Technique and Experience with Azygos Patch Modified Blalock-Taussig: Anastomosis for Congenital Cyanotic Heart bisease

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1 Technique and Experience with Azygos Patch odified Blalock-Taussig: Anastomosis for Congenital Cyanotic Heart bisease Noel L. ills,.d., Luther C. Williams, 111,.D., and Walter S. Culpepper, 111,.D. ABSTRACT Seventeen patients 1 day to 28 months old with congenital cyanotic heart disease underwent a modification of the Blalock-Taussig shunt. Eight were newborn infants weighing 2.6 to 4.8 kg. All infants had complex congenital heart defects that were not considered amenable to early correction. There were no early deaths and no shunt failures. Postoperative complications were restricted to prolonged intubation in 2 patients and a subcutaneous wound infection in a 14-day-old infant. ollowup from 1 to 31 months revealed minimal cyanosis, stable hemoglobin levels, and good shunt murmurs, and there have been no upper extremity complications. There were 2 late deaths; 1 (the oldest patient) was related to medication, and the second resulted from small bowel necrosis. The concept of the azygos vein patch modified Blalock- Taussig shunt involves two factors: (1) mobilizing as much length as possible of the subclavian artery in spite of its distal small size to allow for a tension-free shunt to prevent tension on the anastomosis as growth occurs, and (2) enlarging the subclavian artery distal to the vertebral artery origin with an autologous azygos patch. During performance of a standard Blalock-Taussig shunt, a longitudinal incision is made through the pulmonary artery across the anastomosis into the upper subclavian artery. The appropriate length of harvested azygos vein is used as a patch angioplasty across the shunt. A tension-free shunt with a patulous distal portion is achieved. Pulmonary overcirculation is avoided by the limiting size of the proximal subclavian artery. Temporary occlusion of the shunt at operation resulted in an increased mean blood pressure from 6 to 18% in all infants. Postoperative angiograms in 4 patients revealed excellent shunt anatomy. This modification of the Blalock-Taussig shunt offers physiological palliation with a high degree of reliability in infants with cyanotic heart disease in whom early corrective procedures are not indicated. Treatment of the blue baby with the complex malformed heart was begun by Blalock and Taussig after rom the Departments of Surgery and Pediatric Cardiology, Ochsner Clinic and Alton Ochsner edical oundation, New Orleans, LA. Presented at the Thirty-first Annual eeting of the Southern Thoracic Surgical Association, Hilton Head Island, SC, Nov 1-3, Address reprint requests to Dr. ills, Ochsner Clinic, 1514 Jeffcrson Hgwy, New Orleans, LA the historic operation on November 29, 1944 [l]. The standard Blalock-Taussig operation performed in small newborn infants has been associated with good early palliation and low mortality. However, as the infant grows into the late postoperative period, parrot beaking of the subclavian and pulmonary artery junction gradually develops and limits shunt flow (ig 1). Often this has necessitated a second shunt on the opposite side. Subsequent modifications of the subclavianpulmonary artery shunt have also been found to be associated with major early or late complications [2-41. ore recently, the polytetrafluoroethylene (PTE) systemic-pulmonary artery shunt from the subclavian artery has been popularized [5-71, yet when used for long-term palliation, this procedure has been associated with some degree of unreliability due to fibrous anastomotic ingrowth. Woolf and colleagues [3], after studying patients from three different centers, found a late failure rate of PTE shunts as high as 41%. Also, LeBlanc and associates [8] called attention to the problem of serous fluid leakage complicating this modified Blalock- Taussig shunt in 18.8% of 138 such operations. The purpose of this report is to outline our experience with a Blalock-Taussig shunt that has been modified by using the subclavian artery quite distal near the point of its exit from the thoracic cavity in spite of its small size at that level. The modification consists of an autologous azygos vein patch angioplasty of both the subclavian and pulmonary arteries to widen the distal portion of the anastomosis to an acceptable size. aterial and ethod Seventeen patients, 12 boys and 5 girls 1 day to 28 months old, underwent an azygos vein patch modified Blalock-Taussig shunt. At the time of operation, the patients ranged in weight from 2.6 to 9 kg. Eight patients were neonates weighing 2.6 to 4.8 kg. All infants had complex cyanotic congenital heart anomalies and were deemed unsuitable candidates for more definitive procedures (Table). The ages and weights of the infants are indicated in igure 2. In 1 patient with hypoplastic right ventricle, pulmonary atresia, restrictive atrial septa1 defect, and small pulmonary arteries, the shunt was placed on the ipsilatera1 side of the aortic arch. After the shunt was completed, an arterioplasty at the left subclavian origin was performed to prevent kinking using the technique described by Laks and Castaneda [9]. 547

