Showing papers by "David A. Kass published in 1986"

Determination of left ventricular end-systolic pressure-volume relationships by the conductance (volume) catheter technique.

Abstract: Using a multielectrode conductance catheter to estimate continuous left ventricular volume we determined the end-systolic pressure-volume relationship (ESPVR) in situ in open-chest anesthetized dogs. Dogs (n = 8) were studied in the control state and after pharmacologic sympathectomy (hexamethonium) and surgical vagotomy both before and after the administration of dobutamine. ESPVR was measured during brief (5 to 6 sec) preload reduction by balloon occlusion of the inferior vena cava (IVCBO). The relationship was highly reproducible. The slope (Ecs) and volume intercept (Vo) (mean +/- SD) in the control series were 5.8 +/- 3.6 mm Hg/ml and 6.5 +/- 12.5 ml, respectively. Upon release of the IVCBO (preload recovery), Ecs was 7.7 +/- 3.6 mm Hg/ml and Vo was 12.4 +/- 9.6 ml (p less than .01). Autonomic blockade produced a 50% reduction in Ecs and a concomitant decrease in Vo (p less than .01), and eliminated the difference between ESPVR generated by preload reduction (IVCBO) and preload recovery (IVCBO release). Subsequent dobutamine infusion increased Ecs to 6.1 +/- 3.5 mm Hg/ml and Vo to 4.1 +/- 6.9 ml, consistent with reported changes of the ESPVR with positive inotropic intervention. A small artifact of right ventricular filling was observed in the left ventricular volume catheter signal, but this did not appreciably alter the ESPVR. These results demonstrate the feasibility of the determination of ESPVR in situ by the conductance catheter and brief IVCBO and underline the importance of the use of rapid load changes to minimize reflex activation during the measurements.

End-systolic measures of regional ventricular performance.

Abstract: Dimension change measures of regional ventricular function, such as absolute or percent wall thickening (delta T or % delta T) or segmental shortening (delta L or % delta L), are highly load dependent In 16 anesthetized mongrel dogs we assessed use of the end-systolic pressure-thickness and end-systolic pressure-length relationships (ESPTR, ESPLR) as more load-independent measures of regional function We found that the ESPTR and ESPLR could be measured without detectable baroreceptor-mediated reflex changes in cardiac contractile state Systemic administration of dobutamine shifted the ESPTR to the right and the ESPLR to the left of control, mainly due to a change in the slope (Ees) of the relationships Both delta T, % delta T and delta L, % delta L failed to detect the positive inotropic effect of dobutamine because of an associated reduction in preload With systemic administration of propranolol, ESPTR, ESPLR, delta T, % delta T, and delta L, % delta L detected the negative inotropic effect Thus systemic propranolol shifted the ESPTR to the left and the ESPLR to the right of control, mainly due to a change in Ees Regional administration of dobutamine shifted the ESPTR and the ESPLR in the direction of positive contractility in the region receiving the drug, whereas simple dimension change measures of regional function failed to detect the inotropic effect because preload fell and the timing of regional end-systole was altered With regional propranolol both the ESPTR, ESPLR and simple dimension change measures detected the negative inotropic effect Thus the ESPTR, ESPLR is a reliable measure of regional ventricular function and may be better than simple dimension change measures of regional function, particularly when loading conditions or the timing of regional systole is altered by an intervention