Asian Cardiovasc Thorac Ann 2000;8:238-240
© 2000 Asia Publishing EXchange Pte Ltd
Blalock-Taussig Shunt Using Fresh Saphenous Vein Homograft
Faik Fevzi Okur, MD,
Vedide Tavli, MD1,,
Bekir Kayhan, MD,
Mustafa Kirman, MD,
Cenk Sinan Atalay, MD,
Mehmet Tekdo
an, MD
Department of Cardiac Surgery
1 Department of Pediatric Cardiology
 ifa Heart Center
I•zmir, Turkey
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For reprint information contact: Faik Fevzi Okur, MD Tel: 90 232 446 3738 Fax: 90 232 446 0770 Fevzi Pa a Bulvari 172/2, Basmane, I•zmir 35240, Turkey
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Abstract
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The occurrence of life-threatening early and late complications following the use of expanded polytetrafluoroethylene grafts for modified Blalock-Taussig shunts prompted the application of saphenous vein homografts instead. In 21 patients with cyanotic congenital heart disease, fresh saphenous vein homografts were used for Blalock-Taussig shunts from February 1998. The veins were obtained from blood-group matched patients undergoing coronary bypass grafting in the next operating room. There was no early or late mortality. Clinical and echocardiographic studies showed that all shunts were patent and functioning well at an average follow-up of 11 months. This simple homograft technique has no ischemic time and requires no chemical or antibiotic contact.
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Introduction
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The modified Blalock-Taussig shunt uses an interposition polytetrafluoroethylene (PTFE) graft between the subclavian and pulmonary arteries. It is considered by many to be the palliative procedure of choice in some patients with cyanotic congenital heart disease. It is associated with a low operative mortality, excellent patency, and technical ease of insertion and closure. The shunt can be placed in either pulmonary artery and preserves the patency of the subclavian artery. However, in spite of the obvious advantages of PTFE conduits, they are not free from complications. Prolonged oozing of blood or serous leakage from the suture holes or through the graft can occur, and because of their relative stiffness, these grafts may kink if positioned incorrectly.1 In the first patient in this series, thrombotic obstruction developed at 12 hours postoperatively, requiring urgent intervention. It was decided to use a saphenous vein homograft in this patient instead of another PTFE graft. We have continued to use fresh saphenous vein in subsequent cyanotic patients who needed palliative procedures.
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Patients and Methods
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Between February 1998 and December 1999, 21 con-secutive patients aged 2 months to 20 years (weight, 6 kg to 60 kg), underwent a modified Blalock-Taussig shunt with fresh saphenous vein. All but 1 of the 11 male and 10 female patients had a diagnosis of tetralogy of Fallot; double-outlet right ventricle with pulmonary stenosis and tricuspid atresia was diagnosed in the other one. Patient selection criteria for shunting were hypoplasia of the main pulmonary artery, branch stenosis, and markedly low left ventricular volume index. A previous modified Blalock-Taussig shunt with a PTFE graft had been performed in 5 patients. The standard operative technique for creation of a modified Blalock-Taussig shunt was used in all cases. On 20 occasions, the left subclavian artery was used, the right subclavian artery was used in one case. Before clamping the subclavian artery, heparin 100 IU•kg–1 was given intravenously and later reversed. Saphenous veins were obtained from patients, preferably blood-group matched, who were undergoing coronary bypass grafting at the same time in the next operating room. The vein graft was transferred from one operating room to the other in sterile Ringer's solution at 4°C. Only low-dose aspirin was given in the postoperative period. No other medical therapy was applied, including immuno-suppressive drugs. All patients were followed up for an average of 11 months, the longest follow-up being 22 months.
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Results
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There was no early or late mortality. The operations were technically easy because saphenous vein homografts are soft and pliable, making them easy to handle and sew. There was no bleeding or serous leakage after completion of the anastomoses. Arterial oxygen saturation was measured by pulse oxymetry before and after completion of the shunt. The mean oxygen saturation rose significantly from 78% ± 3.8% to 92% ± 3%. The mean preoperative hematocrit was 53% ± 6.8% and it decreased to 41.1% ± 11% postoperatively. Clinical examination and echo-cardiographic studies showed that all shunts were patent and functioning well (Figure 1
). All patients were well at follow-up and none manifested signs of excessive pul-monary blood flow.
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Figure 1. Doppler echocardiogram at 22 months postoperatively, demonstrating systolic and diastolic flow in the homograft, indicating patency.
