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Biomedical subjects

D C Harrison

Publications and source records attributed to D C Harrison.

At least 235 records · Page 13Linked to original sources
PubMed1975

Treadmill arrhythmias in patients with idiopathic hypertrophic subaortic stenosis.

Treadmill tests were performed in 19 patients with previously documented idiopathic hypertrophic subaortic stenosis (IHSS). Arrhythmias occurred in 79 percent (15) of the patients, and new arrhythmias not previously documented occurred in over 50 percent (10) of the patients. Paroxysmal supraventricular tachycardia (PSVT), ventricular premature beats (VPBs) (two or more per minute) or atrial premature beats (APBs) (three or more per minute) occurred in 10 of 19 patients. There was no association between treadmill arrhythmias and clinical symptoms, hemodynamic data, or electrocardiographic features. Propranolol administration resulted in failure of exercise to induce PSVT in one patient and had no effect on PSVT in two others, nor any effect on maximum frequency of APBs or VPBs. Treadmill testing is more productive than retrospective analysis of ECGs for characterizing arrhythmias in IHSS.

Adult↗
PubMed1975

Hemodynamic effects of procainamide and quinidine and the influence of beta-blockade before and after experimental myocardial infarction.

The use of antiarrhythmie drugs in combination has been limited because of possible side effects secondary to myocardial depression in the acute myocardial infarction patient. Therefore, we investigated in intact dogs (group I) the hemodynamic interaction of propranolol plus procainamide (subgroup A) or quinidine (subgroup B) and in dogs after experimental myocardial infarction produced by coronary artery ligation (group II). Infusion of procainamide (30 mg/kg over 5 min) in animals of group IA produced a significant (P less than 0.05) decrease of 30% in mean aortic pressure, a decrease of 40% in left ventricular dp/dt and 29% in cardiac output. When procainamide was reinfuse after propranolol (1 mg/kg), its hemodynamic effects were not significantly different from those observed before propranolol in both groups IA and IIA. Infusion of quinidine (10 mg/kg over 5 min) in animals of group IB (intact dogs) also produced significant decreases of 24% in mean aortic pressure and 38% in dp/dt while cardiac output was unchanged. However, these hemodynamic changes were seen only after beta-blockade and were significantly different from those obtained before propranolol, where heart rate increased by 14%, dp/dt by 30%, and cardiac output by 35%. These changes occurred despite a similar reduction in mean aortic pressure. This drug combination produced similar response in animals after coronary artery ligation (group IIB). In conclusion, we feel that the administration of propranolol does not prevent the depressive circulatory effects of procainamide. The combined use of quinidine and propranolol also has a negative circulatory effect although not as marked as the effects observed after procainamide with propranolol.

Adrenergic beta-Antagonists↗
PubMed1975

Changes in survival and symptom relief in a longitudinal study of patients after bypass surgery.

The first 350 patients having coronary surgery at Stanford Medical Center (excluding patients with aneurysmectomy or valve replacement) have been followed sequentially utilizing a computer-based information system. Our experience spans 72 months (900 patient-years), with an average follow-up of 30 months. Hospital mortality was 4.9%. Actuarial analysis revealed survival of 91% at 1 year and 80% at 6 years. Forty patients (11.5%) had 43 late myocardial infarctions, of which 5 were fatal. Analyses of selected patient subgroups revealed significantly poorer survival in patients with prior myocardial infarction (P less than 0.05), significant congestive heart failure, or mitral regurgitation (P less than 0.01). Survival in multigrafted (and multivessel) patients was not significantly different from survival in single-grafted (predominantly single-vessel) patients. Actuarial studies suggest improved survival in patients with multivessel disease after coronary artery surgery. Between an initial evaluation at 9 months postoperatively (range: 2 to 40 months) and the most recent evaluation after 30 months (range: 6 to 72 months), 13% of patients showed further clinical improvement, 47% were unchanged, while 40% deteriorated with respect to chest pain. We conclude that initial symptomatic benefits may not be maintained in late follow-up studies owing to progression of underlying vascular disease.

