Case Reports: Frozen Elephant Trunk Procedure for Acute Type B Aortic Dissection
Key findings
- Massachusetts General Hospital surgeons describe the feasibility of total arch replacement and the frozen elephant trunk technique in three cases of acute type B aortic dissection where thoracic endovascular aortic repair was not possible
- This approach is useful for patients with unsuitable proximal landing zones and those at high risk of retrograde dissection who require urgent repair due to complications of acute type B dissection
- Two patients required concomitant visceral artery stenting due to residual malperfusion of the mesenteric and renal arteries
Thoracic endovascular aortic repair (TEVAR) is the standard surgical approach for patients with acute complicated type B aortic dissection. However, endovascular repair is not feasible in 4%-25% of cases (as reported in The Annals of Cardiothoracic Surgery), such as when the dissection extends into the aortic arch. An alternative for these patients is the frozen elephant trunk (FET) procedure, which enables the simultaneous repair of the aortic arch and descending aorta using a hybrid stent-graft device.
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In The Annals of Thoracic Surgery, Andrea Axtell, MD, MPH, cardiothoracic surgical fellow, and Arminder Jassar, MBBS, a surgeon in the Division of Cardiac Surgery at Massachusetts General Hospital, and colleagues have reported on three cases in which they successfully performed total arch replacement and FET to treat acute type B aortic dissection that was complicated by visceral malperfusion.
Case Presentations
All patients presented with acute chest pain, along with abdominal or back pain. Patient 1 also experienced decreased sensation and weakness in his right leg.
Patient 1 was a 76-year-old man in whom computed tomography (CT) demonstrated an acute type B aortic dissection with an intimal tear distal to the left subclavian artery. The dissection flap extended retrograde into the inferior aspect of the aortic arch, precluding TEVAR placement. In addition, the true lumen was severely compressed in the descending aorta, with malperfusion of the superior mesenteric and right renal arteries.
Patient 2 was a 39-year-old man in whom CT demonstrated aortic dissection that originated distal to the left subclavian artery and extended to the iliac arteries. He was originally treated with antihypertensive therapy, but his symptoms recurred and repeat CT angiography demonstrated retrograde extension of the dissection to the left subclavian and common carotid arteries with a new entry intimal tear in the aortic arch.
Patient 3 was a 58-year-old man in whom CT demonstrated aortic dissection with an entry tear in the aortic arch at the level of the left carotid artery, extending distally to the iliac arteries. After he was transferred to Mass General, repeat CT demonstrated contained rupture of the arch, with the dissection extending into the celiac and superior mesenteric arteries, and complete thrombosis of the left renal artery.
In all three cases, there was an inadequate proximal landing zone for TEVAR.
Why FET?
Open descending thoracic aortic replacement for acute type B dissection can be associated with significant morbidity. Endovascular approach involving extensive aortic arch debranching and TEVAR, carry a risk of retrograde type A dissection.
FET is a single-stage treatment for the acute dissection and eliminates the risk of retrograde type A dissection. This technique enables effective distal aortic remodeling and provides a favorable platform for future intervention if needed. The journal article provides details of the technique.
Verified Complete Reperfusion
Patient 1 and Patient 2 also required visceral artery stenting. Successful central aortic repair does not guarantee resolution of visceral malperfusion. Restoration of visceral flow should be confirmed in patients with acute type B dissection, or patients with Debakey type I dissection who undergo TEVAR because their risk of death due to ongoing malperfusion is high even when a central aortic repair is successful.
Mass General has adopted the following approach, termed "verified complete reperfusion," for all Debakey type 1 dissections:
- There is an early discussion between cardiac and vascular surgeons about the operative plan
- Operations are performed in a hybrid operating room
- After the central repair, transesophageal echocardiography, intravascular ultrasound or angiography is used to confirm that the distal aortic true lumen has expanded and visceral malperfusion has been resolved
- If ongoing compromise is noted, additional interventions (usually via the antegrade approach through the ascending aortic graft) can be performed immediately
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