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Discussion
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The Blalock-Taussig shunt is considered a low-risk option for palliation of cyanotic heart disease but the associated morbidity can have a significant impact on patient care. Shunt occlusion may result in death. This had previously occurred in the late follow-up of an infant who underwent a modified Blalock-Taussig shunt using PTFE and discouraged further use of such graft material.1 The potential occurrence of infection at the shunt site is another reason to use homografts for Blalock-Taussig shunts.
Generally, homograft tissues are removed at autopsy. Some homografts are freeze dried or rapidly frozen for storage, whereas others are kept in nutrient medium with antibiotics at 4°C for up to 6 or 8 weeks. All homograft collection techniques require some ischemic time but tissue viability is crucial for long-term graft durability.2 Homograft valves are usually transplanted without matching the donor and recipient for blood group or human leukocyte antigens. The influence of blood-group compatibility on the rejection of transplanted valves was studied by Balch and Karp3 who reported that there was no relationship between blood-group matching and the success or failure of the implanted homograft. Recently, homograft rejection was shown to be related to blood group, human leukocyte antigen incompatibility has also been observed, mainly in infants less than one year of age.4,5 Therefore, we preferred to use blood-group matched donors who were easily available in our division.
An unusual and infrequently reported complication of the PTFE graft is a perigraft seroma. Use of heparin leads to an increased risk of perigraft seroma, complicating systemic-to-pulmonary PTFE grafts. If heparin is not used in the early postoperative period, thrombotic complications may occur with PTFE grafts.6 However, heparinization is not needed for homografts. Moreover, seroma formation is impossible in saphenous veins.
Khouri and colleagues7 reported growth of an autologous saphenous vein graft from 3.5 mm in diameter and 8 cm in length to 5 mm in diameter and 15 cm in length 13 years after coronary bypass in a child with Kawasaki disease. In view of this observation, it is postulated that the use of very fresh saphenous vein homografts in shunts from the aorta to the pulmonary artery could accommodate sufficient growth of the pulmonary arteries. Some of the patients included in this study have undergone corrective surgery between 1 and 2 years after the palliative procedure; we have not observed marked changes in the sizes of the saphenous vein grafts but there have been significant improvements in the McGoon ratios. Currently, these findings are under investigation in the setting of another correlative study using angiocardiographic and magnetic resonance imaging techniques.
It was concluded that human saphenous vein homograft is a good alternative biomaterial for a modified BlalockTaussig shunt. The favorable early results have encouraged us to continue using this simple technique with material that is easily available and cheaper than other options, without the need for cryopreservation technology, without ischemic time, and without chemical or antibiotic contact. The surgical procedure is easier, the graft is less likely to kink, and the handling time is shorter.
Presented at the 6th Balkan Pediatric Cardiology and Cardiac Surgery Congress, Antalya, Turkey, November 4–7, 1998.
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References
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Bogats G, Kertesz E, Katona M, Toszegi A, Kovacs GS. Modified Blalock-Taussig shunt using allograft saphenous vein: six years' experience. Ann Thorac Surg 1996;61: 58–62.[Abstract/Free Full Text]
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Stelzer P, Elkins RC. Homograft valves and conduits: applications in cardiac surgery. Curr Probl Surg 1989; 26:381–452.[Medline]
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Balch CM, Karp RB. Blood group compatibility and aortic valve allotransplantation in man. J Thorac Cardiovasc Surg 1975;70:256–9.[Abstract]
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Rajani B, Mee RB, Ratliff NB. Evidence for rejection of homograft cardiac valves in infants. J Thorac Cardiovasc Surg 1998;115:111–7.[Abstract/Free Full Text]
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Kawauchi M, Nakajima J, Takeda M, Oka T, Takamoto S. Aortic valves are antigenic but less so than myocardium. J Thorac Cardiovasc Surg 1998;116:532–8.[Free Full Text]
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Berger RM, Bol-Raap G, Hop WJC, Bogers AJ, Hess J. Heparin as a risk factor for perigraft seroma complicating the modified Blalock-Taussig shunt. J Thorac Cardiovasc Surg 1998;116:286–93.[Abstract/Free Full Text]
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El-Khouri HM, Danilowicz DA, Slovis AJ, Colvin SB, Artman M. Saphenous vein graft growth 13 years after coronary bypass in a child with Kawasaki disease. Ann Thorac Surg 1998;65:1127–30.[Abstract/Free Full Text]
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Abstract
Introduction
