Air Embolism During TEVAR: An Additional Flush Port on the Delivery System Pusher Significantly Reduces the Amount of Air Released During Deployment of a Thoracic Stent-Graft in an Experimental Setting

Purpose: To investigate the influence of (1) an additional side port for flushing the hollow pusher in Zenith thoracic stent-graft delivery systems and (2) additional carbon dioxide flushing on the amount of air released during stent-graft deployment. Methods: Twenty thoracic stent-grafts with an additional flush port to fill the hollow pusher were separated into 2 equal groups (C and D). Both groups were flushed with 20 mL of normal saline through the extra side port connected to the pusher and with 60 mL of saline through the regular flushing port. One group of grafts (group D) was additionally flushed with carbon dioxide through the regular flushing port prior to saline. All grafts were deployed into a curved plastic pipe attached to the bottom of a water-filled container. The released gas was recorded and measured using a calibrated setup. To evaluate the influence of the extra side port irrespective of the carbon dioxide flushing technique, group C was compared with a previously published reference group A without an extra side port that was flushed with the standard 60 mL of saline. Results: Volumes of gas were released in various amounts from the stent-grafts during deployment. The average amount of released gas was 0.51 mL in group C and 0.07 mL in group D (p<0.001). The mean amount of gas from group C samples (0.51 mL) was also significantly lower (p=0.002) compared with the reference group (0.79 mL). Conclusion: Thoracic endografts release air during deployment. Reducing the air-filled space inside the pusher of the catheter assembly using an additional side port can significantly reduce the amount of released air. Using the extra side port in combination with the carbon dioxide flushing technique reduces gas release further to small volumes. In a clinical setting this could be a promising approach to lower the risk of air embolism and stroke during thoracic endovascular aortic repair.

Endovascular arch replacement with a dual branched endoprosthesis

Background

In the light of current evidence, endovascular repair of aortic arch pathologies with custom-made devices should be considered a valid alternative to decrease operative mortality and morbidity associated with open or hybrid repair. Currently, two double inner branch devices are available on the market. Some papers from multicenter experiences have been published about the use of Cook device. We report our single-center experience with Bolton double branch stent graft in the treatment of aortic arch disease.

Methods

Between 2013 and 2016, nine high-risk patients with arch pathology were treated in our center with a Bolton custom-made branched device. Among these, two with a single branch model were excluded, leaving a subgroup of seven patients of this study.

Results

Out of the seven male patients (mean age, 76; range, 70-85) included in the study, two (28%) died perioperatively after stroke (14%) and retrograde dissection (14%), respectively. No other death, major complications, including aneurysmal diameter evolution and branch related complications, or secondary intervention was recorded at a mean follow up of 24 [6-53] months.

Conclusions

Despite the small sample size, our results are in line with the early experiences published on this technique. Endovascular repair of aortic arch disease with custom-made branched devices should always be considered to give high-risk patients a chance of repair.

Cerebral embolization, silent cerebral infarction and neurocognitive decline after thoracic endovascular aortic repair

Background

Silent cerebral infarction is brain injury detected incidentally on imaging; it can be associated with cognitive decline and future stroke. This study investigated cerebral embolization, silent cerebral infarction and neurocognitive decline following thoracic endovascular aortic repair (TEVAR).

Methods

Patients undergoing elective or emergency TEVAR at Imperial College Healthcare NHS Trust and Guy's and St Thomas' NHS Foundation Trust between January 2012 and April 2015 were recruited. Aortic atheroma graded from 1 (normal) to 5 (mobile atheroma) was evaluated by preoperative CT. Patients underwent intraoperative transcranial Doppler imaging (TCD), preoperative and postoperative cerebral MRI, and neurocognitive assessment.

