Dr. Rahul Sheth: Aortic Arch Aneurysm

Overview

67 year old man, was presented to Dr. Rahul Sheth. He had a cerebrovascular accident, 5 years ago, due to an embolic episode from an aortic arch aneurysm. Hybrid endovascular treatment was suggested at that time to treat the arch aneurysm, however in view of his high risk status, the option was rejected. Hence a novel technique was devised, wherein a new stent, multilayered flow modulator stent was deployed, to stabilise the aneurysm. A 46mm CARDIATIS stent was deployed. The procedure was performed under local anaesthesia.

CT follow up showed good regression in the aneurysm size after 2 years. Patient was lost to follow up till Feb 2019, where he presented with chest pain. XRC showed a large mediastinal shadow, for which a CT scan was done, which showed marked expansion of the previous arch aneurysm, due to loss of proximal seal, of the previously deployed stent; since the ascending aorta had expanded to 5.4cms.

CTA showed a large arch aneurysm measuring 10cms , with a dilated ascending aorta, with a type 1 Endoleak, with another aneurysm in the mid descending thoracic aorta, measuring 5.8cms. (Figure 1).

(Figure 1)

In view of the large aneurysm size, the only option was to perform a hybrid endovascular procedure, wherein the ascending aorta would need to be replaced, and aorto-bicarotid bypass was to be done, followed by endovascular stent grafting from the replaced ascending aorta to the distal descending thoracic aorta.

In the hybrid theatre, an ascending aorta replacement with an aorto-innominate and left common carotid bypass, was done under circulatory arrest. Patient had cardiac changes post surgery, hence on table cardiac angiogram showed a small LAD thrombus which was retrieved. On stabilisation, two endovascular grafts were deployed in the ascending aorta graft upto the descending thoracic aorta. A leak was seen from the proximal segment, hence banding was done on table.

Final angiogram showed complete exclusion of the aneurysm. (Figure 2)

(Figure 2)

He had a stormy recovery in the ICU, and had right sided weakness. He was discharged with full mobility. 3 month follow up CT aortogram revealed complete exclusion of the aneurysm with no endoleak and patent carotid bypasses (Figure 3).

(Figure 3)

DISCUSSION:

Descending thoracic aortic aneurysms are routinely treated using the endovascular stent grafting technique with excellent long term results.¹

Repair of disease of the arch is a significant undertaking and should not be embarked upon lightly. Arch aneurysms before the era of endovascular stent graft procedures were treated with open surgical repair. However due to the significant morbidity and mortality associated with open repair, other treatment modalities such as hybrid endovascular repair or total endovascular repair are being done.

Open repair for arch aneurysms involves circulatory arrest with deep hypothermia, which increases the morbidity and mortality due to the risk of air embolism, stroke, myocardial infarct and excessive bleeding. It has been suggested that as little as 12% of patients undergoing hybrid arch repair are suitable for an open repair, either due to the presence of multi-segmental aortic disease, or significant other co-morbidities.²

Hybrid arch repair is a feasible technique for tackling challenging arch pathologies. It is used in those cases where the landing zone has to be extended to Zone 0 to 2 in the arch.³

Hybrid repair avoids total circulatory arrest and deep hypothermia since there is no need for cross clamping and cardiopulmonary bypass, which significantly reduces the morbidity and mortality associated with traditional open repair. The procedure can be performed as a single stage procedure or a two staged procedure, however with the advent of hybrid operating theatres, single step procedures are preferred.

Hybrid endovascular repair is associated with risks such as stroke (surgical handling of the carotids, device related embolism), spinal cord ischemia.⁴

In this case, due to the previous stent and increase in size of the ascending aorta, the procedure had to be done under circulatory arrest, since the ascending aorta had to replaced with a prosthetic graft. The distal anastomosis would be unstable, due to the previous multi-layered stent, hence a one- step procedure was mandatory. The hybrid theatre offers the advantages of attending procedure related complications, such as cardiac and type 1 endoleaks.

Hybrid repair though less risky is still associated with risks, hence the need for total endovascular repair for arch aneurysms. The use of chimney grafts is well documented with comparable mortality and stroke rates to that of HAR, however the use of chimneys is associated with a significant Type 1a endoleak of 15-18%.⁵

More recently total endovascular approaches to the arch utilising branched endografts have been described as a feasible alternative, although they are still in their infancy compared to hybrid and open solutions. Early evidence suggests that total endovascular approaches perform adequately in regards to 30-day mortality and primary technical success after the learning curve is mastered⁶; however, the current paucity of literature and evidence, particularly in terms of its durability as a technique and long-term outcomes means that it is difficult to make direct comparisons to either HAR or open techniques at present.

In conclusion treatment for arch aneurysms has evolved considerably with marked refinement in surgical, anaesthetic, endovascular techniques making the procedure safer and durable. Hybrid endovascular repair is one of the options for treatment of arch aneurysms which has proved its long term results, hence making it a feasible alternative to open surgery.

References:

1. Gopaldas R R, Huh J, Dao T K, et al. Superior nationwide outcomes of endovascular versus open repair for isolated descending thoracic aortic aneurysm in 11,669 patients. J Thorac Cardiovasc Surg. 2010;140(5):1001–1010.
2. Czerny M, Weigang E, Sodeck G et al. Targeting landing zone 0 by total arch rerouting and TEVAR: midterm results of a transcontinental registry. Annals of Thoracic Surgery 2012;94(1):84-9
3. Moon MC, Morales JP, Greenberg RK. The aortic arch and ascending aorta: are they within the endovascular realm,Semin Vasc Surg 2007; 20(3):195, Semin Vasc Surg 2007; 20(2):97–107.
4. Cao P, De Rango P, Czemy M et al. Systematic review of clinical outcomes in hybrid procedures for aortic arch dissections and other arch disease. Journal of Thoracic and Cardiovascular Surgery 2012;144(6):286-300
5. Hogendoorn W, Schlosser F, Moll F et al. Thoracic endovascular aortic repair with chimney graft technique. Journal of Vascular Surgery 2013;58(2):502-511
6. Haulon S, Greenberg R, Spear R et al. Global experience with inner branched endograft. The Journal of Thoracic and Cardiovascular Surgery 2014:148(4);1709-1716