Objective: we present a prospective study designed to evaluate a new geometrical rule to determine the exact width of the transannular patch for each patient undergoing correction of right ventricular outflow tract obstruction.
Methods: the width of the transannular patch is obtained by subtracting the perimeter of the preoperative pulmonary annulus from the normal desired one. A table to be used in the operating room was designed, in which this value can easily be obtained. This table was tested from May to December 2008. Seven consecutive patients (mean age 13 months) underwent surgery for correction of tetralogy of Fallot with severely hypoplastic pulmonary annulus. Pre and postoperative echocardiograms were performed to assess pulmonary annulus diameter and transpulmonary gradients. Clinical and echocardiographic follow-up were also carried out.
Results: average percentage of deviation of postoperative pulmonary annulus diameters from their normal values was 5%, indicating that each one of them was within 1 mm around the normal diameter. Average transpulmonary gradient was 21 mmHg, meaning mild residual pulmonary stenosis.
Conclusions: this new geometrical rule accurately determines the exact width of the transannular patch for the reconstruction of a hypoplastic pulmonary root, avoiding residual gradients and severe pulmonary regurgitation in order to prevent dilatation of the right ventricle in the late follow-up of these patients.