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Biomedical subjects

A S Geha

Publications and source records attributed to A S Geha.

At least 109 records · Page 6Linked to original sources
PubMed1976

Surgical treatment of unstable angina by saphenous vein and internal mammary artery bypass grafting.

During a 3 year period, direct myocardial revascularization was performed on an urgent basis in 48 patients with intermittent resting chest pain which persisted more than 24 hours despite in-hospital medical therapy and was accompanied by electrocardiographic changes representative of ischemia. Sixteen patients had saphenous vein (SV) grafts exclusively, and 32 patients each had one or two internal mammary artery (IMA) grafts with or without additional vein grafts. Follow-up ranges from 5 to 41 months (mean, 22 months). Twelve patients had single grafts to the left anterior descending coronary artery (LAD), 18 had double grafts, 16 had triple grafts, and 2 had quadruple grafts. The LAD required grafting in every patient. There was one operative death (2 per cent) and one late death from noncardiac causes. There were two (4 per cent) early postoperative myocardial infarcts and no late infarcts. Actuarial analysis projects a survival rate of 96 per cent 3 years postoperatively. Eighty-one per cent of the survivors are in Functional Class I, 17 per cent are in Class II, and 2 per cent are in Class III. All patients had postoperative angiography 2 weeks after operation. Eighty-six per cent of the SV grafts and all IMA grafts were open. No significant differences were observed between mean preoperative and postoperative left ventricular end-diastolic pressures or ejection fractions, but these parameters were noted to improve after operation in several patients. The remarkably high early and late survival rates, the low incidence of myocardial infarction, and the excellent functional results after rather long follow-up indicate that emergency coronary revascularization provides an effective therapy for unstable angina. The use of IMA grafts, when feasible, is a safe and possibly preferable approach in these patients.

Adult↗
PubMed1976

Coronary and cardiovascular dynamics and oxygen availability during acute normovolemic anemia.

The hematocrit of 12 dogs was reduced from 43 to 30 and then to 20% by bleeding and simultaneous infusion of lactated Ringer's solution. At each level of anemia, blood volume, heart rate, cardiac output, left and right pressures, left ventricular (LV) work, aortic mean pressure, and systemic vascular resistance were at prebleeding values. Pulmonary arterial saturation decreased from 76 to 67 and 50%. LV coronary venous saturation fell from 46 to 31% at hematocrit 30, with no further reduction at hematocrit 20. Electromagnetically measured left coronary mean flow was 120 and 185% of control at hematocrits 30 and 20. Coronary flow reserve, or the ratio of peak increase in flow after 10 second occlusion to preocclusion flow, was 3.8 at hematocrit 43, 3.0 at 30, and 1.9 at 20. The change in ratio was due to increased resting flow with anemia, whereas peak reactive hyperemia flow did not change with hematocrit. Acute normovolemic anemia is not associated with significant changes in cardiac work. Despite lowered blood viscosity, systemic resistance is maintained by vasoconstriction. Systemic oxygen availability (Cardiac output X arterial O2 content) is decreased, but uptake is maintained by increased O2 extraction. LV O2 consumption is maintained by maximally increasing the already high myocardial O2 extraction and by increasing coronary flow. At half-normal hematocrit, coronary reserve is compromised significantly, indicating cardiac vulnerability at these levels of anemia, especially if coronary occlusive disease or higher work demands on the heart should coexist.

Anemia↗
PubMed1975

Role of adrenergic mechanisms in the development of cardiac hypertrophy.

