Relationship Between Early Diastolic Intraventricular Pressure Gradients, an Index of Elastic Recoil, and Improvements in Systolic and Diastolic Function

Abstract

Background Early diastolic intraventricular pressure gradients (IVPGs) have been proposed to relate to left ventricular (LV) elastic recoil and early ventricular “suction.” Animal studies have demonstrated relationships between IVPGs and systolic and diastolic indices during acute ischemia. However, data on the effects of improvements in LV function in humans and the relationship to IVPGs are lacking. Methods and Results Eight patients undergoing CABG and/or infarct exclusion surgery had a triple-sensor high-fidelity catheter placed across the mitral valve intraoperatively for simultaneous recording of left atrial (LA), basal LV, and apical LV pressures. Hemodynamic data obtained before bypass were compared with those with similar LA pressures and heart rates obtained after bypass. From each LV waveform, the time constant of LV relaxation (τ), +dP/dt max , and −dP/dt max were determined. Transesophageal echocardiography was used to determined end-diastolic (EDV) and end-systolic (ESV) volumes and ejection fractions (EF). At similar LA pressures and heart rates, IVPG increased after bypass (before bypass 1.64±0.79 mm Hg; after bypass 2.67±1.25 mm Hg; P <0.01). Significant improvements were observed in ESV, as well as in apical and basal +dP/dt max , −dP/dt max , and τ (each P <0.05). Overall, IVPGs correlated inversely with both ESV (IVPG=−0.027[ESV]+3.46, r =−0.64) and EDV (IVPG=−0.027[EDV]+4.30, r =−0.70). Improvements in IVPGs correlated with improvements in apical τ (Δτ =5.93[ΔIVPG]+4.76, r =0.91) and basal τ (Δτ =2.41[ΔIVPG]+5.13, r =−0.67). Relative changes in IVPGs correlated with changes in ESV (ΔESV=−0.97[%ΔIVPG]+23.34, r =−0.79), EDV (ΔEDV=−1.16[%ΔIVPG]+34.92, r =−0.84), and EF (ΔEF=0.38[%ΔIVPG]−8.39, r =0.85). Conclusions Improvements in LV function also increase IVPGs. These changes in IVPGs, suggestive of increases in LV suction and elastic recoil, correlate directly with improvements in LV relaxation and ESV.