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Biomedical subjects

T J Ryan

Publications and source records attributed to T J Ryan.

At least 361 records · Page 20Linked to original sources
PubMed1982

Therapeutic and economic value of a normal coronary angiogram.

A significant number of patients with severe angina or intractable atypical chest pain referred for coronary arteriography are found to have normal coronary vessels. To determine what therapeutic or economic benefit may be derived from these studies, we analyzed the data of 72 consecutive patients with normal vessels referred for cardiac catheterization because of severe chest pain. The clinical status and hospitalizations were analyzed for the 2 year period before and the 2 year period after angiography. There were no deaths or myocardial infarctions. Although 47 were thought to have angina and 25 atypical pain before catheterization, the chest pain was reclassified with only 15 continuing to have anginal pain, 40 atypical pain, and 17 no pain. Functional improvement by at least one New York Heart Association class occurred in 74 percent of patients with 36 (50 percent) having no functional limitation. The use of cardiac medications was also significantly reduced. Despite functional improvement, no change in employment states could be demonstrated. The use of medical facilities was significantly less, the average number of hospital days per patient declining from 17 to 3.9 and hospitalization decreasing from 1.5 to 0.4. The result was a significant decrease in estimated hospital costs. We conclude that in patients referred for coronary angiography for severe chest pain, documentation of a normal coronary arteriogram significantly alters the clinical assessment of symptoms, improves functional status, modifies medical therapy, and reduces hospitalization and medical costs. These therapeutic and economic benefits deserve consideration in the evaluation of coronary angiography for its overall effectiveness.

Adult↗
PubMed1982

The effect of angiotensin converting enzyme inhibition of coronary blood flow and hemodynamics in patients without coronary artery disease.

We examined the role of the renin-angiotensin system in the regulation of systemic and coronary vascular tone by studying the effect of converting enzyme inhibition by teprotide on systemic and coronary hemodynamic parameters in 14 normal patients undergoing routine cardiac catheterization. Serial hemodynamic measurements were made before and up to 30 minutes after 1 mg/kg of intravenous teprotide. A significant rise in cardiac index and stroke volume index occurred with a fall in systemic vascular resistance. The increase in cardiac index was related to the level of resting plasma renin activity. Blood pressure, pulmonary artery and left ventricular end-diastolic pressures remained unchanged. Coronary sinus thermodilution blood flow also showed no significant change; however, some patients demonstrated dramatic increase in flow. The change in blood flow was highly correlated with the resting plasma renin activity (r = 0.939 P less than 0.001). The change in coronary vascular resistance and myocardial oxygen consumption were likewise related to the resting plasma renin level. Converting enzyme inhibition produces significant systemic hemodynamic changes in normal patients which implies that the renin-angiotensin system is important in normal cardiovascular homeostasis. The direct relationship between plasma renin activity and coronary blood flow suggests that the renin-angiotensin system may play an important role in coronary vasomotor regulation.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1982

Left ventricular diastolic capacity in man.

Plasma volume expansion with 500 ml of low-molecular-weight dextran was used in 27 patients (nine normal subjects, 13 patients with ischemic heart disease, four with aortic stenosis and one with cardiomyopathy) to increase left ventricular end-diastolic pressure (LVEDP) from a control value of 12.4 +/- 7.0 mm Hg (mean +/- SD) to 23.3 +/- 7.0 mm Hg and end-diastolic volume (EDV) from 84.0 +/- 23.8 ml/m2 to 97.6 +/- 22.9 ml/m2. EDV-LVEDP curves constructed for 12 patients from multiple angiograms at progressively increasing LVEDPs during plasma volume expansion showed an initial part where EDV increased in parallel with LVEDP and a final steep or perpendicular part where EDV increased minimally or not at all as LVEDP exceeded 20 mm Hg. Exponential equations were used to fit diastolic volume-pressure data obtained with catheter-tip manometers in seven patients: the exponential constant, k, was 0.012-0.044 ml-1 and was inversely related to EDV (Spearman's rank correlation coefficient = -1). For comparable EDV, there were no differences in k values between normal subjects and patients with a variety of heart diseases.

Aortic Valve Stenosis↗
PubMed1982

Survival of medically treated patients in the coronary artery surgery study (CASS) registry.