2 548 The Annals of Thoracic Surgery Vol 39 No 6 June 1985 ig 1. Standard Blalock-Tanssig shunt performed early in life. The so-called parrot beaking of the shunt has developed with groulth of the child. Although the shunt is o p, it is functionally ineffective. Technique The side opposite the aortic arch is used as with the classic Blalock-Taussig shunt. If it is necessary to use the same side as the aortic arch, an arterioplasty at the origin of the subclavian artery from the aorta is performed to prevent kinking at that point. Initially, dissection of the pulmonary artery is done to confirm adequate size. Next, the azygos vein is taken down from its entrance into the superior vena cava for a minimal distance of 3 cm. Branches are ligated with 4-0 silk, and 5-0 Prolene suture ligatures are placed proximally and distally prior to excising the vein segment. The vein is split longitudinally for its entire length, cutting through as many of the branches as possible so that they may be excised to keep them out of the way during suturing. The subclavian artery is dissected to its exit from the chest, and its branches are ligated and divided between 4-0 silk ligatures. Heparin sodium (50 units per kilogram of body weight) is given, and the subclavian artery is divided after being ligated distally with 5-0 Prolene. Then it is brought through the recurrent vagus nerve sling. The proximal pulmonary artery is clamped, and the distal branches are snared. The pulmonary artery is opened on its superior portion. The ipsilateral carotid and innominate arteries are dissected free to allow mobilization. A trough for the conduit is cut with the electrocautery in the mediastinal tissues and thymus. The posterior wall of the anastomosis is done by suturing the opened subclavian artery to the posterior wall of the pulmonary artery with 8-0 polypropylene (ig 3A). Next, the subclavian artery is opened to the level of the origin of the vertebral artery, and the pulmonary artery is opened for 4 to 5 mm along its anterior surface. The azygos patch is sewn with 8-0 polypropylene as an onlay over the shunt, beginning at the pulmonary artery end with interruption of the suture line at the level of the subclavian-pulmonary artery junction (ig 3B). The anastomosis is completed by running both sutures cephalad to close the proximal subclavian arteriotomy. Once the pulmonary artery end is completed, the main pulmonary artery clamp can be released if necessary and the lung ventilated and perfused as the more proximal part of the patch angioplasty is completed. A tiny window is made in the pericardium, and a small Prolene suture is placed around the shunt with its two ends left in the pericardial cavity for easy access for shunt takedown at a later date (ig 3C). This maneuver has been used for many years and has proven very helpful at the time of operative repair. Intraoperative evaluation of the adequacy or inadequacy of the shunt is performed according to the method of Daicoff [lo]. A mean aortic pressure drop of greater than 20% indicates an excessively large shunt, and a pressure drop of less than 8 or 9% may indicate an inadequate shunt unless the patient has competition of flow from a patent ductus arteriosus maintained by prostaglandin infusion. Results There were no hospital deaths, and complications were restricted to prolonged ventilatory support in 2 infants and a subcutaneous wound infection in a 14-day-old infant. ollow-up has been loo%, ranging from 1 to 31 months postoperatively (ig 4). There have been two late deaths. A 34-month-old infant died when medications were withdrawn and pneumonia progressed, and a 19-month-old infant died of mesenteric infarction 9 months after operation. There have been no early or late shunt failures. The changes in mean systemic blood pressure were measured at the time of operation as an estimate of shunt adequacy or inadequacy (ig 5). Eighty-eight percent of the patients had a mean aortic pressure change of 8 to 18%, which was well within the acceptable range for an adequate shunt size. Two patients with a 6% and 7% change in mean systemic pressure were having prostaglandin infusions at the time of shunt test occlusion. All patients had a palpable thrill intraoperatively and postoperatively have had diminution in cyanosis as well as adequate somatic growth. Repeat cardiac catheterization was performed in 4 patients aged 28 months, 19 months, 12 months, and 2 months. All shunts were found to be functioning adequately with a good distal anastomosis. Three patients have had further operations. Patient 12

