Asian Cardiovasc Thorac Ann 2001;9:138-141
© 2001 Asia Publishing EXchange Pte Ltd
Palliative Bilateral Unidirectional Glenn Shunts
Kalpesh Satishkumar Malik, MS,
Praveen Kumar Neema, MD1,,
Sivasubramaniam Sivasankaran, DM2,,
Soman Rema Krishna Manohar, MCh
Department of Cardiovascular and Thoracic Surgery
1 Department of Anesthesiology
2 Department of Cardiology
Sree Chitra Tirunal Institute of Medical Sciences & Technology
Thiruvananthapuram, Kerala, India
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For reprint information contact: Soman Rema Krishna Manohar, MCh Tel: 91 471 52 4648 Fax: 91 471 44 6433 email: manohar{at}sctimst.ker.nic.in Department of Cardiovascular and Thoracic Surgery, Sree Chitra Tirunal Institute of Medical Sciences & Technology, Thiruvananthapuram, Kerala 695011, India.
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Abstract
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A Fontan operation was planned for a 5-year-old girl with complex cyanotic heart disease and bilateral superior venae cavae. The unexpected finding of total anomalous pulmonary venous connection to the left superior vena cava led to a change of strategy. During a bilateral bidirectional Glenn procedure, the pulmonary confluence had to be disconnected to avoid pulmonary venous obstruction. This resulted in bilateral unidirectional cavopulmonary flow.
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Introduction
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It is not uncommon to encounter surprise findings during surgery for complex cyanotic congenital heart disease, especially when the preoperative diagnosis is based mostly on transthoracic echocardiography.1 Such a case is described where an unexpected finding had an important bearing on the surgical strategy.
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Case Report
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A 5-year-old girl presented with a history of cyanosis since infancy and delayed milestones of development. Physical examination revealed central cyanosis, finger clubbing, a single second heart sound, and a grade 3/6 ejection systolic murmur at the right upper sternal border. Her hemoglobin level was 240 g•L–1 and her hematocrit was 76%. Biochemical parameters were within normal limits. Chest radiography showed situs inversus with dextrocardia, a cardiothoracic ratio of 45%, right aortic arch, and pulmonary oligemia. Electrocardiography indicated sinus rhythm at a rate of 100 beats•min–1 with atrial situs inversus and right atrial enlargement. Echo-cardiography revealed dextrocardia, a common atrio-ventricular valve with mild regurgitation, double-outlet right ventricle with pulmonary stenosis (with a gradient of 63 mm Hg), and good-sized pulmonary arteries. The main pulmonary artery (PA) was right of and posterior to the aorta. Cardiac catheterization demonstrated systemic desaturation of 82% and bilateral superior venae cavae. The PA was not entered; therefore, the transpulmonary gradient, pulmonary resistance, and PA index could not be calculated accurately. Since biventricular repair was not feasible due to the complexity of the defects, total cavopulmonary connection was decided upon.
Sternotomy revealed right atrial isomerism with bilateral superior venae cavae and absent innominate vein. PA pressure was mildly elevated (mean, 15 mm Hg); thus a two-stage Fontan operation was decided as preparation for bilateral bidirectional Glenn shunts. After isolating the right PA and right superior vena cava (SVC), cardiopulmonary bypass was instituted with aortic and right atrial cannulation. The left PA and left SVC were dissected while cooling the patient to 20°C. On dissecting the left SVC, a large vessel was discovered joining its posterior wall from behind the left PA. On further dissection, this vessel was found to be draining the common pulmonary vein to the vena cava. The surprise was total anomalous pulmonary venous connection (TAPVC) to the left SVC. The left PA was between the vessel and the left SVC (Figure 1
). We were taken aback by this finding and not mentally prepared to correct the TAPVC simultaneously since the anatomy was not definite. Therefore, we decided to proceed only with the bidirectional superior cavopulmonary anastomosis. Under low flow without aortic crossclamping, the left SVC was divided between clamps, distal to the vertical vein, and its lower end was closed with 6/0 polypropylene sutures, keeping the vertical vein drainage intact. The distal stump of the left SVC was short; thus end-to-side anastomosis to the left PA was not possible without tension, the left PA thereby being pulled up to compress the vertical vein. As an alternative technique, the left PA was disconnected at its junction with the main PA and anastomosed end-to-end to the left SVC. The defect in the main PA was closed with continuous 6/0 polypropylene sutures. The right SVC was divided and anastomosed end-to-side to the right PA, using continuous 6/0 polypropylene suture. The main PA was not interrupted, thereby maintaining prograde flow to the right lung. Thus the right SVC return was directed to the right PA, and the left SVC to the left PA, resulting in bilateral unidirectional cavopulmonary flow (Figure 2). The patient was rewarmed and weaned off cardiopulmonary bypass easily, with arterial oxygen saturation > 90%. She had a smooth postoperative recovery and was discharged after one week.
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Figure 1. Diagram of the operative findings. The left superior vena cava (LSVC) was anterior, the vessel (vertical vein) draining the common pulmonary vein was posterior, and the left pulmonary artery (LPA) was between these two. MPA = main pulmonary artery, RPA = right pulmonary artery, RSVC = right superior vena cava.
