Case Report: Repair of Type A Aortic Dissection After TAVR With an Uncovered Thoracic Endograft Without General Anesthesia

Background

The success of transcatheter aortic valve replacement in high-risk patient populations led to subsequent clinical trials that demonstrated noninferiority or superiority to SAVR in low and intermediate-risk populations. An uncommon but devastating complication of TAVR is acute type A aortic dissection, with a reported incidence of approximately 1.9% (1). Open repair remains the gold standard of care for patients with this pathology. However, patients may not always be amenable for open aortic repair, either due to preference or being medically unfit for the procedure. In-hospital mortality for untreated acute type A dissections is approximately 7% in the first hour of symptom onset and up to 90% at 24 hours (2). The use of stent grafts for thoracic endovascular aortic repair is challenging the long-accepted approach for open repair of an acute aortic dissection. It may, however, be an option for treating this subgroup of patients. The authors report the successful management of a stanford type A aortic dissection after TAVR in a 90-year-old woman using an uncovered aortic stent graft.

Case Report

The patient was a 90-year-old woman with a history of hypertension, hyperlipidemia, psoriasis, and severe symptomatic aortic stenosis. She presented to the authors’ valve center with recently progressive exertional dyspnea (NYHA II). Her Society of Thoracic Surgeons (STS) risk score was determined to be 2.6%, and she met one frailty criteria. The authors’ multidisciplinary TAVR team deemed her intermediate risk for SAVR, and as such an appropriate candidate for TAVR. Preoperative workup included a transthoracic echocardiogram, which revealed a trileaflet aortic valve with an aortic valve area of 0.95 cm2, mean gradient of 37 mm Hg, peak gradient of 66 mm Hg, and an aortic jet velocity of 4 m/s, consistent with severe aortic stenosis; mild mitral regurgitation and a left ventricular ejection fraction of 65-70% were also noted. A routine structural CT angiogram revealed an AV annular perimeter of 75 mm and a mean annular dimension of 23.2 mm; the iliofemoral arteries were all >7 mm in diameter and minimally calcified. Neither the ascending aorta/root nor the LVOT were severely calcified and the ascending aorta measured 34 mm. Based on the aforementioned measurements, the Heart Team recommended proceeding with TAVR with a 29 mm Evolut Pro valve via TF access. With a measured perimeter of 75 mm, the authors estimated the Evolut Pro to be approximately 18% oversized. While not listed in the IFU, their practice is to oversize a self-expanding valve in the 15-25% range. The patient was administered monitored anesthesia care (MAC) and access was achieved using the bilateral common femoral arteries (18Fr for the TAVR and 6Fr for the pigtail catheter) and the left common femoral vein (for the temporary pacing wire). A transthoracic echocardiogram (TTE) was used for the intraoperative imaging. As planned, a 29 mm Medtronic Evolut Pro self-expanding valve was deployed in the appropriate location, after being repositioned once. Completion aortography was performed, as per routine (in patients without significant CKD), and demonstrated a type A aortic dissection extending above the upper frame of the TAVR valve, likely originating from the aortic root. An emergent transesophageal echocardiogram (TEE) was performed which confirmed the diagnosis. Given the patient’s known wishes not to undergo open surgery, the decision was made to treat the dissection with a TEVAR. The authors deployed an uncovered 36 mm x 80 mm Cook Zenith nitinol stent just distal to (i.e. above the outflow) of the TAVR valve. A final aortogram and the TEE demonstrated no evidence of the dissection, which appeared to have been effectively “tacked up” by the stent.

Postoperatively, the patient was neurologically intact and hemodynamically stable. In this context, the authors elected not to perform additional contrast-based imaging at that time to minimize contrast administration. A noncontrast chest CT was performed which did not show signs of aortic dilatation or rupture. The patient remained clinically stable and was discharged home on postoperative day four. At her one-month follow-up, she underwent a TTE (as per TVT Registry protocol) and a repeat CT angiogram. The studies showed a well-seated and stable TAVR valve without AI, PVL, or pericardial effusion, and the endograft in good position with no evidence of dissection.

Discussion

While type A dissections remain a rare complication of TAVR, if and when they occur, the consequences are uniformly severe if left untreated. The overall morbidity and mortality for post-TAVR dissections has not yet been established (3). For patients who can and are willing to undergo open repair, this remains the ideal management strategy. In this patient, in whom surgical repair was not an option, TEVAR allowed for successful management of the acute dissection in the short term. Moreover, there are increasing instances of uncovered stents being used successfully to treat noniatrogenic type A dissections. This case demonstrates that TEVAR may well have a place in the management of this dreaded complication.

References

1. Langer NB, Hamid NB, Nazif TM, Khalique OK, Yahl TP, White J, et al. Injuries to the aorta, aortic annulus, and left ventricle during transcatheter aortic valve replacement Circ Cardiovasc Interv. 2016.
2. Nienaber CA, Sakalihasan N, Clough RE, Aboukoura M, Mancuso E, Yeh JSM, et al. Thoracic endovascular aortic repair (TEVAR) in proximal (type A) aortic dissection: Ready for a broader application? J Thorac Cardiovasc Surg. 2017 Feb;153(2):S3-S11.
3. Berfield KKS, Sweet MP, McCabe JM, Reisman M, Mackensen GB, Mokadam NA, et al. Endovascular repair for type A aortic dissection after transcatheter aortic valve replacement with a Medtronic CoreValve. Ann Thorac Surg. 2015 Oct;100(4):1444-1446.

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