Biventricular Long Axis Function After Repair of Tetralogy of Fallot

Right ventricular restrictive physiology is common after repair of tetralogy of Fallot and relates to exercise performance and symptomatic arrhythmias. In this study, we examined biventricular long axis function in an attempt to clarify further the mechanical substrate of this phenomenon. We studied prospectively 95 patients with tetralogy of Fallot (age range 1–44.3 years) at a median of 4.3 years after repair with Doppler and M-mode echocardiography. Pulmonary arterial, tricuspid, and mitral Doppler spectrals and 2-D guided M-mode recordings of ventricular minor and long axes were obtained with simultaneous phonocardiogram and respirometer recordings. Right ventricular restriction was defined by the presence of antegrade pulmonary arterial flow during atrial systole throughout the respiratory cycle. Restrictive right ventricular physiology was demonstrated in 36 (39%) [group 1] of the 92 patients in whom the data were analyzed. Left ventricular function (FS, isovolumic relaxation time and transmitral E wave deceleration time) was not different in the two groups (p < 0.1, p < 0.6, and p < 0.8, respectively). The presence of antegrade diastolic flow shortened the pulmonary regurgitation in the restrictive group (PR duration/√RR 10.7 ± 2.1 vs 12.1 ± 2.1, p < 0.01). There was delayed onset of shortening (97.4 ± 24 vs 88.8 ± 24 ms, p= 0.01), and the amplitude of right atrioventricular ring excursion, corrected for body surface area, was significantly lower during atrial systole in the restrictive group (0.43 ± 0.15 vs 0.54 ± 0.2 cm/m2, p < 0.01). There was also a tendency toward a smaller ratio of right to left total atrioventricular ring excursion in the same group (1.14 ± 0.19 vs 1.22 ± 0.23, p= 0.1). Impaired long axis function in patients with restrictive right ventricular physiology following repair of tetralogy of Fallot is associated with abnormal diastolic filling and may contribute to the long-term cardioprotective effect of restrictive physiology by limiting the degree of right ventricular dilatation.