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Endovascular treatment of complex thoracic pathologic conditions involving the aortic arch can often be appropriate and safe; however, minimally invasive procedures are not always feasible, especially in emergent cases. We report the case of a 78-year-old woman who emergently presented in hemorrhagic shock with a ruptured chronic dissecting aneurysm that involved the aortic arch. Eight years earlier, she had undergone aortic valve replacement and plication of the ascending aorta, which was complicated a day later by Stanford type B dissection, malperfusion, and ischemia that required an axillobifemoral bypass. At the current admission, we successfully treated her surgically through a left thoracotomy, using moderate hypothermic extracorporeal circulation and advanced organ-protection methods. We discuss the surgical indications and our operative strategy in relation to open surgical repair versus endovascular treatment in patients with complex conditions.
Pathologic involvement of the aortic arch and the presence of dissection are 2 major issues in descending thoracic aortic repair, particularly in emergent settings of aneurysmal rupture. A patient's comorbidities and older age may contraindicate deep hypothermic circulatory arrest; however, a thoracoabdominal dissection could lead to malperfusion if left-side heart bypass is considered for organ protection. Endovascular or hybrid surgery is a less invasive approach in complex cases; however, a good aneurysmal neck and adequate vascular access for the device are mandatory for technical success. We present the case of an elderly woman with comorbidities who required emergent repair of a complex dissecting thoracic aneurysm.
In May 2011, a 78-year-old woman with severe emphysema and chronic renal failure was emergently admitted for acute thoracic pain. Examination revealed signs of hemorrhagic shock. Eight years earlier, she had undergone elective aortic valve replacement and plication of the ascending aorta because of a 48-mm dilation. The next day, acute Stanford type B dissection with static iliac malperfusion and limb ischemia required an emergent axillobifemoral bypass. No descending aortic repair was then indicated. The patient's subsequent postoperative course was uneventful. She was lost to follow-up but adhered to a prescribed regimen of long-term anticoagulative therapy.
At the current presentation, computed tomography (CT) showed a chronic dissecting aneurysm (diameter, 6.5 cm) involving the aortic arch and descending thoracic aorta, with left hemothorax and aortic wall rupture at the isthmus (Fig. 1). Proximally, the dissection involved the entire arch; distally, it extended to the iliac arteries. The right common iliac artery was occluded at its origin, the left common iliac and hypogastric arteries were dissected but patent and were perfused by the false lumen, both external iliac arteries were occluded, and the lower limbs were perfused by the axillobifemoral bypass. The patient was taken for emergency surgery and was placed in a right lateral decubitus position to expose the left thorax. Through a left inguinal incision, the common femoral vein was isolated and an 8-mm Dacron graft was sutured to the femoral (right-to-left) crossover of the previous bypass. As previously described,1 the right atrium was cannulated by means of an endovascular technique: a venous cannula was advanced over a 0.035-in Amplatz® guidewire (Boston Scientific Corporation; Natick, Mass).
The patient underwent total heparinization, and extracorporeal circulation (ECC) with systemic cooling was started. The thorax was opened in the 4th intercostal space, and the hemothorax was drained (500 cc). A mini-thoracotomy in the 6th intercostal space exposed the cardiac apex, and a cannula over a purse-string suture was inserted for ventricular drainage. A wall hematoma involved the aortic arch and descending thoracic aorta, with active bleeding from the ruptured anterolateral wall of the isthmus. Provisional hemostasis was achieved by applying finger pressure over the aortic rupture during the time needed for systemic cooling. The proximal clamping site was between the left common carotid and subclavian arteries. Cardiac fibrillation was observed at 24 °C, and arrest was attained after a systemic potassium bolus was administered. To minimize the risk of spinal cord ischemia, we kept the patient's mean aortic pressure above 100 mmHg. Proximal and distal aortic clamping was performed at 24 °C with an atraumatic clamp; the distal clamp was positioned on the 2nd third of the descending thoracic aorta. The aneurysm was incised, and the dissected region was removed by means of proximal and unclamped distal fenestration. Back-bleeding in 3 pairs of patent intercostal arteries was ligated with pledgeted sutures. A 34-mm Dacron graft (Boston Scientific) was anastomosed to the outer aortic wall by means of a double-barrel technique with use of 3-0 polypropylene suture reinforced with Teflon strips. The Teflon felt was sutured inside and outside the aortic neck (“sandwich” technique) for safe anastomosis. Both anastomoses were then reinforced with BioGlue® Surgical Adhesive (CryoLife Inc.; Kennesaw, Ga). The extent of repair included the isthmus, from immediately after the origin of the left subclavian artery to the mid thoracic aorta.
