Acute and late obstruction of a modified Blalock Taussig shunt: a two-center experience in different catheter-based methods of treatment

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1 doi: /icvts Published by European Association for Cardio-Thoracic Surgery Interactive CardioVascular and Thoracic Surgery 10 (2010) Institutional report - Congenital Acute and late obstruction of a modified Blalock Taussig shunt: a two-center experience in different catheter-based methods of treatment Abstract a, c a c a Tomasz Moszura *, Maria Zubrzycka, Krzysztof W. Michalak, BozŸena Rewers, Pawel { DryzŸek, b a d Jacek J. Moll, Andrzej Sysa, Piotr Burczyński Research Institute, Department of Cardiology, Polish Mother s Memorial Hospital, Lódź, Rzgowska 281y289, Poland b Research Institute, Department of Cardiosurgery, Polish Mother s Memorial Hospital, Lódź, { Poland c Catheterisation Laboratory, Children s Memorial Health Institute, Warsaw, Poland d Children s Memorial Health Institute, Department of Congenital Heart Surgery, Warsaw, Poland a { Received 24 August 2009; received in revised form 9 January 2010; accepted 14 January 2010 Modified Blalock Taussig (B T) shunt occlusion results in a sudden reduction of pulmonary vascular perfusion, causing dramatic saturation drop and cyanosis which pose a direct hazard to a child s life. The results of percutaneous local r-tpa infusion, balloon angioplasty and additionally stent implantation in obstructed modified B T shunts were studied to assess their role as an alternative to a re-do surgery. We outline two pediatric centers experience (period ) regarding the effectiveness of various emergency treatment methods for occlusion or critical stenosis of systemic-to-pulmonary arterial shunts in 23 children. Local r-tpa infusion via catheter was performed in 12y23 patients, balloon angioplasty in 22y23 and additionally stent implantation in 3y23 children. s were successful in 22y23 patients (96%), with an increase in arterial saturation waverage: 30%; standard deviation (S.D.) 15%; Shapiro Wilk test; dependent t-test- P-0.01x. Unrestricted contrast flow was achieved in 18 patients, reduced central flow in three and minimal flow in one child. Neither local nor systemic complications occurred. Our experience demonstrates the possibility of successful early shunt recanalization with the use of local thrombolytic therapy combined with the balloon angioplasty. The presence of old fixed thrombus with neointimal hypertrophy in the shunt constitutes an indication for endovascular stent implantation Published by European Association for Cardio-Thoracic Surgery. All rights reserved. Keywords: Transcatheter treatment; Blalock Taussig shunt; Shunt occlusion 1. Introduction Constant improvements with ongoing development of surgical treatment methods (even in the neonatal period), have continually improved the success ratio of completed surgical repairs of congenital heart defects. Nevertheless, there still exists a large group of patients with restricted pulmonary artery flow, who require systemic-to-pulmonary arterial shunt implantation at the first stage of a multistage treatment. Usually, the method of choice is the modified Blalock Taussig (B T) shunt, in which a polytetrafluoroethylene (PTFE) graft is placed between the subclavian artery and the pulmonary artery w1 3x. Systemic-to-pulmonary artery shunt occlusion is one of the most important complications requiring urgent therapy. It can develop gradually, or suddenly, thus resulting in a dramatic restriction of pulmonary artery flow, severe hypoxia with blood saturation -50%, cyanosis and blood acidosis, leading to a direct hazard to life w1, 3, 4x. *Corresponding author. Tel.: q ; fax q address: tmoszura@wp.pl (T. Moszura). Currently interventional cardiology (fibrinolysis, balloon angioplasty or coronary stent implantation) is employed in the treatment of acute coronary syndromes. These methods were also applied for the treatment in children with B T shunt occlusion w4 8x. This paper outlines a group of 23 children, who underwent emergency treatment. Retrospective analysis of the reasons for the thrombotic event, methods of treatment and the results are provided Aim The purpose of this paper is to evaluate the effectiveness of transcatheter methods for emergency treatment of the occlusion or critical stenosis of systemic-to-pulmonary arterial shunts. 2. Materials and methods During a period of four years ( ), 23 children aged between two weeks and five years underwent emer- Negative Follow-up