3 ~~ ~ ~ 549 ills, Williams, and Culpepper: Azygos Patch odified Blalock-Taussig Anastomosis Summa y of Data on Patients Undergoing Azygos Vein Patch odified Blalock-Taussig Shunt Patient Age at No. Sex Opera tion Cardiac Diagnosis Comment 1 28 mo TGA, pulmonary atresia, DORV, complete atriovcntricular canal mo 3d 4 3d d 19 mo 7 9d Tetralogy of allot, small L ventricle TGA, DORV, VSD, tricuspid atresia, dextrocardia, PS, R aortic arch Tetralogy of allot, small pulmonary arteries, small L ventricle TGA, PS, VSD ailed R Blalock-Taussig shunt, pulmonary atresia, small pulmonary arteries, hypoplastic R ventricle Univentricular heart, pulmonary atresia, PDA Pulmonary atresia, PDA Late death Arterioplasty at L subclavian origin 8 2d Brock operation at 1 yr old itral atresia, DORV, restrictive PO Prior septectomy TCA, PS, VSD, small R ventricle, ASD d d 14 Id mo 4.5 mo 1 mo 21 mo 8mo 10 mo Pulmonary atresia, tricuspid stenosis, small R ventricle, ASD Univentricular heart, mitral atresia, ASD, PS, R arch, aberrant L subclavian artery, PDA Tetralogy of allot, pulmonary atresia, tricuspid insufficiency, small pulmonary arteries TGA, pulmonary atresia, VSD, ASD, Taussig-Bing anomaly, DA TCA, PS, VSD, ASD, LVOT obstruction Univentricular heart, PS, ASD Tricuspid atresia (type IIc), VSD, mitral regurgitation, R ventricular hypoplasia, PO Prior Brock operation Septectomy at 4 mo old Late death TGA = transposition of great arteries; DORV = double-outlet right ventricle; VSD = ventricular septal defect; PS = pulmonary stenosis; PDA = patent ductus arteriosus; PO = patent foramen wale; ASD = atrial septal defect; LVOT = left ventricular outflow tract. (see Table) required an atrial septectomy for a pulmonary venous obstruction 3 months after placement of the shunt. Patient 8 had right ventricular outflow tract decompression one year after the shunt procedure. Patient 6 underwent ligation of one of the bilateral shunts at another institution in preparation for total correction Weight (kilo) ig 2. Ages and zueights of 17 infants who received azygos patch modified Blalock-Tuussig shunts. Comment The Blalock-Taussig operation has remained popular as a means of increasing pulmonary blood flow in patients with cyanotic congenital heart disease. However, its major disadvantage is the fact that the subclavian artery is by necessity sacrificed; the consequences of this in adult life are not well known, since the first operations were done in the mid-1940s. The Potts and Waterston anastomoses obviated that disadvantage, but their use is associated with a higher incidence of pulmonary hyperten-

4 550 The Annals of Thoracic Surgery Vol 39 No 6 June 1985 A B C ig 3. (A) The anastornosis is begun by sewing the operied distal subclavian artery to the posterior run11 of the pulrrroriary nrteriotoriiy u~ith 8-0 Prolene suture. (B) The caual end of the azygos iiciri patch is sutured to the extended pulnionary arteriotomy arid interrrrptcd at the subclavian-pulmorzary artery junction. (C) The anastoiriosis is coriipleted at the proxinral end of the subclavian artery at the level of the ligated vertebral artery. A srriall suture is introduced into the jiericardial cavity through a tiny zuindori~ to facilitate shunt takedo7cvi at a subsequent operatiori. The inriorrririate artety rriay at times be tacked to the pretracheal tissue to further ~~reverit tensiori. % ean Aortic Pressure Change Patient ig 5. The percent rricari systernic blood pressure vise tested at operation (by the rriethod of Daicoff /2011 iri 17 patierits duririg terrrporar~y occlusiori of the az!/gos vein patch ruodified Blalock-Taussi<y shurits. (t = late death; * = arterioplnsty of origiri of left subrlauiarr outer!/; 0 = yrostaglandiri-dej~crident large }?atetit ductus artrriosrrs; 0 = septectomy and shunt.) Died Small Bowel Necrosis onths ollow up ig 4. olloiij-up of the 17 patients. Survivors have riiairitairicd ade quatc shunt function as evidenced by good shunt iriurrrrurs, stable herrioglobiri levels, and control of qanosis. (t and tt = late deaths.) sion and higher morbidity and mortality for shunt takedown. A second disadvantage of the Blalock-Taussig shunt has been its unreliability in offering long-term palliation because of narrowing at the anastomosis from lack of growth or traction or both. Therefore, the synthetic arterial graft (PTE) has become popular after the initial re- ports of the use of plastic prosthetic material for systemic-pulmonary artery shunts in 1963 [ll]. Surgeons at Great Ormond Street popularized the use of the PTE graft for interposition end to side between the undivided subclavian artery and the ipsilateral pulmonary artery [6, 121. Although excellent for short-term use, this particular graft, aside from the disadvantages of a significant incidence of serous fluid leak and a substantial failure rate, has some adverse long-term results due to pannus ingrowth not unlike that seen in the right ventricle-pulmonary artery conduits. Lamberti and colleagues " in a studv of 34 long-term survivors found Y that 15 had no reoperation (the mean length of follow-up was not given), 12 required a second shunt, and 7 had correction of the lesion. The need still exists for a reliable shunt that can be used in neonates with extremely complex congenital heart problems in whom correction would be more desirable at a large body size. Half of the operations in the present report were performed on small infants for whom no early repair was contemplated. After observing good early reliability of the shunt, we have used it in somewhat larger infants. Although the follow-up in this

