|Antegrade selective cerebral perfusion in aortic arch surgery|
|Saturday, 01 January 2011|
Pacini D, Di Marco L, Leone A, et al. Cerebral functions and metabolism after antegrade selective cerebral perfusion in aortic arch surgery. Eur J Cardiothorac Surg 2010; 37: 1322-31
In a nutshell
This study provides an objective documentation of cerebral neuronal integrity following antegrade selective cerebral perfusion (ASCP) in patients undergoing aortic arch surgery.
Two groups of patients were compared: aortic arch surgery (n=17: antegrade cerebral perfusion [ASCP] at moderate hypothermia, 26ºC) vs CABG (n=15: on-pump, mild hypothermia, 32ºC). Bilateral ASCP was achieved by cannulating the left common carotid artery and either the brachiocephalic trunk or right axillary artery, whilst leaving the left subclavian artery clamped.
By using proton emission tomography, diffuse weight imaging and proton magnetic resonance spectroscopy, the investigators were able to detect neuronal alteration, metabolic deficit and early signs of cerebral ischemia.
There were no post-operative strokes but one patient from each group suffered from temporary neurological dysfunction. A temporary metabolic deficit in the occipital region without neuronal injury was attributed to lack of left subclavian artery perfusion during ASCP. Transient vasogenic oedema related to cardiopulmonary bypass was seen in the ASCP group without any evidence of ischemic injury. Furthermore, no significant cognitive decline was observed and cognitive outcomes were similar to CABG group.
Cerebral protection strategies in the modern era have allowed more complex thoracic aortic surgery to be performed safely. The cornerstone of neuro-protection is the maintenance cerebral perfusion during aortic arch repair.
The results from this study confirmed that neuronal integrity and metabolism are preserved by ASCP during hypothermic circulatory arrest, and cognitive outcomes are not more inferior than in patients who just undergo cardiopulmonary bypass.
The applicability of these results in clinical practice is beset by a wide variation of approach in ASCP techniques. This study investigated the bilateral approach and whether unilateral ASCP provides similar results is unanswered. Transient hypometabolism in the occipital region, which may be attributable to lack of left subclavian perfusion, raises concerns about a unilateral approach, although no neuronal injury was observed.
Importantly, there are also other crucial factors which determine clinical outcomes and these include the duration of circulatory arrest, the degree of hypothermia, the maintenance of brain temperature, prevention of undesirable rewarming, as well as flow and pressure of the perfusate. This study does not account for these variations, however it does provide evidence to support the clinical impression that ASCP is safe.
E WK Peng