2 728 T. Moszura et al. / Interactive CardioVascular and Thoracic Surgery 10 (2010) Table 1 Characteristic of the patients No. Sex Age Period from B T shunt Pulmonary artery Additional Additional blood flow surgery operation diameter (mm) diameter (mm) blood flow from second B T, until B T occlusion from ventricle PDA or MAPCA 1 F 3 months 3 days No Yes MAPCA 2 M 18 days 5 days No Yes MAPCA 3 M 3 weeks 7 days Yes No 4 F 2 weeks 8 days No Yes PDA 5 M 3 weeks 2 days No Yes PDA 6 F 2 weeks 10 days Yes No 7 F 2 months 14 days Yes No 8 M 2 years 3 months 4 7 No Yes second B T 9 M 1 month 11 days No Yes PDA 10 F 3 weeks 2 days No Yes PDA 11 M 3 weeks 3 days No Yes PDA 12 F 3 years 4 months 4 8 No Yes MAPCA 13 M 5 years 3 years 5 10 No Yes second B T 14 F 3 weeks 10 days No Yes PDA 15 F 5 years 1.5 years 4 6 Yes No 16 M 3 weeks 9 days No Yes PDA 17 M 2 years 8 months No Yes second B T 18 F 22 days 15 days No Yes PDA 19 M 2 months 1.5 months Yes No 20 F 6 months 11 months Yes No 21 F 2 months 1 month Yes No 22 M 2 years 2 months No Yes second B T 23 M 2 months 15 days 4 5 Yes No B T, Blalock Taussig; M, male; F, female; PDA, patent ductus arteriosus; MAPCA, major aortopulmonary collateral arteries. gency treatment for B T shunt occlusions at the Departments of Cardiology of the Polish Mother s Memorial Hospital and the Children s Memorial Health Institute. Within the group examined (Table 1), in 14 patients shunt occlusion occurred in the early postoperative period (1 14 days), in nine children it occurred during the long-term follow-up period. The occluded shunts did not constitute an isolated pulmonary inflow. The eight patients had inflow from the right ventricle, 15 patients were diagnosed with additional pulmonary inflow by aortopulmonary collaterals, a second systemic-to-pulmonary arterial shunt, or patent ductus arteriosus. All patients underwent echocardiographical examination before percutaneus procedure to assess pulmonary flow and B T shunt patency. The emergency cardiological procedures were performed under general anesthesia with mechanical ventilation. In both catheterization laboratories a singleplane Philips Integris CV angiograph was employed in the procedures. s were performed from the femoral artery approach. Heparin was administered intravenously ( units per kg of body weight) after cannulation of the artery. Angiography through a diagnostic Judkins catheter inserted into the subclavian artery was performed. Then tissue plasminogen activator (Actilyse) was administered in a dose of mg per kg of body weight for 10 min (12 patients). In 11 patients in critical condition with low saturation and acidosis, which correlated with low body mass and coagulologic disturbances, the administration of plasminogen activator was considered inadvisable due to high risk of hemorrhagic complications. Stage one of the interventional procedure was to pass a coronary guide wire through the occluded shunt (in eight cases, a hydrophilic-coated wire was used). Balloon catheter was inserted over the wire, and angioplasty was performed (Fig. 1). If the hemodynamic effect proved to be unsatisfactory (no increase of arterial saturation, 50% stenosis of the shunt), a decision to implant coronary stents was made. Following the emergency treatment, low-molecular-weight heparin (Clexane) was administered subcutaneously for three to 11 days in a dose of 1 mg per kg of body weight. After postanesthetic recovery, acetylsalicylic acid (Acesan) was administered orally in a dose of 2 3 mg