5 551 ills, Williams, and Culpepper: Azygos Patch odified Blalock-Taussig Anastomosis series has been only moderate for the majority of patients (mean, 21 months for the first 8 patients), shunt failure has not occurred, cyanosis and hematocrit levels have been controlled, and there have been no late deaths related to the shunt. The azygos vein is readily accessible and has been divided in the past for standard Blalock-Taussig shunts, and we have noted no untoward effects with its use. The concept of using a vein patch to enlarge the outflow of a standard Blalock-Taussig shunt arose when a deeply cyanotic infant was referred with early thrombosis of the distal 2 mm of the subclavlan artery at the anastomotic site. A contralateral shunt was not feasible because of complex anatomy, and a homologous saphenous vein patch was used with success. In the event that operation is necessary on a side with no azygos vein, a section of autologous peripheral vein, such as the saphenous vein, is preferred. Shunt effectiveness has been adequate, no contralateral shunts have been necessary to date, and the advantage of using no prosthetic material has been achieved. Polytetrafluoroethylene shunts have been suggested as the safest and most effective in neonates; however, it is noted that elective shunt replacement or correction may be warranted in the first or second year of life (3, 121. The object of this endeavor is to utilize a shunt that provides for growth in patients with very complex congenital heart problems to a size and time at which corrective operations may be performed with minimal risk. Addendum Since submission of the abstract of this article, 2 patients, both 3 days old and with right-sided aortic arch, underwent a modified Blalock-Taussig anastomosis through a left thoracotomy. One patient had complete atrioventricular canal with pulmonary atresia and a prostaglandin-dependent ductus arteriosus. The other patient had tetralogy of allot with a persistent left superior vena cava and a small left ventricle. Because of the lack of an available vein patch through the left thoracotomy, the proximal internal mammary artery was used as a patch to modify the anastomosis in both patients. In 1 of these neonates, the internal mammary artery had an internal diameter of 1.5 mm, and in the other, the left internal mammary artery was 2 mm in internal diameter. In the first infant, the mammary artery measured 4.7 mm wide when split and used as a patch; this increased the internal diameter of the left subclavian artery from 2 to 3.5 mm after completion of the modified anastomosis. The internal diameter of the anastomosis in the second infant was enlarged from 2 to 4 mm by this technique. We recommend use of the proximal internal mammary artery for patch angioplasty when the azygos vein is not available. References 1. Blalock A, Taussig H: The surgical treatment of malformations of the heart in which there is pulmonary stenosis or pulmonary atresia. JAA 251:2123, Reitman I, Galioto Jr, El-Said G, et al: Ascending aorta to right pulmonary artery anastomosis: immediate results in 123 patients and one month to six year follow-up in 74 patients. Circulation 49:952, Woolf PK, Stephenson LW, eijboom E, et al: A comparison of Blalock-Taussig, Waterston, and polytetrafluoroethylene shunts in children less than two weeks of age. Ann Thorac Surg 38:26, Somerville J, Barbosa R, Ross D, et al: Problems with radical corrective surgery after ascending aorta to right pulmonary artery shunt (Waterston anastomosis) for cyanotic congenital heart disease. Br Heart J , iyamoto K, Zavanella C, Lewin AN, Subramanian 5: Aorta-pulmonary artery shunts with expanded polytetrafluoroethylene (PTE) tube. Ann Thorac Surg 27:413, de Leva1 R, ckay R, Jones, et al: odified Blalock- Taussig shunt: use of subclavian artery orifice as flow regulator in prosthetic systemic-pulmonary artery shunts. J Thorac Cardiovasc Surg 81:112, Kulik TJ, oker JE, Lucas RV Jr, et al: Postoperative hemodynamics in children with polytetrafluoroethylene shunts. Circulation 64:Suppl 2:123, LeBlanc J, Albus AR, Williams WG, et al: Serous fluid leakage: a complication following the modified Blalock-Taussig shunt. J Thorac Cardiovasc Surg 88:259, Laks H, Castaneda AR: Subclavian arterioplasty for the ipsilateral Blalock-Taussig shunt. Ann Thorac Surg 19:319, Daicoff GR: Intraoperative evaluation of surgical systemicto-pulmonary artery shunts. Ann Thorac Surg 11:97, Le Pere RH, Kohler C, organ BC, Klinger P: Plastic prostheses in systemic-pulmonary artery shunts. JAA 183:283, Lamberti JJ, Carlisle BS, Waldman JD, et al: Systemicpulmonary shunts in infants and children. J Thorac Cardiovasc Surg 88:76, 1984