Relationship between ventricular contractility and early diastolic intraventricular pressure gradients: a diastolic link to systolic function.
BACKGROUND
Early diastolic intraventricular pressure gradient (IVPG), as derived by color M-mode echocardiography, has been proposed to correlate with left ventricular (LV) elastic recoil. However, any relationship to quantifiable indices of LV contractility is poorly defined.


METHODS
To relate IVPG with invasive and noninvasive indices of contractility, 6 closed-chest dogs each had a high-fidelity conductance catheter placed into the LV for continuous determination of end-diastolic pressures, volumes, +dP/dt(max), and the time constant of LV relaxation (tau) under baseline conditions and 4 different stages of beta-receptor modulation. At each stage, IVPGs were determined from color M-mode echocardiography images. Doppler-derived strain rate (epsilon') and myocardial systolic myocardial velocities (S(m)) were also measured. E(max) was obtained from the slope of the end-systolic pressure-volume relationship during caval occlusion. Results of contractility indices were compared to IVPG with regression analysis.


RESULTS
IVPG ranged from 0.72 to 3.95 mm Hg whereas E(max) ranged from 0.66 to 14.9 mm Hg/mL and end-systolic volume ranged from 1.9 to 59.7 mL. IVPG correlated with epsilon' (r = 0.71), S(m) (r = 0.67), end-systolic volume (r = 0.53), and invasive indices (+dP/dt(max), r = 0.71, and E(max), r = 0.82).


CONCLUSIONS
Early diastolic IVPGs are associated with LV contractility. These findings may explain the proposed mechanism in which potential energy stored during systole is released during diastole to provide for adequate ventricular filling, even under low filling pressures.
Firstenberg
Michael S
MS
Division of Cardiothoracic Surgery, Department of Surgery, The Ohio State Medical Center, Columbus, Ohio 43210, USA. Michael.Firstenberg@osumc.edu
Greenberg
Neil L
NL
Garcia
Mario J
MJ
Thomas
James D
JD
D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D003971:Diastole / Q000502:physiology; D004285:Dogs; D004452:Echocardiography / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D009200:Myocardial Contraction / Q000502:physiology*; D013599:Systole / Q000502:physiology; D016276:Ventricular Function