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Biomedical subjects

R C Bahler

Publications and source records attributed to R C Bahler.

At least 37 records · Page 2Linked to original sources
PubMed1983

The relation of heart rate and shortening fraction to echocardiographic indexes of left ventricular relaxation in normal subjects.

To determine the relation of heart rate and systolic function to echocardiographically derived indexes of left ventricular relaxation, M-mode echocardiograms of the left ventricle and mitral valve with a simultaneous phonocardiogram were recorded at rest from 28 normal men. The effects of altering the inotropic state and ventricular loading conditions were examined during isometric handgrip exercise and the Valsalva maneuver in a subset of 15 men. The left ventricular endocardial echocardiograms were digitized to provide a display of left ventricular internal dimension and its first derivative (dD/dt). The time course of relaxation, defined as the interval from left ventricular minimal systolic dimension to the point when the rate of change of dimension (dD/dt) decreased to 50% of peak, was directly related to the RR interval (r = 0.64, p less than 0.0001) in the entire group, and this relation remained throughout the interventions. The slopes of the regression lines of relaxation time (RT) and electromechanical systole (QS2) on the RR interval were similar. Diastolic time decreased proportionately more than relaxation time as the RR interval decreased, so that the proportion of diastole occupied by the relaxation time varied with cycle length. Peak diastolic dD/dt, normalized for variations in end-diastolic dimensions [( dD/dt]/D), was directly related to left ventricular shortening fraction (r = 0.71 p less than 0.0001) and this relation remained during isometric grip. There was no correlation between the heart rate at rest and (dD/dt)/D over the range of 44 to 99 beats/min.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1982

Ultracentrifugal study of metabolic effects of probucol: plasma lipoproteins in patients with proven coronary artery disease.

The primary metabolic effect of probucol is characterized by significant lowering of plasma low-density lipoproteins (LDL2) (p less than 0.01), frequently connected with a decrease in concentration of very-low density lipoproteins (VLDL) (p less than 0.05). This main effect is correlated (r = 0.84-0.75) with a decrease of chylomicrons (CHY) and macromolecular very, very-low density lipoproteins (VVLDL). High density lipoproteins (HDL2,3) tended to decrease in the majority of cases, although a restoration of their levels was observed after the therapy. The strong significance of probucol's lowering action of LDL2 does not statistically relate to any other metabolic phenomenon, confirming its relative independence on remaining pathways.

Adsorption↗
PubMed1980

Lipoproteins in patients with proved coronary artery disease: qualitative and quantitative changes in agarose-gel electrophoretic patterns.

The relationship between the configuration of agarose-gel lipoprotein electrophoresis patterns and the extent of coronary artery disease (CAD) was studied in consecutive patients undergoing diagnostic coronary angiography. Three groups were identified: patients with normal coronary arteries (group 1), patients with minor luminal irregularities (group 2) and patients with significant coronary artery obstructions (group 3). Densitometric scans of the electrophoretograms were studied to determine the relative proportion of lipoproteins in each major fraction and the configuration of the pre-beta complex. The presence of multiple subfractions within the pre-beta lipoprotein complex had a sensitivity of 66% for the presence of CAD and a specificity of 99%. A decreased level of alpha 1 lipoproteins, defined as less than 25% of total lipoproteins, occurred almost entirely in groups 2 and 3, whereas an increased level (greater than or equal to 28%) of pre-beta lipoproteins was less specific for CAD. The proportions of alpha and pre-beta lipoproteins were inversely related (r = 0.677). Although abnormalities of serum cholesterol and/or triglycerides were common in groups 2 and 3, the detailed study of lipoprotein patterns provided a more sensitive index of disordered lipoprotein metabolism. The angiographic severity of CAD was significantly related to age and to levels of serum triglycerides, alpha 1 lipoproteins, and pre-beta lipoproteins. The lipoprotein electrophoretogram, in conjunction with serum lipid levels, is a valuable tool for demonstrating abnormalities of lipoprotein metabolism associated with CAD.

