The impact of cardiac loading on a novel metric of left ventricular diastolic function in healthy middle-aged adults: Systolic-diastolic coupling

Abstract

Aims: Left ventricular (LV) restoring forces are primed by ventricular deformation during systole and contribute to cardiac relaxation and early diastolic suction. Systolic-diastolic coupling, the relationship between systolic contraction and diastolic recoil, is a novel marker of restoring forces, but the effect of left atrial pressure (LAP) is unknown. We tested preliminary methods of systolic-diastolic coupling comparing mitral annular velocities versus excursion distances and hypothesized a recoil/contraction distance ratio would remain unaffected across varying LAP, providing a surrogate for quantifying LV restoring forces.

Methods and results: Healthy subjects (n = 61, age 52 ± 5 years) underwent manipulation of LAP with lower body negative pressure (LBNP) and rapid normal saline (NS) infusion. Pulmonary capillary wedge pressure (PCWP; pulmonary artery catheter) and tissue Doppler imaging of the mitral annulus were measured. Two models of systolic-diastolic coupling--early diastolic excursion (ED_exc )/systolic contraction (S_exc ) distances and e'/systolic (s') velocities were compared. Velocity (e'/s') coupling ratios varied significantly (mean e'/s', slope = 0.022, p < 0.001) in relationship with PCWP (5-20 mmHg). Excursion (ED_exc /S_exc ) coupling ratio did not vary in relationship with PCWP (ED_exc /S_exc : slope = -0.001, p = 0.19).

Conclusions: Systolic-diastolic coupling using mitral annular distance ratios to standardize early diastolic recoil to systolic contraction was not significantly impacted by LAP, in contrast to coupling ratios using velocities. The pressure invariance of annular distance coupling ratios suggests this metric quantifies the efficiency of LV restoring forces by isolating systolic contributions to early diastolic restoring forces independent from changes in LAP.

Keywords: coupling; diastole; echocardiography; hemodynamics.

FIGURE 1

Early diastolic velocity (E’) and systolic velocity (S’) have differential response to preload. Average (black) and individual linear regressions (gray) for subjects’ e’ (left) and s’ (right) as influenced by pulmonary capillary wedge pressure (PCWP). The slope value shown is the fixed effect slope and p value of a random regression model. Slope and p value shown derived from random regression coefficients model. Mean R ² is derived from linear regressions of individual participants (n = 61, 52% identified as women, 48% identified as men)

FIGURE 2

Early diastolic excursion (ED_exc) and systolic excursion (S_exc) have similar response to preload. Average (black) and individual linear regressions (gray) for subjects’ ED_exc (left) and S_exc (right) as influenced by pulmonary capillary wedge pressure (PCWP). The slope value shown is the fixed effect slope and p value of a random regression model. Slope and p value shown derived from random regression coefficients model. Mean R ² is derived from linear regressions of individual participants (n = 61, 52% identified as women, 48% identified as men)

FIGURE 3

Metrics of systolic–diastolic coupling across loading conditions show different response to preload: left panel demonstrates no change in excursion (ED_exc/S_exc) ratio with changes to pulmonary capillary wedge pressure (PCWP) while right panel show a significant change in velocity (E’/S’) ratio with changes to PCWP. Individual linear regressions for subjects are shown in gray and average regression shown in black. The slope value shown is the fixed effect slope and p value of a random regression model. Mean R ² is derived from linear regressions of individual participants (n = 61, 52% identified as women, 48% identified as men)