|Year : 2015 | Volume
| Issue : 1 | Page : 31-33
Extra Anatomic Bypass of Coarctation of the Aorta in an Adolescent: Avoiding Spinal Cord Ischemia
T Raina, R Rathnakar, S Agarwal, V Dutt, A Tomar, DK Satsangi
Department of Cardiothoracic Surgery and Anaesthesiology, G.B Pant Hospital, New Delhi, India
|Date of Web Publication||27-Jan-2015|
Dr. S Agarwal
G.B Pant Hospital, New Delhi
Source of Support: None, Conflict of Interest: None
Coarctation of the aorta in an adult patient often requires extra-anatomic bypass techniques. Posterior pericardial bypass technique is one among the various techniques that has been described where a Dacron conduit is anastomosed between the lateral aspect of the ascending aorta and the descending thoracic aorta posterior to the pericardium. In the present patient, we describe an additional femoral artery canulation via a graft anastomosed end-to-side to the femoral artery to avoid spinal cord ischemia during the period that the descending aorta is clamped for anastomosis of the conduit.
Keywords: Coarctation, extra-anatomic bypass, spinal ischemia
|How to cite this article:|
Raina T, Rathnakar R, Agarwal S, Dutt V, Tomar A, Satsangi D K. Extra Anatomic Bypass of Coarctation of the Aorta in an Adolescent: Avoiding Spinal Cord Ischemia. MAMC J Med Sci 2015;1:31-3
|How to cite this URL:|
Raina T, Rathnakar R, Agarwal S, Dutt V, Tomar A, Satsangi D K. Extra Anatomic Bypass of Coarctation of the Aorta in an Adolescent: Avoiding Spinal Cord Ischemia. MAMC J Med Sci [serial online] 2015 [cited 2019 Dec 12];1:31-3. Available from: http://www.mamcjms.in/text.asp?2015/1/1/31/150060
| Introduction|| |
Coarctation of the aorta in an adolescent patient often requires unconventional modes of surgery. Extra-anatomic bypass techniques in adults have been previously well-described. We describe a patient in whom posterior pericardial bypass of the coarctation was performed with an additional modification to reduce the possibility of spinal cord ischemia.
| Case Report|| |
A 14-year-old male patient weighing 25 kg presented with the complaints of recurrent headache. On examination, the patient was diagnosed to have secondary hypertension. Additional findings included absent bilateral femoral pulses. Thus, a clinical diagnosis of coarctation of the aorta was made. Contrast-enhanced computed tomography (CECT) with angiography was performed which revealed severe postductal coarctation measuring 5 mm in length just distal to the origin of the left subclavian artery. The reformation of the distal flow was through large collaterals from the intercostal arteries, vessels around the scapula, and the internal mammary artery, which were immediately distal to the coarctation site [Figure 1]. Echocardiography was within normal limits apart from the coarctation. Conventional technique of surgery would have entailed resection and end-to-end anastomosis with or without an interposition graft. This technique could result in the interruption of the large collaterals with a strong possibility of spinal cord ischemia and additional problems of severe hemorrhage. Thus, the patient was planned for posterior pericardial bypass from the lateral aspect of the ascending aorta to the descending thoracic aorta posterior to the pericardium via a median sternotomy.
|Figure 1: Coarctation segment and collaterals (small white arrows indicate large collaterals). Arrow on right showing coarcted segment|
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After median sternotomy and opening the anterior pericardium, heparin was administered. Routine normothermic cardiopulmonary bypass with ascending aortic canulation just proximal to the origin of the brachiocephalic artery and bicaval cannulation was employed. The femoral artery was exposed in the left groin and was found too thin for direct cannulation. Hence, an 8 mm polytetrafluoroethylene graft was anastomosed in an end-to-side fashion to the femoral artery. Through this graft, a 20 Fr femoral arterial canula was inserted and connected to the arterial limb of the bypass circuit with a Y shaped connector [Figure 2]. The femoral canula was kept clamped. The heart was kept beating and perfused but empty. The heart was lifted up by an assistant standing to the right of the operating surgeon and the posterior pericardium opened.
