Left ventricular end-diastole hemodynamics is strongly associated with spontaneous cardiac baroreflex in humans

In animals, hemodynamic conditions during left ventricular (LV) end-diastole are crucial for the excitation of autonomic afferents distributed throughout cardiac chambers and large thoracic vessels. The objective of the study was to select the echocardiographic indices of LV diastolic function that are the most potent predictors of the heart's spontaneous baroreflex in humans.

In 47 untreated hypertensive patients (26 with normal and 21 with increased left atrium diameter) and 24 healthy controls, baroreflex sensitivity (BRS) was assessed in the low (αLF; 0.04-0.15 Hz) and high frequency (αHF; 0.15-0.4 Hz) components in the supine and during tilting. The [Formula: see text] normalized to LV end-diastolic diameter (the [Formula: see text] index) is a marker of the septum late diastolic distension rate ([Formula: see text] denotes peak late diastolic velocity at the septal mitral annulus) under the corresponding transmitral pressure gradient that determines the peak velocity of blood flow (A) into the LV chamber.

The [Formula: see text] markedly stronger than [Formula: see text] ratio correlated with the BRS. In the best-fit models of multivariable linear regression, the [Formula: see text] index was the independent predictor of the αLF BRS at tilting (β = -0.3; p = 0.01). Independent of clinical and echocardiographic parameters, the [Formula: see text] index predicted also both the αHF BRS in the supine position (β = -0.23; p = 0.01) and the αHF BRS reinforcement due to increased preload (β = -0.28; p = 0.001).

The [Formula: see text] index is a reliable marker of diastolic dysfunction that evokes significant heart's baroreflex impairment and is markedly stronger than [Formula: see text] ratio associated with these systemic consequences of altered LV diastole hemodynamics.