Abstract 1756: Determination of the Mechanism of Elevated Left Ventricular Filling Pressures with Exercise: A Simultaneous Echocardiographic-Catheterization Study
Background: Exercise normally enhances LV relaxation with minimal change in filling pressure (P). We hypothesize that exercise in hypertensive (HTN) patients increases LV diastolic P through a direct effect on relaxation and ventricular-vascular coupling.
Methods: Patients (n=21) with HTN, normal EF, and no coronary disease underwent simultaneous micromanometer LV P and echo-Doppler measurements at rest and with low level supine exercise (12 bicycle; 9 arm weight). Continuous volume (V) was obtained from mitral Doppler inflow and end-diastolic (ED) and end-systolic (ES) V from 2-D echo. Relaxation-corrected LV diastolic P was used for PV relationship P = α.eβ*V; to account for covariance in α and β, LV capacitance (EDV20 = Ln[20mmHg/α]/β) was reported. Single beat method was used for LV ES elastance (Ees). Group 1 did not increase mean LV diastolic P (mDP) with exercise, Group 2 increased mDP >6mmHg.
Results: LV diastolic P and arterial and LV ES elastance increased with exercise; EDV was stable; EDV20 decreased. Compared to Group 1, Group 2 had a greater exercise-induced increase in afterload, associated with increase in LV minimal P and impaired augmentation of relaxation rate (Table⇓ & Figure⇓).
Conclusions: In patients with HTN, impairment of ventricular relaxation plays a major role in causing LV filling P increase with exercise, which is related to ventricular-vascular coupling.