The objective of this study was to evaluate the impact on survival of the anatomic extent of obstructive coronary artery disease and of two measures of left ventricular (LV) performance. This study is based on 20,088 patients without previous coronary artery bypass graft surgery who were enrolled in the registry of the National Heart, Lung, and Blood Institute Coronary Artery Surgery Study from 1975 to 1979. The cumulative 4-year survival of medically managed patients was analyzed to determine the survival of specific subsets of patients with obstructive coronary disease. The vital status of 99.8% of the patients was known. The 4-year survival of medically treated patients with no significant obstructive disease was 97%, in contrast to 92%, 84% and 68% in patients with one-, two- and three-vessel disease, respectively. The presence of left main coronary artery disease decreased survival significantly. The 4-year survival decreased from 70% to 60% in patients with three-vessel disease when significant obstruction of the left main coronary artery was also present. Patients with significant coronary artery disease who had an ejection fraction of 50--100%, 35--49%, and 0--34% had a 4-year survival of 92%, 83% and 58%, respectively. The systolic contraction pattern was assessed in five selected segments and given a score of 1--6, with a score of 1 for normal function, increasing to 6 if an aneurysm was present. In a patient with normal LV contraction in all five segments of the LV ventricular angiogram, the LV score would equal 5. Patients with an LV score of 5--11, 12--16 and 17--30 had 4-year survivals of 90%, 71% and 53%, respectively. Patients with good LV function (a score of 5--11) had a 4-year survival of 94%, 91% and 79% for one-, two- and three-vessel disease, respectively. Patients with poor left ventricular function (score of 17--30) had a 4-year survival rate of 67%, 61% and 42% in one-, two- and three-vessel disease, respectively. Thus, LV function is a more important predictor of survival than the number of diseased vessels.

Coronary Artery Bypass↗
PubMed1982

Treatment of stable angina of effort with verapamil: a double-blind, placebo-controlled randomized crossover study.

The effects of verapamil were assessed in 26 patients with stable exertional angina pectoris in a double-blind, placebo-controlled, randomized crossover protocol using serial treadmill tests. Verapamil, 480 mg/day, reduced anginal frequency from 5.6 +/- 7.3 to 2.2 +/- 3.9 attacks per week (p less than 0.001) and nitroglycerin consumption from 3.4 +/- 4.9 to 1.2 +/- 2.5 tablets per week (p less than 0.05) compared with placebo. Treadmill time increased from 6.4 +/- 2.1 minutes during the placebo phase to 7.5 +/- 1.8 minutes during the verapamil phase (p less than 0.001). Verapamil's beneficial effect appeared to be related, in part, to a 10% reduction of the rate-pressure product at rest (p less than 0.05) and a 12% reduction during submaximal exercise (p less than 0.001). Verapamil also caused less marked ST-segment depressions at peak exercise (p less than 0.05) at a similar rate-pressure product, suggesting a favorable redistribution of coronary blood flow to the ischemic zone. Side effects from verapamil were minimal, consisting mainly of constipation (six patients). Verapamil appears to be a safe and effective drug for treating angina of effort.

Adult↗
PubMed1982

Myopotential inhibition of unipolar lithium pacemakers.

The effect of isometric upper extremity exercise on pacemaker function was evaluated in 27 patients who remained pacemaker-dependent during testing. Inhibition was demonstrated in eight (31 percent) of which five were symptomatic. Based on design of the sensing amplifier and return to an all-metal housing in the unipolar lithium pulse generators, myopotential inhibition is being recognized as one cause of symptomatic pacemaker inhibition that is more common than generally appreciated. A method of evaluation and management options for symptomatic patients are discussed. Routine testing of all patients should be performed at the time of a regular office evaluation. If one model pulse generator appears to be particularly prone to myopotential inhibition, this knowledge should be considered in the choice of future pacing systems.

Action Potentials↗
PubMed1982

Transluminal angioplasty in experimental atherosclerosis. Analysis for embolization using an in vivo perfusion system.

We used polarized light microscopy and thin-layer chromatography to determine whether embolization of atherosclerotic material occurs after transluminal angioplasty. The experimental model consisted of an in vivo perfusion system of the atherosclerotic rabbit left iliac artery. Of eight rabbits that underwent successful angioplasty, four had angiographic evidence of dissection and three showed aneurysm formation. Histologic studies demonstrated fracture of the intimal plaque, dissection, and stretching of the noninvolved portion of the vessel. Perfusate analysis revealed no detectable cholesterol by thin-layer chromatography in six of eight rabbits. In two rabbits, a very small amount of cholesterol was measured, which was totally accounted for by hemorrhage into the perfusate rather than from cholesterol in the plaque. No evidence of arterial wall embolic debris could be detected by polarized light microscopy in seven rabbits, but lipid debris from the plaque was found in the perfusate of one rabbit that had excessive arterial trauma. We conclude that the major mechanism of successful transluminal angioplasty in this experimental model is intimal fracture combined with stretching of a noninvolved portion of the vessel. Furthermore, embolization of atheromatous lipid debris was an uncommon event related to arterial trauma during catheter placement rather than transluminal angioplasty itself.

Angioplasty, Balloon↗
PubMed1982

[Use of the ECG under physical load for assessing the status of ischemic heart disease patients].

