Abstract 16180: Hemodynamic Impact of Histological Abnormalities in the Pulmonary Trunk in Patients With Tetralogy of Fallot
Introduction: Recent histological studies in patients with tetralogy of Fallot (TOF) have revealed a reduction in normal elastic fibers in the pulmonary trunk as in the ascending aorta in Marfan syndrome and bicuspid aortic valve. Such histological changes may significantly alter arterial wall mechanical properties, and may thereby predispose to more pulmonary regurgitation and propagate right ventricular (RV) dysfunction.
Methods: We studied 28 patients with repaired TOF and 32 age-matched control subjects who had a small ventricular septal defect with a calculated pulmonary to systemic flow ratio < 1.1. Pulmonary arterial hemodynamics were investigated by measuring pulmonary input impedance during cardiac catheterization.
Results: Median age was 5.9 years (5.3 years in controls) and 61% were female. TOF group included two patients with pulmonary atresia and ventricular septal defect and six patients who had a history of aortopulmonary shunt. Patients with TOF had higher characteristic impedance, which represents the stiffness of proximal pulmonary arterial wall (100 +/- 72.0 versus 45.4 +/- 22.6 dyne·s·cm-5·m2, P<0.001), and lower total pulmonary vascular compliance (1.45 +/- 1.31 versus 5.93 +/- 2.96 ml/mm Hg/m2, P<0.001). Moreover, TOF patients had increased arterial pressure wave reflection (ratio of reflected pressure wave to forward pressure wave; 0.34 +/- 0.16 versus 0.19 +/- 0.10, P<0.001). The degree of stiffness was not related to the history of aortopulmonary shunt.
Conclusions: Marked decrease in pulmonary elasticity, in line with known histological changes, is present in patients with TOF. Enhanced pulmonary vascular stiffness and pressure wave reflection increases pulsatile afterload on RV and potentially alters RV preload by worsening pulmonary regurgitation. Further studies are warranted to assess whether medical therapy aiming at reducing vascular stiffness in patients with TOF delays deterioration in RV function later in life.
- © 2011 by American Heart Association, Inc.