Adult↗
PubMed1975

Evaluation of portable radionuclide method for measurement of left ventricular ejection fraction and cardiac output.

Seventeen patients with coronary artery, valvular, or myopathic heart disease were studied to determine correlations of the cardiac output and ejection fraction when comparing the results obtained with a portable probe technique using 113mIn with those obtained with standard methods (cineangiographic, Fick, and dye dilution). With ejection fractions ranging from o.10 to 0.85, the coefficient of correlation was 0.90 when comparing cineangiographic and radionuclide techniques. Cardiac output determinations by the radionuclide technique also correlated well with standard methods (r equals 0.88). The radionuclide method shows promise as an accurate, safe, and simple method in the evaluation of cardiac function at the bedside.

Angiocardiography↗
PubMed1975

Ventricular arrhythmias during unstable angina pectoris.

In order to study the occurrence and frequency of ischemia-induced ventricular arrhythmias, we analyzed 105 episodes of spontaneous angina pectoris occurring at rest in 28 hospitalized patients with unstable angina pectoris and proved coronary artery disease. Of 24 patients with serious ventricular arrhythmias during pain, 17 (57%) were arrhythmia-free during monitoring. In the other four patients, 17 of 29 (59%) pain episodes were associated with serious ventricular arrhythmias, and three of these four had serious ventricular arrhythmias during pain-free periods. Each patient tended to manifest the same type of arrhythmia during repeat episodes of pain. It appears that continuous electrocardiogram (ECG) monitoring is important during the initial hospitalization of the patient with unstable angina. The presence of ventricular arrhythmias during pain-free periods indicates a high risk for serious ventricular arrhythmias during episodes of spontaneous pain. These patients should be considered for continued ECG monitoring and antiarrhythmic therapy.

Adult↗
PubMed1975

Comparative hemodynamic responses to chlorpromazine, nitroprusside, nitroglycerin, and trimethaphan immediately after open-heart operations.

The hemodynamic effects of intravenous chlorpormazine, nitroprusside, nitroglycerin, and trimethaphan camsylate were studied in 51 patients with high mean arterial pressures immediately after open-heart operations. Chlorpromazine was given by bolus intravenous injection to 24 patients (average dose 10.3 mg); nitroprusside (17 patients), nitroglycerin (8 patients), and trimethaphan (12 patients) were administered by constant intravenous infusion at average doses of 77 mug/min, 59 mug/min, and .097 mg/min, respectively. Measured or derived variables included right atrial pressure, pulmonary artery pressure, left atrial pressure, systemic arterial pressure, heart rate (HR), cardiac index (CI), stroke index (SI), stroke work index (SWI), and systemic vascular resistance index (SVRI). All four vasodilators significantly reduced systemic and intracardiac pressures and SWI (P less than 0.01). Associated changes in left ventricular pumping performance, however, differed importantly between groups. Chlorpromazine caused a significant rise (+19%) in HR with preservation of SI; thus, CI rose significantly (P less than 0.01). Only nitroprusside, however, resulted in enhancement of SI (P less than 0.05) at the lowered left atrial pressure; CI increased by 19% (P less than 0.01), HR rose minimally (6.5%), and calculated SVRI diminished 33% (P less than 0.01). Both nitroglycerin and trimethaphan caused decreases in SI and CI. These results indicate that in general, among the vasodilators studied, nitroprusside is associated with the most favorable hemodynamic responses in early postoperative cardiac surgical patients.

Blood Pressure↗
PubMed1974

Physiological distribution of digoxin in human heart.

Using the recipient's human heart removed at cardiac transplantation, the distribution of digoxin at both the cellular and subcellular level has been studied. In the presence of diffuse histological myocardial abnormalities tissue digoxin is decreased, but the subcellular distribution, presumably reflecting binding to a possible receptor site, is uniform. When the histological abnormality is focal then digoxin distribution is uniform.These results suggest that in the presence of myocardial ischaemia plasma digoxin concentrations may not reflect total myocardial levels accurately.

Adenosine Triphosphatases↗