Ann Thorac Surg 1996;61:58-62
© 1996 The Society of Thoracic Surgeons
Original Articles: Cardiovascular
Modified Blalock-Taussig Shunt Using Allograft Saphenous Vein: Six Years' Experience
Gábor Bogáts, MD,
Erzsébet Kertész, MD,
Márta Katona, MD, PhD,
Anna Tószegi, MD, PhD,
Gábor S. Kovács, MD, PhD
Departments of Cardiac Surgery, Pediatrics, and Pathology, Albert Szent-Györgyi Medical University, Szeged, Hungary
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Abstract
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Background. The occurrence of life-threatening late infectious complications after the use of expanded polytetrafluoroethylene conduits as modified Blalock-Taussig shunts prompted us to apply allograft saphenous veins instead.
Methods. In 23 cyanotic patients (age, 1 week to 18 years) allograft saphenous veins were used for performing Blalock-Taussig shunts from July 1989 onward. Veins stored in Hank's solution were implanted in 8 patients and cryopreserved ones in 15. All patients were followed up regularly up to 15 months.
Results. There were two early and two late deaths: none were related to shunt occlusion. Clinical, angiographic, and echocardiographic studies proved that, except for one early occlusion, all shunts were patent and functioning well after an average of 41 months. Donor cells disappeared 1 to 3 days after implantation, and several months after the operation both the wall and the luminal surface of the grafts were repopulated with cells possibly of recipient origin. No difference was found between veins stored in Hank's solution only and cryopreserved grafts, concerning clinical outcome and histology.
Conclusions. Allograft saphenous veins function well as modified Blalock-Taussig shunts at least up to 6 years. Owing to the good results and lack of complications their clinical use is recommended.
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Introduction
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Modification of the original Blalock-Taussig shunt [1] by interposing a synthetic conduit between the subclavian and pulmonary arteries [2, 3] has several advantages: it is technically simpler because less dissection is needed, blood flow to the respective arm is not jeopardized because the subclavian artery is not sacrificed, and there is no subclavian steal effect [4]. With the introduction of expanded polytetrafluoroethylene grafts [5] (Gore-Tex, W.L. Gore & Assoc, Flagstaff, AZ; Impra Medica SA, Geneva, Switzerland) smaller conduits (4 to 6 mm) can be safely used without increasing thrombotic obstruction rate [3, 6, 7]. Because the orifice of the subclavian artery serves as a flow regulator, early overperfusion of the lungs can be avoided, and an increase in shunt flow can be expected with growth [3]. Thus the procedure can be applied even to small infants, and has become the most common shunt operation [6, 7]. Despite the obvious advantages of the polytetrafluoroethylene conduits, however, they are not free of special complications. Lengthy oozing of blood or serous leakage from the stitch holes or through the graft can occur [8], and owing to their relative stiffness, the grafts may kink if wrongly positioned.
Until 1989, Impra or Gore-Tex was used almost exclusively at this institution for modified Blalock-Taussig shunts. However, the appearance of a life-threatening late complication in 2 consecutive patients discouraged their further use. In 2 patients pseudoaneurysm developed at the site of the proximal anastomosis after infectious complications several years after the shunt operation; in 1 of these cases it occurred 1 year after successful operation and ligation of the Impra shunt.
Having employed successfully some saphenous vein allografts as coronary artery bypass grafts, we decided to use homograft veins left out from previous coronary artery bypass graft operations for the creation of modified Blalock-Taussig shunts, first preferably in infected patients. Later the preliminary good results encouraged us to use them more extensively. This papers deals with 6 years' clinical experience obtained in 23 patients, and with the fate of the homograft veins.
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Material and Methods
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Saphenous veins were collected during coronary artery bypass graft operations using a no-touch technique. They were then stored in heparinized autologous blood at room temperature until completion of the revascularization. Unused vein segments were then washed with sterile saline solution and distended temporarily to 80 to 100 mm Hg. Their outside diameter was measured with sterile caliper squares, and then they were placed for 24 hours at 4°C in a modified Hank's solution containing a low concentration of antibiotics (cefotoxin, 140 µg/mL; lincomycin, 120 µg/mL; polymyxin B, 100 µg/mL; vancomycin, 50 µg/mL, and amphotericin B, 25 µg/mL) [9]. Before September 1990 all vein segments were stored at 4°C in the modified Hank's solution for 6 weeks at the longest; if they were not used by then, they were discarded. Veins stored in Hank's solution were used in 8 patients after storage from 3 to 38 days (average, 22.4 days) [10]. Since September 1990 the vein segments were cryopreserved after the 24-hour sterilization procedure in Hank's solution. They were placed in a solution containing 10% dimethylsulfoxide and 10% human albumin, and cooled down to -196°C in a computer-controlled Sy-Lab model 1510 (Sy-Lab GmbH, Parkersdorf, Austria) deep-freezing apparatus. The cooling rate was even at 1°C per minute; thus the cells were not damaged and the tissue structure was well preserved (Fig 1
) [11, 12]. Tissue samples that underwent the same procedures were taken from the grafts both at harvesting and at the operation, and were sent for bacteriologic and histologic studies. Similarly blood was taken from the donors for serologic tests for hepatitis, human immunodeficiency virus, cytomegalovirus, and syphilis. If any of these tests turned out to be positive, the grafts were not used.
