HEMODYNAMIC CORRELATES OF EFFECTIVE ARTERIAL ELASTANCE IN MITRAL-STENOSIS BEFORE AND AFTER BALLOON VALVOTOMY

This study had the purpose of documenting the hemodynamic correlates o f effective arterial elastance (Ea; i.e., an accurate estimate of hydr aulic load) in mitral stenosis (MS) patients. The main hypothesis test ed was that Ea relates to the total vascular resistance (R)-to-pulse i nterval duration (T) ratio (R/T) in MS patients both before and after successful balloon mitral valvotomy (BMV). High-fidelity aortic pressu re recordings were obtained in 10 patients (40 +/- 12 yr) before and 1 5 min after BMV. Ea value was calculated as the ratio of the steady-st ate end-systolic aortic pressure (ESAP) to stroke volume (thermodiluti on). Ea increased after BMV (from 1.55 +/- 0.63 to 1.83 +/- 0.71 mmHg/ ml; P < 0.05). Throughout the procedure, there was a strong linear rel ationship between Ea and R/T: Ea = 1.09R/T - 0.01 mmHg/ml, r = 0.99, P = 0.0001. This ultimately depended on the powerful Link between ESAP and mean aortic pressure [MAP; r = 0.99, 95% confidence interval for t he difference (MAP - ESAP) from - 18.5 to + 4.5 mmHg]. Ea was also rel ated to total arterial compliance (area method) and to wave reflection s (augmentation index), although to a lesser extent. After BMV, enhanc ed and anticipated wave reflections were observed, and this was likely to be explained by decreased arterial compliance. The present study i ndicated that Ea depended mainly on the steady component of hydraulic load (i.e., R) and on heart period (i.e., T) in MS patients.