The electrocardiogram in asymmetric septal hypertropy.

Electrocardiograms and echocardiograms in 44 patients with asymmetric septal hypertrophy were reviewed. Patients with asymmetric septal hypertrophy had incidences of left ventricular hypertrophy (33 percent; 16/44) and left atrial hypertrophy (25 percent; 11/44) by ECG that were less than in a group of patients with significant aortic stenosis (70 percent [31/44] and 64 percent [28/44], respectively). Left ventricular hypertrophy on the ECG was associated with a greater septal-posterior wall thickness ratio in asymmetric septal hypertrophy.

Alteration in heart rate response to hemorrhage in conscious dogs with volume overload.

The heart rate response to hemorrhage was studied in conscious dogs before and up to 2 mo after the establishment of volume overload due to systemic arteriovenous (a-v) fistulas. Before a-v fistula, heart rate increased markedly during hemorrhage. When hemorrhage was preceded by dextran infusion, bleeding resulted in a gradual reduction in heart rate.

Diastolic left ventricular pressure-volume and stress-strain relations in patients with valvular aortic stenosis and left ventricular hypertrophy.

Left ventricular (LV) chamber and myocardial stiffness were determined in 17 patients, four subjects with normal LV function and 13 subjects with valvular aortic stenosis and concentric myocardial hypertrophy, using simultaneous catheter micromanometry and LV cineangiography. Pressure (P), volume (V), and wall thickness (h) were measured. Variability in both chamber and myocardial stiffness parameters was found with five of the aortic stenosis patients (Group 1, left ventricular end-diastolic pressure = 15 +/- 2 (SEM) mm Hg) exhibiting normal values for end-diastolic dP/dV and dP/dV/V, for chamber stiffness constants (a,a') derived from P-V and normalized P-V relations, respectively, for end-diastolic myocardial elastic stiffness (ES or EE, where S = spherical model and E = ellipsoidal model) at the midwall of the minor axis circumference, and for the myocardial stiffness constants (KS or KE) of the circumferential stress-strain relation.

Right ventricular ejection fraction in patients with acute anterior and inferior myocardial infarction assessed by radionuclide angiography.

We measured right and left ventricular ejection fracttion (EF) from high frequency time-activity curves obtained during the initial passage of an intravenous bolus of 99mTc (Sn) pyrophosphate. In 22 normal controls right ventricular EF averaged 0.52 +/- 0.

Comparison of left ventricular free wall and septal diastolic compliance in the dog.

Septal to free wall dimensions are frequently employed for the analysis of diastolic compliance. However, the diastolic properties of these anatomically distinct regions of left ventricle are not well characterized. Regional compliance was studied in eight open-chest anesthetized dogs.

Effects of oral equiblocking doses of a cardioselective and noncardioselective beta-adrenergic blocking agent on left ventricular function in the normal conscious dog.

The effects of propranolol, a noncardioselective beta-adrenergic blocking agent, and practolol, a cardioselective agent, on left ventricular function were compared in an awake dog model at an equiblocking dose range. Both agents produced modest depression of inotropic state at rest, and during volume and phenylephrine loading. No significant differences between the two agents were detected.

Pharmacologic and hemodynamic influences on the rate of isovolumic left ventricular relaxation in the normal conscious dog.

We studied the effects of acute pharmacologic and hemodynamic interventions on isovolumic left ventricular relaxation in 19 conscious dogs using micromanometer tip catheters. Isoproterenol (11 studies) augmented peak rate of rise of left ventricular pressure [(+) dP/dt] by 1,275+/-227 (SE) mm Hg/s (P < 0.001) and dP/dt at an isopressure point of 35 mm Hg during isovolumic relaxation [(-) dP/dt(35)] by 435+/-80 mm Hg/s (P < 0.

The effects of oral propranolol, digoxin and combination therapy on the resting and exercise electrocardiogram.

The effects of propranolol, digoxin and combination therapy (/D) on the resting and exercise ECG were studied in ten normal subjects and 20 patients with coronary artery disease (CAD) given a sequence of oral placebo, propranolol, P/D, digoxin and placebo, for two week periods. Digoxin produced a significant decrease in T-wave amplitude and often resulted in ST segment depression in the resting ECG. Propranolol, digoxin, and P/D tended to decrease the QTc interval and prolong the PR interval.

Regional shortening patterns in canine right ventricle.

The right ventricular outflow tract (OT) is a functionally distinct area of the right ventricle. However, there is little information on the contrdingly, inflow tract (IT) and OT chords and right ventricular free wall segmental changes were measured with implanted ultrasound crystals. The timing and extent of shortening of IT and OT chords and free wall segments were determined both at rest and after stellate ganglion stimulation.

Combined propranolol and digoxin therapy in angina pectoris.

The effects of oral propranolol and digoxin and digoxin alone and in combination on angina frequency, heart size, systolic time intervals and treadmill exercise tolerance, were assessed in 20 patients with coronary heart disease. Oral propranolol alone reduced the average frequency of angina pectoris from 16 to 7 attacks per week (P less than 0.02).

Functional evaluation of the porcine heterograft in the mitral position.

In vivo function of glutaraldehyde-fixed porcine heterografts used for mitral valve replacement was evaluated by cardiac catheterization in 14 of our first 33 patients who have undergone mitral valve replacement with this prosthesis. Diastolic gradients were present in each patient. Average mean diastolic gradient was 6.

Regional differences in myocardial performance in the left ventricle of the dog.

To determine whether significant regional differences in shortening exist in the canine left ventricle, the shortening characteristics of small segments of the circumferentially oriented hoop axis fibers and the more longitudinally oriented fibers near the epicardium were examined using pairs of ultrasound crystals placed at three levels of the left ventricular free wall in the open-chest dog. Mean control shortening of the hoop axis fibers near the apex of the left ventricle averaged 20% of the end-diastolic length, significantly greater than shortening at the midventricular (13%) or basal (14%) levels. During transient periods of aortic constriction, end-diastolic length increased significantly and the extent of shortening was maintained for the hoop axis fibers at the apical and midventricular levels; end-diastolic length did not change and shortening decreased at the basal level.

Effects of oral propranolol in normal subjects.

The effects of oral propranolol were evaluated in 10 normal volunteers. The resting heart rate decreased from the mean control value of 68 plus or minus 3.3 (SE) to 56 plus or minus 2.