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Biomedical subjects

R Rivera

Publications and source records attributed to R Rivera.

At least 145 records · Page 8Linked to original sources
PubMed1980

Clinical and hemodynamic assessment of the Angell-Shiley porcine xenograft.

Valve replacement with an Angell-Shiley bioprosthesis was accomplished in 449 patients. To evaluate the bioprostheses from this total series, 344 patients who did not undergo associated operation, had no previous operations, or had no other valve substitutes were selected. Hospital mortality was 2.6% for aortic (4 out of 156), 7.2% for mitral (9 out of 125), and 12.7% for multiple-valve replacements (8 out of 63). The 323 patients discharged from the hospital were followed for 6 to 36 months. There were 15 late deaths. Hepatitis, bleeding, thromboembolism, endocarditis, and residual valvular incompetence, always periprosthetic, were the major complications. Forty-five patients with single-valve replacement (16 mitral and 29 aortic) without clinical valve dysfunction were electively recatheterized to assess hemodynamic performance. Measurements were recorded at rest and during exercise on a bicycle ergometer. Functional aortic valve orifice averaged 1.23 +/- 0.33 cm2 and the mean systolic gradient was 21.51 +/- 6.68 mm Hg at rest. During exercise, aortic gradient increased to 26.60 +/- 7.54 mm Hg and mean functional area to 1.51 +/- 0.34 cm2. In the mitral position, the mean diastolic gradient at rest was 8.44 +/- 3.17 mm Hg and the functional orifice area averaged 1.67 +/- 0.51 cm2. Exercise increased the mean gradient to 11.92 +/- 3.8 mm Hg and the mean orifice area to 2.05 +/- 0.57 cm2.

Adolescent↗
PubMed1980

Surgical treatment of coronary insufficiency produced by cardiac echinococcosis.

We report two cases in which the pertinent angiographic studies disclosed the presence of hydatid cysts of the left ventricle, producing complete obstruction of the left anterior descending coronary artery in one patient and of the left anterior descending coronary artery and the circumflex coronary artery in the other patient. Both patients were successfully treated by excision of the cyst and myocardial revascularization with saphenous venous bypass grafts. From the analysis of symptoms in cardiac echinococcosis, we concluded that precordial pain is the most common complaint, that it can be due to coronary insufficiency, and that at the present, coronary angiographic studies have to be performed systematically in these patients, since coronary involvement by the cyst can explain some of the clinical manifestations and complications of the disease and can also influence its surgical management.

Angiography↗
PubMed1979

Factors influencing better results in operation for postinfarction ventricular aneurysms.

A series of 66 consecutive patients operated on for postinfarction ventricular aneurysm is reviewed with regard to the factors influencing the progressive decline of mortality (3.2% in the last 31 patients seen). The method of myocardial protection has a significant influence on mortality, which was 45% in patients operated on with aortic cross-clamping under conventional hypothermia and 5% in patients operated on under profound local hypothermia. Associated revascularization with vein bypass graft was performed in 28 patients, without mortality. The technique of aneurysmectomy adapted to the extension and location of the fibrotic scar is described, with exclusion of the septal portion of the aneurysm in 85% of the patients. In 36 patients who had postoperative cardiac catheterization, this technique produced normal ejection fraction and near normal left ventricular volumes

Angiocardiography↗
PubMed1978

Circulatory responses to systemic infusions of estrone and estradiol-17alpha in nonpregnant, oophorectomized ewes.

Uterine arterial blood flow dose-response curves to systemic infusions of either estrone (E1) or estradiol-17alpha (E2alpha) were determined in ten oophorectomized, nonpregnant ewes. Maximum uterine blood flow occurred with 5 microgram per kilogram of E1 and greater than or equal to 20 microgram per kilogram of E2alpha. Total uterine blood flow measured with isotope-labeled microspheres rose more than tenfold following 30 microgram per kilogram of either estrogen, as did blood flow to the myometrium, endometrium, and uterine caruncles (p less than 0.05). Distribution of uterine blood flow was unaltered. Cervical and vaginal blood flows increased ten-to twenty-fold with E1 and E2alpha, while mammary gland blood flow rose 54 and 77 per cent. Significant increases in adrenal and thyroid blood flows were documented. The only significant decrease in blood flow occurred in the pancreas (- 13 percent; p less than 0.05) following E2alpha infusion. At the dose studied, E1 and E2alpha are potent vasodilators of reproductive tissues, especially the cervix and vagina. As they appear to be the major estrogens during ovine pregnancy, it is likely they participate in the preparation of these tissues for parturition.

Animals↗