Surgical Management of Type A Aortic Dissection

<div>In this video, the authors discuss the three common approaches to reconstruct the aortic arch in the setting of a type A aortic dissection. First, they discuss a hemiarch replacement, followed by a total arch replacement, and finally a total arch replacement with a frozen elephant trunk and carotid artery replacement. Approximately 40% of patients at UPMC undergo a total arch replacement for type A aortic dissection. This is a typical presentation of someone with an acute aortic dissection. They typically have a long-standing history of hypertension. On admission to the ED they are complaining of chest pain with radiation to the back. An urgent CT scan is done to assess the situation.</div><div>Demonstrated in the video is a Debakey II aortic dissection with an intimal tear in the proximal aortic arch and no flap in the descending thoracic aorta.</div><div><p><strong>Hemiarch Replacement</strong><br></p><p>To arterially cannulate patients with acute aortic dissection, the authors use the modified Seldinger technique. They have found central cannulation to be practical and efficient and employ this technique in most of their patients. The inset picture is the transesophageal view of the wire in the true lumen which should be confirmed prior to dilating the track or inserting the aortic cannula. Venous drainage is through a dual stage right atrial cannula and an additional right angle curved venous cannula is placed in the superior vena cava for retrograde cerebral perfusion during the period of circulatory arrest. During circulatory arrest, the SVC cannula is clamped distal to the connection with the cardioplegia system and retrograde cerebral perfusion is utilized via the SVC cannula. They generally cool to four minutes after EEG silence or approximately 45 minutes of cooling. Retrograde cerebral perfusion is utilized for all hemiarch reconstructions and antegrade cerebral perfusion for all total arch reconstructions. The video demonstrates hypothermic circulatory arrest with retrograde cerebral perfusion. The distal ascending aorta is trimmed to the base of the innominate artery and the lesser curvature is resected An appropriately sized woven polyester graft is beveled, brought into the field and sewn to the aortic arch using running 4-0 prolene. It is important to note that no external felt or bioglue is utilized. When needed, a neomedia technique using Teflon felt is used where felt is sandwiched between the adventitia and the intima which are sewn to each other using running 4-0 prolene. The aortic graft is then recannulated. The aortic arch and the graft are deaired aggressively, the patient is placed back on cardiopulmonary bypass and rewarmed to normothermia. During the period of cooling and/or rewarming proximal aortic reconstruction is performed. When there is no tear in the sinus segment and the aortic root is not aneurysmal, the aortic valve is resuspended and the aortic valve and the aortic root complex is preserved. The authors perform the proximal anastomosis with 4-0 prolene without any felt reinforcement or the use of bioglue but utilize a felt neomedia technique where needed.</p><p><strong>Total Arch Replacement</strong></p><p>For total arch reconstructions, an arch first technique is employed in most patients. A trifurcated brachiocephalic graft is utilized and the innominate artery and the left carotid artery are revascularized prior to lower body circulatory arrest thereby ensuring bilateral antegrade cerebral perfusion. In this particular case, the distal aortic anastomosis was performed first as they did not anticipate a secondary tear in the aortic arch. This was done under RCP. Once the brachiocephalic anastomosis was performed, unilateral ACP was initiated and subsequently bilateral ACP was utilized after left carotid revascularization. Brachiocephalic anastomoses are performed using running 5-0 prolene without any external felt or glue. This dissection flap proximally here is an example of where they would potentially reconstruct the aortic wall with felt using neomedia technique. The aortic valve is then analyzed and interrogated. If the valve appears to be competent and the cusps are healthy, the aortic valve is resuspended with 4-0 pledgeted sutures. Valve sizers are used to size the proximal aortic graft and the proximal anastomosis is performed with running 4-0 prolene. The brachiocephalic graft is then reimplanted back on to the neoaorta using running 2-0 prolene. This is reimplanted on the right lateral side of the aortic graft so that it is not compressed or constricted when the chest is closed and minimizes chances on graft injury on re-entry. Here you can see the completed aortic reconstruction.</p><p><strong>Concomitant carotid artery replacement</strong></p><p>When the carotid arteries are dissected into the neck and the patient presents with cerebral malperfusion, the carotid arteries are routinely reconstructed in the neck. The carotid artery bifurcation is exposed using a standard carotid incision and a track is created from the carotid artery through the thoracic inlet into the mediastinum. After dividing the proximal carotid artery, a 6-8 mm graft is tunneled from the chest to the neck and anastomosed distally to the carotid bifurcation using running 6-0 prolene. The video shows an image of a thrombosed carotid artery. This is a demonstration of a frozen elephant trunk. The subclavian anastomosis is performed prior to deployment of the endograft. A frozen elephant trunk is utilized if there is a pseudocoarctation of the descending thoracic aorta or if there is a large re-entry tear in the descending thoracic aorta distal to zone 3. IVUS or TEE is utilized after a soft J tip wire is passed retrograde from the femoral artery while ensuring wire access throughout the true lumen. This is exchanged for a pigtail catheter followed by a super stiff lunderquist wire. An appropriately sized endograft is then deployed over the wire under direct vision. The distal anastomosis is then performed using 3-0 prolene without any external felt reinforcement. With each bite of the distal anastomosis, the goal is to catch 2mm of the stent graft, 5-10 mm of the aorta, 3-4 rings of the aortic graft, and to intussuscept the aortic graft into the stent graft to minimize type 1 endoleak. Shown in the video is a representative 3D reconstruction postoperatively.</p><hr><p><strong>References</strong></p><ol><li>Sultan I, McGarvey J, Vallabhajosyula P, Desai ND, Bavaria JE, Szeto WY. Routine use of hemiarch during acute type aortic dissection repair. <a href="https://dx.doi.org/10.21037/acs.2016.04.01"><em>Ann Cardiothorac Surg</em>. 2016. May. 5(3):245-457.</a></li><li>Sultan I, Bianco V, Patel HJ, Arnaoutakis GJ, Eusanio MD, Chen EP, et al. Surgery for type A aortic dissection in patients with cerebral malperfusion: Results from the International Registry of Acute Aortic Dissections. <a href="https://doi.org/10.1016/j.jtcvs.2019.11.003"><em>J Thorac Cardiovasc Surg</em>. 2019. Nov 15. pii: S0022-5223(19)32762-X.</a></li><li>Sultan I, Aranda-Michel E, Bianco V, Kilic A, Habertheuer A, Brown JA, et al. Outcomes of carotid artery replacement with total arch reconstruction for type A aortic dissection. Annals of Thoracic Surgery. Accepted. Sept 28th 2020. In press</li></ol><hr></div>