Asian Cardiovasc Thorac Ann 2003;11:229-232
© 2003 Asia Publishing EXchange Ltd
Accordion-Like Prosthesis for Modified Blalock-Taussig Shunt
Antonio F Corno, MD,
Michel Hurni, MD,
Piergiorgio Tozzi, MD,
Ludwig K von Segesser, MD
Department of Cardiovascular Surgery, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
For reprint information contact: Antonio F Corno, MD Tel: 41 21 314 2280 Fax: 41 21 314 2278 email: antonio.corno{at}chuv.hospvd.ch Department of Cardiovascular Surgery, Centre Hospitalier Universitaire Vaudois, 46 rue du Bugnon, CH-1011, Lausanne, Switzerland.
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ABSTRACT
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From March 1996 to July 2002, 26 consecutive patients, with a mean age of 17.9 months and a mean body weight of 6.6 kg, underwent the modified Blalock-Taussig shunt with a tubular accordion-like prosthesis. In a mean follow-up period (defined as the interval between the shunt procedure and repair or last evaluation) of 10.9 months (range, 1 to 32 months), there were 1 death due to excessive pulmonary blood flow in a neonate with hypoplastic left heart syndrome and 3 reoperations to correct shunt-related problems, 2 of them early and 1 late (to regulate pulmonary blood flow after left ventricular retraining for transposition of the great arteries). There was no occurrence of shunt obstruction or kinking. Other shunt-related early complications, such as bleeding, infection, or serous fluid leakage, did not occur, and no patient needed pulmonary artery reconstruction during surgical repair. Shunt patency was confirmed by Doppler echocardiography in all patients and also by angiography in 73% of the patients. This prospective study confirmed our preliminary results with this prosthesis. The use of this prosthesis is justified for reducing early and late complications potentially associated with the modified Blalock-Taussig shunt, particularly distortion of the pulmonary arteries.
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INTRODUCTION
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Despite the trend towards early repair of congenital heart defects,1 the modified Blalock-Taussig shunt, a palliative procedure, is still frequently performed in children with cyanotic congenital heart defects and reduced pulmonary blood flow. This observation is confirmed by numerous recent reports on this procedure, including those on a computational model of this procedure,2 its wide clinical application as a palliative approach,3 a technical modification,4 postoperative diagnosis,5 and postoperative complications.5–10 Furthermore, the modified Blalock-Taussig shunt is needed for the first-stage palliation of hypoplastic left heart syndrome9 and for the more complex surgical approach of left ventricular retraining in preparation for arterial switch in late referral cases of transposition of the great arteries.10,11
Following our initial clinical experience a few years ago12 with the modified Blalock-Taussig shunt using a tubular accordion-like prosthesis, we report now the intermediate-term results of a prospective study in a larger group of patients operated on with the same technique.
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PATIENTS AND METHODS
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From March 1996 to July 2002, 26 consecutive patients, with a mean age of 17.9 months (median, 4 months; range, 2 days to 12 years) and a mean body weight of 6.6 kg (median, 5.3 kg; range, 2.8 to 29.0 kg), underwent the modified Blalock-Taussig shunt with an Atrium prosthesis (Atrium Medical, Hudson, NH, USA). The diagnoses of the patients are listed in Table 1
. The size of the prostheses implanted varied from 3.5 mm in 6 patients, 4 mm in 11 patients, 5 mm in 7 patients, to 6 mm in 4 patients.
Associated procedures were performed in 11 patients, all on cardiopulmonary bypass: atrioseptectomy with or without pulmonary artery banding in 5 patients (all with transposition of the great arteries and undergoing left ventricular retraining), pulmonary artery unifocalization in 3 (all with pulmonary atresia with ventricular septal defect and major aortopulmonary artery collaterals), pulmonary valvectomy in 1 (with pulmonary atresia with intact ventricular septum), as a central shunt in 1 (with hypoplastic pulmonary arteries), and as part of a Norwood operation in 1 (with hypoplastic left heart syndrome).
All patients received oral antiplatelet treatment (aspirin 3 to 5 mg•kg-1•day-1) from the first postoperative day for 6 months, or until surgical repair if this occurred within 6 months.
To evaluate the adequacy of the palliative procedure, in particular with this type of tubular prosthesis, several parameters were taken into consideration: systemic oxygen saturation on room air before surgery and at discharge; shunt patency, evaluated by Doppler echocardiography and/or angiography; occurrence of early complications, such as bleeding, infection, and serous fluid leakage; the need for shunt-related reoperation because of shunt occlusion or dysfunction; and the need for pulmonary artery reconstruction at the time of surgical repair.