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Figure 2. Diagram of the bilateral unidirectional superior cavopulmonary shunts. The right superior caval blood flows to the right pulmonary artery (RPA). The left superior caval blood flows to the left pulmonary artery (LPA). The main pulmonary artery (MPA) remains connected to the right pulmonary artery only. LSVC = left superior vena cava, RSVC = right superior vena cava.
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At 3 months postoperatively, the child was in New York Heart Association functional class I, she was mildly cyanotic, her hemoglobin level was 160 g•L–1, and her hematocrit was 54%. Repeat cardiac catheterization showed supracardiac TAPVC draining unobstructed into the left atrium through the left SVC stump (Figure 3). Digital subtraction angiography showed good function of the bilateral unidirectional Glenn shunts (Figure 4).
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Figure 3. Postoperative angiogram showing supracardiac total anomalous pulmonary venous connection draining into the left-sided atrium through the proximal stump of the left superior vena cava.
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Figure 4. Postoperative digital subtraction angiography showing good functioning bilateral unidirectional Glenn shunts. A large collateral is also seen. LPA = left pulmonary artery, LSVC = left superior vena cava, RPA = right pulmonary artery, RSVC = right superior vena cava.
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Discussion
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Transthoracic echocardiography can give near-perfect diagnosis of cardiac anomalies, and the chance of TAPVC being overlooked is 1%.1 The combination of cardiac malformations in this case should have strongly suggested right atrial isomerism.2 In this condition, abnormal pulmonary venous connection is very frequent, including the extrahepatic type of TAPVC.3 In this patient, the preoperative evaluation was not properly achieved, and since the atrial isomerism was missed, anomalous pulmonary venous connection was not looked for during cardiac catheterization. If anticipated, magnetic resonance imaging would have been helpful. If the anomalous pulmonary venous connection had been known pre-operatively, the surgery would have been planned differently.
In this case, TAPVC was detected while dissecting the left SVC for cavopulmonary anastomosis, and it was felt then that simultaneous TAPVC correction might be risky. In proceeding with cavopulmonary anastomosis and leaving the TAPVC uncorrected on the left side, it was necessary to spare the proximal left SVC to retain pulmonary venous drainage to the left atrium unobstructed, and this ultimately resulted in acquired disconnection of the PA confluence. This could have been avoided by simultaneous TAPVC correction, ligation and division of the vein joining the left SVC, and bilateral bidirectional Glenn shunts. A second-stage diversion of the inferior vena cava to the right or main PA using a tube graft, preferably extracardiac to prevent any pulmonary venous obstruction, would have resulted in complete correction.4 With such complex anomalies, risk factors jeopardizing a successful Fontan procedure should be treated at the time of the initial bidirectional Glenn procedure. Un-fortunately, leaving the TAPVC uncorrected resulted in the unfavorable situation of nonconfluent pulmonary arteries, precluding optimal surgical strategy when a staged approach was planned.
Although the child is well palliated now, with each SVC draining to the ipsilateral lung, second-stage completion of total cavopulmonary connection is extremely difficult. This will need reconstruction of the PA confluence using an interposition tube graft, correction of TAPVC, division of the draining vein, and redirection of the inferior vena cava to the right or main PA using an extracardiac tube graft. If the child is left with the unidirectional Glenn shunts, the left lung which is devoid of hepatic venous blood is exposed to the high risk of developing a pulmonary arteriovenous fistula in the future.5
This case is reported for the rarity of the combination of lesions encountered during a Fontan operation, and to highlight the pitfalls in surgical decision-making. The lesson hereby learnt is that on encountering unexpected TAPVC during the Fontan procedure, it has to be dealt with first, and correctly and adequately rerouted, irrespective of the plan for a single-stage or two-stage Fontan procedure. Otherwise, similar mistakes will recur making the subsequent completion of total cavopulmonary connection extremely hazardous, thus forcing palliation only, albeit not a very good one.
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References
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Chowdhury UK, Airan B, Sharma R, Bhan A, Kothari SS, Saxena A, et al. Surgical considerations of univentricular heart with total anomalous pulmonary venous connection. Indian Heart J 2000;52:192–7.[Medline]
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Uemura H, Ho SY, Anderson RH, Yagihara T. Ventricular morphology and coronary arterial anatomy in hearts with isomeric atrial appendages. Ann Thorac Surg 1999; 67:1403–11.[Abstract/Free Full Text]
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Uemura H, Ho SY, Devine WA, Kilpatrick LL, Anderson RH. Atrial appendages and venoatrial connections in hearts from patients with visceral heterotaxy. Ann Thorac Surg 1995;60:561–9.[Abstract/Free Full Text]
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Black MD, van Son JAM, Haas GS. Extracardiac Fontan operation with adjustable communication. Ann Thorac Surg 1995;60:716–8.[Abstract/Free Full Text]
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Moore JW, Kirby WC, Madden WA, Gaither NS. Development of pulmonary arteriovenous malformations after modified Fontan operations. J Thorac Cardiovasc Surg 1989;98:1045–50.[Abstract]
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Abstract
Introduction