The patient was warmed, and cardiac defibrillation was successful at 28 °C. Her postoperative course was complicated by surgical revision 6 hours later to drain a hemothorax and secure secondary hemostasis. Intubation was prolonged (total, 72 hr). She exhibited no central neurologic deficit or paraplegia, and her serum creatinine level remained stable at 1.5 mg/dL. She remained in intensive care for 5 days and was then transferred to a surgical ward. A CT scan 7 days postoperatively showed patency of the renal arteries, the axillobifemoral bypass, and both aortic lumina (Fig. 2). After 9 days of hospitalization, the patient was discharged to a rehabilitation facility in good clinical condition. Three months later, she reported by telephone that she was well. Routine outpatient visits were planned, and no further contrast imaging was scheduled.
Given the patient's poor clinical condition preoperatively, an endovascular approach would have been useful to avoid the need for thoracotomy and aortic clamping.2,3 However, to our knowledge, the dilated and dissected aortic arch and the absence of bilateral femoral access for an endograft prevented any chance of successfully introducing the endovascular device and sealing the ruptured aorta.
We considered using a frozen elephant trunk with open arch repair and hypothermic circulatory arrest and implanting a hybrid graft (such as the E®-Vita open plus, JOTEC GmbH; Hechigen, Germany) in the true lumen of the descending thoracic aorta. However, deep hypothermia and repeat sternotomy would have placed this acutely ill patient at high risk of cerebral and hemorrhagic events. Furthermore, the extensive thoracoabdominal dissection with several re-entry tears could have precluded adequate exclusion of the ruptured false lumen.4 The hypogastric arteries have a substantial role in the spinal cord's blood supply by virtue of a collateral network, especially when several intercostal arterial feeders are occluded. The direct perfusion of the patient's left hypogastric artery by the false lumen (Fig. 1) might have been impaired had exclusion of the endovascular false lumen been achieved, with resultant increased risk of postoperative paraplegia. Postoperative acute renal failure was also a risk, because the left renal artery was perfused only by the false lumen. We therefore directed our approach toward the distal reperfusion of both lumina. Given the patient's critical condition and the emergent setting, an open repair of only the ruptured aorta was indicated. In similar cases, our preference for organ protection is distal aortic perfusion during aortic cross-clamping. The bilateral occlusion of the iliofemoral axis prevented the axillobifemoral graft from being used as a passive shunt for retrograde visceral and medullar perfusion, and the dissection of the aorta at the distal cannulation site contraindicated left-side heart bypass. Accordingly, moderate hypothermia was our choice for medullar and visceral protection.
A 90° right lateral decubitus operative position precludes using the right axillary artery as an inflow site for cardiopulmonary bypass. In our patient, the previous right axillobifemoral graft (of 8-mm radially supported Dacron) enabled easy access for the left inguinal arterial cannula. During extracorporeal circulation, the proximal aorta and aortic trunk were adequately perfused with use of a roller pump through the axillary graft. Because of the proximal arterial perfusion through the peripheral graft, deep hypothermia was not needed; this reduced the risk of coagulopathy, respiratory distress, and endothelial dysfunction in a patient who was in shock. With continuous cerebral perfusion, moderate hypothermia (24–26 °C) can serve as an adjunct to protect the visceral organs from ischemia/reperfusion damage. Infusing cardioplegic solution during the left thoracotomy could have been problematic; however, with the adequate ventricular drainage, the systemic infusion of hyperkalemic solution provided good myocardial protection. Surgical access to the distal arch through the 4th intercostal space enabled good exposure of the proximal neck, but a minithoracotomy in the 6th space was required for access to the cardiac apex for left ventricular drainage. The aorta was ruptured at the isthmus, and surgical exposure was limited to the arch between the left carotid and subclavian arteries and distally to the middle third of the descending aorta. The rupture in the aortic wall was recognized, and immediate hemostasis was readily achieved with finger compression while the patient was cooled. To reduce the risk of postoperative bleeding from dissected tissues, we recommend minimizing aortic exposure and using atraumatic clamps.
A chronically dissected aorta is typically stronger than one in the acute phase; however, the evolution of the wall's condition is multifactorial and not completely understood. The false lumen in our patient was very frail, and we used the sandwich technique, suturing Teflon felt inside and outside the aortic neck, for safe anastomosis of the graft. We then reinforced both anastomoses with glue.
Intercostal artery reattachment has been useful in preventing postoperative paraplegia.5 Because of the severe weakness of our patient's dissected aorta, we decided not to reattach the intercostal arteries to the aortic graft. To minimize the risk of spinal cord ischemia, we deliberately kept the mean aortic pressure above 100 mmHg, and we used pledgeted sutures to control back-bleeding from 3 pairs of patent intercostal arteries. The patient had been taking anticoagulative agents long-term, and, given the emergent setting, the use of a spinal-fluid drain was contraindicated.
In the era of endovascular treatment, minimally invasive procedures are not always feasible, especially in emergent cases. Good knowledge of different techniques for open aortic repair and organ protection, and collaboration between vascular and cardiac surgeons, can lead to technical operative success in patients with complex conditions.
Address for reprints: Efrem Civilini, MD, Vascular Surgery Department, Scientific Institute H. San Raffaele, Vita-Salute University School of Medicine, Via Olgettina 60, 20132 Milan, Italy