Adult↗
PubMed1979

Vectorcardiographic detection of early hemodynamic abnormalities in chronic obstructive pulmonary disease.

The ability of the vectorcardiogram to detect mild circulatory abnormalities in patients with chronic obstructive pulmonary disease (COPD) is unclear. Therefore, vectorcardiographic changes were correlated with hemodynamic measurements made at rest and during supine exercise in 32 patients with COPD and no clinical or electrocardiographic evidence of right ventricular hypertrophy. Twelve patients had normal hemodynamic data (group 1), nine had abnormal hemodynamic data only during exercise (group 2), and 11 had abnormal hemodynamic data at rest and during exercise (group 3). The extent of rightward terminal QRS forces noted on the vectorcardiogram was significantly less in group 1 (5.5 +/- 8.7 percent) than in either group 2 (19.0 +/- 10.7 percent) or group 3 (17.8 +/- 14.8 percent). Sixty-five percent (13) of the 20 patients with hemodynamic abnormalities had rightward terminal QRS forces of 15 percent or more, whereas only 8 percent (one) of the 12 patients with normal hemodynamic data had such forces of 15 percent or more. The mean of the rightward terminal QRS forces in 27 age-matched normal subjects was 5.0 +/- 5.4 percent, and only one subject had forces of 15 percent or more. We conclude that hemodynamic abnormalities are frequent in patients with COPD and no clinical evidence of right ventricular hypertrophy and that the vectorcardiogram provides an indirect method of detecting these abnormalities.

Adult↗
PubMed1977

Postexercise systolic time intervals in the midsystolic click syndrome.

Postexercise systolic time intervals (STI) were measured in ten patients (PMV group) with auscultatory evidence of the midsystolic click syndrome (i.e. one or more systolic nonejection clicks alone or in association with the late systolic murmur), and compared to eight age-matched volunteers (control group) with no evidence of heart disease. Following measurement of supine STIs, the subjects pedalled an upright bicycle ergometer at progressive work loads until a target heart rate (HR) representing 85% of the age-adjusted maximum was attained, or an abnormal end point was noted. Immediately postexercise, a repeat measurement of STIs, was obtained. A shortened or unchanged postexercise left ventricular ejection time corrected for HR (deltaLVETc) and a marked shortening of total electromechanical systole after exercise (deltaQS2c) constituted a normal STI response to stress testing and was noted in all control subjects. All of the PMV group exhibited evidence of left ventricular dysfunction characterized by a prolonged deltaLVETc. It is concluded that an abnormal STI response to exercise consistent with left ventricular dysfunction can be demonstrated in patients with prolapse of the mitral valve by the response of the STI.

Adolescent↗
PubMed1977

Multidisciplinary treatment of chronic pulmonary insufficiency. 3. The effect of physical training on cardiopulmonary performance in patients with chronic obstructive pulmonary disease.

We examined the effect of physical training on cardiopulmonary function in 21 patients with chronic obstructive pulmonary disease and compared the results with similar observations in eight untrained patients. The training consisted of daily walking on a treadmill at increasing speeds and grades and other graded physical exercises. Evaluation of pulmonary function, including spirometric studies, lung volumes, and arterial blood gas levels, showed no significant change after training. Hemodynamic functions, including heart rate, cardiac index, stroke index, pulmonary vascular resistance, and arteriovenous oxygen content difference, were similarly unchanged at comparable submaximal loads. Pulmonary arterial wedge pressure increased after training in the treated group at rest and during exercise, but this may be related to changes in respiratory mechanics. Consumption of oxygen and minute ventilation decreased in the treated group during treadmill exercise, suggesting improved neuromuscular coordination and efficiency of walking on the treadmill. Total work performed on the treadmill increased significantly in the trained group. This increase was unexplained by physiologic observations but was thought to be due in part to increased efficiency of walking and increased motivation. We conclude that improvement in the capacity for exercise following physical training for four weeks is not associated with improvement in cardiopulmonary function at submaximal exercise.

