Vicious circle between progressive right ventricular dilatation and pulmonary regurgitation in patients after tetralogy of Fallot repair? Right heart enlargement promotes flow reversal in the left pulmonary artery

Abstract

BackgroundThe left pulmonary artery (LPA) contributes more than the right (RPA) to total pulmonary regurgitation (PR) in patients after tetralogy of Fallot (TOF) repair, but the mechanism of this difference is not well understood. This study aimed to analyze the interplay between heart and lung size, mediastinal geometry, and differential PR.MethodsForty-eight Cardiovascular Magnetic Resonance (CMR) studies in patients after TOF repair were analyzed. In addition to the routine blood flow and ventricular volume quantification cardiac angle between the thoracic anterior-posterior line and the interventricular septum, right and left lung areas as well as right and left hemithorax areas were measured on an axial image. Statistical analysis was performed to compare flow parameters between RPA and LPA and to assess correlation among right ventricular volume, pulmonary blood flow parameters and lung area.ResultsThere was no difference between LPA and RPA diameters. The LPA showed significantly less total forward flow (2.49 ± 0.87 L/min/m2 vs 2.86 ± 0.89 L/min/m2; p = 0.02), smaller net forward flow (1.40 ± 0.51 vs 1.89 ± 0.60 mL/min/m2; p = <0.001), and greater regurgitant fraction (RF) (34 ± 10 % vs 43 ± 12 %; p = 0.001) than the RPA. There was no difference in regurgitant flow volume between RPA and LPA (p = 0.29). Indexed right ventricular end-diastolic volume (RVEDVi) correlated with LPA RF (R = 0.48, p < 0.001), but not with RPA RF (p = 0.09). Larger RVEDVi correlated with a more leftward cardiac axis (R = 0.46, p < 0.001) and with smaller left lung area (R = −0.58, p < 0.001). LPA RF, but not RPA RF, correlated inversely with left lung area (R = −0.34, p = 0.02). The follow-up CMRs in 20 patients showed a correlation of the rate of RV enlargement with the rates of LPA RF worsening (R = 0.50, p = 0.03), and of increasing left lung compression (R = −0.55, p = 0.012).ConclusionAn enlarged and levorotated heart is associated with left lung compression and impaired flow into the left lung.

Surgical strategies protecting against right ventricular dilatation following tetralogy of Fallot repair

“…Severe pulmonary valve regurgitation following tetralogy of Fallot (TOF) repair leads to right ventricular (RV) volume overload. Volume overload of the right ventricle is aggravated with any associated tricuspid regurgitation and it is considered the major cause of function impairment and increased morbidity and mortality in those patients [ 1 – 3 ]. Several techniques have been proposed to alleviate the acute and chronic right ventricular volume overload after TOF repair and recently pulmonary valve sparing procedure has gained popularity [ 4 – 7 ].…”

Clinical characteristics, prognosis and outcome of patients with repaired tetralogy of Fallot

“…Mlađi pacijenti tolerišu dobro postoperativnu pulmonalnu regurgitacije, ali u odraslom dobu hemodinamsko opterećenje hroničnom pulmonalnom regurgitacijom počinje da utiče na toleranciju napora i preživljavanje. Dugoročne studije ishoda pacijenata sa TOF bilježe promjenu krive preživljavanja u drugoj deceniji nakon hirurške korekcije [25,26]. Pulmonalna regurgitacija je snažno povezana sa kasnim neželjenim događajima koji mogu da dovedu do iznenadne smrti.…”

Review of Journal of Cardiovascular Magnetic Resonance (JCMR) 2015-2016 and transition of the JCMR office to Boston

“…The left pulmonary artery contributes more than the right pulmonary artery to total pulmonary regurgitation in patients after tetralogy of Fallot (TOF) repair. Kato and co-workers [ 196 ] studied 48 patients with TOF repair and found no difference in left and right pulmonary artery diameters, but the left pulmonary artery had less total forward flow, smaller net forward flow, and greater regurgitant fraction. There was no difference in regurgitant flow volume.…”