Hemolysis Due to Branch Pulmonary Stenosis After the Arterial Switch Procedure James Schroeder, MD, James Albert, MD, David Clarke, MD, Michael Schaffer, MD, Robert Wolfe, MD, and Taru Hays, MD Section of Pediatric Cardiology, Division of Cardiothoracic Surgery, and Department of HematologylOncology, The Children’s Hospital and University of Colorado Health Sciences Center, Denver, Colorado

An infant with d-transposition of the great arteries un- derwent arterial switch operation using the modified Jatene technique. Severe bilateral branch pulmonary artery stenosis and mechanical hemolysis subsequently developed. The hemolysis resolved after surgical repair of the stenotic arteries. Probable causes are discussed.

(Ann Thorac Surg 1991;51:491-2)

he arterial switch operation of Jatene and colleagues T [l] has become the procedure of choice for infants with dextro-transposition of the great arteries at many institutions. In recent years, generally favorable results have been reported [2-51. Certain well-described compli- cations continue to occur, including supravalvar pulmo- nary stenosis, left ventricular outflow obstruction, neoco- arctation, and kinking of the coronary arteries [2-71. We describe a unique secondary complication of branch pul- monary artery stenosis after the arterial switch procedure.

A 3.5-kg cyanotic male newborn was diagnosed by echo- cardiography and cineangiography as having d-transpo- sition of the great arteries. Rashkind balloon atrial sep- tostomy was performed on the second day of life and arterial switch procedure, on the third day, using the Lecompte modification of the Jatene technique [6]. Under deep hypothermia and circulatory arrest, the atrial septa1 defect was repaired primarily. The aorta and pulmonary artery were transected, and the pulmonary artery was brought anterior to the aorta. The coronary ostia were excised with buttons of aortic wall and were sutured in place on the neoaortic root. The proximal pulmonary artery (neoaorta) was anastomosed to the distal ascending aorta. The proximal aorta (neo-pulmonary artery) was reconstructed with a Gore-Tex patch and attached to the distal main pulmonary artery with an end-to-end anasto- mosis. The postoperative course was unremarkable, and the child was discharged from the hospital on the seventh postoperative day.

At 11 weeks of age the child was readmitted to the hospital with rhinitis, cough, tactile fever, fussiness, emesis, and jaundice. He had mild hepatomegaly and no

Accepted for publication Aug 16, 1990.

Address reprint requests to Dr Schroeder, Pediatric Cardiology, The Children’s Hospital, 1056 E 19th St, Denver, CO 80218.

splenomegaly. There was a harsh, grade 4 6 systolic ejection murmur. Laboratory data included: hemoglobin, 0.042 g/L; hematocrit, 0.12; white blood cell count, 16.6 x 109/L (16,6OO/pL); and platelet count, 399 X 109/L (399,000/ pL). Peripheral blood smear showed anisocytosis, poikilo- cytosis, microspherocytes, schistocytes, polychromasia, and a reticulocyte count of 0.20. Total serum bilirubin level was 51.3 pmoYL (3.0 mg/dL) (normal, 3.4 to 25.7 pmolk). Aspartate aminotransferase level was 282 U/L (normal, 10 to 40 U/L), and alanine aminotransferase level was 37 U/L (normal, 5 to 25 UIL).

Two-dimensional echocardiography showed a normal pulmonary outflow tract with distal narrowing of the pulmonary artery. Continuous-wave Doppler interroga- tion showed a flow velocity of 4.5 d s reflecting approx- imately an 80-mm Hg pressure gradient.

The child received weekly transfusions of packed red blood cells during the next 4 weeks. During this interval, further hematological evaluation was carried out, includ- ing direct Coomb’s test, serum viral antibody titers, and urine culture for cytomegalovirus, all of which were negative. Glucose-6-phosphate dehydrogenase assay was normal.

A second cardiac catheterization showed that the main pulmonary artery pressure was suprasystemic at 110/0 mm Hg. The right pulmonary artery pressure was 33/10 mm Hg. Cineangiography showed severe stenosis of both proximal branch pulmonary arteries with the left more severely affected than the right (Fig 1). The pulmonary anastomosis site was not stenotic.

The child underwent surgical repair of the stenotic portion of the pulmonary artery at 15 weeks of age. The pulmonary artery was noted to be constricted by periduc- tal tissue at the bifurcation, distal to the pulmonary anastomosis site. Under cardiopulmonary bypass, a lon- gitudinal pulmonary arteriotomy was performed along the bifurcation and extended to within 5 mm of the first branch bilaterally. The arteriotomy was patched with a 3.0 x 1.0-cm Gore-Tex patch with running suture of 5-0 Gore-Tex.

The child is currently 7 months old and is off all medications. He has grown well and has no evidence of ongoing hemolysis. His hematocrit is 0.34, and he has not required any blood transfusions since the operation. He continues to have Doppler measurements of a mild to moderate degree of pulmonary artery stenosis.

