Introduction Aortic arch disease is a challenging clinical problem, especially in high-risk patients where open repair can have morbidity and mortality rates of 30–40% and 2–20%, respectively. Aortic arch “chimney”(AAC) stents used during thoracic endovascular aortic repair(TEVAR) are a less invasive treatment strategy than open repair, but the current literature is inconclusive about the role of this technology. The focus of this analysis is to describe our experience with TEVAR and AAC stent(s). Methods All TEVAR procedures performed from 2002–15 were reviewed to identify those with AAC stents. Primary end-points were technical success, as well as 30-day and 1-year mortality. Secondary end-points included complications, reintervention, and endoleak. Technical success was defined as a patient surviving the index operation with deployment of the AAC stent(s) at the intended treatment zone with no evidence of type 1 or 3 endoleak on initial postoperative imaging. The Kaplan-Meier method was used to estimate survival. Results Twenty-seven patients(age:69±12 years[male 70%]) were identified, and all were described as prohibitive risk for open repair by the treating team. Relevant comorbidity rates were: coronary artery disease/myocardial infarction(59%), O2-dependent emphysema(30%), preoperative creatinine>1.8mg/dL(19%), and congestive heart failure(15%). Presentations included: elective-67%(n=18), symptomatic-26%(n=7), and ruptured-7%(n= 2). Eleven(41%) had prior endovascular and/or open arch/descending thoracic repair. Indications were: degenerative aneurysm(49%), chronic residual type A dissection with aneurysm(15%), type 1a endoleak after TEVAR(11%), post-surgical pseudoaneurysm(11%), penetrating ulcer(7%), and acute type B dissection(7%). 32 BC vessels were treated: innominate, n=7; left common carotid artery(LCCA), n=24; left subclavian artery(LSA), n=1. Five patients(19%) had simultaneous innominate-LCCA chimneys. BCC stents were planned in 75%(n=24) with the remainder placed for either LCCA or innominate artery encroachment(n=8). Overall technical success was 89%(1-intraoperative death, 2-persistent type 1a endoleaks in follow-up). 30-day mortality was 4%(n=1; intraoperative in a patient with a ruptured arch aneurysm) and median LOS was 6[IQR 4, 9] days. Seven(26%) patients experienced a major complication(stroke-3[all with unplanned BCC], respiratory failure-3, and death-1). Nine(33%) patients underwent aorta-related reintervention, and no chimney occlusion events occurred during follow-up(median follow-up:9[IQR 1,23] months). One and 3-year survival is estimated to be 88±6% and 69±9%, respectively. Conclusions TEVAR with AAC can be performed with high technical success and acceptable morbidity and mortality in high-risk patients. Unplanned AAC placement during TEVAR results in an elevated stroke risk, which may be related to the branch vessel coverage necessitating AAC placement. Acceptable mid-term survival can be anticipated, but aorta-related reintervention is not uncommon, and diligent follow-u...

Chimney stent-grafts at increased risk for occlusion demonstrated anatomic and hemodynamic signatures within 1 month of juxtarenal chEVAR. Analysis of these parameters in the early postoperative period may be useful for identifying and remediating these high-risk stent-grafts.

WHAT THIS PAPER ADDS Technologies allowing endografting in the aortic arch are in active clinical trials with various configurations of branch stent graft design. A systematic computational fluid dynamic analysis was carried out to quantitatively evaluate the haemodynamic characteristics of stenting within the left subclavian artery (LSA). The results showed that a shorter extension of the LSA branch stent graft into the aortic lumen up to 5 mm has a smaller risk of potential thrombus generation; a longer extension could lead to thrombus formation impacting outcomes. These findings may help optimise the deployment and design of the stent graft system for treating aortic pathologies involving arch branches. Objective: Branched stent grafts represent a viable option for left subclavian artery (LSA) revascularisation in patients treated by thoracic endovascular aortic repair (TEVAR) for Zone 2 lesions. This study investigated the haemodynamic performance of different LSA branched stent graft configurations as potential determinants of thrombotic and stroke risks. Methods: A three dimensional aortic arch geometry extracted from post-operative computed tomography images of a TEVAR patient using a single LSA branched aortic endograft was modified in silico to obtain ten potential LSA branched stent graft configurations: five down facing (0e5 e 10 mm aortic protrusion with 10e12 mm internal diameter), four curved (30e60 with antegrade/retrograde orientation), and one LSA orifice misalignment. The 0 mm down facing stent graft was considered base configuration. Computational fluid dynamic analyses were performed to identify differences in pressure, energy, and wall shear stress (WSS) based parameters. Results: Total pressure drop and energy loss variations among configurations were not greater than 5 mmHg (6% of mean arterial pressure) and 5.7 mW (0.7% of cardiac power), respectively. Protrusions up to 5 mm created clinically insignificant flow disturbances. However, stent graft protrusions further into the aortic lumen created more complex haemodynamics, characterised by larger energy loss and more prominent flow recirculation. Protrusion greater than 5 mm into the lumen was associated with larger areas of elevated maximum WSS (>20 Pa) along the outer surface of the branched stent graft. Conclusion: Arterial haemodynamic characteristics are affected by LSA branched stent graft configurations, with pressure drops and energy losses likely to be clinically insignificant. The length of the stent graft protrusion into the aortic lumen generated the largest haemodynamic variations in the aortic system. Protrusions up to 5 mm have smaller risk of potential thrombus generation. Conversely, larger protrusions into the aortic lumen showed more disturbed haemodynamics, suggesting a greater risk of potential thrombus formation, which may be clinically important over time.

Objective:To investigate the diameter and flow rate of aortic arch arteries, their post-operative changes, and relationship in patients undergoing thoracic endovascular repair (TEVAR). Approach:Patient-specific diameters and flow rates were collected in common carotid (CCA), subclavian (SA), and vertebral (VA) arteries using duplex ultrasound pre-operatively and up to post-operative 6 months. Main results:For either diameter or flow rate of CCA, SA, and VA, there was no significant difference between the left and right sides for the 12 patients (age 64 ± 12 years, mean ± SD). The diameters of CCA, SA, and VA did not change over time and the average diameters of all measures were 7.4 ± 1.0, 7.3 ± 1.0, and 3.9 ± 1.9 mm, respectively. The CCA and VA flow rates did not change over time and averaged 494 ± 142 and 100 ± 56 ml min−1, respectively, while the SA flow rates were 147 ± 80, 230 ± 104, 136 ± 73, and 116 ± 55 ml min−1 at pre-operative, post-operative 1 week, 1 months, 6 months, with a decrease from 1 week to 6 months (P = .017). The total flow rate of all branches decreased at 6 months compared to 1 week (P = .020). The CCA, SA, and VA best diameter-flow rate relationships showed power values of 1.6 (R2 = 0.51), 1.8 (R2 = 0.20), and 2.4 (R2 = 0.60), respectively. Excluding the SA, a strong quadratic diameter-flow rate relationship was observed for the CCA and VA combined (Q = 8.5*D2, R2 = 0.87). Significance:There is a strong quadratic relationship between diameters and flow rates for the CCA and VA, but not SA. Our study provides reference diameter and flow rate boundary condition data of aortic arch arteries for computational modeling of patients undergoing TEVAR procedures.