Classic Blalock-Taussig Shunt Research Articles

Long-term palliation with the classic Blalock-Taussig shunt

Eighty-five patients received a classic Blalock-Taussig shunt between 1973 and 1986. Their age range was 1 day to 9.3 years and their median age was 4 months. Forty-one percent (35/85) were less than 1 month of age. The basic operative technique was unchanged throughout the time period. The subclavian artery opposite the side of the arch was used in 89% (79/88) of the patients. All anastomoses were done with monofilament suture and there was a tendency toward smaller suture material (7-0) in the latter years. All anastomoses except one were done with an interrupted suture technique. The operative mortality rate was 4.7% (4/85) and was not statistically related to age, diagnosis, or year of operation. Palliation was considered to be satisfactory until either a second shunt or a premature corrective operation were necessary. Seven patients required a second shunt and three, a premature corrective operation. The mean time between the initial shunt and the second procedure, either a second shunt or a corrective operation, was 2.9 years and 2.4 years, respectively. Twenty-five patients have had an elective corrective operation and the mean interval to that procedure was 3.9 years. Two years after the operation, 97% of patients older than 1 month of age at operation remain in well-palliated condition, as do 87% of those less than 1 month of age. At 4 years, 87% of those older than 1 month and 54% of those less than 1 month of age continue to be in well-palliated condition. The classic Blalock-Taussig shunt provides excellent palliation at a low operative mortality for virtually all patients for a minimum of 2 years. It will provide adequate pulmonary blood flow for most patients for an extended period of time beyond 2 years.

Systemic-pulmonary polytetrafluoroethylene shunts in palliative operations for congenital heart disease: Revival of the central shunt

The concept of central shunting in smaller children with the Waterston shunt was initially well accepted. It has been abandoned because of the difficult estimation of lumen size, preferential flow to the right side, and difficulty in the take-down of the shunt. We have replaced the Waterston shunt with a short segment of polytetrafluoroethylene between the ascending aorta and the main pulmonary artery. From January 1979 to December 1986, 190 shunt operations were performed in 157 patients, with the use of 26 classic Blalock-Taussig shunts (13.7%), six Waterston shunts (3.1%), nine Glenn shunts (4.7%), 80 central aortopulmonary polytetrafluoroethylene shunts (42.2%), and 69 modified Blalock-Taussig shunts (36.3%). Polytetrafluoroethylene grafts were used for 149 of the 190 (78.4%) shunts. Overall mortality was 15.2%, with nine early deaths (4.7%) and 20 late deaths (10.5%). Deaths were due to the complex nature of the congenital anomaly or definitive surgical repair. The patients weighed from 1.6 to 48 kg and ages ranged from 1 day to 22 years. We have modified our technique so that (1) graft length is less than 0.5 cm and both ends are beveled, (2) the aortotomy is fashioned with a punch, (3) the center of the polytetrafluoroethylene graft is never clamped, (4) heparin is given during the construction of the shunt, and (5) aspirin (10 mg/kg/day) is administered daily. Patency ranges from 1 to 4 years. We conclude that the polytetrafluoroethylene shunt provides excellent palliation and that the central shunt, in the smaller child and infant, offers the benefits of shunting without distortion of the peripheral pulmonary arteries.

Indication for Systemic-Pulmonary Artery Shunts Guided by Two-Dimensional and Doppler Echocardiography: Criteria for Patient Selection

From June, 1983, to February, 1987, 91 patients with pulmonary outflow tract obstruction underwent a systemic-to-pulmonary artery shunt without an invasive study. The surgical indication was based on two-dimensional (2-D) and Doppler echocardiography only. In 82 patients (90.1%), 2-D and Doppler echocardiography allowed correct assessment of the intracardiac anatomy and of the morphology of the pulmonary arteries, pulmonary veins, and aortic arch. The aortic arch anatomy was misdiagnosed in 6 patients (6.6%) who underwent a modified instead of a classic Blalock-Taussig shunt. In 3 patients (3.3%), the indication for the systemic-pulmonary artery shunt was inappropriate; in 1, operative death resulted from the incomplete diagnosis. After the preselection of patients based on knowledge of the anatomical patterns, a systemic-pulmonary artery shunt may be performed without cardiac catheterization if these rules for definitive patient selection are followed: (1) accurate clinical assessment to identify the patients with restricted pulmonary blood flow; (2) precise intracardiac diagnosis by 2-D and Doppler echocardiography; and (3) definitive 2-D echocardiographic visualization of the pulmonary venous connection and the confluence of the pulmonary arteries.

