Abstract
BACKGROUND: Maximal left ventricular (LV) pressure rise (LV dP/dt(max)), a classical marker of LV systolic function, requires LV catheterization, thus surrogate arterial pressure waveform measures have been proposed. We compared LV and arterial (femoral and radial) dP/dt(max) to the slope of the LV end-systolic pressure-volume relationship (Ees), a load-independent measure of LV contractility, to determine the interactions between dP/dt(max) and Ees as loading and LV contractility varied. METHODS: We measured LV pressure-volume data using a conductance catheter and femoral and radial arterial pressures using a fluid-filled catheter in 10 anesthetized pigs. Ees was calculated as the slope of the end-systolic pressure-volume relationship during a transient inferior vena cava occlusion. Afterload was assessed by the effective arterial elastance. The experimental protocol consisted of sequentially changing afterload (phenylephrine/nitroprusside), preload (bleeding/fluid bolus), and contractility (esmolol/dobutamine). A linear-mixed analysis was used to assess the contribution of cardiac (Ees, end-diastolic volume, effective arterial elastance, heart rate, preload-dependency) and arterial factors (total vascular resistance and arterial compliance) to LV and arterial dP/dt(max). RESULTS: Both LV and arterial dP/dt(max) allowed the tracking of Ees changes, especially during afterload and contractility changes, although arterial dP/dt(max) was lower compared to LV dP/dt(max) (bias 732 ± 539 mmHg⋅s(- 1) for femoral dP/dt(max), and 625 ± 501 mmHg⋅s(- 1) for radial dP/dt(max)). Changes in cardiac contractility (Ees) were the main determinant of LV and arterial dP/dt(max) changes. CONCLUSION: Although arterial dP/dt(max) is a complex function of central and peripheral arterial factors, radial and particularly femoral dP/dt(max) allowed reasonably good tracking of LV contractility changes as loading and inotropic conditions varied.