RIGHT VENTRICULAR MYOCARDIAL BIOPSIES IN TETRALOGY OF FALLOT

Abstract

Full thickness RV myocardial biopsies were taken during surgery in 21 patients with Tetralogy. Specimens stained with Trichrome and Verhoff VonGieson were analyzed. Grade I: Endocardial fibroelastosis with perivascular fibrous and collagen invasion. Grade II: Subendocardial collagen and fibroblast invasion with myocardial hypertrophy. Grade III: Myocardial cell disruption plus intimal thickening of intramural coronary arteries. Quantitative anglographic RV function was correlated with RV myocardial histology.

Grade III changes were found in older age group which showed markedly depressed RV ejection fraction. Grade I and II changes characterized the myocardium of patients below 2 yrs. Between 2 and 4 yrs. some patients showed Grade I and II changes with moderately depressed RV functions. Of 10 patients with mild changes, 6 showed RV ejection fraction in the low normal range; 3 had ejection fraction below 0.55 and only 1 had RV ejection below 0.50. 11 patients over 2 yrs. showed Grade III changes and markedly depressed RV ejection, 7 below 0.50.

Summary: RV myocardial changes correlated with the degree of RV function depression as well as the pts. age. Grade III myocardial changes accompanied severe RV function depression in Tetralogy pts. over 4 years of age; between 2 and 4 yrs. some pts. with marked RV depression showed only Grade I and II changes and pts. below 2 yrs. showed only Grade I and II changes with milder RV function depression. This study lends support to early corrective surgery for Tetralogy before marked myocardial changes accompanies deterioration of right heart function.

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