Vmax as an Index of right ventricular function in pulmonary hypertension

Abstract Background For assessing right ventricular function in pulmonary hypertension (PH), the optimal approach is through the use of load-independent parameters. While pressure-volume (PV) loops are not feasible in clinical settings, the maximum velocity of the contractile element under no load, known as Vmax, serves as an alternative measure that could be derived only from right-heart catheterization (RHC). Objectives To determine Vmax in patients undergoing RHC and to evaluate its correlation with echocardiographic parameters. Methods 15 PH patients scheduled for risk stratification were subjected to RHC and echocardiography. The contractile velocity element (VCE) was calculated as VCE = 1 / (28.8 x P) x dP/dt, with P representing RV pressure in mm Hg and dP/dt its first derivative in mmHg/s. The P vs. VCE plot displays a peak VCE value, leading into a linear slope (red line, figure 1A) with Vmax as the zero-pressure intercept. Vmax was compared with 6 different echocardiographic parameters of RV function. Results They were six females and 9 males aging 61±6 y. Mean PH was 37,6±10,1 mm Hg and Vmax averaged 2,1±0,9 length/s (range from 0,8 to 4,4 length/s). Figure 1B illustrates 3 patients with deteriorated, mildly reduced and normal VCE. When compared to Vmax, tricuspid peak systolic tissue Doppler velocity and TAPSE shown the best correlation while RV fractional area change demonstrated the worse correlation (figure 2). Conclusion Vmax, an indicator of right ventricular systolic function that does not depend on load, can be obtained through right heart catheterization. Both tissue Doppler peak systolic velocity and tricuspid annular plane systolic excursion (TAPSE) have demonstrated a strong correlation with Vmax.Invasive pressureECHO parameters