PULSED DOPPLER-ECHOCARDIOGRAPHIC ASSESSMENT OF PATTERNS OF VENOUS FLOW AFTER THE MODIFIED FONTAN OPERATION - POTENTIAL CLINICAL IMPLICATIONS

To assess the effect of a modified Fontan operation on systemic venous blood flow and the hepatic circulation, we compared 11 patients havin g an atriopulmonary connection and 35 with total cavopulmonary anastom osis. The Doppler echocardiographic study of the caval venous, hepatic venous and portal venous flow was performed so as to calculate the pu lsatility ratio and the variation of flow with respiration. All patien ts had undergone cardiac catheterization. In addition, we included spe cific laboratory investigations to assess function of various organs. Significantly-lower maximum velocities of flow at inspiration (0.31 +/ - 0.12 m/sec vs 0.45 +/- 0.14 m/sec) and expiration (0.23 +/- 0.09 m/s ec vs 0.32 +/- 0.11 m/sec), less pulsatility (0.43 vs 0.16) and a lowe r ratio of systolic to diastolic velocity (1.22 vs 1.85) were found in the patients having a cavopulmonary as compared to an atriopulmonary anastomosis. Peak velocities of hepatic venous flow during inspiration and expiration were significantly lower in those with a cavopulmonary anastomosis (p = 0.001 and p < 0.001, respectively). In these patient s, forward flow was extremely dependent on respiration, with decrease or cessation of antegrade flow during expiration in 22 patients. The v elocity of portal venous flow was also significantly lower in these pa tients, although the pulsatility ratio did not differ significantly be tween the groups (0.5 +/- 0.21 and 0.57 +/- 0.23, respectively). The r atio of inspiratory and expiratory velocities showed no significant di fference between the groups, nor was there any correlation between the pulsatility ratio of the venous vessels or the ratio of peak flow vel ocities during expiration and the mean systemic venous/right atrial pr essure on postoperative cardiac catheterization. Hypoproteinemia was f ound in 8 patients after total cavopulmonary anastomosis; 9 of 10 pati ents with protein C deficiency belonged to this group. The dependence of hepatic venous flow on respiration in the presence of a chronically elevated systemic venous pressure in patients after the total cavopul monary anastomosis may influence hepatic function in the postoperative period.