Abstract

Background: Recent histological studies of the aortic wall of patients with tetralogy of Fallot (TOF) have shown massive degeneration of the tunica media of the aorta. Such changes in arterial wall structure may significantly alter arterial wall mechanical properties, and thus cause abnormal arterial haemodynamics.

Objective: To test the hypothesis that after repair of TOF, there are abnormal arterial haemodynamics which are associated with aortic dilatation and which increased after load on the left ventricle.

Methods and results: The subjects comprised 38 patients who had undergone complete repair of TOF, and 55 control subjects. Systemic arterial haemodynamics were investigated by measuring aortic input impedance during cardiac catheterisation. The patients with TOF had significantly higher characteristic impedance (158 (43) dyne.s.cm⁻⁵.m² vs 105 (49) dyne.s.cm⁻⁵.m²) and pulse wave velocity (561 (139) cm/s vs 417 (91) cm/s) and significantly lower total peripheral arterial compliance (0.93 (0.39) ml/mm Hg/m² vs 1.24 (0.58) ml/mm Hg/m²) than the controls (for all three variables, p<0.01 vs controls), suggesting that central and peripheral arterial wall stiffness are increased after TOF repair. Additionally, patients with TOF had significantly higher arterial wave reflection than the controls (reflection coefficient: 0.21 (0.12) vs 0.16 (0.06)). These abnormalities in patients with TOF increased the pulsatile load on the left ventricle and significantly contributed to decreased cardiac output, even when right ventricular function was taken into account by multivariate regression analysis. The increase in aortic wall stiffness was closely associated with the increase in aortic root diameter.

Conclusion: These results indicating abnormal arterial haemodynamics after TOF repair highlight the importance of regular monitoring of the systemic arterial bed and potentially relevant cardiovascular events in long-term follow-up of TOF.