Growth of the Pulmonary Arteries Following Blalock-Taussig Shunt

The Blalock-Taussig (BT) shunt remains the standard systemic-to-pulmonary artery shunt. We reviewed our experience with the classic BT shunt in terms of mortality, patency, duration of palliation, and growth of the pulmonary artery. Records were reviewed in 49 consecutive patients, 25 of whom were less than one month old at the time of operation. They underwent a total of 53 BT shunts. Also, the pulmonary artery index (PAI), or the sum of the cross-sectional areas of the right and left pulmonary arteries standardized by the body surface area (BSA), was calculated. There were 4 operative deaths (7.5%) and 1 late death (2.0%). Early shunt thrombosis (within 72 hours postoperatively) occurred in 3 patients. Four patients required a second BT shunt, 5 underwent a palliative outflow tract reconstruction, and 5 required a polytetrafluoroethylene graft. Twenty-one patients underwent a corrective procedure, and 26 underwent a second cardiac catheterization. Of these 26 patients, 24 represent the subgroup used to assess the growth of the pulmonary arteries. The mean duration of palliation was 25.15 months. Mean PAI increased significantly from 127 ± 40 mm 2/BSA pre-shunt to 286.1 ± 144 mm 2/BSA post-shunt ( p < .004). This series demonstrates that the pulmonary arteries do grow after BT shunt. Pulmonary artery growth in patients with tetralogy of Fallot was greater than that in patients with single ventricle, and the duration of palliation was acceptable in most patients. Calculation of PAI may aid in the decision whether to perform a corrective surgical procedure or a second palliative shunt procedure.

Surgical treatment of double inlet ventricle ("single ventricle").

The surgical techniques described are the result of an evolution over a number of years in the performance of the septation operation and the modified Fontan-Kreutzer repair for patients with double inlet ventricles. Those with associated pulmonary stenosis are best palliated by a classical Blalock-Taussig or Goretex shunt if an operation is required during the first few years of life and later, between two and four years of age, definitive repair by the modified Fontan-Kreutzer operation is advised. Although controversial, we prefer the use of a large nonvalved right atrial-pulmonary artery connection. Ventricular septation remains the best definitive surgical option when pulmonary stenosis is absent or mild. It is contraindicated by severe pulmonary vascular disease and also by less than moderate ventricular enlargement. The need for concomitant AV valve replacement and the use of an extracardiac conduit are associated with increased hospital mortality in our experience. Infants identified during the first year of life who do not have pulmonary stenosis are a difficult subset to manage. If the VSD and subaortic area is large and unobstructed, pulmonary artery banding early in life will control pulmonary vascular resistance and from this standpoint, permit these patients to become ultimately suited to a modified Fontan-Kreutzer repair. Unfortunately, ventricular hypertrophy usually results from pulmonary artery banding and has been associated with higher hospital mortality at the time of definitive repair. When pulmonary artery banding is undertaken for this subset, debanding and definitive repair seems best advised at about two years of age. Pulmonary artery banding is well known to accelerate the development of subaortic stenosis by spontaneous progressive restriction of the VSD. This results in small ventricular cavity size and increased ventricular hypertrophy, which are incremental risk factors for increased hospital mortality by either definitive procedure. When the VSD or subaortic area is narrow and the patient is identified during the first year of life, isolated pulmonary artery banding is inappropriate. The surgical options for these patients include Ebert's two-stage management program consisting of the initial placement of a loose partial septation patch with concomitant pulmonary artery banding, and later debanding and complete septation. Alternatively, a trial of primary complete septation may be warranted, or the use of a procedure consisting of division of the main pulmonary artery with distal closure and anastomosis of the proximal portion to the side of the ascending aorta, coupled with a systemic-pulmonary artery shunt.

