View Abstract

A6137 - A Multi-Harmonic Approach Towards Characterizing Right Ventricle - Pulmonary Artery Interaction
Author Block: A. Muralidhar1, C. Meadows2, C. Abbott2, C. Carter3, K. R. Stenmark4, K. S. Hunter5, T. M. Bull1; 1Pulmonary Sciences and Critical Care Medicine, University of Colorado, Aurora, CO, United States, 2University of Colorado Denver, Aurora, CO, United States, 3Center for Pulmonary Vascular Disease, University of Colorado, Aurora, CO, United States, 4Univ of Colorado Denver, Aurora, CO, United States, 5Bioengineering, University of Colorado at Denver, Aurora, CO, United States.
RATIONALE:
Invasive measurement of right ventricle – pulmonary artery (RV-PA) interaction has been used as a load independent measure of how the RV functions under increasing afterload. In pulmonary arterial hypertension (PAH), ventriculovascular coupling ratio (VVCR) correlates with survival. Interestingly, patients with scleroderma (SSc) related PAH have a worse VVCR then those with idiopathic PAH (IPAH). Several methods exist for measuring this VVCR, presented here as the arterial elastance (Ea) over the end systolic elastance (Ees). No method has been shown to be a superior predictor of worsening PAH or clinical outcomes. We have utilized a recently developed multi-harmonic approach to measure VVCR via right heart catheterization (RHC). We hypothesize this is a superior marker of PAH compared to a more commonly used single-harmonic approach, and that it correlates with hemodynamic measurements of disease severity.
METHODS:
We studied a prospectively collected cohort of 70 patients who had simultaneous RHC and echocardiography. This included 43 subjects with PAH consisting of IPAH (n=24;average mean pulmonary artery pressure (mPAP)=46±15.73) and SSc-PAH (n=19;mPAP=39.58±11.5) against 27 case-controls consisting of SSc without PAH (n=12;mPAP=18.25±3.86) and patients with Patent Foramen Ovale (PFO) closure without PAH (n=15;mPAP=16.8±3.97). VVCR analysis was performed on the right ventricular wave forms using algorithms developed in MatLab (Mathworks, Natick, MA). Correlation analysis and linear regression analysis were performed using Prism (Graphpad, San Diego, CA).
RESULTS:
Mean group Ea/Ees as computed by the multi-harmonic method showed significant differences (p=0.0101) between PAH (0.84±0.07) and non-PAH groups (0.59±0.04), whereas the single-harmonic method was not significant (p=0.2067) between these groups (PAH=1.50±0.16;non-PAH=1.19±0.16). Additionally, the multi-harmonic Ea/Ees approaches significance (p=0.0634) between SSc-PAH (0.84±0.12) and SSc without PAH (0.55±0.05). Pulmonary vascular resistance (PVR) weakly correlates with Ees/Ea using the multi-harmonic (R=0.293;p=0.014) approach.
CONCLUSIONS:
We have shown that Ea/Ees determined by the multi-harmonic approach of measuring VVCR is superior to the single-harmonic approach in identifying PAH in subjects undergoing RHC. Additionally, the former method approaches significance in identifying subjects with SSc who have PAH compared to those who do not. Finally, PVR only weakly correlates with VVCR measurement, which may suggest that RV adaptation to increased afterload may not be measured accurately by PVR. These results prompt further investigation regarding how the multi-harmonic approach to VVCR might correlate with clinical outcomes such as disease progression and survival.