per kg of body weight. In one patient with intense mural lesions, after BX-Sonic stents were implanted into the shunt, ticlopidine (Ticlo) was then additionally administered. A 5-year-old female patient with tetralogy of Fallot, hypoplasia of the pulmonary artery branches and systemicto-pulmonary collaterals with mural lesions which reduces inflow by 90% in the systemic-to-pulmonary shunt, the shunt was not redilatated initially due to low oxygen saturation (-60%). After the Palmaz Genesis stent (6=24 mm) was implanted into the right ventricle outflow tract (RVOT) we performed balloon angioplasty of the critical shunt stenosis. One year later, as a result of stenosis developing in front of the stent during catheterization one more stent was implanted into RVOT using the stent-in-stent method. After interventional treatment of occluded B T shunts in all cases echocardiographical examination is performed on the first and third days after procedure to confirm good flow through the pulmonary arteries and in each case we monitor INR, fibrinogen and D-dimers level for early detection of hemorrhagic or thrombotic complications. Downloaded from by guest on 05 December 2018

3 T. Moszura et al. / Interactive CardioVascular and Thoracic Surgery 10 (2010) Fig. 1. (a) The proximal occlusion of a modified right Blalock Taussig shunt; (b) the balloon angioplasty procedure; (c) the angiographic view of the contrast medium flow after a successful recanalization. 3. Results Within the group analyzed, the procedure of emergency transcatheter recanalization was successful in 22 of 23 patients (96%) (Table 2). An increase in arterial saturation was achieved waverage: 30%; standard deviation (S.D.) 15%; Shapiro Wilk test; dependent t-test-p-0.01x. In the case of 18 of 23 children, unrestricted blood flow in the recanalized shunt was achieved; in the case of one patient with an old systemic-to-pulmonary arterial shunt and diffuse mural lesions, a significant flow increase was observed only after implanting two coronary BX-Sonic stents (4=23 mm), which completely filled the B T graft. In one patient, shunt occlusion coexisted with pulmonary artery hypoplasia and stenosis on the other side of the shunt. Simultaneous implantation of a coronary stent into the hypoplastic segment of the pulmonary artery allowed stabilization of the newborns critical condition. In three patients, mural lesions remained after shunt recanalization, in two cases narrowing the lumen by -50%, and in one case, due to coexisting critical distal stenosis, the lumen was narrowed by 90%. In one case passing a hydrophiliccoated guide wire through the shunt proved to be impossible, despite fibrinolysis. If shunt occlusion coexists with critical pulmonary branch stenosis, isolated angioplasty of the stenosis may be burdened with the risk of a further perioperative decrease in arterial saturation and the patient s death. Hence, in this particular situation, it seems more favorable to complement percutaneous shunt recanalization with stent implantation through the recanalized shunt into the stenosed pulmonary artery branches. In our case, it allowed a hemodynamically significant arterial saturation increase and delayed the next step of surgical treatment (Fig. 2). A 5-year-old female patient with tetralogy of Fallot and hypoplasia of the pulmonary artery branches, we decided first to stabilize the critical condition of the child by implantation of a Palmaz Genesis stent (6=24 mm) into the right ventricular outlet tract, an increase saturation over 80% was achieved. In a group of 12 patients who had been administered plasminogen activator no severe complication connected with high risk of bleeding occurred. 