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Coronary Artery Injury by a Valved External Conduit
CASE REPORTS
Coronary Artery Injury by a Valved External Conduit J. Peter Harris, M.D., Scott Stewart, M.D., Virginia Anderson, M.D., Mark L. Mitchell, M.D., and James A. Manning, M.D. ABSTRACT A 4-month-old infant underwent repair of type I truncus arteriosus and died immediately after as a consequence of left main coronary artery compression by the metallic stent in the Dacron conduit. To avoid injury to the coronary vasculature, the future location of the porcine valve ring should be assessed and relocated if necessary.
The introduction of valved external conduits in 1966 substantially improved the long-term outlook for many children with complex congenital heart disease [l]. Aortic homografts were utilized initially, but late calcific obstruction and difficulties in procurement led many surgeons to favor a Dacron conduit containing a glutaraldehyde-stabilized porcine valve* [2, 31. However, obstructive complications due to the technique of insertion of the Dacron conduit, fibrocalcific changes in the porcine valve, and luminal fibrosis have been reported subsequently [4-61. Recently we encountered an infant who died as a consequence of coronary artery compression by the metallic stent in a Hancock conduit. The 2,500-gm patient was born after an uncomplicated 37-week gestation. Initial examination by the pediatric cardiology division when he was 11 days old revealed an adequately nourished acyanotic infant with no evidence of respiratory distress. The chest was clear, but the precordium was hyperdynamic. A grade 3/6 systolic ejection murmur was audible along the left sternal border with a single accentuated second sound at the left base. The liver was not enlarged, and the peripheral pulses were full throughout. An electrocardiogram revealed an axis of +lo0 degrees and biventricular hyperFrom the Departments of Pediatrics, Surgery, and Pathology, University of Rochester, Rochester, NY.
Accepted for publication May 29, 1980. Address reprint requests to Dr. Harris, Division of Pediatric Cardiology, University of Rochester Medical Center, 601 Elmwood Ave, Rochester, NY 14642. ‘Hancock Laboratories, Anaheim, CA.
trophy. On fluoroscopy, the cardiothoracic ratio was 0.50 with a mild increase in pulmonary blood flow. At reevaluation two weeks later, a soft apical middiastolic murmur was noted, and T wave inversion was present over the left precordial leads of the electrocardiogram. An increase in heart size and in pulmonary vascularity was seen on fluoroscopy. Catheterization and angiography when the patient was 2 months old revealed a variant of type I truncus arteriosus. There was a short main pulmonary artery arising from the posterior aspect of the common trunk, and the aortic arch was on the left. Digitalis and diuretics were administered at this time for mild congestive failure, and it was recommended that complete repair be done when the patient was 4 months old. At operation, the angiographic findings were confirmed. Cold cardioplegia was utilized for myocardial preservation during periods of aortic cross-clamping. The short main pulmonary artery was excised from the truncus and the incision closed with a running Prolene suture. The ventricular septa1 defect was closed with a Dacron patch, and a 12 mm Hancock conduit was inserted between the vertical incision in the right ventricle and the main pulmonary artery. Following rewarming, poor left ventricular contractility and a pale left anterior descending coronary artery were noted. Cardiopulmonary bypass was reinstituted and the left coronary ostium inspected, but no abnormality was found. Despite a prolonged period of partial bypass and maximal inotropic support, satisfactory left ventricular contractility could not be reestablished, and the infant died in the operating room. At postmortem examination, the metallic stent in the Dacron conduit was found to straddle the bifurcation of the left coronary artery. A contusion of this vessel at the site of compression was noted, and the left coronary artery appeared pale and bloodless (Fig 1).Microscopic sections and pH measurements revealed an
271 0003-4975/81/030271-03$01.25 @ 1980 by The Society of Thoracic Surgeons
272 The Annals of Thoracic Surgery Vol 31 No 3 March 1981
Fig I . The metallic stent of the Dacron conduit overrides the left main coronary artery. Ventricular pallor and a pale, bloodless, and furrowed left coronary artery are present.
