Left ventricular afterload and contractility estimated non-invasively by pulse wave analysis in patients with aortic valve stenosis

INTRODUCTION. Background and Goal of Study: In subjects with aortic valve stenosis myocardial contractility changes in relation to variations in left ventricular (LV) afterload. Arterial pressure measurements are often used as an indicator of LV afterload. The aortic augmentation index (Aix %, augmented systolic pressure adjusted to pulse pressure) is an indirect indicator of LV afterload. It reflects the different morphology between peripheral and central pressure wave. Aix can be estimated with applanation tonometry (AT), a non-invasive technique that provides information on arterial vascular tone, and hence LV afterload. AT is capable of assessing also dP/dt (mmHg/msec), which is an indirect index of LV performance (i.e., myocardial contractility). OBJECTIVES. The goal of this study was to evaluate how aortic valve replacement (AVR) could influence Aix and dP/dt values. METHODS. We studied 15 patients with aortic valve stenosis undergoing AVR. AT (Sphygmocor - AtCor Medical, Australia) was used to estimate AT-derived parameters from the radial artery at three times: (T1), preoperative; (T2), ICU admission; (T3) ICU discharge. The values of Aix and dP/dt were collected at each time. RESULTS. Patients (mean age 64±12; male/female = 13/2) had a normal preoperative ejection fraction (57±9 %) and a EuroScore of 6±2. Aix at T1 was 29±9% and it reduced significantly at T2 (13±16%; p< 0.05). Conversely, Aix remained quite stable at T3 (16±17%; p=n.s.). dP/dt showed a significant increase from T1 to T2 (614±165 vs 787±211 mmHg/msec, respectively; p< 0.05). At T3, dP/dt did not show further improvements (744±177; p=n.s.). CONCLUSIONS. Our findings demonstrated that after AVR there is a significant reduction in LV afterload: Aix changes might be considered as an “early indicator” of this phenomenon. Also, myocardial contractility (dP/dt) improves after AVR, possibly in relation to the physiological “re- established arterial-ventricular coupling”. Although quite operator dependent AT seems a useful technique that allows evaluating the effect of AVR on LV afterload and contractility.