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Consistency is Key: A Reproducible Approach to Managing Acute Type A Aortic Dissection

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posted on 04.12.2020, 22:20 by John J. Kelly, Joshua C. Grimm, Wilson Y. Szeto
Acute type A aortic dissection confers considerable morbidity and mortality and can be extremely challenging to manage from a surgical perspective. It is critical that these patients receive emergent intervention as the periprocedural risk increases each hour following diagnosis (1). A CTA of the chest, abdomen, and pelvis can provide vital information regarding operative planning for arterial cannulation for cardiopulmonary bypass (axillary vs femoral vs central aortic cannulation) and a transesophageal echocardiogram (TEE) can quantify baseline heart function and valvular pathology (2). The authors often request multiple arterial lines and a pulmonary arterial cannula for invasive monitoring throughout the perioperative period. If any ischemic ECG changes or distinct wall motion abnormalities are noted, coronary malperfusion should be suspected and saphenous vein made readily available for bypass if needed. A full sternotomy was performed and the pericardium opened widely to expose the arch. Unless the true lumen looks exceedingly difficult to access, the authors prefer direct aortic cannulation with the Seldinger technique under direct TEE guidance (3, 4). A right atrial venous drainage cannula, retrograde cardioplegia catheter, and left ventricular vent were secured and bypass was instituted. TEE and surface ultrasound of the carotid arteries confirmed that no dynamic flow changes occured during this period and following cross-clamp to ensure adequate cerebral perfusion throughout the operation. The patient was then cooled systematically and cardioplegia administered in a retrograde and direct ostial fashion.

Following cardiac arrest, the aorta was transected and the root was intensely evaluated. Unless there was a strong indication for root replacement (baseline valvulopathy, sinus segment entry tear, or root aneurysm), the authors routinely perform proximal repair with felt neo-media reconstruction of the sinus segment (5-7). Semicircular segments of felt were sized appropriately and secured within the layers of the aorta with a running 4-0 prolene suture. Care was taken not to impinge or distort both the left and right coronary arteries. The valve was then resuspended with a 4-0 prolene pledgeted stitch placed as a horizontal mattress 2 mm above each commissure. To maintain normal root dynamics, it is important that this suture does not ‘pin’ the commissure. The valve was then crudely tested for competence with saline while the left ventricular vent was turned to approximately 400 cc/minute.

The authors target moderate hypothermia and utilize antegrade cerebral perfusion via a 9 Fr cardioplegia cannula placed directly into the innominate artery (if not dissected). If the arch vessels are dissected, then direct ostial cannulation during circulatory arrest is preferred. Circulatory arrest was initiated and the arch was inspected for a primary tear. If there was no tear identified, the authors reconstruct the proximal arch with felt neo-media in a similar fashion as described for the root. An appropriately sized Dacron graft was then selected and sewn to the arch, proximal to the innominate artery. The graft was re-cannulated, the brain was de-aired, and cardiopulmonary bypass was reinstituted (8). The proximal anastomosis was then performed to the aorta at the approximate level of the sinotubular junction.

The patient was warmed and weaned from cardiopulmonary bypass. TEE should demonstrate minimal aortic valve insufficiency and acceptable biventricular function. Carotid artery ultrasound was also performed to confirm symmetric and adequate flow in both carotid arteries.

References

  1. McClure RS, Ouzounian M, Boodhwani M, El-Hamamsy I, Chu M, Pozeg Z, et al. Cause of death following surgery for acute type A dissection. AORTA. 2017;05:33–41.
  2. Abe T, Usui A. The cannulation strategy in surgery for acute type A dissection. Gen Thorac Cardiovasc Surg. 2017;65:1.
  3. Kreibich M, Chen Z, Rylski B, Bavaria JE, Brown CR, Branchetti E, et al. Outcome after aortic, axillary, or femoral cannulation for acute type A aortic dissection. J Thorac Cardiovasc Surg. 2019;158(1):27-34.e9.
  4. Asai T, Suzuki T, Kinoshita T, Sakakura R, Minamidate N, Vigers P. The direct aortic cannulation for acute type A aortic dissection. Ann Cardiothorac Surg. 2016;5:401–403.
  5. Bojko MM, Suhail M, Bavaria JE, Habertheuer A, Hu RW, Harmon J, et al. Fate of the preserved sinuses of valsalva after emergency repair for acute type A aortic dissection [published online ahead of print, 2020 Mar 7]. Ann Thorac Surg. 2020;S0003-4975(20)30353-2.
  6. Bojko MM, Habertheuer A, Bavaria JE, Suhail M, Hu RW, Harmon J, et al. Recurrent aortic insufficiency after emergency surgery for acute type A aortic dissection with aortic root preservation [published online ahead of print, 2020 Apr 18]. J Thorac Cardiovasc Surg. 2020;S0022-5223(20)30908-9.
  7. Rylski B, Bavaria JE, Milewski RK, Vallabhajosyula P, Moser W, Kremens E, et al. Long-term results of neomedia sinus valsalva repair in 489 patients with type A aortic dissection. Ann Thorac Surg. 2014;98:582–589.
  8. Sultan I, McGarvey J, Vallabhajosyula P, Desai ND, Bavaria JE, Szeto WY. Routine use of hemiarch during acute type A aortic dissection repair. Ann Cardiothorac Surg. 2016;5:245–247.
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