Comparison of hemodynamics between Norwood procedure and systemic-to-pulmonary artery shunt for single right ventricle patients

Objective: Despite that surgical outcomes of patients with hypoplastic left heart syndrome have improved, one of the problems remaining is the high interstage mortality after a stage I Norwood procedure. The purpose of this study was to determine the hemodynamic characteristics of hypoplastic left heart syndrome after a Norwood procedure. We examined the perioperative hemodynamic differences of the staged operation between the first stage of the Norwood procedure and systemic pulmonary shunt for single right ventricle patients. Methods: Data from 39 patients who underwent a Norwood procedure (right ventricle to pulmonary artery conduit: 19, Blalock-Taussig shunt, 20) were analyzed. There were nine early and seven interstage deaths. Bidirectional cavopulmonary shunt was performed in 15 patients and the Fontan procedure in 9 (group H). We defined the control group as 26 patients who underwent the first stage of a systemic pulmonary shunt for a single ventricle. Bidirectional cavopulmonary shunt was performed in 14 patients and the Fontan procedure in 8 (group C). We compared the perioperative hemodynamics of the staged operation between the two groups. Results: Cardiothoracic ratio and single ventricular diastolic dimension before bidirectional cavopulmonary shunt were acutely increased in group H (P=0.02, <0.001). There was no significant difference between the two different types of Norwood procedures. The pulmonary artery index for the right heart bypass operation was lower in group H than in group C (P<0.001). Oxygen saturation before bidirectional cavopulmonary shunt in group H decreased (P<0.001) and thus was lower than that in group C (P=0.003). Mortality and the postoperative clinical parameters of the right heart bypass operation were not different between the two groups. Conclusions: Patients with hypoplastic left heart syndrome showed hemodynamic instability of acutely increased cardiothoracic ratio, and single ventricular diastolic dimension despite decreased oxygen saturation interstage after stage I of a Norwood procedure. This suggests that this hemodynamic characteristics in hypoplastic left heart syndrome correlates with the higher mortality before second stage palliation than in found with single right ventricle patients.