Background: Residual pulmonary regurgitation following repair of tetralogy of Fallot, in particular the use of a transannular patch has been shown to correlate with the development of right ventricular dysfunction. Optimal timing of pulmonary valve replacement, therefore, is important to preserve right ventricular function. The valve replacement should not be performed too late so as to preserve function, yet not too early to avoid the requirement of frequent valve replacements, since the inserted prostheses have a limited lifespan.

Recently, MRI data for the determination of optimal timing of pulmonary valve replacement has been recommended. These recommendation are based on the measurement of right ventricular size and assessment of pulmonary regurgitation by MRI. To define right ventricular function more detailed informations about right ventricular contractility is required.

Methods: Analysis of right ventricular function by pressure-volume loops has been extensively evaluated in experimental studies and is generally considered the optimal way to quantify right ventricular function.This approach has been validated and used to assess right ventricular function in patients with congenital heart disease and following corrective surgery.

By recording a family of pressure-volume loops during reduction of preload, achieved by temporary balloon occlusion of the inferior caval vein, the contractility can be calculated by the slope of the endsystolic pressure-volume relation (elastance). Changes of contractility following dobutamine infusion could be noted by changes of elastance. The difference between the slopes with/without dobutamine demonstrates the contractility reserve function of the right ventricle.

Purpose: To evaluate the correlation between right ventricular contractility reserve function and functional assessment by MRI to determine the optimal timing of pulmonary valve replacement after repair of tetralogy of Fallot.