Noninvasive Assessment of Left Ventricular Force-Frequency Relationships Using Tissue Doppler–Derived Isovolumic Acceleration

Abstract

Background-We have demonstrated that myocardial acceleration during isovolumic contraction (IVA) is a sensitive index of right ventricular contractile function. In this study, we assessed the usefulness of IVA to measure left ventricular (LV) contractile function and force-frequency relationships in an experimental preparation. Methods and Results-In study 1, we examined 6 pigs by use of tissue Doppler imaging of LV free wall and simultaneous measurements of intraventricular pressure, volume, maximal elastance (E max ), and dP/dt max by conductance catheterization. Animals were paced via the right atrium at a rate of 130 bpm. IVA was compared with elastance during contractility modulation by esmolol and dobutamine and assessed during preload reduction and afterload increase. In study 2, in 6 more pigs, force-frequency data were obtained during incremental atrial pacing from 120 to 180 bpm. Study 1: Esmolol led to a decrease in IVA and E max (PϽ0.03 and Ͻ0.02, respectively), both of which increased during dobutamine infusion (PϽ0.02 and Ͻ0.03, respectively). IVA was unaffected by significant (PϽ0.001) acute reduction of LV volume and a significantly increased LV afterload (systolic pressure increase, PϽ0.001). Study 2: There was a positive correlation between IVA and dP/dt max (r 2 ϭ0.92, PϽ0.05). As heart rate was increased from 120 to 160 bpm, there were significant increases in both IVA and dP/dt max (PϽ0. 0004 and Pϭ0.02, respectively). Over the same range of heart rates, there was no significant change in E max (Pϭ0.22). Conclusions-IVA is a measurement of LV contractile function that is unaffected by preload and afterload changes within a physiological range and can be used noninvasively to measure LV force-frequency relationships.

Evaluation of the effect of mitral stenosis severity on the left ventricular systolic function using isovolumic myocardial acceleration

“…Isovolumic acceleration is a new tissue Doppler parameter for the assessment of systolic function of both left and the right ventricles [13,14]. It remains unaffected by the changes in the preload and afterload within the physiological range [13][14][15][16] including age, sex and body mass index [25].…”

“…IVA remains unaffected by the changes in the preload and afterload within the physiological range [13][14][15][16]. It can detect small changes in the contractile function and is well correlated with the invasive or noninvasive measures of LV dP/dt [13,17].…”

“…Isovolumic acceleration (IVA) is a new tissue Doppler parameter for the assessment of systolic function of both left and the right ventricles [13,14]. IVA is calculated as a ratio of tissue Doppler-derived peak myocardial velocity during isovolumetric contraction (IVV) divided by the acceleration time (AT).…”

“…IVA is calculated as a ratio of tissue Doppler-derived peak myocardial velocity during isovolumetric contraction (IVV) divided by the acceleration time (AT). This parameter has been validated in a variety of experimental [13,14] and clinical [15,16] settings. IVA remains unaffected by the changes in the preload and afterload within the physiological range [13][14][15][16].…”

Induction of anesthesia does not alter tricuspid annular velocities: a tissue Doppler assessment

“…It has, however, been shown to be HR-dependent. 22,23 The S wave velocity is a load-dependent measure of contractility, 9 which represents the maximum myocardial ejection velocity achieved under the prevailing load conditions and contractility. The myocardial S velocity reflects the rate of work of the particular segment of myocardium under current conditions.…”