Quantitative Assessment of Ventricular Septal Contour for Estimation of Right Ventricular Pressure

BACKGROUND: Qualitative assessment of ventricular septal flattening is commonly used in pediatric patients with pulmonary hypertension (PH) who lack adequate tricuspid regurgitation (TR) Doppler signal. We sought to determine the relation between quantitative measures of septal flattening including the eccentricity index (EIs) and a novel marker, the septal flattening angle (SFA) with right ventricular systolic pressure (RVSP). METHODS: Subjects (≤18 years) with an anatomically normal heart, an adequate TR signal to obtain a peak velocity, and a simultaneous systemic systolic blood pressure (SBP) was included. RVSP was derived using TR gradient. Eccentricity index (EIs) and the SFA in systole were measured offline and correlated with RVSP/SBP. RESULTS: Of the 108 subjects, RVSP/SBP was < 50% in 77 and ≥ 50% in 31. In those with RVSP/SBP ≥50%, the median SFA was significantly lower (7.4° vs. 22°, p < 0.0001), and the median EIs was higher (1.61 vs. 1.07, p < 0.0001). SFA and EIs had a significant correlation with RVSP/SBP (rs = -0.70 and 0.61, respectively). Area under the curve was higher for SFA compared to EIs (0.92 and 0.85, respectively). The sensitivity and specificity of SFA for predicting an RVSP/SBP ≥ 50% using a cut point of 16° was 84% and 95% and for an EIs cut point of 1.35 was 74.2% and 96.1%, respectively. CONCLUSION: Septal flattening angle and EIs are quantitative measures of ventricular septal flattening that correlate well with RVSP/SBP and should be considered more routinely in clinical practice, especially in patients with inadequate TR Doppler signal.