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Fig 1. . Microscopic view of a cryopreserved saphenous vein after thawing. The wall structure is normal. (Hematoxylin and eosin; x180 before 23% reduction.)
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The allografts were then stored in liquid nitrogen vapor; thus, they could be preserved practically indefinitely. Grafts stored in Hank's solution were rinsed thoroughly in saline solution at the operating table; the cryopreserved tissues were thawed in a waterbath of 40°C, and then the dimethylsulfoxide was rinsed off thoroughly in several changes of saline solution before implantation.
Since July 1989 modified Blalock-Taussig shunt operations using allograft saphenous veins have been performed in 23 patients (Table 1). In 8 patients vein segments preserved in Hank's solution were applied, and in 15 others cryopreserved tissues were used. No effort was made to take blood groups or tissue typing into consideration at the selection of the respective grafts.
The 10 female and 13 male patients' ages varied from 6 days to 18 years (average, 38.7 months), and their weight was between 2.29 and 41 kg (average, 10.36 kg). The diagnosis was tetralogy of Fallot in 12, pulmonary atresia in 6, double-outlet right ventricle with pulmonary stenosis in 2, and single ventricle with pulmonary stenosis in 3 patients. In older children or adults the indications for shunt operation were extreme cyanosis with small left ventricle and low ejection fraction or uncorrectable lesion. Previous palliative interventions had been performed in 3 patients: in 2 a closed Brock operation had been carried out, and in 1 an original Blalock-Taussig operation was done at infancy, and after its occlusion percutaneous balloon valvuloplasty was performed repeatedly.
The operative technique did not differ from that generally used in creation of a modified Blalock-Taussig shunt: on 20 occasions the left and in 3 cases the right subclavian arteries were used. On clamping off the subclavian artery 1 mg/kg heparin was given intravenously, which was not reversed later. A longitudinal incision was made in the subclavian artery near its origin, and a cobra-head anastomosis was performed with the obliquely cut saphenous vein. A graft the size of the subclavian artery or larger was chosen if available. For the distal anastomosis the left or right main pulmonary artery was incised longitudinally (18 patients) or transversely (5 patients). The anastomoses were performed with a single running suture of 6-0 or 7-0 Prolene (Ethicon, Somerville, NJ). The lengths of the venous segments ranged from 30 to 80 mm (average, 44 mm), and their diameter was between 4 and 8 mm (average, 5.36 mm).
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Results
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There was no operative death in the 23 operations. Technically the operations were easy and simple; because the allografts are pliable and soft, they were easy to handle and to sew. There was no bleeding or serous leakage after completion of the anastomoses. Blood flow through the shunt was measured with an ultrasonic flowmeter (Transonic AT 107; Transonic Systems, Ithaca, NY) in 7 patients at the completion of the shunt, and in 1 patient at reoperation; the flows were between 430 and 1,800 mL/min (see Table 1
). Arterial blood samples were taken before and after the shunt operation: the average arterial oxygen tension rose from 35.22 < 4.88 mm Hg to 45.57 < 6.96 mm Hg as a results of the increased pulmonary flow.
There were two early deaths, 1 and 3 days postoperatively, unrelated to the function of the shunt. One patient, a 6-day-old neonate with pulmonary atresia, was operated on for severe hypoxia as an emergency. Although the shunt functioned well and the patient became much less cyanotic, she never recovered and died of cerebral damage on the third postoperative day. Another 4-year-old patient had double-outlet right ventricle with a ventricular septal defect, atrial septal defect, severe pulmonary stenosis, and dextrocardia. An original left-sided Blalock-Taussig shunt was performed at 6 months, which occluded years later. He underwent two unsuccessful pulmonary valve balloon dilations, and finally the modified Blalock-Taussig shunt was performed on the right side for severe hypoxia as an emergency operation. The shunt functioned well postoperatively, but cerebral damage developed, and the patient died 14 hours after the operation. In both cases the vein segment was completely patent, and no kinking or thrombus formations were observed. On histologic examination both 1 and 3 days after implantation the original structure of the venous wall disappeared; it became a homogenous eosinophilic, loose tissue containing no cells except some in the adventitial layer. Signs of rejection or foreign body reactions were not observed (Fig 2).