Modified Blalock-Taussig shunt in infants and young children: Clinical and catheterization assessment

The effectiveness of 19 modified Blalock-Taussig shunts performed with expanded polytetrafluoroethylene was evaluated clinically and by cardiac catheterization with angiography 4 to 24 months after operation. Fifteen patients underwent operation in infancy. Conduit diameters included 4 mm (nine cases), 5 mm (eight cases), and 6 mm (two cases) sizes. Two of the 4 mm conduits failed after 1 year following implantation. The remaining 17 shunts (89%) remained widely patent. In patients with patent shunts, the oxygen saturation values were significantly improved from the preoperative values. Two children demonstrated associated subclavian artery occlusion distal to the graft anastomosis. There were no deaths. Thirteen children underwent more complete elective cardiac repair 5 to 24 months later. Although the modified Blalock-Taussig procedure is an effective short-term alternative to the classic Blalock-Taussig shunt, the effectiveness of the 4 mm diameter conduit may be limited without postoperative anticoagulant therapy.

Systemic-pulmonary shunts in infants and children: Early and late results

From September, 1978, to January, 1983, 44 cyanotic infants and children underwent a systemic-pulmonary artery shunt for the treatment of reduced pulmonary blood flow. Age ranged from 18 hours to 4 years (mean age = 0.49 years). Weight ranged from 1.7 kg to 13.2 kg (mean weight = 4.9 kg). There were 12 classic Blalock-Taussig shunts, five central polytetrafluoroethylene shunts, six interposition modified Blalock-Taussig shunts, and 21 Great Ormond Street type of modified Blalock-Taussig shunts. No direct aorta-pulmonary artery anastomoses were performed. There was one postoperative death (1/44 = 2.3%) in a 1,700 gm neonate born with pulmonary atresia and intact ventricular septum (shunt patent). Four shunts required early revision: one thrombosed central shunt, a kinked patent interposition Blalock-Taussig shunt, a small but patent Blalock-Taussig shunt, and one excessive Great Ormond Street type of Blalock-Taussig shunt. Two late deaths were probably shunt-related: one Blalock-Taussig and one central. All four types of shunts provided good palliation, but the Great Ormond Street type of Blalock-Taussig shunt is our preferred shunt because of (1) low operative risk, (2) predictable patency (100% in our series), (3) lack of distortion of pulmonary arterial anatomy, and (4) technical ease of insertion as well as takedown.

Modified Blalock-Taussig shunt: Use of subclavian artery orifice as flow regulator in prosthetic systemic-pulmonary artery shunts

Between April, 1975, and December, 1979, 99 modified Blalock-Taussig shunts (MBTSs) were carried out at The Hospital for Sick Children, Great Ormond Street. The operation consists of interposing between the subclavian artery and the pulmonary artery a prosthesis of greater diameter than that of the subclavian artery. The first 13 operations were performed with a prosthesis of woven Dacron. Conduits of expanded polytetrafluorethylene (PTFE) were used for 86 MBTSs, and these form the basis of this report. Forty-four (51.1%) shunts were performed in infancy, 25 in patients under the age of 1 month (29.0%). Prostheses of 4 mm were used in 34 cases, 5 mm in 14, and 6 mm in 38. There were five shunt failures (5.8%) documented at postmortem or angiocardiographic investigation. Including two late deaths for which postmortem examinations were not obtained, the overall failure rate was 8.1% (seven patients). All these patients were operated upon in infancy, four of them in the neonatal period. Although a longer follow-up is necessary to assess the validity of these shunts, the early results are encouraging. We believe we can now recommend MBTS as an alternative when the classical Blalock-Taussig shunt is considered unsuitable.