The importance of the maximum pulmonary artery regurgitant velocity following repair of tetralogy of Fallot: a pilot study

Tetralogy of Fallot repairs invariably result in pulmonary regurgitation with the long term sequelae of ventricular dilatation and dysfunction. The purpose of this study is to correlate pulmonary flow parameters with right ventricular size and function. Pulmonary artery velocity was mapped by magnetic resonance flow analysis in seven children with pulmonary regurgitation following tetralogy of Fallot repair. Right and left ventricular volumes were determined by Simpson's rule from double oblique cine gradient echo images of the heart. The ejection fraction was calculated for each ventricle. Right ventricular enlargement was normalized for patient size by calculating the ratios of right ventricle end diastolic and end systolic volumes to the left ventricle end diastolic and end systolic volumes respectively (EDV RV:LV and ESV RV:LV). The maximum pulmonary artery antegrade and retrograde velocities and the ratio of the time for antegrade to regurgitant flow were compared to ventricular function and volume measurements by regression analysis. A significant linear relationship between the maximum regurgitant pulmonary artery velocity and EDV RV:LV was identified (r2 = 0.82). An elevated maximum pulmonary regurgitant velocity correlated well with the degree of right ventricular enlargement in patients following tetralogy of Fallot repair. If the results are verified by a larger study, the maximum pulmonary regurgitant velocity may be substituted for the more cumbersome direct measurement of right ventricular size.