Results

Fifty-two patients underwent TEVAR. Higher rates of TCD-detected embolization were observed with greater aortic atheroma (median 207 for grade 4–5 versus 100 for grade 1–3; P = 0·042), more proximal landing zones (median 450 for zone 0–1 versus 72 for zone 3–4; P = 0·001), and during stent-graft deployment and contrast injection (P = 0·001). In univariable analysis, left subclavian artery bypass (β coefficient 0·423, s.e. 132·62, P = 0·005), proximal landing zone 0–1 (β coefficient 0·504, s.e. 170·57, P = 0·001) and arch hybrid procedure (β coefficient 0·514, s.e. 182·96, P &lt; 0·001) were predictors of cerebral emboli. Cerebral infarction was detected in 25 of 31 patients (81 per cent) who underwent MRI: 21 (68 per cent) silent and four (13 per cent) clinical strokes. Neurocognitive decline was seen in six of seven domains assessed in 15 patients with silent cerebral infarction, with age a significant predictor of decline.

Conclusion

This study demonstrates a high rate of cerebral embolization and neurocognitive decline affecting patients following TEVAR. Brain injury after TEVAR is more common than previously recognized, with cerebral infarction in more than 80 per cent of patients.

Fenestrated TEVAR Using a Guidewire Fixator for Anchoring in Aortic Arch Target Vessels

Purpose: To report a new facilitated method for securing target vessel access during single fenestrated and branched thoracic endovascular repair using a guidewire fixator. Technique: The Liungman Guidewire Fixator (LGF) includes a 0.035-inch guidewire that is fitted with a stopper close to the distal end and a self-expanding anchoring element that is freely movable over the guidewire to the point of the stopper. The technique of using a LGF for anchoring in a target vessel is described in a 75-year-old woman with a 53-mm saccular arch aneurysm. She was treated with a fenestrated Zenith stent-graft that had a catheter-preloaded fenestration for the left subclavian artery (LSA) and a scallop for the left common carotid artery. To avoid through-and-through wire and brachial access, the LGF was used to secure the guidewire in the LSA during stent-graft deployment. Conclusion: The use of an LGF for anchoring in the target LSA during fenestrated arch endografting was feasible and safe.

Air bubbles are released by thoracic endograft deployment: An in vitro experimental study

Purpose:

Embolic stroke is a dreaded complication of thoracic endovascular aortic repair. The prevailing theory about its cause is that particulate debris from atherosclerotic lesions in the aortic wall are dislodged by endovascular instruments and embolize to the brain. An alternative source of embolism might be air trapped in the endograft delivery system. The aim of this experimental study was to determine whether air is released during deployment of a thoracic endograft.

Methods:

In an experimental benchtop study, eight thoracic endografts (five Medtronic Valiant Thoracic and three Gore TAG) were deployed in a water-filled transparent container drained from air. Endografts were prepared and deployed according to their instructions for use. Deployment was filmed and the volume of air released was collected and measured in a calibrated syringe.

Results:

Air was released from all the endografts examined. Air volumes ranged from 0.1 to 0.3 mL for Medtronic Valiant Thoracic and from <0.025 to 0.04 mL for Gore TAG. The largest bubbles had a diameter of approximately 3 mm and came from the proximal end of the Medtronic Valiant device.

Conclusion:

Air bubbles are released from thoracic endografts during deployment. Air embolism may be an alternative cause of stroke during thoracic endovascular aortic repair.

Air Embolism During TEVAR

Purpose: To investigate the amount of gas released from Zenith thoracic stent-grafts using standard saline flushing vs the carbon dioxide flushing technique. Methods: In an experimental bench setting, 20 thoracic stent-grafts were separated into 2 groups of 10 endografts. One group of grafts was flushed with 60 mL saline and the other group was flushed with carbon dioxide for 5 minutes followed by 60 mL saline. All grafts were deployed into a water-filled container with a curved plastic pipe; the deployment was recorded and released gas was measured using a calibrated setup. Results: Gas was released from all grafts in both study groups during endograft deployment. The average amount of released gas per graft was significantly lower in the study group with carbon dioxide flushing (0.79 vs 0.51 mL, p=0.005). Conclusion: Thoracic endografts release significant amounts of air during deployment if flushed according to the instructions for use. Application of carbon dioxide for the flushing of thoracic stent-grafts prior to standard saline flush significantly reduces the amount of gas released during deployment. The additional use of carbon dioxide should be considered as a standard flush technique for aortic stent-grafts, especially in those implanted in proximal aortic segments, to reduce the risk of air embolism and stroke.