Right ventricular to pulmonary arterial coupling in patients with repaired tetralogy of Fallot: a case series

Figure 1. Pressure–volume loops using the single-beat method from Brimioulle et al.7Figure 1 shows the pressure–volume loops of Case 1, Case 2, and a normal RV in the age group 12–18 years. Right ventricular to pulmonary arterial (RV-PA) coupling was calculated as the ratio of the Ees and the arterial Ea and represents the efficiency of energy transfer from the RV to the pulmonary vasculature (Ees/Ea normal RV = ≥1, Ees/Ea Patient 1 = 0.8, Ees/Ea Patient 2 = 0.2). Ees, which is considered a load-independent measure of ventricular contractility, was calculated as the slope of the ESPVR using (RV maximal isovolumetric pressure − RV systolic pressure)/stroke volume (Ees normal RV = ≥0.5, Ees Patient 1 = 0.9, Ees Patient 2 = 0.1). The maximal isovolumetric pressure of the RV was computed by sine wave extrapolation using RV pressure values recorded before maximal first derivative of pressure development over time (dP/dt) and after minimal dP/dt.7 Ea, which is mainly a reflection of pulmonary vascular resistance, was calculated as RV afterload using RV systolic pressure/stroke volume (Ea normal RV = ≤0.31, Ea Patient 1 = 1.2, Ea Patient 2 = 0.5).9 In addition, diastolic stiffness was assessed…

ASD, atrial septal defect; CMR, cardiac magnetic resonance; LPA, left pulmonary artery; MV, mitral valve; PA, pulmonary artery; PV, pulmonary valve; RHC, right heart catheterization; RPA, right pulmonary artery; RV, right ventricle; RV-PA conduit, right ventricular pulmonary arterial conduit; RVOT, right ventricular outflow tract; ToF, tetralogy of Fallot; VSD, ventricular septal defect.

Figure 2. Right ventricular to pulmonary arterial coupling in two cases with tetralogy of Fallot and right ventricular pressure overload. Right ventricular to pulmonary arterial (RV-PA) coupling measurements in two cases with repaired ToF and RV pressure overload compared with reference values for RV-PA coupling from healthy literature controls. The dotted line represents the reference value for Ees, Ea, and Ees/Ea in healthy controls according to the literature.13 The end-sysolic elastance (Ees), which is considered a load-independent measure of ventricular contractility, was calculated as the slope of the end-systolic pressure–volume relationship (ESPVR) using (RV maximal isovolumetric pressure − RV systolic pressure)/stroke volume (Ees normal RV = ≥0.5, Ees Patient 1 = 0.9, Ees Patient 2 = 0.1).7 The maximal isovolumetric pressure of the RV was extrapolated from RV pressure curves. The Ea, which is mainly a reflection of pulmonary vascular resistance, was calculated as RV afterload using RV systolic pressure/stroke volume (Ea normal RV = ≤0.31, Ea Patient 1 = 1.2, Ea Patient 2 = 0.5).9 The ratio of Ees/Ea (RV-PA coupling) represents the efficiency of energy transfer from the RV to the…

Figure 3. Pre- and post-interventional imaging of Case 1. Figure 3 shows the pre- and post-interventional imaging of Case 1 using transthoracic echocardiography. (A) Pre-interventional peak gradient of the left pulmonary artery (LPA) measured using continuous wave Doppler echocardiography. (B) Post-interventional peak gradient of the LPA measured using continuous wave Doppler echocardiography. Note the different scales in the vertical axis in panels A and B. (C) Pre-interventional four-chamber cardiac magnetic resonance cine image. (D) Post-interventional RV focused apical four-chamber echocardiography image. A–B show a decrease in post-interventional LPA peak gradient compared with pre-interventional LPA peak gradient using continuous wave Doppler echocardiography. C–D show pre- and post-interventional preserved RV volumes. Right ventricular systolic function was found to be preserved during echocardiography.

Figure 4. Pre- and post-interventional imaging of Case 2. Figure 4 shows the pre- and post-interventional imaging of Case 2 using transthoracic echocardiography and cardiac magnetic resonance imaging. (A) Pre-interventional peak gradient of the right ventricular outflow tract (RVOT) measured using continuous wave Doppler echocardiography. (B) Post-interventional peak gradient of the RVOT measured using continuous wave Doppler echocardiography. Note the different scales in the vertical axis in panels A and B. (C) Pre-interventional four-chamber cardiac magnetic resonance (CMR) cine image. (D) Pre-interventional four-chamber CMR cine image. A–B show no decrease in post-interventional RVOT peak gradient compared with pre-interventional RVOT peak gradient using continuous wave Doppler echocardiography. C–D show pre- and post-interventional RV dilatation. Right ventricular systolic function was found to be reduced during CMR.