AV Flow Cannula: A New Device for Antegrade Selective Cerebral Perfusion

AV cannula is a silicone cannula with a malleable steel shaft. It has been specifically designed in order to be introduced directly into supra-aortic vessels (SAV) and not just from the ostia of the vessel. This cannula is similar to existing cannulas with an inflatable balloon at the tip in order to seal the vessel proximally while perfusing distally.

The novelty of this device is the possibility of a guidewire introduction using the Seldinger technique (1). A 5/0 prolene (possibly pledget reinforced) suture is placed on the innominate artery and on the left common carotid artery wall.

Antegrade selective cerebral perfusion has become the preferred choice for brain protection during aortic arch surgery. It was first described in 1989-1991 by Kazui and Bachet (2, 3, 4). Since then, in order to perform antegrade selective cerebral perfusion (ASCP), cannulas have been introduced directly into the ostia of the SAV after institution of hypothermic circulatory arrest (HCA) and opening the aortic arch.
The authors describe a different surgical technique with a new type of cannula for ASCP. This cannula, called AV Flow, has been designed to be introduced in the supra-aortic vessels directly using a standard guidewire technique. The AV Flow can also be introduced from the ostia of the supra-aortic vessels if preferred.

The vessel is then punctured with a specific needle, and a guidewire is introduced a few centimeters into the lumen of the vessel. If required, before introducing the cannula, a small incision with a number 11 blade can also be done on the vessel wall. If necessary, standard available vessel introducing dilators can be used in order to facilitate this maneuver.

The AV Flow is then inserted into the innominate artery and in the left common carotid artery and a purse string suture is tied and secured. If required, the left subclavian artery can also be cannulated with the same devices and technique.

The AV Flow can be introduced before the institution of HCA and before opening the aortic arch. One great advantage to this technique is that the ostia of the SAV remains free from a cannula, allowing the operator easier access and a faster anastomosis or reimplantation.

Because the cannula in the original technique had to be placed through the ostia of the supra-aortic vessel, it needed hypothermic circulatory arrest and opening of the aortic arch before instituting ASCP. The brain was not protected during this initial period (opening of the arch) that although it is usually very short, in some cases, it can take a few minutes or substantially more in redo procedures. The presence of the cannula in the SAV ostia can also get in the way of the operator leading to a more demanding anastomosis with longer circulatory arrest time.

The authors inflate the balloon at the tip of the cannula in order to seal the innominate and the carotid artery proximally, and therefore can start ASCP just before the removal of the aortic cross-clamp and the beginning of the circulatory arrest. In this patient, the authors want to perform a hemiarch operation because the aneurysm of the ascending aorta is extending into the arch. Subsequently, they resect the distal part of the ascending aorta containing the aortic cannula and the concavity of the arch. Please note that the only cannula in the field is the pump-sucker because the AV Flow is out of the way of the operator. Then they reinforce the distal fragile aorta with two strips of teflon. Now they are ready to perform the distal anastomosis very quickly and easily. Transarterial introduction using Seldinger technique of the AV Flow represents an alternative to the current well-established techniques. The major advantages of this technique are complete cerebral protection throughout the HCA time and easier arch vessels reimplantation or hemiarch operations, as the AV Flow is out of the way of the surgeon.

The only contraindication at present is the presence of dissection of the SAV vessel itself. In this situation, the traditional technique remains the preferred option (5). The AV Flow is a safer option for instituting cerebral perfusion during HCA in selected patients; in many situations, it is a faster and easier alternative to the existing surgical technique. The required arch operation is carried out and only after restarting full flow cardiopulmonary bypass, the AV Flow cannulas can be removed. This is one of the advantages of the AV Flow compared with the existing cannulas that have to be removed before the completion of the anastomosis, exposing the brain to further unprotected ischemic time. This is the final result. The patient did not have any major or minor neurological events and was discharged on postoperative day seven.

References

1. Seldinger SI. Catheter replacement of the needle in percutaneous arteriography: a new technique. Acta radiol. 1953; 39:368-376.
2. Kazui T, Inoue N, Komatsu S. Surgical treatment of aneurysms of the transverse aortic arch. J Cardiovasc Surg (Torino). 1989;30:402-406.
3. Bachet J, Guilmet D, Goudot B, Termignon JL, Teodori G, Dreyfus G, et al. A new technique of cerebral protection during operations on the transverse aortic arch. J Thorac Cardiovasc Surg. 1991;102:85-93; discussion 93-94.
4. Kazui T, Inoue N, Yamada O, Komatsu S. Selective cerebral perfusion during operation for aneurysms of the aortic arch: a reassessment. Ann Thoracic Surg. 1992;53:109–114.
5. Di Bartlomeo R, Di Eusanio M, Pacini D, Pagliaro M, Savini C, Nocchi A, et al. Antegrade selective cerebral perfusion during surgery of the thoracic aorta: risk analysis. Eur J Cardiothorac Surg. 2001;19(6):765-770.