Fig 2 . An early fibrin thrombus was found in the collapsed left coronary artery at the site of compression. ( H 6 E ; ~10.)
acute massive circumferential hemorrhagic infarction of the left ventricle and papillary muscles. A review of the coronary arterial system demonstrated a fibrin clot within the lumen of the left coronary artery at the point of external compression (Fig 2).
Comment Palliative procedures, particularly banding of the pulmonary artery, for complex congenital
heart defects are not always effective and can carry a high morbidity and mortality. The results of pulmonary artery banding for truncus arteriosus have been particularly discouraging [7]. Consequently, a program of definitive repair in infancy has been advocated by some groups [B]. Many of the repairs require the insertion of a valved external conduit to reestablish continuity between the venous ventricle and the pulmonary artery. Since the mediastinal volume in the smaller patient is limited, various techniques have been developed to allow sternal closure without resultant conduit distortion. The conduit is usually positioned with a curve to the left of the ascending aorta (or to the right in patients with transposition complexes) to avoid compression between the aorta and the chest wall. The porcine valve is placed close to the distal anastomosis to avoid compression of the valvular apparatus between the heart and the sternum. Furthermore, a vertical ventriculotomy is used, and wide proximal and distal anastomoses are created to reduce the incidence of venous ventricle outflow obstruction. It is also imperative that the major coronary arteries be identified and preserved since incision or ligation of an artery can result in a myocardial infarction and subsequent death [9-121. Compression of a coronary artery by the metallic ring of the Dacron conduit has not been reported. Our patient experienced a massive and lethal infarction as a result of occlusion of the bifurcation of the left coronary artery. This patient illustrates the importance of positioning the external conduit in a manner that will avoid injury to or pressure on the coronary vessels. Obstruction of the left coronary artery by the conduit can be prevented by an accurate assessment of the future position of the porcine valve ring prior to final trimming of the proximal and distal conduit. A variation of only a few millimeters at one end or the other can determine whether or not the conduit ring will oppose the coronary artery.
References 1. Ross DN, Somenrille J: Correction of pulmonary atresia with a homograft aortic valve. Lancet 2:1446, 1966
273 Case Report: Harris et al: Coronary Artery Injury by Valved Conduit
2. Merin G, McGoon DC: Reoperation after insertion of aortic homograft as a right ventricular outflow tract. Ann Thorac Surg 16:122, 1973 3. Moodie DS, Mair DD, Fulton RE, et al: Aortic homograft obstruction. J Thorac Cardiovasc Surg 72:553, 1976 4. Ciaravella JM, McGoon DC, Danielson GK, et al: Experience with the extracardiac conduit. J Thorac Cardiovasc Surg 78:920, 1979 5. Heck HA Jr, Schieken RM, Lauer RM, Doty DB: Conduit repair for complex congenital heart disease: late follow-up. J Thorac Cardiovasc Surg 75:806, 1978 6. Geha AS, Laks H, Stansel HC, et al: Late failure of porcine valve heterografts in children. J Thorac Cardiovasc Surg 78:351, 1979 7. Applebaum A, Bargeron LM Jr, Pacific0 AD, Kirklin JW: Surgical treatment of truncus arteriosus, with emphasis on infants and small
children. J Thorac Cardiovasc Surg 71:436, 1976 8. Ebert PA, Robinson SJ, Stanger P, Engle MA: Pulmonary artery conduits in infants younger than six months of age. J Thorac Cardiovasc Surg 72:351, 1976 9. Anderson KR, McGoon DC, Lie JT: Surgical significance of the coronary anatomy in truncus arteriosus communis. Am J Cardiol 41:76, 1978 10. Berry BE, McGoon DC: Total correction for tetralogy of Fallot with anomalous coronary artery. Surg 742394, 1973 11. Dabizzi RP, Caprioli G, Aiazzi L, et al: Distribution and anomalies of coronary arteries in tetralogy of Fallot. Circulation 61:95, 1980 12. Meyer J, Chiarello L, Hallman GL, Cooley DA: Coronary artery anomalies in patients with tetralogy of Fallot. J Thorac Cardiovasc Surg 69:373, 1975
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Coronary Artery Injury by a Valved External Conduit J. Peter Harris, M.D., Scott Stewart, M.D., Virginia Anderson, M.D., Mark L. Mitchell, M.D., and James A. Manning, M.D. ABSTRACT A 4-month-old infant underwent repair of type I truncus arteriosus and died immediately after as a consequence of left main coronary artery compression by the metallic stent in the Dacron conduit. To avoid injury to the coronary vasculature, the future location of the porcine valve ring should be assessed and relocated if necessary.
