Showing papers by "Marc A. Pfeffer published in 1978"
TL;DR: Specific ECG indices can be identified in association with the known progressive increase in left ventricular mass in SHR and should provide a better means to understand evolving ECG changes in LVH.
Abstract: Although many ECG criteria exist for diagnosis of left ventricular hypertrophy (LVH) in hypertensive man, little is known of which specific ECG changes accompany progression of LVH with duration of hypertension. The spontaneously hypertensive rat (SHR) provides the best animal model thus far developed for studying this process since these animals demonstrate a progressive increase in left ventricular/body weight ratio with age. Electrocardiograms were performed under light ether anesthesia in four age groups of SHR and two nonnotensive Wistar strains (NR and WKY). Analysis of variance for two factors (rat strain and age) revealed progressively increased QRS and P-wave duration and delay in intrinsicoid deflection in SHR (p<0.001). Bipeak P-wave notching was also noted in SHR similar to left atrial abnormality in hypertensive man. Thus, specific ECG indices can be identified in association with the known progressive increase in left ventricular mass in SHR and should provide a better means to understand ev...
34 citations
TL;DR: Ex exercised SHR had the same alterations in cardiac mass and performance as exercised normotensive rats, despite the initial presence of left ventricular hypertrophy.
Abstract: Spontaneously hypertensive rats (SHR) and two strains of normotensive Wistar rats were subjected to a 5 day/wk swimming program to determine whether the heart of the SHR could respond to an additional stimulus to cardiac growth. Swimming was tolerated well by all rats. Although body weight of the exercised groups was not significantly reduced, both the right and left ventricular weights of all exercised groups were increased. Left ventricular circumference and chamber volume were increased without a change in free wall thickness in all exercised groups. Ventricular performance was assessed by peak cardiac output and stroke volume attained during rapid intravenous volume loading, both before and after autonomic inhibition. After combined cholinergic and beta-adrenergic inhibition, all exercised rats had slower heart rates and higher peak stroke volume than respectively sedentary controls. Thus, exercised SHR had the same alterations in cardiac mass and performance as exercised normotensive rats. Despite the initial presence of left ventricular hypertrophy, the SHR responded appropriately to an additional stimulus for adaptive cardiac growth.
32 citations
TL;DR: As a result of lifelong beta-adrenergic receptor blockade, CO was reduced; and this was associated with a redistribution of blood flow so that flow to the kidney, brain, and splanchnic organs could be maintained at the expense of skeletal muslce perfusion.
Abstract: To determine quantitatively organ blood flow distribution as the result of lifelong β -adrenergic receptor blockade, 23 and 24 normotensive Wistar-Kyoto (WKY) and spontaneously hyper
27 citations