The follow-up period was defined as the interval between shunt implantation and surgical repair or the last Doppler or angiographic evaluation.
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RESULTS
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In a mean follow-up period of 10.9 months (range, 1 to 32 months), there was 1 death, due to sudden cardiac arrest in a 3-day-old neonate weighing 2.8 kg with hypoplastic left heart syndrome. Death occurred in the immediate postoperative period after a Norwood operation with a 3.5-mm tubular prosthesis implanted from the innominate artery to the right pulmonary artery. Since retrospectively we found clinical signs of excessive pulmonary blood flow, we speculated that a prosthesis of 3.5 mm was probably too large for a 2.8-kg neonate, which led to inadequate coronary artery perfusion and subsequently cardiac arrest.
Three patients required reoperation, 2 early and 1 late, for shunt-related problems. An infant with transposition of the great arteries, who underwent pulmonary artery banding and modified Blalock-Taussig shunt for left ventricular retraining, required an early reoperation to replace an implanted 3.5-mm prosthesis with another one of 4 mm because of excessive arterial oxygen desaturation, despite patency of the shunt.
Another infant with transposition of the great arteries, who underwent atrioseptectomy, pulmonary artery banding, and modified Blalock-Taussig shunt for left ventricular retraining, required early reoperation to reduce the size of the implanted 4-mm prosthesis because of excessive pulmonary blood flow. Shunt reduction was obtained with the longitudinal application of 12 consecutive metal clips on the entire length of the prosthesis. The prosthesis remained patent, as documented by angiography, until the subsequent arterial switch.
The last shunt-related reoperation occurred in a neonate with transposition of the great arteries, ventricular septal defect, left ventricular outflow tract obstruction, and an anomalous coronary artery, who 4 months after a modified right Blalock-Taussig shunt with a 4-mm prosthesis returned with increasing cyanosis, despite patency of the shunt confirmed by both Doppler echocardiography and angiography. Because of the patient’s age and the diagnosis, we decided to perform another modified Blalock-Taussig shunt on the other side, again with a 4-mm prosthesis.
Other shunt-related early complications, such as bleeding, infection, or serous fluid leakage, did not occur. The mean systemic oxygen saturation on room air increased from 67% before surgery (range, 63% to 78%) to 89% at hospital discharge (range, 85% to 93%). For obvious reasons, the patients who underwent left ventricular retraining and Norwood operation were excluded from this evaluation. Shunt patency was confirmed by Doppler echocardiography in all patients and also by angiography in 19 of the patients (73%). During the entire follow-up period, no patient needed pulmonary artery reconstruction at the time of surgical repair.
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DISCUSSION
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The classical indications for the modified Blalock-Taussig shunt, based on echocardiographic diagnosis, are well established.13 Also well established are shunt-related complications,3–8,14 postoperative evaluation of the shunt itself and of the pulmonary arteries,6,15 and the growth of the pulmonary arteries after a systemic–pulmonary artery shunt.15,16 A more recent indication is its use with pulmonary artery banding and atrioseptectomy on cardiopulmonary bypass for children with transposition of the great arteries undergoing left ventricular retraining because of late referral. The criteria for this specific indication have been discussed elsewhere.10,11 Despite positive results in our initial clinical experience,12 very little has since been reported on the use of Atrium for constructing a modified Blalock-Taussig shunt; all other studies used Gore and Impra polytetrafluoroethylene prostheses.3,6,16–19
An important consideration for the construction of a modified Blalock-Taussig shunt is the determination of the length of the tubular prosthesis in order to avoid tension and redundancy, and thus potential kinking or distortion of the pulmonary arteries.20 The accordion-like Atrium prosthesis allows a much easier determination of the length during construction of the systemic-to-pulmonary artery shunt because of its compensatory characteristics.12 The main characteristics of this prosthesis are a concentric radial node design, easy handling and conformability, high flexibility with extraordinary resistance to compression and kinking, and reduced needle hole bleeding.12
In conclusion, our preliminary results with this tubular prosthesis have been confirmed by this larger prospective study. The use of this prosthesis seems to be justified for reducing early and late complications potentially associated with the modified Blalock-Taussig shunt, particularly distortion of the pulmonary arteries. In fact, during the entire follow-up period, no patient needed pulmonary artery reconstruction at the time of surgical repair.
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REFERENCES
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ABSTRACT
Introduction
