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Biomedical subjects

R Gorlin

Publications and source records attributed to R Gorlin.

At least 145 records · Page 8Linked to original sources
PubMed1976

Principles in selection of therapy.

The physician today is presented with a plethora of possibilities in the therapy of each of the aspects of ischemic heart disease (Fig. 15-5). There is the temptation to recommend complex and impossible dietary prescriptions coupled with several pharmaceutical agents for control of anginal pain, hypertension, arrhythmias, hypercholesterolemia, and clinical congestive heart failure. While each of the objectives may be in part valid, the burden on the patient of following such a constraining and difficult life may make it virtually impossible either to enjoy life or to follow the physician's recommendations explicitly. Often a compromise must be reached between theoretically optimal therapy and that which is reasonable and acceptable to the patient. Again, a review of each aspect of the program with the patient may aid in establishing that which is possible rather than that which is ideal.

Adrenergic beta-Antagonists↗
PubMed1976

Myocardial ischemia.

Myocardial ischemia results from an imbalance of energy supply and demand. Because of the essentially aerobic nature of myocardial metabolism and the high oxygen extraction from the blood, ischemia is usually equatable with limitation of blood supply. Coronary atherosclerosis is a patchy disorder, and therefore, ischemia usually occurs in segmental fashion throughout the topography of the heart. Ischemia is invariably seen earliest and most intensely in the deep or subendocardial layers of myocardium. Ischemia leads to biochemical disruption, including initiation of glycolysis, which in turn causes electrophysiological and mechanical disturbances. Myocardial ischemia can be induced naturally or experimentally in the human subject in a variety of ways, some of which have been studied in the laboratory.

Angina Pectoris↗
PubMed1976

Impaired myocardial contraction in the chronic stage.

The consequences of ischemia for the affected myocardium are highly variable. As a result, in chronic coronary heart disease there is little correlation between coronary arterial obstruction and myocardial dysfunction. Dysfunction can be permanent and related to replacement fibrosis or fixed disruption of the chain of events leading to effective contraction. Dysfunction can also be transient, as a direct consequence of acute myocardial ischemia. The mechanical lesions include generalized and localized myocardial dysfunction, mitral incompetence, and rarely, a left-to-right shunt through loss of integrity of the interventricular septum. Diagnosis per se is not difficult, but deciding on the true contribution of any given lesion to the overall symptoms and disability of the patient is. Therapy must be individually planned according to the total set of factors in each patient.

Arrhythmias, Cardiac↗
PubMed1976

Natural history of coronary heart disease.

We now possess enough data concerning prognosis so that we can highlight the areas of concentration for the practicing physician. A history of congestive failure, hypertension,or diabetes is of greatest importance. Smoking is in a similar category, but cholesterol elevation is not. Electrocardiographic findings can be used as an immediate discriminator, depending on whether they are normal or abnormal. Further refinements are possible, depending on whether there are ST-segment depressions or elevations, ventricular conduction defects, repetitive ventricular dysrhythmias, left ventricular hypertrophy, or Q waves of prior infarctions. The exercise electrocardiogram provides additional important information and, if markedly abnormal, can detect with reasonable degree of accuracy the presence and degree of ischemic heart disease. The coronary arteriogram, which influences many of the preceding clinical criteria, permits an accurate prediction of five-year mortality and in a preliminary fashion can be integrated with electrocardiographic and ventriculographic abnormalities to derive a significant measure of prognosis. Finally, cardiac function, if assessed according to specific criteria, becomes an extremely important variable in predicting natural history in coronary heart disease.

Coronary Angiography↗
PubMed1976

Coronary anatomy.

The coronary arteries have a serpentine but interdependent relationship to one another. The left artery supplies the majority of the left ventricular myocardium irrespective of right or left arterial "dominance." A coronary artery obstruction begins to assume significance when it approaches 75% of the cross-sectional area of the vessel. Increasing degrees of stenosis impose limitations to blood flow during stress and finally even under resting conditions. Analysis of the arteriogram requires not only knowledge of normal anatomy and its variations but also appreciation of difficulties in distinguishing a normal from an abnormal artery and in quantifying the functional severity of an obvious obstruction.

Aorta, Thoracic↗
PubMed1976

Coronary collaterals.

Coronary collaterals are probably enlargements of pre-existing channels which respond to local vasodilators and which function whenever pressure differences exist across them. Thus, in human coronary atherosclerosis collaterals are only seen when there is a severe intervening arterial obstruction (in excess of 75%). Coronary collaterals follow epicardial and intramycardial pathways, and the intermediary connections may be at vessels of highly varying caliber. The flow potential of most collateral pathways in man is possibly adequate for segmental myocardial function at lower than normal demands but clearly is inadequate for most, if not all, stressful interventions. In the last analysis, coronary collaterals in man are more an indication of severe regional ischemia (present or potential) than a sign of biological "compensation'' for a perfusion deficit.

Animals↗
PubMed1976

Physiology of myocardial blood flow and metabolism.

In this chapter the normal functioning of the coronary circulation has been described with major emphasis placed on the hydraulic and small vessel resistance factors in its regulation. The impact of various forms of disease to compromise effective delivery of blood flow either in general or segmentally has also been stressed. The vulnerability of the deep or subendocardial layers to ischemia has been emphasized. The distinction has been drawn between primary and secondary vasodilatation, the primary type representing effects on the arteriole, irrespective of effects on myocardial mechanical and metabolic activity, while the secondary type represents changes in response to changes in the metabolic rate. An interrelationship has been demonstrated among the several factors which regulate blood supply and affect myocardial mechanical activity.

Biological Transport↗
PubMed1975

An additional angiographic sign for determining coronary artery dominance in obstructive coronary artery disease.

An additional angiographic sign for determining coronary artery dominance is proposed. This sign is based on the anatomic pattern of the infraventricular branches in the left anterior oblique view. It is especially helpful in patients in whom the right coronary and/or left circumflex coronary arteries are completely occluded and distal vessels are filled via collaterals.

Adult↗
PubMed1975

Coronary artery anatomy before and after direct revascularization surgery: clinical and cinearteriographic studies in 67 selected patients.

This report relates the postoperative clinical and cineangiographic status of 67 patients selected from a total of 202 patients who underwent coronary artery surgery at the Peter Bent Brigham Hospital from July, 1970, to July, 1972. The mean interval after operation was 12.6 months. Ninety-one per cent of the 67 patients were improved from their preoperative status. Forty-eight patients (71 per cent) were studied to evaluate recurrence of mild to moderate angina or occurrence of interval myocardial infarction, and 19 patients (29 per cent) were entirely asymptomatic. In the 67 patients studied, 112 coronary arteries received a total of 115 grafts. (There were 89 ungrafted coronary arteries.) Total graft patency rate for the 58 patients in whom angina was totally or significantly relieved was 65 per cent. However, one or more grafts were patent in 52 (90 per cent) of these 58 patients. In grafted arteries, progression was found in segments proximal to the graft in 37 per cent of arteries, at the site of anastomosis in 10 per cent, and distal to the site of anastomosis in 17 per cent. The frequency of obstruction distal to the site of anastomosis was not significantly different from the frequency of progression in nongrafted arteries, in contrast to preliminary data from this laboratory. Overall and regional progression in grafted arteries appeared to occur primarily within the first four months after surgery and was found, thereafter, in a constand percentage of vessels studied. Progression in coronary arteries was independent of patency or occlusion of the graft to the vessel. It is hypothesized that while proximal progression is probably a consequence of altered hydraulic factors, distal lesions seem to represent natural progression of atherosclerotic disease.

Angina Pectoris↗