Impact of Pulmonary Valve Regurgitation on Pressure Difference of Pulmonary Valve Stenosis in Patients with Tetralogy of Fallot After Repair.

Pressure difference (PD) is an important parameter in evaluating the degree of stenotic lesion. However, PD is influenced by the blood flow volume passing through the stenosis. In patients with tetralogy of Fallot (TOF), pulmonary valve regurgitation (PR) and pulmonary valve stenosis (vPS) are common post-operative complications. The aim of this study was to evaluate the influence of PR on the PD. First, we examined the relationship between the peak-to-peak PD and the valve orifice area in 7 patients with vPS from their cardiac catheterization data. Second, an estimated PD, i.e., PD assuming no PR, was calculated in 8 patients with TOF with vPS and PR from their valve orifice area using the relational equation in patients with vPS. Moreover, an excess of PD, equating to the difference between the measured and estimated PD, was calculated. Finally, the relationship between the regurgitant fraction (RF) and the excess PD was analyzed. There was a strong relationship between the reciprocal of the valve orifice area and the PD in patients with vPS (r = 0.904, p = 0.0053). The excess PD showed a significant correlation with the RF in patients with TOF (r = 0.889, p = 0.0032). PR of over 25% in RF augmented the PD depending on the regurgitant volume. Severity of vPS could be overestimated in post-operative patients with TOF who had significant PR when their RF was above 25%.