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Eur J Cardiothorac Surg 2005;27:638-643
© 2005 Elsevier Science NL
eref A. Küçükera,*
ta
a
uz Tademirb
a Kardiyovasküler Cerrahi Klinii, Türkiye Yüksek 
htisas Hastanesi, Shhiye, Ankara 06100, Turkey
b Cankaya Hospital, Ankara, Turkey
Received 10 September 2004; received in revised form 10 January 2005; accepted 12 January 2005.
* Corresponding author. Tel.: +90 312 310 3080x1242; fax: +90 312 312 4120. (E-mail: serefalp{at}yahoo.com).
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Abstract |
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 Top Abstract 1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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Key Words: Cerebral protection • Antegrade cerebral perfusion • Brachial artery cannulation
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1. Introduction |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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For this reasons, many authors have switched to selective antegrade cerebral perfusion (ACP) techniques and published their experiences [8–10]. However, uniformity does exist neither for neurological results nor for the technical applications of ACP [9–13].
Our group reported an unilateral antegrade cerebral perfusion technique via right brachial artery, in conjunction with moderate hypothermia (26°C) with exellent neurological outcomes [14]. However, we received criticism about the adequacy of unilateral perfusion for the contralateral hemisphere, and were questioned about the possibility of visceral ischemic complications resulting from selective non-cerebral systemic arrest and capacity of brachial artery to carry full flow of cardiopulmonary bypass (CPB). The data gathered in this study is combined with our recent reports [14–16] to address the above mentioned issues of unilateral antegrade cerebral perfusion via right brachial artery.
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2. Materials and methods |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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Dissection and cannulation of the right upper brachial artery was done prior to median sternotomy. A medial longitudinal incision was made along the bicipital groove into the axillary fossa. The incision followed the medial border of the biceps along its groove, which separates the biceps anteriorly from the triceps posteriorly. An incision 6–8cm long was adequate for exposure of artery. The skin incision should be made anterior to the basilic vein. The incision was carried down to the fascia of the biceps after identifying its medial border. The muscle was then retracted anteriorly; the neurovascular bundle appeared under a thin aponeurotic sheath, which was then opened. The median nerve was exposed, mobilized laterally, thus exposing the artery (Fig. 1). After heparin administration, arterial soft clamps were placed proximal and distal to the cannulation site. Transverse arteriotomy was made by scalpel. The artery was cannulated with a non-wire-reinforced venting catheter (California Medical Laboratories, Irvine, CA), the tip of which was trimmed to 16–18F diameters according to the size of patient's brachial artery. The catheter was gently inserted into the artery, as its tip was positioned 5–7cm proximal to the arteriotomy (Fig. 2). The cannula was then connected to the CPB circuit as usual for any arterial return cannula.
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The flow was decreased to 500–600mL/min (8–10mL/kg per min) at 26°C rectal temperature. The innominate, left common carotid, and, occasionally, the left subclavian artery (but only if the returning blood interferes with suturing) were clamped with soft vascular clamps. We believe leaving the left subclavian artery unclamped will not lead to steeling of cerebral blood due to small size of vertebral and posterior communicating arteries but will serve as a siphon to prevent brain edema during ACP. Cross-clamp on the aorta was released. Early in our experience, perfusion pressure during antegrade selective low-flow period was monitored and kept between 40 and 50mmHg, by inserting an 18 gauge IV cannula into the brachiocephalic artery just distal to the clamping site. As we continually observed that a flow rate of 8–10ml/kg per min is satisfactory to generate a pressure of 40–50mmHg we stopped routine pressure monitoring during antegrade cerebral perfusion. All arch reconstructions and distal anastomosis were performed with open aortic anastomosis technique while low-flow perfusion through the brachial artery continued. After terminating the distal repair the flow through the upper brachial artery cannula was increased gradually as the soft clamps on the brachiocephalic vessels were released. Air was removed from the vessels and grafts, which were then filled with blood, and the distal graft was cross-clamped. Normal flow rate was reached through the brachial artery cannula and rewarming begun in accordance with the time necessary for proximal repair.
Collagen-impregnated Hemashield (Meadox Medicals, Oakland) or collagen-coated Intergard (InterVascular, Cédex) grafts were used. For patients needing total root replacement, composite grafts were prepared with St Jude or Carbomedics bileaflet mechanical aortic valves (St Jude Medical, St Paul, and Carbomedics, Inc., Austin). Table 2 outlines the surgical procedures used for the repair in this series.
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In an additional 20 patients, to identify potential hemolytic effects of relatively small size of brachial artery cannula that may occur during full flow of CPB, free plasma hemoglobin (free Hg) and lactate dehydrogenase (LDH) levels were measured preoperatively and on third postoperative day. Patients receiving mechanical valves, or intraaortic balloon pump and patients having reexploration for any reason were not included in this study cohort.