4. Discussion Modified B T shunts are performed in patients with complex heart defects involving pulmonary artery flow restriction. The size of the employed PTFE graft depends strictly on the patient s age, body weight and the size of pulmonary artery branches. A small diameter of the B T graft, narrow pulmonary arteries coexisting with increased pulmonary tension as well as polycythemia are all significant risk factors for shunt occlusion, estimated in the literature at 3 20% w1, 2, 5x. Shunt occlusion may occur suddenly resulting in an abrupt deterioration of the patient s condition or death. At times the graft occlusion process is gradual, causing a slow increase in hypoxia, cyanosis and exercise tolerance impairment w3x. The usual cause of shunt occlusion is acute thrombus closing the narrow lumen of the graft, which in a majority of cases is additionally narrowed by coexisting distal stenosis present at the junction of the B T graft and the narrow pulmonary artery branch. Successful early recanalization of a graft is possible with the use of local or systematic thrombolytic therapy combined with a successful balloon angioplasty procedure w4, 7, 9, 10x. This type of treatment is usually ineffective in patients with gradually Negative Follow-up

4 730 T. Moszura et al. / Interactive CardioVascular and Thoracic Surgery 10 (2010) Table 2 The type of intervention and results No. Balloon angioplasty B T stenosis t-pa Heparin Oxygen Oxygen Contrast medium Additional comments (catheter type) (mm) (YesyNo) saturation saturation flow after before after procedure* procedure (%) procedure (%) 1 TYSHAK 4=20 Yes No Yes qqq 2 FIRESTAR 3.5=16 Yes No Yes qqq q Stent COROFLEX 3.5=16 mm 3 TYSHAK 4=20 Yes No Yes qqq 4 TYSHAK 4=20 Yes Yes Yes qqq 5 TYSHAK 4=20 Yes No Yes qqq 6 No Yes Yes Yes The wire crossover was not attempted 7 AQUA 2=20 Yes Yes Yes qq Semicircle plaque 8 TYSHAK 4=20 Yes No Yes q B T distall stenosis 9 TYSHAK 4=20 Yes No Yes qqq 10 SPRINTER 3.5=20 Yes No Yes qqq 11 TYSHAK 4=20 Yes No Yes qqq 12 TYSHAK 4=20 Yes No Yes qq Semicircle plaqueq MAPCA angioplasty 13 RIDER 5=20 Yes Yes Yes q Semicircle plaque before qqq 2 stents (BX-Sonic with stent 4=23 mm) implantation 14 SPRINTER 3.5=20 Yes Yes Yes qqq 15 Palmaz Genesis Yes No Yes qqq RVOT stent implantation 6=24 TYSHAK 4=20 simultanously with B T balloon angioplasty 16 TYSHAK 4=20 Yes No Yes qqq 17 TYSHAK 4=20 Yes Yes Yes qqq with stent q Stent Genesis PG TYSHAK 4=20 Yes Yes Yes qqq 19 TYSHAK 4=20 Yes Yes Yes qqq 20 TYSHAK 4=20 Yes Yes Yes qq Left B T shunt next day 21 TYSHAK 4=20 Yes Yes Yes qqq 22 No Yes Yes Yes qqq 23 TYSHAK 5=20 Yes Yes Yes qqq *0, no flow through a completely blocked shunt; q, minimal central flow; qq, central flow with semicircle plaque; qqq, unrestricted flow; B T, Blalock Taussig; RVOT, right ventricle outflow tract; MAPCA, major aortopulmonary collateral arteries. developing occlusion, as the mechanics of narrowing or closing is quite different, with focal neointimal hypertrophy as well as calcifications and mural thrombus detected in the shunt lumen. In this case, effective graft recanalization is possible if it follows endovascular stent implantation, which can stabilize hypertrophic neointima in the graft lumen w1, 4, 8, 11, 12x. The length of the follow-up period after percutaneous stent recanalization suggested by the literature ranges from a few months to a few years. This time allows preparation of the patient for a complete surgical repair of the defect or the next stage of their treatment w5, 7, 8x. In the case of extreme )90% B T shunt stenosis in patients with pulmonary artery hypoplasia and retained flow from the right ventricle, any attempt at endovascular redilatation is burdened with a high risk of perioperative death. A possible alternative may be found in increasing systemic-to-pulmonary flow from another source, e.g. via simultanously dilatating the RVOT and B T stenosis, or performing an interventional procedure with extracorporeal membrane oxygenation (ECMO) support. We employed an RVOT stenting technique described by Gibbs et al. w13x. It enabled us to retain ventricular inflow into the hypoplastic pulmonary artery branches, which had the favorable effect of stimulating the growth of primary pulmonary artery branches w13, 14x. With time, however, hypertrophy of the muscular coat was observed in front of the implanted stent, which induced successful reintervention. 