Objectives. Open-heart surgery has been reported to increase coronary flow (CF). Myocardial fibrosis and restrictive right ventricular physiology (RRVP) might also affect the magnitude of CF in postoperative patients with Fallot’s tetrology (TOF).
Methods. Echocardiography was used in 32 patients anatomically corrected for TOF to measure the flow in the pulmonary artery, posterior descending coronary artery (PDCA) and left anterior descending artery (LAD). Magnetic resonance imaging (MRI) was used to detect fibrosis in the right ventricular outflow tract. Twenty age-matched healthy children served as controls.
Results. The median age at surgery was 7.5 months (1-24 months). RRVP was found in 16 of 32 patients. Coronary flow could be registered successfully from PDCA and LAD during the same study in 24/32. In those, right ventricular fibrosis was registered in 10 and 11 had no fibrosis. Coronary flow parameters were increased in both coronary arteries. In PDCA peak flow velocity in diastole, velocity time integral and coronary flow were increased more in those with RRVP as compared with those without (39±7 versus 32±5, p<0.02; 17±4 versus 15±3, p<0.0001; 48±5 versus 32±5, p<0.0007, respectively). The flow parameters increased and distributed almost equally when the patients were grouped on the basis of fibrosis instead of RRVP.
Conclusion. RRVP is associated with increased coronary flow.Increased systolic workload against stiff fibrotic myocardium and earlier surgery with cardiopulmonary by-pass increase the basal coronary flow. The reported decrease of coronary flow reserve after surgery might be due to increased basal flow.