Risk Factors for Mortality After the Norwood Procedure Using Right Ventricle to Pulmonary Artery Shunt Ann Thorac Surg 2009;87:178 86 86 Addressor: R1 胡祐寧 2009/3/4 AM7:30 SICU 討論室 Introduction Hypoplastic left heart syndrome was a fatal disease Norwood stage palliation greatly improved the outcome Technical challenge and still carries significant mortality and morbidity Anatomical diagnosis, aortic atresia, smaller ascending aortic diameter Prematurity, low birth weight Additional cardiac anomalies, noncardiac anomalies, chromosomal abnormalities Lower preoperative ph, initial operation after 14 or 30 days, fetal diagnosis, longer circulatory arrest Presence of significant tricuspid regurgitation (TR) Background Recent modification of Norwood stage 1 palliation (S1P) using a right ventricle to pulmonary artery (RV-PA) shunt Provide stable hemodynamics (higher diastolic pressure) Lead to an excellent early survival Avoid pulmonary overflow and beneficial for low body weight infants 9-year experience with Norwood S1P using RV-PA shunt and identify the factors associated with outcome Study Design Retrospective review for 62 infants with HLHS or a variant who underwent a modified Norwood procedure using the RV-PA shunt from Feb 1998 to Dec 2007 Received bilateral PA banding was not included The medical, operative records, and angiographic and echocardiographic data for all patients were reviewed Operative Procedure-I An arterial cannula was inserted into a 3.5-mm expanded polytetrafluoroethylene (eptfe)) tube This single arterial cannula was soon changed to a dual arterial cannula Ductus arteriosus was ligated and divided during cooling phase Autologous pericardium was used initially to patch the distal main PA and then changed to cuffed eptfe tubes (for RV-PA shunt) Another arterial cannula Venous cannula 1
Coronary puncher Extend width of aortic arch Cuffed eptfe tube Operative Procedure-II Delay sternal closure was performed routinely Bidirectional Glenn (BDG) procedure was performed after mean interval of 5.5 months Fontan procedure was performed at approximately 2 years of age Heart transplantation was not a realistic option Patient Population 62 patients received Norwood S1P of HLHS 47 patients had classical HLHS and 15 had variants of HLHS Among 47 patients with classical HLHS 26 with aortic atresia and mitral atresia 11 with aortic stenosis and mitral stenosis 7 with aortic atresia and mitral stenosis 3 with aortic stenosis and mitral atresia Median age at operation was 9 days 11 patients were more than 14 days old and 3 were older than 30 days old Median weight was 2.7 Kg 18 patients less than 2.5 Kg and 7 patients less than 2 Kg 44 patients were premature Mean myocardial ischemic time 49 minutes Mean total bypass time 142 minutes All were not associated with stage 1 operative mortality Overall survival to 9 years was 76% 2
80 73 93 76 93 64 For patients with either one of the three factors (prematurity, body weight 2.5 kg, TR 2+), the overall mortality was 48% (13 of 27) For patients with none of the three factors, the overall mortality was 7% (2 of 35) The classical hypoplastic left heart syndrome versus the variants The difference was only of borderline significance (p=0.06, log-rank test) Discussion Body weight less than 2.5 kg and TR 2+ or greater were two independent factors associated with significantly shorter duration of survival Operative survival rate was 92% and the 1-year and 5-year 5 survival rates were 80% and 73% Previous series operative survival rate:71.4~79% Previous series 1-year 1 survival rate: 51~66% Previous series 5-year 5 survival rate: 40~60% Body weight less than 2.5 kg and significant TR were independent risk factors associated with poor outcomes Factors Associated With Outcomes The prematurity, body weight less than 2.5 kg, TR 2+ or greater were not associated with operative mortality at S1P These were significantly associated with the late mortality All the 4 premature babies died later Early operative mortality for the patients (18) weighing less than 2.5 kg at S1P was only 16%, but 7 early survivors died in the late stage, with the overall mortality increased to 55% (10 of 18) Low Body Weight Management of pulmonary blood flow is problem The traditional modified Blalock- Taussig shunt 3.5-mm graft resulted in pulmonary overcirculation and systemic malperfusion 3.0-mm graft leaves little room for technical error and increases risk of thrombosis 3
Significant TR 5-mm RV-PA shunt was used in the majority of patients 4-mm graft was used in 6 patients including low body weight infants The patients with a 4-mm 4 RV-PA shunt all survived initially, but the late mortality rate was 66% (4 of 6), including 2 sudden shunt occlusions Small RV-PA shunt (4 mm) could only improve short-term term outcome More than half (7 of 13; 54%) of the patients with TR 2+ or greater died before Fontan operation 2 patients with tricuspid valve plasty and 1 with valve replacement Failing right ventricle in systemic circulation is not compatible with life Heart transplantation is not a realistic management option Anatomic subtypes of HLHS Aortic atresia have been considered as a risk factor for poor outcome The data did not show significant difference in the anatomic subtypes Possibly because of limited sample size Other Traditional Risk Factors Bypass time Age more than 14 days at operation Small ascending aortic diameter Not associated with mortality, similar to a recent report from Ann Arbor Chromosomal abnormalities, noncardiac anomalies were also reported risk factors associated with the outcome, but did not associate with outcome in the study Late Mortality Previous study reported 12% of the survivors of the initial procedure died before 1 year of age These deaths are usually sudden and often unexplained Unexpected death occurred in 4.1% (22 of 536) at a median age of 79 days Coronary insufficiency, arrhythmia, ventricular dysfunction, residual arch obstruction, PA distortion, restrictive ASD, and inadequate pulmonary blood flow In this study, the interstage mortality is still substantial: 9 (16%) of the early survivors died before Fontan completion Intense surveillance after discharge was suggested by recent study Heart transplantation for high-risk patients with HLHS has been suggested 4
RV-PA Conduit Versus Modified Blalock- Taussig Shunt in Stage 1 Palliation Report from Philadelphia by Ballweg and coworkers No difference in survival at 3 years (RV-PA conduit: 73% versus modified Blalock-Taussig shunt: 69%; p=0.6) RV-PA group had younger age, lower arterial saturation, and higher diastolic blood pressure before stage 2 More ventricular dysfunction, atrioventricular valve regurgitation, and neoaortic valve regurgitation in the RV-PA group before stage 3 Study Limitation Too-small number of patients to perform meaningful subgroup analysis General improvement in surgical technique and perioperative care as experience accumulated could not be analyzed in the study Heart transplantation is a choice for HLHS patients with poor right ventricular function, but it is not possible in Japan Conclusion Use of an RV-PA shunt and refinement of surgical technique, the traditional risk factors for Norwood S1P mortality had less impact on early results Low body weight and significant TR still had a negative impact on midterm survival More efforts should be made to improve the long-term results for patients with hypoplastic left heart syndrome 5