This experiment was designed to study the role of cardiac beta-adrenergic mechanisms in the development of hypertrophy in rats. The suprarenal abdominal aorta was banded, resulting in an increase in cardiac wt-body wt ratio. A group of rats received a sham operation. Half of the banded rats were treated with practolol, 2.0 mg/kg intraperitoneally every 12 hr for the 6 days after banding. The effectiveness of cardiac beta-adrenergic blockade was confirmed by absence of an increase in heart rate following intravenous isoproterenol at various times between practolol injections. Practolol did not affect the gradient in the banded groups. Six animals in each banded group were sacrificed daily for 6 days. The right and left ventricles were dissected separately and weighed. RV-body weight ratios increased similarly in both banded groups. LV-body weight ratio (g/kg) was 2.17 +/- 0.043 in sham rats, and it attained maximal levels of 3.03 +/- 0.10 within 6 days in banded untreated rats and 2.96 +/- 0.14 in banded rats receiving practolol. Therefore, beta-adrenergic mechanisms were not involved in the development of hypertrophy due to increased afterload. Also, these findings are not consistent with the Meerson hypothesis, since hypertrophy occurred despite the reduction in myocardial O2 consumption due to practolol.

Animals↗
PubMed1975

Successful emergency replacement of the ascending aorta and aortic and mitral valves in the Marfan syndrome.

A 37-year-old man with the Marfan syndrome and chronic mitral regurgitation suffered an acute dissecting aneurysm of the ascending aorta with aortic regurgitation. Emergency replacement of the mitral valve, aortic valve, and ascending aorta was carried out, and the patient made an uneventful recovery. He is doing well 18 months after surgery. This is the first reported case of survival from such a procedure in the face of acute dissection with Marfan's syndrome. Indications for elective surgery are discussed and the uncertainties about the prognosis outlined. Continued reporting of the results and follow-up data are necessary for final assessment of the surgical treatment of the cardiovascular manifestations of this disease.

Adult↗
PubMed1975

Blood flow and vasoactive drug effects in internal mammary and venous bypass grafts.

Cardiac output and pressure-flow measurements were made in left internal mammary artery-to-left anterior descending coronary artery grafts and left subclavian artery-to-left circumflex coronary artery vein grafts after proximal coronary artery ligation. Similar measurements were also made in left internal mammary artery-to-left anterior descending coronary artery grafts and aortocoronary saphenous vein grafts in patients with coronary artery disease. Hemodynamic parameters and graft blood flows were measured during control baseline conditions and after pharmacological interventions using isoproterenol, phenylephrine, and epinephrine in random order. Blood flow through vein grafts and internal mammary artery grafts was similar under basal conditions and increased similarly with each of these vasoactive agents. Other hemodynamic parameters changed variably with the various pharmacological agents used. There was no close correlation between mammary artery or vein graft blood flow and arterial mean pressure and cardiac output over the wide range observed with the different drugs was associated with either an increase in perfusion pressure or a decrease in coronary vascular resistance. If the percentage increase in coronary blood flow above the basal control value in response to pharmacological stress is considered as a reflection of coronary vascular reserve, these studies suggest that coronary vascular reserve in patients with coronary artery disease is less than that of the normal dog heart.

Adrenergic Agonists↗
PubMed1975

Selection of coronary bypass. Anatomic, physiological, and angiographic considerations of vein and mammary artery grafts.

Results of direct coronary revascularization with 511 grafts in 213 patients from 1971 to 1974 are reviewed. To improve an early saphenous vein graft (SVG) patency of 84 per cent in the first 85 patients, we have used internal mammary artery grafts (IMAG), when possible, since January, 1973. In 1973 to 1974, 15 patients had SVG's only (36 grafts) and 113 received one or two IMAG's with or without additional SVG's (total 282 grafts); in 26 we used a crossed double IMAG. Forty-seven of 48 patients with unstable angina survived and did well. Flows in SVG's and IMAG's were comparable. Flows in right IMAG's to diagonal or marginal vessels were higher than in right IMAG's to right or left anterior descending (LAD) vessels. In 12 patients with both SVG and IMAG, there was no difference in flow response of either graft to vasoactive drugs. Survival, functional, and patency results with IMAG's were as good as or better than results with SVG's. We conclude that IMAG's yield higher patency and comparable flow rates to SVG's and should be used when the IMA approximates the recipient artery in size and when a high pulsatile free flow is measured from the end of the graft. IMAG's are also safe and feasible for unstable angina.

Adult↗