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

Background: Tetralogy of Fallot repairs invariably result in pulmonary regu rgitation with the long term sequelae of ventricular dilatation and dysfunc tion. Objective: The purpose of this study is to correlate pulmonary flow p arameters with right ventricular size and function. Materials and methods: 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 rul e from double oblique cine gradient echo images of the heart. The ejection fraction was calculated for each ventricle. Right ventricular enlargement w as 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 maxim um pulmonary artery antegrade and retrograde velocities and the ratio of th e time for antegrade to regurgitant flow were compared to ventricular funct ion and volume measurements by regression analysis. Results: A significant linear relationship between the maximum regurgitant pulmonary artery veloci ty and EDV RV:LV was identified (r(2) = 0.82). Conclusion: An elevated maxi mum 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 regurg itant velocity may be substituted for the more cumbersome direct measuremen t of right ventricular size.