The introduction of valved external conduits in 1966 substantially improved the long-term outlook for many children with complex congenital heart disease [l]. Aortic homografts were utilized initially, but late calcific obstruction and difficulties in procurement led many surgeons to favor a Dacron conduit containing a glutaraldehyde-stabilized porcine valve* [2, 31. However, obstructive complications due to the technique of insertion of the Dacron conduit, fibrocalcific changes in the porcine valve, and luminal fibrosis have been reported subsequently [4-61. Recently we encountered an infant who died as a consequence of coronary artery compression by the metallic stent in a Hancock conduit. The 2,500-gm patient was born after an uncomplicated 37-week gestation. Initial examination by the pediatric cardiology division when he was 11 days old revealed an adequately nourished acyanotic infant with no evidence of respiratory distress. The chest was clear, but the precordium was hyperdynamic. A grade 3/6 systolic ejection murmur was audible along the left sternal border with a single accentuated second sound at the left base. The liver was not enlarged, and the peripheral pulses were full throughout. An electrocardiogram revealed an axis of +lo0 degrees and biventricular hyperFrom the Departments of Pediatrics, Surgery, and Pathology, University of Rochester, Rochester, NY.
Accepted for publication May 29, 1980. Address reprint requests to Dr. Harris, Division of Pediatric Cardiology, University of Rochester Medical Center, 601 Elmwood Ave, Rochester, NY 14642. ‘Hancock Laboratories, Anaheim, CA.
trophy. On fluoroscopy, the cardiothoracic ratio was 0.50 with a mild increase in pulmonary blood flow. At reevaluation two weeks later, a soft apical middiastolic murmur was noted, and T wave inversion was present over the left precordial leads of the electrocardiogram. An increase in heart size and in pulmonary vascularity was seen on fluoroscopy. Catheterization and angiography when the patient was 2 months old revealed a variant of type I truncus arteriosus. There was a short main pulmonary artery arising from the posterior aspect of the common trunk, and the aortic arch was on the left. Digitalis and diuretics were administered at this time for mild congestive failure, and it was recommended that complete repair be done when the patient was 4 months old. At operation, the angiographic findings were confirmed. Cold cardioplegia was utilized for myocardial preservation during periods of aortic cross-clamping. The short main pulmonary artery was excised from the truncus and the incision closed with a running Prolene suture. The ventricular septa1 defect was closed with a Dacron patch, and a 12 mm Hancock conduit was inserted between the vertical incision in the right ventricle and the main pulmonary artery. Following rewarming, poor left ventricular contractility and a pale left anterior descending coronary artery were noted. Cardiopulmonary bypass was reinstituted and the left coronary ostium inspected, but no abnormality was found. Despite a prolonged period of partial bypass and maximal inotropic support, satisfactory left ventricular contractility could not be reestablished, and the infant died in the operating room. At postmortem examination, the metallic stent in the Dacron conduit was found to straddle the bifurcation of the left coronary artery. A contusion of this vessel at the site of compression was noted, and the left coronary artery appeared pale and bloodless (Fig 1).Microscopic sections and pH measurements revealed an
271 0003-4975/81/030271-03$01.25 @ 1980 by The Society of Thoracic Surgeons
272 The Annals of Thoracic Surgery Vol 31 No 3 March 1981
Fig I . The metallic stent of the Dacron conduit overrides the left main coronary artery. Ventricular pallor and a pale, bloodless, and furrowed left coronary artery are present.