|Figure 2: Y junction of femoral cannula (clamped) and aortic cannula. Intervening venous cannulae and ascending aorta to descending aorta graft is seen in situ|
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Transesophageal echocardiography probe helped in the identification of the esophagus. Descending thoracic aorta was identified just to the left of the esophagus. A side biting clamp was used to occlude the descending thoracic aorta, and aortotomy was performed. At this time, the femoral limb of the arterial canula of the bypass circuit was opened for retrograde perfusion of the descending aorta up to the clamp. A radial pressure monitoring line ensured adequate upper body perfusion. An 18 mm Dacron graft was anastomosed end-to-side to the descending aorta and the clamp released. Simultaneously, perfusion was stopped. Clamp time was 25 min. The graft was brought anterior to the inferior vena cava and along the lateral border of the heart to the ascending aorta and necessary adjustments in the length of the graft was made. The proximal anastomosis was performed at the lateral aspect of the distal most part of the ascending aorta using a side biting clamp [Figure 3]. The graft was deaired, and the clamp released slowly. There was a transient decrease in blood pressure which was managed by vasopressors. The patient was uneventfully weaned off bypass and heparin reversed with protamine. The chest was closed, and the patient was transferred to the intensive care unit. Postoperative chest X-ray showed the conduit shadow along the lateral heart border [Figure 4]. CECT performed a week after the procedure showed a patent graft with good distal flow [Figure 5].
|Figure 3: Final orientation of graft (lower part represents head end of the patient)|
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|Figure 4: Preoperative (a) and postoperative (b) chest X-ray showing the graft (arrow)|
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|Figure 5: Postoperative patent graft is seen on contrast-enhanced computed tomography thorax (arrow)|
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| Discussion|| |
Unrepaired coarctation of the aorta is eventually lethal with 50% patients dying by 32 years of age and 90% by 58 years of age.  Anatomical repair is possible in infants and young children as the elasticity of the tissues allows for the mobilization.  In older children and adults, however, the reduced elasticity of the tissues in addition to the substantial risk of hemorrhage and interruption of the collaterals with risk of spinal cord ischemia, make end-to-end anastomosis a difficult procedure.  Thus, extra-anatomic bypass operations are an attractive proposition for this subset of patients.
Various extra-anatomic repair techniques have been described in the literature with approaches utilizing usually left posterolateral thoracotomy. Left posterolateral thoracotomy and anastomosis of the graft between the subclavian artery and the descending thoracic aorta were not considered in the present patient because of small subclavian artery diameter. This approach to expose the ascending aorta is also difficult to achieve in adults  and there is always the risk of torrential bleeding from intercostal vessels.
The use of median sternotomy and posterior pericardial bypass for coarctation was first described by Vijayanagar et al. in 1980. The conduit was routed around the left side of the heart by these authors.  This technique was subsequently modified by others where the conduit was routed along the right margin of the heart. Various other modifications like routing the conduit posterior or anterior to the inferior vena cava have been reported with excellent results. , Oliveira et al. have documented a near 100% graft patency rate with this approach.  More than 50% patients have no residual hypertension and in the rest, hypertension was mainly controlled by one antihypertensive medication.
Spinal cord ischemia resulting in paraplegia is a dreaded complication of any repair requiring clamping of the descending thoracic aorta. This occurs in about 0.5% of patients being operated for coarctation.  Although a side biting clamp is used during this technique, the flow through the residual small descending aorta in an adolescent may be negligible and spinal cord ischemia may still result. In addition, there is a chance of interruption of the collaterals. The addition of retrograde perfusion by femoral artery canula through a graft sutured to the artery during the time of clamping the descending aorta has never been described before in the literature and this technique will protect the spinal cord during the period of ischemia. This could buy time for a perfect anastomosis in the deep posterior pericardium. Direct cannulation of the artery would limit the size of the femoral arterial cannula. Repair of the artery with a small pericardial patch at the site of the graft at the end of the procedure resulted in a normal caliber femoral artery. One additional modification was suturing a temporary graft to the femoral artery as the size of the femoral artery was too small for direct cannulation.
Thus in conclusion, posterior pericardial bypass for coarctation of aorta is a well-described procedure in adolescents and adults with excellent long-term results, and addition of a femoral artery retrograde perfusion could be an useful adjunct to avoid the complication of spinal cord ischemia in these patients.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]