Abstract 16854: Arterial Determinants of Time-varying Myocardial Stress in Humans
Background: Myocardial and arterial load are time-varying phenomena. Despite its importance in myocardial biology and function, the arterial properties that determine time-resolved myocardial wall stress have not been directly investigated.
Methods: We studied 1215 adults enrolled in the population-based Asklepios study. Time-resolved central pressure and flow were measured with carotid tonometry and Doppler echocardiography. Time-resolved short- and long-axis LV geometry was measured with speckle tracking echocardiography. Using custom-designed software, we computed arterial load, circumferential (CWS) and longitudinal (LWS) wall stress (Regen method) using time-resolved measurements.
Results: For any given end-diastolic LV cavity size and wall thickness and any given cardiac output, peak CWS correlated directly with systemic vascular resistance (SVR; Beta weight=1.07; P<0.0001) and aortic characteristic impedance (Beta weight=0.24; P<0.0001) but not with wave reflection indices. The ejection-phase CWS-time integral correlated with SVR (Beta weight=1.1; P<0.0001), lower total arterial compliance (Beta weight=-0.15; P=0.004) and earlier wave reflections (Beta weight=-0.10; P<0.0001) but not with reflection magnitude, whereas end-systolic stress was a function of SVR (Beta weight=1.06; P<0.0001) and reflection magnitude (Beta weight=0.11; P<0.0001). After adjustment for all measured arterial properties and end-diastolic LV geometry, women demonstrated greater peak (Beta weight=0.14; P<0.0001) and mean (Beta weight=0.19; P<0.0001) CWS. Findings were essentially identical for LWS and not affected by adjustments for body size.
Conclusions: Different arterial properties have selective effects on time-resolved myocardial wall stress which are not apparent from single-time-point measurements. Women appear to demonstrate less efficient myocardial-ventricular-arterial coupling (higher time-varying stress for a given output) independently of various arterial properties and end-diastolic LV geometry. These observations could provide insight into the well known differential susceptibility of women to heart failure with preserved ejection fraction.
- © 2010 by American Heart Association, Inc.