Follow up of Post-repair Tetralogy of Fallot

Overview

Tetralogy of Fallot is the most frequent complex congenital heart malformation. Over the past five decades, surgical repair has been performed with respectable results. However, relevant postoperative residues frequently remain. Pulmonary insufficiency, in particular, has been identified as a factor limiting the right ventricular function and, accordingly, the quality of life and life expectancy. With increasing use of cardiac MRI for both measurement of ventricular function and imaging of pulmonary arteries, residual defects have been discovered that were not detectable by echocardiography. There is mounting evidence of right ventricular pressure and volume stress in Fallot patients after surgical correction. At present, it is impossible to detect right ventricular insufficiency at an early stage. Hence, it is to be assumed that right ventricular insufficiency is underdiagnosed and therapeutic action frequently is initiated beyond the point of no return of ventricular function. The objective of this study is the systematic collection of cross-sectional and longitudinal data from extensive standardised examinations, including MRI, echocardiography, pulmonary function and ergometry tests, ECG and quality of life assessments, in a large number of patients with surgically corrected tetralogy of Fallot, and the setup of a database. The data obtained are supposed to provide information on the long-term outcome of surgical correction, to help establish criteria for necessity and time of re-intervention or re-operation, and to assess the effectiveness of re-interventions and re-operations.

In the repair of tetralogy of Fallot, pulmonary insufficiency used to be tacitly accepted as a result of extensive transannular patching (TAP) and considered unobjectionable. In fact, this is well tolerated during the first postoperative years, but today there is increasing evidence that the resulting chronic volume stress to the right ventricle is harmful on the long run, in particular if there are stenoses of the pulmonary artery in addition. Such stenoses, partly due to distortions after shunt surgery, together with pulmonary insufficiency, lead to a combined volume and pressure load of the right ventricle. The chronic volume stress results in a decrease in biventricular function and exercise tolerance, associated with increasing electrical instability with frequent, mostly ventricular, dysrhythmias. This constellation brings about a significantly increased risk of cardiac death. Pulmonary valve replacement can improve haemodynamics, exercise tolerance and dysrhythmia. However, it is still unclear, which criteria best indicate the need for re-operation or other re-intervention, such as balloon dilatations of peripheral pulmonary stenoses, and what may be the best point in time. Cardiac MRI has been established as non-invasive method to quantify right and left ventricular function without radiation exposure. Correlating quantitative functional data to clinical conditions may permit the evaluation of factors that influence the long-term course after surgical repair of Fallot's tetralogy. The objective of this study is to establish a broad database of cross-sectional and longitudinal (after one year) findings from extensive standardised examinations, including MRI, echocardiography, pulmonary function and ergometry tests, ECG, quality of life assessments performed and cardiac catheterisation, if indicated, on a large number of subjects with surgically corrected tetralogy of Fallot. The data obtained are supposed to determine parameters indicating beginning irreversibility of decreased cardiac function, to provide information on the long-term outcome of surgical correction, to help establish criteria for necessity and time of re-intervention or re-operation, and to assess the effectiveness of re-interventions and re-operations.