Fig 2 . An early fibrin thrombus was found in the collapsed left coronary artery at the site of compression. ( H 6 E ; ~10.)
acute massive circumferential hemorrhagic infarction of the left ventricle and papillary muscles. A review of the coronary arterial system demonstrated a fibrin clot within the lumen of the left coronary artery at the point of external compression (Fig 2).
Comment Palliative procedures, particularly banding of the pulmonary artery, for complex congenital
heart defects are not always effective and can carry a high morbidity and mortality. The results of pulmonary artery banding for truncus arteriosus have been particularly discouraging [7]. Consequently, a program of definitive repair in infancy has been advocated by some groups [B]. Many of the repairs require the insertion of a valved external conduit to reestablish continuity between the venous ventricle and the pulmonary artery. Since the mediastinal volume in the smaller patient is limited, various techniques have been developed to allow sternal closure without resultant conduit distortion. The conduit is usually positioned with a curve to the left of the ascending aorta (or to the right in patients with transposition complexes) to avoid compression between the aorta and the chest wall. The porcine valve is placed close to the distal anastomosis to avoid compression of the valvular apparatus between the heart and the sternum. Furthermore, a vertical ventriculotomy is used, and wide proximal and distal anastomoses are created to reduce the incidence of venous ventricle outflow obstruction. It is also imperative that the major coronary arteries be identified and preserved since incision or ligation of an artery can result in a myocardial infarction and subsequent death [9-121. Compression of a coronary artery by the metallic ring of the Dacron conduit has not been reported. Our patient experienced a massive and lethal infarction as a result of occlusion of the bifurcation of the left coronary artery. This patient illustrates the importance of positioning the external conduit in a manner that will avoid injury to or pressure on the coronary vessels. Obstruction of the left coronary artery by the conduit can be prevented by an accurate assessment of the future position of the porcine valve ring prior to final trimming of the proximal and distal conduit. A variation of only a few millimeters at one end or the other can determine whether or not the conduit ring will oppose the coronary artery.
References 1. Ross DN, Somenrille J: Correction of pulmonary atresia with a homograft aortic valve. Lancet 2:1446, 1966
273 Case Report: Harris et al: Coronary Artery Injury by Valved Conduit
2. Merin G, McGoon DC: Reoperation after insertion of aortic homograft as a right ventricular outflow tract. Ann Thorac Surg 16:122, 1973 3. Moodie DS, Mair DD, Fulton RE, et al: Aortic homograft obstruction. J Thorac Cardiovasc Surg 72:553, 1976 4. Ciaravella JM, McGoon DC, Danielson GK, et al: Experience with the extracardiac conduit. J Thorac Cardiovasc Surg 78:920, 1979 5. Heck HA Jr, Schieken RM, Lauer RM, Doty DB: Conduit repair for complex congenital heart disease: late follow-up. J Thorac Cardiovasc Surg 75:806, 1978 6. Geha AS, Laks H, Stansel HC, et al: Late failure of porcine valve heterografts in children. J Thorac Cardiovasc Surg 78:351, 1979 7. Applebaum A, Bargeron LM Jr, Pacific0 AD, Kirklin JW: Surgical treatment of truncus arteriosus, with emphasis on infants and small
children. J Thorac Cardiovasc Surg 71:436, 1976 8. Ebert PA, Robinson SJ, Stanger P, Engle MA: Pulmonary artery conduits in infants younger than six months of age. J Thorac Cardiovasc Surg 72:351, 1976 9. Anderson KR, McGoon DC, Lie JT: Surgical significance of the coronary anatomy in truncus arteriosus communis. Am J Cardiol 41:76, 1978 10. Berry BE, McGoon DC: Total correction for tetralogy of Fallot with anomalous coronary artery. Surg 742394, 1973 11. Dabizzi RP, Caprioli G, Aiazzi L, et al: Distribution and anomalies of coronary arteries in tetralogy of Fallot. Circulation 61:95, 1980 12. Meyer J, Chiarello L, Hallman GL, Cooley DA: Coronary artery anomalies in patients with tetralogy of Fallot. J Thorac Cardiovasc Surg 69:373, 1975
c