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J Thorac Cardiovasc Surg 2006;132:153-154
© 2006 The American Association for Thoracic Surgery
Brief Communication |
Department of Thoracic and Cardiovascular Surgery, Johann Wolfgang Goethe University Hospital, Frankfurt/Main, Germany
* Address for reprints: Farhad Bakhtiary, MD, Department of Thoracic and Cardiovascular Surgery, Johann Wolfgang Goethe University, Theodor Stern Kai 7, 60590 Frankfurt/M, Germany. (Email: farhad{at}bakhtiary.de).
Antegrade cerebral perfusion (ACP) has been popularized, offering a more physiologic method of perfusion and extending the safe limits for arch repair.
1
Deep hypothermia has been used as an adjunct to ACP almost universally. The absolute necessity for deep hypothermia once ACP with flow rates and pressures within the physiologic range is provided has been questioned recently. Ehrlich and colleagues
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showed that brain oxygen consumption is reduced by 50% of baseline values if the patient is cooled systemically to 28°C core temperature. Yet the regional cerebral blood flow with antegrade perfusion decreases more rapidly at less than 28°C than between 36°C and 30°C.
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Thus a perfusate temperature of greater than 28°C should be optimal for ACP to meet the lowered metabolic demands of the brain. By using this modified temperature management, the drawbacks of long cooling and rewarming periods on cardiopulmonary bypass (CPB) could be avoided. This article describes the operative management with this concept.
Technique
After systemic heparinization (300 IU/kg), the right subclavian artery is exposed through a 4-cm subclavian incision. Cannulation is performed with an 18F to 22F flexible standard arterial cannula in an occlusive technique.
After median sternotomy, the right atrium is cannulated with a standard double-stage venous cannula. CPB is started, and the heart is arrested with blood cardioplegia. Cooling is limited to a rectal temperature of 32°C. The innominate and left common carotid arteries, as well as the left subclavian artery, are exposed, snared with vessel loops, and occluded at the time of initiation of ACP.
ACP is conducted with a 30°C to 32°C arterial perfusate flow in a pressure-controlled manner. The upper permissible level was 75 mm Hg, and this allowed for a flow of 1340 ± 148 mL/min. With the cerebral vessels occluded, a bloodless operative field during arch repair is accomplished. At this point, the arch resection and repair is initiated. In dissections the inner and outer layers of the arch wall are dried carefully and glued with standard bicomponent glue. The distal anastomosis with a collagen-coated woven polyester graft is completed in a continuous fashion with polypropylene 4-0 sutures and, if necessary, reinforced with Teflon felt. Once distal repair is completed and hemostasis is secured, deairing is performed, and finally, the prosthetic graft is clamped just proximal to the innominate artery. At this point, the arterial flow on CPB is returned to full-body perfusion. All procedures were performed by a single surgeon.
Results
Between April 2001 and August 2004, 46 patients (27 male and 19 female patients) underwent operative treatment of diseased ascending aorta, transverse arch, or both caused by chronic aneurysmal involvement (n = 22, 48%) or acute dissection (n = 24, 52%) in mild hypothermic conditions (Table 1).
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Mild hypothermia decreases the brain oxygen demand by half.
2
If the brain temperature is kept in this range, the regional cerebral blood flow should not decrease.
3
Providing a blood flow in the physiologic range, the cerebral oxygen demands should be met, even in patients presenting with hemodynamic instability.
On the basis of these studies, we have started to use 32°C mild systemic hypothermia together with ACP for operations on the aortic arch. The aim of the use of mild hypothermia was to decrease CPB time and its negative side effects during cooling and rewarming while providing protection for the rest of the body. This article shows the safety and reproducibility of mild hypothermia in 46 patients with aortic arch aneurysms of different causes. Our mortality and new-stroke rates in this series are well comparable with those in previously published reports.
1,4
In conclusion, selective ACP with mild systemic hypothermia appears to be a safe and sufficient concept for brain protection during arch repair. In avoiding deep hypothermia, this technique might help to reduce CPB time and deep hypothermia–related side effects.
References
This article has been cited by other articles:
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  F. Bakhtiary, S. Dogan, A. Zierer, O. Dzemali, F. Oezaslan, P. Therapidis, F. Detho, T. Wittlinger, S. Martens, P. Kleine, et al. Antegrade Cerebral Perfusion for Acute Type A Aortic Dissection in 120 Consecutive Patients Ann. Thorac. Surg., February 1, 2008; 85(2): 465 - 469. [Abstract] [Full Text] [PDF]
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 F. Bakhtiary, S. Dogan, P. Risteski, H. Ackermann, F. Oezaslan, P. Kleine, A. Moritz, and T. Aybek Mild hypothermic (30{degrees}C) body perfusion during replacement of the aortic arch with a novel arterial perfusion cannula J. Thorac. Cardiovasc. Surg., June 1, 2007; 133(6): 1637 - 1639. [Full Text] [PDF]
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 D. Pacini, A. Leone, L. Di Marco, D. Marsilli, F. Sobaih, S. Turci, V. Masieri, and R. Di Bartolomeo Antegrade selective cerebral perfusion in thoracic aorta surgery: safety of moderate hypothermia Eur. J. Cardiothorac. Surg., April 1, 2007; 31(4): 618 - 622. [Abstract] [Full Text] [PDF]
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