Blood Pressure↗
PubMed1977

Multidisciplinary treatment of chronic pulmonary insufficiency. 4. The influence of intrathoracic pressure variations on increases in pulmonary vascular pressure during exercise in patients with chronic obstructive pulmonary disease.

In the present era of direct monitoring of pressure in patients with chronic obstructive pulmonary disease (COPD), an appreciation of all factors that may influence the observed pulmonary vascular pressures is essential. Our study examines the impact of respiratory variations in intrathoracic pressure on the recorded pulmonary vascular pressures in 28 patients with COPD. Althouth pulmonary hypertension was present in only nine subjects at rest, all had an abnormal increase in the mean pulmonary arterial pressure during supine exercise. In 15 subjects, this abnormal response was, in part, related to an increase in pulmonary arterial wedge pressure to 15 mm Hg or more. The increase in pulmonary arterial wedge pressure was directly related to the amplitude of the peak-to-peak respiratory variation of such wedge pressure. This variation correlated with the specific airway resistance but was not related to the arterial oxygen pressure or pulmonary vascular resistance. These findings indicate the important influence of exaggerated respiratory effort on the measurement of pulmonary arterial wedge pressure and mean pulmonary arterial pressure in patients with chronic obstructive pulmonary disease.

Airway Obstruction↗
PubMed1976

Left axis deviation: diagnostic contribution of stress testing and post-exercise systolic time intervals.

The response to graded submaximal upright bicycle ergometry combined with resting and postexercise systolic time intervals (STIs) was investigated in ten ambulatory subjects (study group) with normal electrocardiograms except for a frontal plane axis of greater than or equal to -30 degrees, or left axis deviation (LAD) mean -40 degrees); and eight age-matched volunteers (control group) with a normal ECG and frontal plane axis (mean +35 degrees). Following a 12-lead resting ECG, supine STIs were measured. The subjects then exercised on a bicycle ergometer at progressive workloads with ECG and blood pressure monitoring until a heart rate based on 85 percent of tha age-predicted maximum was attained or an abnormal end point was noted. STIs were repeated immediately postexercise. Prolongation of left ventricular ejection time corrected for heart rate (LVETc) of 8 msecs or more from rest to post-exercise. (deltaLVETc) was considered an abnormal STI response. The deltaLVETc can elicit left ventricular dysfunction and possible latent organic heart disease in patients with isolated left axis deviation.

Adult↗
PubMed1975

Cardia venous blood flow in atrial pacing versus exercise-induced angina pectoris.

Thirteen patients with angina pectoris underwent measurements of great cardiac vein blood flow at rest, with the onset of angina pectoris induced by atrial pacing, and again during angina pectoris induced by exercise in order to compare the regional coronary blood flow response to differing myocardial stresses. All patients had significant obstructions of the left anterior descending artery. Exercise-induced angina, compared to pacing-induced angina, was associated with a higher systolic pressure, higher left ventricular end-diastolic pressure, and a lower heart rate. Indices of myocardial oxygen demand, that is, the systolic pressure-heart rate product and the tension-time index, increased to a similar degree during both types of myocardial stress and great cardiac vein blood flow paralleled these changes. We conclude that in a given patient the level of regional coronary blood flow is similar at the onset of either pacing- or exercise-induced angina, despite significant differences in the hemodynamic response to these myocardial stresses.

Adult↗
PubMed1975

Prolapsed mitral valve associated with the Holt-Oram syndrome.

The association of hypoplastic thumb and atrial septal defect, (Holt-Oram syndrome) with a prolapsed mitrial valve is described. Recognition of this association adds further support to the concept that the prolapsed mitrial valve syndrome is not necessarily an isolated cardiac disorder but may be part of a more generalized heritable disorder of connective tissue.

Abnormalities, Multiple↗