Effect of increasing heart rate in patients with aortic regurgitation. Effect of incremental atrial pacing on scintigraphic, hemodynamic and thermodilution measurements.

This study was performed to assess the effect of pacing-induced tachycardia in patients with aortic regurgitation. In 12 patients (5 men and 7 women with a mean age of 53 years) with aortic regurgitation, left ventricular end-diastolic and end-systolic volume indexes were measured with multigated equilibrium blood pool imaging, and forward cardiac index was determined with thermodilution, both at rest (mean heart rate +/- standard deviation 72 +/- 8 beats/min) and during atrial pacing at 100 and 120 beats/min. Pacing caused a decremental reduction in left ventricular end-diastolic and end-systolic volume indexes and radionuclide-determined stroke volume index but no change in radionuclide-determined cardiac index or left ventricular ejection fraction.

Oral verapamil for paroxysmal supraventricular tachycardia: a long-term, double-blind randomized trial.

The effectiveness and safety of orally administered verapamil was tested in 11 patients with frequent paroxysmal supraventricular tachycardia. In a 4-month randomized, double-blind, placebo-controlled trial, the frequency of paroxysmal supraventricular tachycardia fell from 0.3 +/- 0.

The myocardial oxygen supply/demand ratio in patients with and without coronary artery disease.

This study was performed to assess the relationship between coronary sinus blood flow (by thermodilution) and myocardial oxygen demand (heart rate-systolic arterial pressure double product) during atrial pacing in patients with and without coronary artery disease. In 11 individuals with coronary artery disease, pacing was performed to ischemia, as reflected by electrocardiographic changes or lactate production; 8 patients without coronary artery disease served as controls. Coronary sinus blood flow (in ml/min) was similar for the two groups at rest.

Continuous electrocardiographic monitoring in patients with unstable angina pectoris: Identification of high-risk subgroup with severe coronary disease, variant angina, and/or impaired early prognosis.

We assessed the value of two-channel Holter monitoring during the initial hours of hospitalization in patients with unstable angina pectoris (UAP) to identify those with severe coronary artery disease (CAD), variant angina, and/or poor prognosis over the next 3 months. Accordingly, 116 UAP patients had Holter monitoring for 27 +/- 7 (mean +/- SD) (range 12 to 50) hours following hospitalization. Of these, 24 evolved myocardial infarction (MI) during monitoring and 92 did not.

Effects of systemic hypertension on ischemic and nonischemic regional left ventricular function in awake, unsedated dogs after experimental coronary occlusion.

Hypertension and atherosclerotic coronary arterial obstruction frequently coexist in patients. However, the effect of increased aortic pressure on ischemic segmental dysfunction is not well understood. We studied the effects of aortic pressure increases on segmental left ventricular function during myocardial ischemia.

Prostaglandins and ischemic heart disease.

There is an abundance of information suggesting that prostaglandins are involved in the development and clinical expression of atherosclerosis. Many studies demonstrate a relationship between prostaglandins and the risk factors for peripheral and coronary artery disease. Thus, part of the mechanism by which hyperlipidemia, diabetes mellitus, smoking, hypertension, sex hormones, age, heredity, emotional stress and diet contribute to the development and progression of atherosclerosis may be through an imbalance between thromboxane A2 and prostaglandin I2.

Evaluation of postextrasystolic T wave alterations in identification of patients with coronary artery disease or left ventricular dysfunction.

This study was performed (1) to assess the value of postextrasystolic T wave alterations in identification of patients with cardiac disease and (2) to determine if their frequency depends on length of compensatory pause. In 52 patients a pacing catheter was placed in the right ventricular (RV) apex, and premature beats were programmed to occur 30 msec beyond RV refractory period. Postextrasystolic T wave alterations occurred in 32 patients, 13 with an 19 without coronary artery disease (CAD) (NS).

Double-blind, randomized, placebo-controlled comparison of propranolol and verapamil in the treatment of patients with stable angina pectoris.

This study was performed to compare the relative efficacies of propranolol and verapamil in patients with stable angina pectoris. In 18 patients (16 men, two women, mean age 58 years) with coronary artery disease and angina of effort, the results of low (40 mg every 6 hours) and high-dose (80 mg every 6 hours) propranolol therapy were compared to those of low (80 mg every 6 hours) and high-dose (120 mg every 6 hours) verapamil therapy in a double-blind, randomized, placebo-controlled evaluation which lasted eight weeks: two weeks of placebo therapy, two weeks of propranolol or verapamil (one week low-dose, one week high-dose) therapy, three days of down-titration followed by one week of placebo therapy, two weeks of propranolol or verapamil therapy (whichever was not given earlier in the trial) (one week low-dose, one week hgh-dose) and three days of down-titration. During each period the following were quantitated: (1) chest pains/week; (2) nitroglycerin used/week; (3) transient ischemic S-T segment deviations and highest grade of ventricular ectopic activity on two-channel Holter monitor; (4) S-T segment deviations during supine bicycle exercise; (5) left ventricular volumes and ejection fraction at rest and during exercise (assessed by equilibrium gated blood pool scintigraphy); and (6) pulmonary function studies.

Evolution of epicardial R wave voltage following experimental coronary artery occlusion: effects of hyaluronidase.

The goals of this investigation were: 1) to examine the pattern of evolution of epicardial R wave voltage during the 24 h after experimental coronary artery occlusion; and 2) to determine whether hyaluronidase, an agent shown previously to reduce myocardial ischaemic injury, alters this evolution. Coronary artery occlusion was performed in 36 dogs. In the control dogs, the average R wave voltage (R) recorded over the ischaemic myocardium increased by 7.

