10.10 HEMODYNAMIC CORRELATES OF THE LEFT VENTRICULAR MEAN EJECTION PRESSURE: A CAROTID TONOMETRY STUDY

Abstract

Background: The systemic arterial load imposed to the left ventricle (LV) is a major determinant of normal/abnormal cardiovascular function. The LV mean ejection pressure (LVMEP) is the best estimate of load faced by the LV throughout ejection. The contribution of the steady and pulsatile blood pressure (BP) component of arterial load to LVMEP is debated. We studied the hemodynamic correlates of LVMEP using carotid tonometry. Intensive care unit patients equipped with an indwelling catheter were studied, thus allowing precise calibration of the tonometer. Methods: Carotid tonometry (Complior Analyse ® ALAM Medical, France) was prospectively performed on 28 hemodynamically stable, spontaneously breathing patients (12F, mean age+/−SD = 64+/−18 years). Carotid waveforms were calibrated from diastolic BP and time-averaged mean BP invasively obtained at the radial (n=18) and femoral (n=10) artery. All patients were free of aortic stenosis. LVMEP was the area under the systolic part of the carotid pressure waveform divided by ejection time. Results: LVMEP (111+/−17 mmHg) was strongly related to central systolic BP (126+/−21 mmHg r2=0.97) and was also related to mean BP (r2=0.82), peripheral systolic BP (r2=0.83), peripheral (r2=0.35) and central (r2=0.50) pulse pressure (each P<0.05). The LVEMP was not related to age, heart rate and stroke volume. Systolic pulse wave amplification ratio from carotid to periphery was 1.07+/−0.08. Conclusions: Central systolic BP was strongly related to LVMEP, a measure of the load faced by the LV throughout ejection (r2=0.97). Peripheral systolic BP may be less informative given variable systolic pulse wave amplification across patients.