5. Conclusions 1. Percutaneous emergency cardiological procedures are a safe and effective method of recanalization of occluded Blalock shunts and as such may constitute an alternative to surgical treatment, most importantly in patients with increased hypoxia in life-threatening condition. 2. The presence of fixed lesions with neointimal hypertrophy significantly reduces the effectiveness of isolated balloon angioplasty and constitutes an indication for endovascular stent implantation. 3. In special cases, a transcatheter balloon angioplasty with a previous stent implantation in the RVOT is worth considering. 4. No major systemic or local complications associated with the emergency treatment performed were observed within the data analyzed. Downloaded from by guest on 05 December 2018

5 T. Moszura et al. / Interactive CardioVascular and Thoracic Surgery 10 (2010) Fig. 2. (a) Patient after B T recanalization and left pulmonary artery hypoplasia, before stent implantation; (b) patient after B T recanalization and left pulmonary artery hypoplasia, after stent implantation. Acknowledgements Special thanks are due to GrazŸyna Brzezinska-Rajszys and Bohdan Maruszewski for their assistance and comments which proved very useful in improving the quality of the final version of our manuscript. References w1x Sivakumar K, Anil SR, Ravichandra M, Natarajan KU, Kamath P, Kumar RK. Emergency transcatheter balloon recanalization of acutely thrombosed modified Blalock Taussig shunts. Indian Heart J 2001;53: w2x Bove EL, Kohman L, Sereika S, Byrum CJ, Kavey RE, Blackman MS, Sondheimer HM, Rosenthal A. The modified Blalock Taussig shunt: analysis of adequacy and duration of palliation. Circulation 1987;76: w3x Al Jubair KA, Al Fagih MR, Al Jarallah AS, Al Yousef S, Ali Khan MA, Ashmeg A, Al Faraidi Y, Sawyer W. Results of 546 Blalock Taussig shunts performed in 478 patients. Cardiol Young 1998;8: w4x Gillespie MJ, Rome JJ. Transcatheter treatment for systemic-to-pulmonary artery shunt obstruction in infants and children. Catheter Cardiovasc Interv 2008;71: w5x Kogon B, Villari C, Shah N, Kirshbom P, Kanter K, Kim D, Raviele A, Vincent R. Occlusion of the modified Blalock Taussig shunt: unique methods of treatment and review of catheter-based intervention. Congenit Heart Dis 2007;2: w6x Sreeram N, Emmel M, Ben-Mime L, Brockmeier K, Bennink G. Transcatheter recanalization of acutely occluded modified systemic to pulmonary artery shunts in infancy. Clin Res Cardiol 2008;97: w7x Rao PS, Levy JM, Chopra PS. Balloon angioplasty of stenosed Blalock Taussig anastomosis: role of balloon-on-a-wire in dilating occluded shunts. Am Heart J 1990;120: w8x Sreeram N, Walsh K, Peart I. Recanalisation of an occluded modified Blalock Taussig shunt by balloon dilatation. Br Heart J 1993;70: w9x Wang JK, Wu MH, Chang CI, Chiu IS, Lue HC. Balloon angioplasty for obstructed modified systemic-pulmonary artery shunts and pulmonary artery stenoses. J Am Coll Cardiol 2001;37: w10x Ries M, Singer H, Hofbeck M. Thrombolysis of a modified Blalock Taussig shunt with recombinant tissue plasminogen activator in a newborn infant with pulmonary atresia and ventricular septal defect. Br Heart J 1994;72: w11x Tomita H, Hayashi G, Echigo S. Bail-out stenting for acute obstruction of a modified Blalock Taussig shunt following selective angiography. Cardiol Young 2002;12: w12x Moszura T, Ostrowska K, Dryzek P, Moll J, Sysa A. Thrombolisis and stent implantation in a child with acute occlusion of the modified Blalock Taussig shunt a case report. Kardiol Pol 2004;60: w13x Gibbs JL, Uzun O, Blackburn MEC, Parsons JM, Dickinson DF. Right ventricular outflow stent implantation: on alternative to palliative surgical relief of infundibular pulmonary stenosis. Heart 1997;77: w14x Dryzek P, Mazurek-Kula A, Moszura T, Sysa A. Right ventricle outflow tract stenting as a method of palliative treatment of severy tetralogy of Fallot. Cardiol J 2008;15: Negative Follow-up