Abnormalities in arterial-ventricular coupling in older healthy persons are attenuated by sodium nitroprusside

Abstract

The coupling between arterial elastance ( EA; net afterload) and left ventricular elastance ( ELV; pump performance), known as EA/ ELV, is a key determinant of cardiovascular performance and shifts during exercise due to a greater increase in ELV versus EA. This normal exercise-induced reduction in EA/ ELV decreases with advancing age. We hypothesized that sodium nitroprusside (SNP) can acutely ameliorate the age-associated deficits in EA/ ELV. At rest and during graded exercise to exhaustion, EA was characterized as end-systolic pressure/stroke volume and ELV as end-systolic pressure/end-systolic volume. Resting EA/ ELV did not differ between old (70 ± 8 yr, n = 15) and young (30 ± 5 yr, n = 17) subjects because of a tandem increase in EA and ELV in older subjects. During peak exercise, a blunted increase in ELV in old (7.8 ± 3.1 mmHg/ml) versus young (11.4 ± 6.5 mmHg/ml) subjects blunted the normal exercise-induced decline in EA/ ELV in old (0.25 ± 0.11) versus young (0.16 ± 0.05) subjects. SNP administration to older subjects lowered resting EA/ ELV by 31% via a reduction in EA (10%) and an increase in ELV (47%) and lowered peak exercise EA/ ELV (36%) via an increase in ELV (68%) without a change in EA. Importantly, SNP attenuated the age-associated deficits in EA/ ELV and ELV during exercise, and at peak exercise EA/ ELV in older subjects on drug administration did not differ from young subjects without drug administration. In conclusion, some age-associated deficiencies in EA/ ELV, EA, and ELV, in older subjects can be acutely abolished by SNP infusion. This is relevant to common conditions in older subjects associated with a significant impairment of exercise performance such as frailty or heart failure with preserved ejection fraction.