0 1991 by The Society of Thoracic Surgeons 0003-4975/91/$3.50

492 CASE REPORT SCHROEDER ET AL HEMOLYSIS AmER ARTERIAL SWITCH

Ann Thorac Surg 1991;51:491-2

Fig 2 . A single frame from a right ventricular cineangiogram (35 mm) demonstrating bilateral pulmonary branch stenosis with the left pulmonary artery (open arrow) more severely affected than the right pulmonary artery (closed arrow).

Comment This case demonstrates several unique features. Supraval- var stenosis, although well described as a postoperative complication of the arterial switch operation for d-trans- position of the great arteries, has usually been described as occurring at or proximal to the reanastomosis site [3, 7, 81. In a large multicenter review of the arterial switch operation, of 12 patients undergoing reoperation for right- sided obstructive lesions, 9 had obstruction in the neo- pulmonary trunk and 3 had valvar stenosis [7]. In another series, 8 of 8 patients who underwent reoperation had stenosis at or proximal to the reanastomosis site [B]. The stenosis in our case occurred at a more distal location; that is, at the bifurcation of the pulmonary artery. The causal mechanism of the stenosis at this location is not known, but we speculate that undue tension on the pulmonary artery owing to the LeCompte maneuver may have played a role. Additionally, there may have been constric- tion of ductal tissue extending into the pulmonary arter- ies.

Mechanical hemolysis as a result of cardiac conditions has been well described [9]. Hemolysis has been attrib- uted to a variety of cardiac conditions including prosthetic heart valves, Teflon patches, mechanical pump devices, cardiomyopathy, and endocarditis. Regurgitant valves, primarily aortic or mitral, have also been implicated as causes of hemolysis as has postoperative stenosis of the pulmonary valve. We are unable to find previous reports of mechanical hemolysis due to stenosis of a distal pul- monary artery.

Theoretical considerations put forth by Nevaril and colleagues [lo], based on in vitro analysis of shearing forces on red blood cells, indicate that a shearing stress of

greater than 3,000 dynes can create hemolysis. They estimate that a 50-mm Hg gradient would be sufficient to generate this amount of shearing force; however, hemo- lysis is extremely rare despite the relative frequency of pressure gradients greater than 50 mm Hg in our patient population. The unique feature of this case that may have resulted in hemolysis is the presence of a reverse gradient across the stenosis during diastole. This phenomenon could conceivably cause to-and-fro blood flow across an extremely narrow segment, which would predispose to an additional “Waring blender” effect. Surgical interven- tion, although not completely relieving the stenosis, has decreased its severity and resulted in resolution of the hemolysis. The child does not have any other evidence of a hematological abnormality that would lead to increased fragility of the red blood cells.

Further refinement of surgical techniques for the arte- rial switch procedure should lead to continued improve- ment of both short- and long-term outcome in children with d-transposition of the great arteries. Avoidance of undue tension on the pulmonary arteries by liberal mobi- lization of the distal segment of the transected pulmonary artery is a desirable aspect of the LeCompte maneuver. Awareness of the potential complications, careful postop- erative evaluation, and timely intervention to relieve major obstructions are necessary.

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Jatene AD, Fontes VF, Paulista PP, et al. Anatomic correction of transposition of the great vessels. J Thorac Cardiovasc Surg 1976;72:3644. Castaneda AR, Trusler GA, Paul MH, Blackstone EH, Kirklin JW. The early results of treatment of simple transposition in the current era. J Thorac Cardiovasc Surg 1988;95:14-28. Jatene AD, Fontes VF, Souza LCB, et al. Anatomic correction of transposition of the great arteries. J Thorac Cardiovasc Surg 1982;83:20-6. Quaegebeur JM, Rohmer J, Ottenkamp J, et al. The arterial switch operation: an eight-year experience. J Thorac Cardio- vasc Surg 1986;92:361-84. Castaneda AR, Norwood WI, Jonas RA, Colon SD, Sanders SP, Lang P. Transposition of the great arteries and intact ventricular septum: anatomical repair in the neonate. Ann Thorac Surg 1984;38:43843. Lecompte Y, Zannini L, Hazan E, et al. Anatomic correction of transposition of the great arteries. J Thorac Cardiovasc Surg 1981;82:629-31. Norwood WI, Dobell AR, Freed MD, Kirklin JW, Blackstone EH. Intermediate results of the arterial switch repair. A 20 institution study. J Thorac Cardiovasc Surg 1988;96:854-63. Gleason MM, Chin AJ, Andrews BA, et al. Two-dimensional and Doppler echocardiographic assessment of neonatal arte- rial repair for transposition of the great arteries. J Am Coll Cardiol 1989;13:1320-8. Stockman JA. Hematologic expressions of systemic disease. In: Nathan DG, Oski FA, eds. Hematology of infancy and childhood. Philadelphia: W.B. Saunders, 19871633-4. Nevaril CG, Lynch EC, Alfrey CP, Hellums JD. Erythrocyte damage and destruction induced by shearing stress. J Lab Clin Med 1968;71:7&90.