Histopathological changes of right ventricle outflow tract myocardium in relation to age in tetralogy of Fallot and its relation to clinical outcome

Background

Right ventricle outflow tract myocardium in tetralogy of Fallot reflects the effect of hemodynamic stresses on right ventricle muscle and correlates with clinical right ventricle dysfunction. It may be a useful adjunct in determining the time for intracardiac repair and predicting the clinical outcome.

Methods

Septal and parietal bands of infundibular septum and obstructing muscle bands were excised in 48 patients undergoing intracardiac repair for tetralogy of Fallot. Microscopic study of histopathological changes in resected muscle bands was done. Post operative 2D echocardiography and tissue doppler imaging were done at the end of first and third month evaluating the right ventricular function.

Results

Moderate myocardial fibrosis was seen in 42.9% (12/28) patients with age >5 years compared to 37.5% (6/16) patients with age between 1-5 years and 0% patients with age < 1 year (P >0.05). Right ventricular dysfunction was seen in 41.9% (18/43) patients who had no myocardial ischemia compared to 60% (3/5) patients with myocardial ischemia. Right ventricular dysfunction was noted in 13.33% (4/30) patients having mild myocardial fibrosis compared to 33.33% (6/18) patients with moderate myocardial fibrosis (P >0.05). Early postoperative right ventricular dysfunction was seen in more number of patients with increasing age as calculated by fractional area changes and Tei index.

Conclusions

Myocardial fibrosis was seen in more number of patients as age progresses. Early postoperative right ventricular dysfunction was more frequent in patients with higher grade of myocardial fibrosis and higher age group.