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Original Articles: Adult Cardiac

Invited Commentary

Department of Cardiac Surgery, Policlinico S. Orsola-Malpighi Hospital, University of Bologna, Via Massarenti, 9, Bologna 40138, Italy

(Email: dpacini{at}hotmail.com).

Nowadays, antegrade selective cerebral perfusion (ASCP) represents the best method of brain protection during aortic arch surgery, and different strategies are currently in use depending on each individual surgeon's experience. This variety in ASCP methods is due to the fact that the ideal temperature and the optimal flow rate during cerebral perfusion have not yet been definitively established.

Strauch and colleagues [1] have once again made an important contribution to the ever-increasing body of knowledge concerning ASCP. Specifically, in this article, they report their findings with a porcine experimental preparation using ASCP and randomization to either moderate hypothermia (25°C) or mild hypothermia (30°C). The end points measured included cerebral blood flow, cerebral oxygen consumption, and intracranial pressure.

Despite the limitations of the experimental model, the authors have collected important data demonstrating the following:

• The various regions of the brain have their own characteristics for cerebral blood perfusion during ASCP, and some regions, such as the cerebellum or pons, are more sensitive to ischemic injury.

• Cerebral blood perfusion is better preserved at high temperatures, such as 30°C rather than 25°C, but the flow gradually declines during the perfusion time.

• Cerebral oxygen consumption is significantly reduced during cooling, but at higher temperatures (30°C) it starts to increase after 15 minutes of ASCP while the reduced oxygen consumption remains stable with time at 25°C.

As is well known, inadequate brain protection results from the imbalance between the supply of cerebral blood flow and cerebral oxygen consumption. This imbalance, as demonstrated by Strauch and colleagues [1], is more evident during prolonged ASCP. In fact, prolonged periods of ASCP cause a progressive reduction of cerebral blood perfusion and an increase in cerebral oxygen consumption, above all at higher temperatures (30°C), and in those areas, such as the pons and cerebellum, which are more sensitive to ischemia.

Similar experimental studies [2, 3] in pigs demonstrated better cerebral protection using deeper systemic hypothermia and a lower temperature of ASCP (15°C to 20°C), but on the other hand there is also increasing evidence that deep hypothermia is associated with direct negative effects on cerebral neuronal integrity [4].

We demonstrated in humans that moderate systemic hypothermia at a nasopharyngeal temperature of 26°C, as compared with lower temperatures of hypothermia (21°C), provides the same clinical results in terms of mortality and morbidity, with particular reference to the neurologic outcomes [5]. This degree of hypothermia may represent an effective compromise, allowing good overall body protection and avoiding the well-known hypothermia-related side effects.

However, further randomized prospective studies are necessary to define the ideal systemic temperature and the optimal flow rate, also keeping in mind that not only the brain but the entire body (the visceral organs, the spinal cord, and so forth) have to be effectively protected.

	References

Top References

 

1. Strauch JT, Haldenwang PL, Müllem K, et al. Temperature dependence of cerebral blood flow for isolated regions of the brain during selective cerebral perfusion in pigs Ann Thorac Surg 2009;88:1506-1514.[Abstract/Free Full Text]
2. Strauch JT, Spielvogel D, Lauten A, et al. Optimal temperature for selective cerebral perfusion J Thorac Cardiovasc Surg 2005;130:74-82.[Abstract/Free Full Text]
3. Khaladj N, Peterss S, Oetjen P, et al. Hypothermic circulatory arrest with moderate, deep or profound hypothermic selective cerebral perfusion: which temperature provides best brain protection? Eur J Cardiothorac Surg 2006;30:492-498.[Abstract/Free Full Text]
4. Cooper WA, Duarte IG, Thourani VH, et al. Hypothermic circulatory arrest causes multisystem vascular endothelial dysfunction and apoptosis Ann Thorac Surg 2000;69:696-702.[Abstract/Free Full Text]
5. Pacini D, Leone A, Di Marco L, et al. Antegrade selective cerebral perfusion in thoracic aorta surgery: safety of moderate hypothermia Eur J Cardiothorac Surg 2007;31:618-622.[Abstract/Free Full Text]

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Davide Pacini Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Pacini, D. Search for Related Content PubMed PubMed Citation Articles by Pacini, D. Related Collections Cerebral protection Related Article