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J Thorac Cardiovasc Surg 2002;123:587
© 2002 The American Association for Thoracic Surgery
Letters to the Editor |
Department of Cardiovascular Surgery
Tokyo Saiseikai Central Hospital
1-4-17 Mita, Minato-Ku
Tokyo 108-0073, Japan
Reply to the Editor:
We appreciate the comments on our article,
1 which were raised by Ceviz and coworkers.
The retrograde cerebral perfusion technique introduced by Ueda and colleagues 2 has been used in some institutes to increase the safety limits of circulatory arrest. However, it is unknown whether the retrograde cerebral perfusion actually perfuses the brain because of the interference of component valves at the level of the internal jugular vein 3 and multiple venovenous anastomoses and shunting between the deep and superficial cerebral venous drainage systems of the head. 4 These considerations prompted us to create prophylaxis for resuscitation of the brain or brain protection against ischemic damage. To increase the safety limits of circulatory arrest, we have been using pharmacologic mixtures of thiopental sodium, nicardipine, and mannitol as prophylactic agents to protect the brain against ischemia in all patients requiring the circulatory arrest technique for aortic arch repairs since 1991. We demonstrated the protective effect of thiopental on cerebral ischemia during circulatory arrest in a previous study, 5 which indicated that the cerebral metabolic rate during circulatory arrest was lower in patients receiving a high dose (30 mg/kg) of thiopental than in those receiving a low dose (15 mg/kg) of thiopental before circulatory arrest. In another previous study, 6 75 consecutive patients undergoing an aortic arch repair with the hypothermic circulatory arrest technique associated with pharmacologic cerebral protection were retrospectively analyzed, and no correlations between the incidence of neurologic complications and the duration of circulatory arrest were found. Thus, our pharmacologic combination of thiopental, nicardipine, and mannitol appears to increase the safety limits of hypothermic circulatory arrest, although absolute statistical proof would require a larger scale prospective study including a control group.
We agree with David and colleagues 7 in the point that avoidance of aortic crossclamping, resection of the primary tear, and anterior perfusion after completion of the distal anastomosis improve the early and late outcomes of surgery for acute type A aortic dissection. In our institute, the ascending aorta was routinely crossclamped just proximal to the origin of the innominate artery. The clamped aorta, however, was routinely resected finally and was replaced with a prosthetic graft. Thus, there is no apprehension about the possibility that aortic crossclamping causes a new intimal tear.
Many reports have indicated the importance of total resection of the primary tear of the aortic dissection. We also consider that total resection of all possible primary tears contributes to improvements in the early and late outcomes of surgery for acute type A aortic dissection. However, the intimal tear in the aortic arch is sometimes invisible through an aortotomy of the ascending aorta. In fact, we have sometimes found that intimal tears, which were judged not to exist in the aortic arch during the operation, were later found in the resected aortic arch specimen. We therefore consider that total aortic arch replacement also has an advantage over ascending aortic replacement alone, because all possible primary tears in the aortic arch can be totally resected. The 24 survivors were followed up monthly for an average of 4.0 years after the operation, and the state of the residual false channel was evaluated by computed tomography every 6 months. The false lumen patency rate was 30% in these patients, and only one case of recurrent dissection has been noted.
We preferred to use both the femoral artery and the right axillary artery for arterial perfusion of cardiopulmonary bypass until circulatory arrest was established. After the distal anastomosis was completed, one limb preanastomosed to the main prosthetic graft was routinely used for arterial access for bypass to establish normograde perfusion. A 20F femoral artery cannula and a 12F right axillary artery cannula were joined to a Y connector, which was attached to a single head on the arterial roller pump. Therefore, we could not manage the flow rate to each arterial access.
We also have several concerns about the long-term complications that may be caused by the use of gelatin-resorcin-formol (GRF) glue for obliterating any false channel. Fortunately, we have encountered no complications likely caused by the use of GRF glue. However, we believe that close observation over a longer period will be required.
12/8/121674
References
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