EFFECT OF VOLUME UNLOADING SURGERY ON CORONARY FLOW DYNAMICS IN PATIENTS WITH AORTIC ATRESIA

Objectives: The objectives of this study were to define physiologic ef fects on and a clinical correlate to coronary blood flow during volume unloading surgery in patients with aortic atresia. Methods: Twenty-tw o patients with aortic atresia (group I, 13 patients with stage I reco nstruction undergoing hemi-Fontan operation; group II, 9 patients with hemi-Fontan undergoing Fontan operation) underwent perioperative tran sesophageal echocardiography. Doppler spectral patterns, peak velocity , velocity time integral, and blood flow in the native ascending aorta were measured. Preoperative hemodynamics and postoperative clinical d ata were analyzed. Significance was defined as p < 0.05. Results: High er values of coronary blood Bow (982.9 +/- 321.7 vs 548.6 +/- 333.8 ml /min per square meter), velocity time integral (20.7 +/- 5.6 vs 12.6 /- 4.0 cm), and peak velocity (96.1 +/- 21.4 vs 51.0 +/- 18.2 cm/sec) were found before operation in group I than after operation and in gro up II at both times. Flow changed from predominately systolic in preop erative group I to both systolic and diastolic after operation and in group II. Before operation in groups I and II, a number of hemodynamic parameters such as superior vena cava oxygen saturation correlated wi th coronary blood flow dynamics. After operation in group II, urine ou tput (r = 0.86) and central venous pressure (r = -0.85) correlated wit h coronary blood flow dynamics. Conclusion: Coronary blood flow parame ters were higher in group I as a result of the increased energy needs required to pump to two circulations. No changes were found in group L I. A number of coronary blood how parameters correlated with preoperat ive hemodynamics and postoperative clinical data. These parameters app ear to be useful in assessing the performance status of the myocardium after the Fontan operation, consistent with the notion that myocardia l perfusion relates directly to ventricular function.