reported in the literature. Adjunctive measures consisting of myocardial revascularization and intracoronary infusion of mannitol were thought to be important in the successful outcome of the operative procedure. The importance of complete preoperative cardiac catheterization with coronary arteriography is stressed. The theoretical role of endothelial and myocardial cellular edema as a cause of depressed myocardial function immediately following an ischemic insult is proposed as a practical consideration in the high mortality associated with this condition. Methods used to prevent or reverse such cell swelling are described. The details of the operation in which viable ventricle myocardium was used to fill the septal defect are presented.

Coronary Artery Bypass↗