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Fig 2. . Histologic picture of a cryopreserved venous allograft implanted 14 hours before death, and recovered at autopsy. The wall is homogenous and eosinophilic; no intimal and medial cells can be found. (Hematoxylin and eosin; x180 before 23% reduction.)
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Two patients died 11 months after the operation in remote hospitals after respiratory infection. One of them had received a graft kept in Hank's solution only, and the other a cryopreserved vein. In both cases the shunt was patent with no apparent macroscopic change. Both grafts appeared similar on histologic examination: the wall of the veins was still somewhat homogeneous, with a few noninflammatory cells, which presumably originated from the recipient. The luminal surface was thinly and noncontinuously covered with endothelial-like neointimal cells (Fig 3).
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Fig 3. . Histologic picture of a cryopreserved venous allograft recovered at autopsy from a patient who died 11 months after the shunt operation. The luminal surface is covered loosely with neointima, and the media contains some cellular elements. (Hematoxylin and eosin; x180 before 23% reduction.)
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Graft occlusion occurred in only 1 patient (patient 17) in the early postoperative period. This was very likely due to kinking of a too long segment of cryopreserved vein 4 mm in diameter. Because outflow obstruction was mainly at valvular level, a closed Brock operation was performed shortly afterward as a further palliation, with good results.
No medical therapy was applied either in the early or in the late postoperative period for the protection of the shunts: no immunosuppressive drugs, anticoagulants, or antiplatelet drugs were given. All patients were routinely followed up during an average period of 41.21 months, the longest follow-up being almost 6 years. All patients living with their shunts are well, their growth was normal, they are slightly cyanotic, and their hematocrit is between 0.39 and 0.50. Except for 1 patient whose graft had occluded, no other patient needed further palliation. On auscultation a strong continuous systolodistolic murmur can be heard. On echocardiography a high shunt flow can be demonstrated in all patients. Angiocardiography was performed in 9 patients: the shunts were all functioning well, and no stenosis, kinking, or aneurysm formation could be observed (Fig 4).
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Fig 4. . (Patient 2.) Aortic arch angiogram 4 years after a left-sided modified Blalock-Taussig shunt using a saphenous allograft. Shunt flow is filling both pulmonary arteries.
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Final corrective operation was performed in 4 patients (patients 2, 5, 7, and 9) from 25 to 55 months after the shunt operation. There were no complications, and the dissection and ligature of the allograft was similar to that experienced at the dissection of the subclavian artery in the original Blalock-Taussig operation. (However, dissection of a Gore-Tex shunt is easier, because of its stiffer nature and lack of tissue adhesion to the synthetic material.) There was no apparent fibrosis or calcification around the allografts. In 2 patients (25 and 55 months after the shunt operation) the grafts were doubly ligated proximally and distally and a short segment was excised for histologic examination. In both cases the luminal surface was completely covered with neointima and the medial layer was almost normally populated with cells presumably of recipient origin (Fig 5).
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Fig 5. . Histologic picture of an allograft saphenous vein preserved in Hank's solution and implanted 55 months before the corrective operation, when a segment had been excised from the ligated shunt. The luminal surface is covered with neointima, and the media contains many normal cells. (Hematoxylin and eosin; x180 before 23% reduction.)
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Comment
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In cases where proper autologous saphenous veins were not available, allografts have been used in the past both in peripheral and in coronary artery operations [13–18]. The results obtained with the allograft, however, have been worse than those after the use of autologous veins [14, 15, 17, 18]. In operations on congenital heart diseases some efforts have been made to use biografts for the creation of systemic-pulmonary shunts [19–21]. In the present material the patency rate of the allografts was superior to those reported in coronary artery operations: of 21 allograft saphenous vein segments, 20 were patent at 11 months after implantation (95.2%). This may be due to the different immunoreactivity of infants and small children, or more probably to the much higher flow rates in these short segments.
Thus it seems that human saphenous vein allograft is a good alternative biomaterial for the performance of a modified Blalock-Taussig shunt. It is easily available, its use simplifies the operative procedure, and it is devoid of bleeding complications and serous leakage. Being a biomaterial, presumably it is less prone to take part in infectious complications. Ligation of the shunt at the corrective operation should not cause any difficulties either. In the presented material there were no apparent differences either clinically or in the histologic picture between veins preserved in Hank's solution and the cryopreserved ones.
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Footnotes
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Presented at the Poster Session of the Twenty-ninth Annual Meeting of The Society of Thoracic Surgeons, San Antonio, TX, Jan 25-27, 1993.
Address reprint requests to Dr Kovács, Department of Cardiac Surgery, Albert Szent-Györgyi Medical University, Pécsi-utca 4, POB 464, Szeged, Hungary.
