Aortic Hemiarch Replacement Without Hypothermic Circulatory Arrest
The Patient
The patient is a seventy-two-year-old male with stage 3 chronic kidney disease, a BMI of 35, and prior RCA stent placement who presented with symptomatic severe aortic stenosis and a CT angiogram demonstrating aneurysmal dilation of the aortic root and ascending aorta. The CTA highlighted the 4.5 cm sinus of Valsalva, 4.5 cm ascending aorta, and 3.8 cm proximal aortic arch. After thorough discussion, the patient elected to proceed with surgical correction of his valvulopathy and aortopathy, and consent was obtained for BioBentall, ascending aorta replacement, and hemiarch replacement. Surgeons decided the best strategy was to proceed with hemiarch replacement without hypothermic circulatory arrest in order to eliminate the negative effects of hypothermia.
Surgery
The patient was taken to the operating room and the aorta was cannulated just distal to the left subclavian artery takeoff, between zones two and three. The innominate artery was circumferentially dissected and controlled with a vessel loop. Cardiopulmonary bypass was initiated, and a cross clamp was applied to the ascending aorta. The proximal dissection was continued until the target temperature of 32 degrees Celsius was reached. The innominate artery was then snared, and a second cross clamp was applied to zone one and angled into zone two. At this point, cerebral perfusion was provided via the patent left carotid artery. The ascending aortic clamp was subsequently removed and hemiarch excision was performed, ensuring the ostium of the innominate artery was preserved.
A 30 mm woven polyester graft was then prepared and the graft to hemiarch anastomosis was completed with a running 4-0 polypropylene suture. The innominate artery was released, and the graft was deaired. The ascending cross clamp was reapplied to the graft and the zone one cross clamp was removed. Hemostasis was assessed, followed by completion of the Bio Bentall and ascending replacement. The patient’s postoperative course was uneventful.
In this case, the authors demonstrated aortic hemiarch replacement without the use of hypothermic circulatory arrest. Since this requires temporary occlusion of the innominate artery to maintain a bloodless field, intraoperative neurophysiological monitoring was employed similarly to the technique used for carotid endarterectomies and aortic arch debranchings. It is prudent to ensure that right brain perfusion options are available if needed. For cases requiring innominate perfusion, surgeons should cannulate the innominate artery with an antegrade cardioplegia cannula and provide direct perfusion.
It is important to note that this case was not an extensive hemiarch replacement, as the extent of excision was limited by the second aortic cross clamp position and the need to avoid the ostium of the innominate artery. As the aorta needs to be cross clamped in two different areas, this technique should not be employed in cases with significant aortic calcification. Finally, since the distal aortic arch needs to be dissected out and cannulated because the left recurrent laryngeal nerve is at risk for injury. This risk can be mitigated with careful dissection on the arch with judicious use of electrocautery.