Effect of oral propranolol on rest and exercise left ventricular ejection fraction, volumes, and segmental wall motion in patients with angina pectoris. Assessment with equilibrium gated blood pool imaging.

The effect of oral propranolol on left ventricular ejection fraction, left ventricular volumes, cardiac output, and segmental wall motion was assessed with multigated blood pool imaging both at rest and during supine exercise in 15 patients with angina pectoris. Propranolol had no effect on resting left ventricular ejection fractions. Before propranolol, they did not change during exercise, whereas after propranolol the ejection fractions increased slightly.

Effect of various degrees of systemic arterial hypertension on acute canine myocrdial ischemia.

There is continuing uncertainty about the effects of various degrees of systemic arterial hypertension on myocardial ischemia. In 46 open-chest anesthetized dogs, intramural carbon dioxide tension (PmCO2) was measured directly with a mass spectrometer during repetitive 10-min coronary artery occlusions separated by 45-min periods of reflow. During each occlusion, transmural regional myocardial blood flow (RMBF) in the ischemic area was quantitated with the injection of radioactive microspheres (7-10 micrometers diam).

Effect of verapamil and nifedipine on left ventricular function at rest and during exercise in patients with Prinzmetal's variant angina pectoris.

To assess the effects of verapamil and nifedipine on left ventricular function at rest and during exercise in patients with Prinzmetal's variant angina pectoris, 10 patients (6 men and 4 women with a mean age of 52 years) with variant angina were each treated for 2 months periods with placebo, verapamil (400 +/- 80 mg/day, mean +/- standard deviation [SD]) and nifedipine (82 +/- 31 mg/day). During the final week of each 2 month treatment period equilibrium gated blood pool scintigraphy was performed at rest and during exercise. At rest, heart rate during verapamil therapy was lower than during treatment with nifedipine; systolic blood pressure and left ventricular volumes and ejection fraction were similar for the three interventions.

Verapamil administration in variant angina pectoris. Efficacy shown by ecg monitoring.

Six patients with Prinzmetal's variant angina were treated with oral verapamil administration. Before and after the initiation of therapy, ambulatory ECG monitoring was performed to assess objectively the response to therapy. With verapamil administration, the frequency of both chest pain and transient ST-segment deviations was sharply diminished.

Direct measurement of cardiac output by gated equilibrium blood pool scintigraphy: validation of scintigraphic volume measurements by a nongeometric technique.

A nongeometric technique for the determination of left ventricular volumes from the count data derived from gated equilibrium blood pool scans was previously described and validated by the demonstration of an excellent correlation between the derived data and angiographically determined left ventricular volumes. To provide a further prospective evaluation of this method and to validate its ability to determine stroke volume and cardiac output by a technique that is itself independent of geometric assumptions, simultaneous measurements of cardiac output by the thermodilution technique and gated scintigraphy were performed in 21 patients without valve regurgitation or intracardiac shunts. To substantiate the reliability of scintigraphic measurements at high levels of cardiac output, seven patients had multiple measurements of cardiac output at rest and during an infusion of isoproterenol.

The role of coronary arterial spasm in ischemic heart disease.

With the arteriographic demonstration of coronary arterial spasm, fundamental questions have been raised concerning the role of spasm in myocardial ischemia and infarction. It is now clear that coronary arterial spasm is the cause of Prinzmetal's variant angina pectoris in patients with and without coronary atherosclerosis. In most patients with coronary heart disease, major ischemic events frequently result from increased myocardial oxygen demand or coronary thrombosis.

A controlled trial of verapamil for Prinzmetal's variant angina.

To assess the efficacy and safety of verapamil in variant angina pectoris, we entered 16 patients in a double-blind, randomized trial of nine months, duration. During treatment with verapamil, the frequency of angina fell substantially (12.6 +/- 25.

Release of prostaglandins and thromboxane into the coronary circulation in patients with ischemic heart disease.

Endogenous modulators of platelet aggregability and vascular tone may play a part in coronary-artery disease. We therefore measured the release of prostaglandins and thromboxane into the coronary circulation in patients with various kinds of cardiac disease. Simultaneous coronary-sinus (CS) and ascending-aortic (AO) blood samples were obtained from 60 patients for measurement of 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha, a prostaglandin I2 metabolite) and of thromboxane B2 (TxB2).

The effect of nitroglycerin and nitroprusside on intramural carbon dioxide tension during acute experimental myocardial ischemia in dogs.

There is continuing controversy over the effects of nitroglycerin and nitroprusside on myocardial ischemia. In 36 open-chest, anesthetized dogs with normal left ventricular filling pressures, intramural carbon dioxide tension (PmCO2) was measured directly with a mass spectrometer during repeated 10-minute coronary artery occlusions separated by 45-minute periods of reflow. Simultaneously, regional myocardial blood flow (RMBF) in the ischemic area was quantified by the microsphere technique.

Effect of selective coronary arteriography on left ventricular volumes and ejection fraction in man.

This study was performed to assess the influence of selective coronary arteriography on left ventricular volumes and ejection fraction in man. In 30 patients with assorted cardiac diseases, left ventricular end-diastolic and end-systolic volumes and ejection fraction were quantitated immediately before and after selective coronary arteriography. In 19 patients (Group A), contrast left ventriculography was performed immediately before and after selective coronary arteriography.

Marked thrombosis and calcification of porcine heterograft valves.

Prosthetic valvular dysfunction resulting in clinically significant complications occurred in six patients with Hancock porcine heterografts. In one patient with a prosthetic valve in the aortic position, massive prosthetic thrombosis resulted in sudden death. In two patients who had a mitral prosthesis, thrombosis resulted in congestive heart failure and systemic embolization; in one of the latter patients, the thrombi were infected with Candida sp.