Korean Circ J.  2023 Jun;53(6):406-417. 10.4070/kcj.2022.0228.

Impact of Pulmonary Arterial Elastance on Right Ventricular Mechanics and Exercise Capacity in Repaired Tetralogy of Fallot

• Kim SJ
• Li MH
• Noh CI
• Kim SH
• Lee CH
• Yoon JK

• KMID: 2543053
• DOI: http://doi.org/10.4070/kcj.2022.0228

Abstract

Background and Objectives
Pathophysiological changes of right ventricle (RV) after repair of tetralogy of Fallot (TOF) are coupled with a highly compliant low-pressure pulmonary artery (PA) system. This study aimed to determine whether pulmonary vascular function was associated with RV parameters and exercise capacity, and its impact on RV remodeling after pulmonary valve replacement.
Methods
In a total of 48 patients over 18 years of age with repaired TOF, pulmonary arterial elastance (Ea), RV volume data, and RV-PA coupling ratio were calculated and analyzed in relation to exercise capacity.
Results
Patients with a low Ea showed a more severe pulmonary regurgitation volume index, greater RV end-diastolic volume index, and greater effective RV stroke volume (p=0.039, p=0.013, and p=0.011, respectively). Patients with a high Ea had lower exercise capacity than those with a low Ea (peak oxygen consumption [peak VO₂ ] rate: 25.8±7.7 vs. 34.3±5.5 mL/kg/min, respectively, p=0.003), while peak VO₂ was inversely correlated with Ea and mean PA pressure (p=0.004 and p=0.004, respectively). In the univariate analysis, a higher preoperative RV end-diastolic volume index and RV end-systolic volume index, left ventricular end-systolic volume index, and higher RV-PA coupling ratio were risk factors for suboptimal outcomes. Preoperative RV volume and RV-PA coupling ratio reflecting the adaptive PA system response are important factors in optimal postoperative results.
Conclusions
We found that PA vascular dysfunction, presenting as elevated Ea in TOF, may contribute to exercise intolerance. However, Ea was inversely correlated with pulmonary regurgitation (PR) severity, which may prevent PR, RV dilatation, and left ventricular dilatation in the absence of significant pulmonary stenosis.

Keyword

Fallot tetralogy; Vascular stiffness; Pulmonary artery; Vascular resistance; Afterload; Cardiopulmonary exercise test; Right ventricular function

Figure

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  Figure 1 Correlation between pulmonary Ea and right ventricular volumetric indices. The Ea is negatively correlated with PRVi (r=−0.416, p=004), RVEDVi (r=−0.507, p<0.0001), RVESVi (r=−0.37, p=0.01), and RVSVi (r=−0.55, p<0.0001).Ea = arterial elastance; PRVi = pulmonary regurgitant volume index; RVEDVi = right ventricular end-diastolic volume index; RVESVi = right ventricular end-systolic volume index; RVSVi = right ventricular stroke volume index.

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  Figure 2 Correlation between exercise capacity and several variables. (A) Pulmonary Ea had a negative correlation with VO2max (r=−0.474, p=0.015). (B) Ea did not have significant correlation with % predicted peak VO2 (r=−0.386, p=0.052). (C) Mean PAP exhibit a negative correlation with VO2max (r=−0.544, p=0.004) and (D) % predicted peak VO2 (r=−0.593, p=0.001).Ea = arterial elastance; PAP =pulmonary artery pressure; peak VO2 = peak oxygen consumption; VO2max = maximal oxygen consumption.

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