To determine to what extent the diagnostic accuracy of stress testing is influenced by the prevalence of coronary artery disease, we correlated the description of chest pain, the ST-segment response to exercise, and the results of coronary arteriography in 1465 men and 580 women from the registry for the Coronary Artery Surgery Study (CASS). A positive ST-segment response increased the pre-test risk by only 7 to 20%, whereas a negative ST-segment response decreased the risk by only 2 to 28%. Although the percentage of false positive results differed between men and women (12 +/- 1% vs 53 +/-- 3%, p less than 0.001), this difference was not seen in a subgroup matched for prevalence of coronary artery disease. Thus, the ability of stress testing to predict coronary artery disease is limited in a heterogenous population in which the prevalence of disease can be estimated through classification of chest pain and the sex of the patient. Additional multivariant linear discriminant function analysis on treadmill and angiographic data from 500 men with definite angina, 584 men with probable angina and 267 men with nonspecific chest pain identified independent predictors of presence and extent of coronary disease. The discriminant function developed clinical, and clinical and exercise risk indices for each patient subset. Probability curves demonstrated that exercise testing provided more diagnostic information than clinical data alone in patients with definite and probable angina. However, exercise testing in men with nonspecific chest pain was of limited value since disease prevalence was already low. We conclude that (a) analysis of the ST-segment response to exercise provides limited information regarding the diagnosis of coronary artery disease when used alone, and (b) use of other exercise variables in addition to clinical data improves the diagnostic ability of the exercise test in men with definite or probable angina.

Angina Pectoris↗
PubMed1982

Cardiovascular responses to isometric exercise in patients with mitral stenosis. Comparison with normal subjects and patients with depressed ejection fraction.

The hemodynamic response to isometric handgrip was evaluated in 15 patients with mitral stenosis (MS), 12 normal subjects, and 13 patients with severe left ventricular failure (LVF). Acceleration of heart rate and rise in left ventricular systolic pressure were not significantly different between the three groups. Left ventricular end-diastolic pressure did not change in normal subjects and patients with MS during handgrip, but it was raised markedly in patients with LVF. Cardiac index increased in normal subjects but did not change in patients with MS and LVF. Stroke index declined in patients with LVF. In all groups there was a modest and similar increase in oxygen consumption and significant widening of the arteriovenous oxygen difference in patients with LVF. In patients with MS, pulmonary capillary pressure increased by an average of 10.6 mm Hg, with a parallel rise in mean pulmonary vascular resistance. It is concluded that patients with MS demonstrate a normal chronotropic and pressor response to isometric exercise. Normal left ventricular end-diastolic pressure response to isometric handgrip stress in patients with MS suggests good left ventricular performance.

Adult↗
PubMed1981

Angiotensin inhibition in severe heart failure: acute central and limb hemodynamic effects of captopril with observations on sustained oral therapy.

The systemic, pulmonary, and limb circulatory responses to the angiotensin-converting enzyme inhibitor, captopril, were determined in 10 patients with severe, chronic heart failure. Immediate effects include sustained reductions in arterial pressure and pulmonary capillary wedge pressure and improvement in cardiac output, as reported with other vasodilator drugs. Calf vascular resistance did not change despite substantial lowering of total systemic vascular resistance, indicating that arteriolar dilatation occurred on a selective basis. Transient reduction in mean right atrial pressure paralleled slight calf venodilatation, but effects upon the resistance vasculature predominated. Plasma renin activity and norepinephrine concentrations increased after therapy in the acute phase as plasma aldosterone levels consistently fell. During maintenance oral treatment over 7 to 15 months (median, 11.5 months), patients displayed symptomatic benefit, improved functional capacity, and greater exercise tolerance. No major adverse reactions developed. These findings suggest that angiotensin converting enzyme inhibition with captopril in congestive heart failure patients improved cardiocirculatory function through selective arteriolar dilatation. The reordering of regional blood flow which appears to result from release of angiotensin-mediated vasoconstriction, as well as the suppression of aldosterone, may underlie the prolonged benefit observed in these patients. This oral vasodilator appears to represent an effective adjunct for the treatment of advanced, chronic heart failure refractory to conventional measures.

Administration, Oral↗
PubMed1981

Serial exercise testing after coronary artery bypass surgery.

To determine the duration of functional benefit from coronary bypass surgery, 111 patients with angina pectoris were serially evaluated by standard exercise testing prior to and for up to 4 years after surgery. Exercise testing 6 to 18 months after surgery showed greater heart rate-blood pressure product at peak work load, improved work capacity, and less symptomatic and electrocardiographic evidence of ischemia than was demonstrated preoperatively. Twenty patients were tested 37 to 48 months postoperatively and showed improved exercise performance in comparison with preoperative results, but the frequency of positive tests during this period no longer differed. Thus, improved exercise performance appears to persist for at least 4 years after coronary bypass surgery.

Angina Pectoris↗