Skin‐surface cooling increases left‐ventricular preload but not contractility in older humans

Abstract

Skin‐surface cooling acutely increases arterial blood pressure, left‐ventricular (LV) afterload, and myocardial oxygen demand. To determine whether skin surface cooling increases LV preload and contractility more in older than in young adults, we measured indices of LV preload and myocardial contractility using standard and tissue‐Doppler imaging (TDI) echocardiography in 6 young (23 ?1 yrs; mean ?SE) and 6 older (65 ?3 yrs) adults during normothermia (35° C water perfused through a tube‐lined suit) and skin‐surface cooling (15‐18° C water perfused for 20 min). Cooling increased LV end‐diastolic volume (EDV, from 98±1 to 108±1 ml, P<0.001) and LV internal diameter in diastole (IDd, from 4.61±0.03 to 4.77±0.03 cm, P<0.01) in older, but not young adults (EDV=101±1 and 99±1 ml, IDd=4.67±0.03 and 4.62±0.03 cm, for normothermia and cooling, respectively). In contrast LV ejection fraction and TDI myocardial functional indices (myocardial acceleration during contraction and peak velocities during systole and diastole) were unchanged by cooling in both young and older adults. These data indicate that skin surface cooling acutely increases LV preload, without influencing LV contractility in older, but not young adults. Increases in LV preload and afterload likely contribute to greater increases in myocardial oxygen demand during cold exposures in older than in young adults.Support: NIH AG24420 and M01 RR10732