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References
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- Blalock A, Taussig HB. Surgical treatment of malformations of the heart in which there is pulmonary stenosis or atresia. JAMA 1945;128:189–202.[Abstract/Free Full Text]
- Klinner VW, Pasini M, Schaudig A. Anastomose zwischen System- und Lungenarterie mit Hilfe von Kunstoffprothesen bei cyanotischen Herzvitien. Thoraxchirurgie 1962;10:68–75.
- De Leval MR, McKay R, Jones M, Stark J, Macartney FJ. Modified Blalock-Taussig shunt. Use of subclavian artery orifice as flow regulator in prosthetic systemic-pulmonary artery shunts. J Thorac Cardiovasc Surg 1981;81:112–9.[Abstract]
- Watkins MT, Ricotta JJ, Manning JA, Stewart S. Upper extremity claudication 10 years after a Blalock-Taussig shunt: treated with a carotid-to-subclavian graft. Ann Thorac Surg 1988;45:445–6.[Abstract/Free Full Text]
- Gazzaniga AB, Elliott MP, Sperling DR, et al. Microporous expanded polytetrafluoroethylene arterial prosthesis for construction of aortopulmonary shunts: experimental and clinical results. Ann Thorac Surg 1976;21:322–7.[Abstract/Free Full Text]
- Ullom RL, Sade RM, Crawford FA Jr, Ross BA, Spinale F. The Blalock-Taussig shunt in infants: standard versus modified. Ann Thorac Surg 1987;44:539–43.[Abstract/Free Full Text]
- Ilbawi MN, Grieco J, DeLeon SY, et al. Modified Blalock-Taussig shunt in newborn infants. J Thorac Cardiovasc Surg 1984;88:770–5.[Abstract]
- LeBlanc J, Albus R, Williams WG, et al. Serous fluid leakage: a complication following the modified Blalock-Taussig shunt. J Thorac Cardiovasc Surg 1984;88:259–62.[Abstract]
- Strickett MG, Barratt-Boyes BG, MacCulloch D. Disinfection of human heart valve allografts with antibiotics in low concentration. Pathology 1983;15:457–62.[Medline]
- Davies AH, Parums DV. Storage of donor long saphenous vein. J Cardiovasc Surg (Torino) 1992;33:92–7.[Medline]
- O'Brien MF, Stafford G, Gardner M, et al. The viable cryopreserved allograft aortic valve. J Card Surg 1987;2(Suppl):153–67.[Medline]
- Armiger LC, Thomson RW, Strickett MG, Barratt-Boyes BG. Morphology of heart valves preserved by liquid nitrogen freezing. Thorax 1985;40:778–86.[Abstract/Free Full Text]
- Brockbank KG, McNally RT, Walsh KA. Cryopreserved vein transplantation. J Cardiac Surg 1992;7:170–6.[Medline]
- Martin RS III, Edwards WH, Mulherin JL Jr, Edwards WH Jr, Jenkins JM, Hoff SJ. Cryopreserved saphenous vein allografts for below-knee lower extremity revascularization. Ann Surg 1994;219:664–70.[Medline]
- Sellke FW, Stanford W, Rossi NP. Failure of cryopreserved saphenous vein allografts following coronary artery bypass surgery. J Cardiovasc Surg (Torino) 1991;32:820–3.[Medline]
- Hoover WW, Kresowik TF, Cook RT. Biologic fate of cryopreserved human saphenous allografts: case report and hypothesis. J Cardiovasc Surg (Torino) 1991;32:708–10.[Medline]
- Laub GW, Muralidharan S, Clancy R, et al. Cryopreserved allograft veins as alternative coronary artery bypass conduits: early phase results. Ann Thorac Surg 1992;54:826–31.[Abstract/Free Full Text]
- Vermassen F, Degrieck N, De Kock L, Goubeau J, Van Landuyt K, Derom F. Venous allografts for vascular reconstructions. J Cardiovasc Surg (Torino) 1992;33:641–9.[Medline]
- Danilowicz D, Ishmael RG, Doyle EF, Isom OW, Colvin SB, Greco MA. Use of saphenous vein allografts for aortopulmonary artery anastomoses in neonates with complex cyanotic congenital heart disease. Pediatr Cardiol 1984;5:13–7.[Medline]
- Vincent JG, Lacquet LK, v.d.Wal HJ, Daniels O, van Oort A. A denaturated venous homograft as an alternative material for shunts and other reconstructions in congenital cardiac surgery. J Cardiovasc Surg (Torino) 1990;31:766–70.[Medline]
- Wojtalik M, Religa Z, Goldstein L, Frycz M, Grzybowski A, Zembala M. Follow up of infants after systemic-pulmonary shunts, performed with fresh frozen vein homografts. Presented at the Fourth World Congress of International Society of Cardio-Thoracic Surgeons. Jerusalem, Israel, Feb 20-23, 1994.
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Abstract
Introduction
