In some cases of tetralogy of Fallot the post-operative course is characterized by episodes of low cardiac output, elevated central filling pressures and prolonged ventilation and inotropic support. This may be due to impaired diastolic function of the right ventricle despite preservation of biventricular systolic function.
Sixty-four consecutive patients (mean age 7.06+/-4.9 years) undergoing repair of tetralogy of Fallot were prospectively studied to assess right ventricular diastolic function. 'Restrictive physiology' was defined as presence of laminar antegrade diastolic pulmonary artery flow (A wave) throughout the respiratory cycle, which was coincident with atrial systole. Right ventricle restriction was present in 45/64 (70%, Group 1) patients and absent in 19/64 (30%, Group 2) patients. There was a marked inspiratory augmentation of the pulmonary artery A wave velocity, flow integral and duration. Transtricuspid flow revealed significantly lower peak E velocity, lower E/A ratio, shorter E deceleration time and higher A velocity time integral in those with right ventricular restriction. Biventricular systolic function and transmitral flow were normal in all patients. Those with restrictive physiology had significantly longer mean inotrope support duration, longer ventilation and chest drainage times. Correspondingly, the mean intensive care unit stay (56.7+/-9.3 v. 34.7+/-5.38 hours, p<0.01) and mean hospital discharge time (9.3+/-2.3 v. 6.2+/-0.5 days, p <0.001) was also significantly longer in group 1.
Right ventricular restriction (as seen by laminar antegrade diastolic pulmonary artery flow throughout the respiratory cycle) exists in a significant subset of patients with tetralogy of Fallot following operative repair. Following surgery, such patients have higher inotropic requirement, longer ventilation times and longer hospital stay.