2.3. Adequecy of unilateral perfusion
Neurological outcome and postoperative complications were evaluated and recorded in the intensive care unit (ICU). Besides the neurological outcomes, data from recently reported neuropsychological testing and transcranial Doppler studies [15,16] performed on two different cohort of this series, was used in the discussion section of this study for providing a unifying answer to the challenge of adequacy of unilateral perfusion.
2.4. Statistical analysis
Data were expressed as means±standard deviations. All results representing pre and postoperative blood sample values of the same patients were analyzed with paired sample t-test. P values below 0.05 were considered statistically significant.
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3. Results |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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Hospital deaths occurred in 12 (6.6%) patients. One patient was lost intraoperatively due to uncontrollable bleeding from anastomotic sites. All other patients survived the operation. Seven dissection cases, including five acute cases operated urgently and five aneurysm cases including one ruptured case were lost during early postoperative period. Operative mortality for dissection and aneurysm cases was 6.2% (7 of 112) and 7.2% (5 of 69), respectively. Hospital mortality data is summarized in Table 3.
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Out of 181 patients only one patient had a temporary neurological event namely right hemiparesis during early postoperative period but this has resolved on second postoperative month. No other cerebral complication occurred in this series. Excluding the patient lost intraoperatively, total and permanent neurological incidence rate of this series of 180 patients was 2.2 and 1.6%, respectively.
3.2. Renal and hepatic function measurements
Mean age for this study cohort of 20 patients was 54±9 years. Mean CPB, cross-clamp and ACP times were 106±37, 61±20, and 36±12min, respectively. Preoperative BUN and serum creatinin levels were 33.9±9.2 and 0.9+0.4mg/dL, respectively. Postoperative levels were 40.7±11.7 and 1.4±0.5mg/dL and differences were significant for both parameters (P 0.008 and 0.003, respectively) (Table 4).
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3.3. Hemolytic parameters
Mean age for this study cohort of 20 patients was 60±12 years. Mean CPB, cross-clamp and ACP times were 93±27, 54±23, and 37±17min, respectively. Mean body surface area was 1.79±0.34m2 (ranging between 1.52 and 2.16m2). Free Hgb and LDH levels were measured preoperatively as 20.1±7.4µmol/L and 222.7±90.5U/L, respectively. Postoperative values for the same parameters were 44.8±11.3µmol/L and 440.5±133U/L, respectively. These changes were statistically significant for both parameters (P<0.001 for both values) (Table 4). Like wise no mortality or neurological event was noted for this cohort of 20 patients.
3.4. Postoperative complications
Postoperative hemorrhage requiring re-sternotomy occurred in 15 patients. Excluding these 15 patients, average packed red blood cell requirement was 2.4±1.2 units and average postoperative chest tube drainage was 736±230mL.
Complications involving the upper brachial artery cannulation occurred in six patients. One was acute occlusion of brachial artery in which radial and ulnar pulses were lost on the second postoperative day and the upper brachial artery was re-explored under local anesthesia. Embolectomy was performed with a Fogarty catheter and approximately 1cm arterial segment was excised and then re-anastomosed in end-to-end fashion. The patient recovered without any further complication. Five patients complained of numbness and weakness of right hand fingers, however, all recovered within 10 days of operation.
Hospital survivors have been followed up for 1 month to 8 years postoperatively. Average patient follow-up reached 3.7±1.5 years. Seven late deaths were recorded, three of which occurred early after hospital discharge and were attributed to arrhythmia. Six late re-operations were necessary, four due to extension of the native aortic disease and two due to coronary artery disease. The followed-up patients are in NYHA I or II functional classes.
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4. Discussion |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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Ideal ACP technique should not necessitate deep hypothermia. Cessation of cerebral circulation at any time point during the operation should not be necessary. The position of the cannula should not bypass vertebral arteries along with posterior cerebral circulation. Cannulas and grafts used should not increase the clutter in the operative field and manipulation of the arch vessels should be minimal in order not to increase the risk of particulate and air embolization.
Frist et al. [23] described a technique involving unilateral low-flow brain perfusion via either innominate or left carotid artery. Our group has modified this technique by switching the cannulation site to the right brachial artery. We previously reported our ACP results on 104 patients [14]. However, we received criticisms about the adequacy of unilateral perfusion for the contralateral hemisphere, and were questioned about the possibility of visceral ischemic complications resulting from selective non-cerebral systemic arrest and capacity of brachial artery to carry full flow of cardiopulmonary bypass (CPB).
The concept of unilateral selective cerebral perfusion relaying on the patency of circle of Willis for the perfusion of contralateral hemisphere, is the epicenter of many critics. We previously discussed the anatomy and potential results of theoretical anatomical variations of the circle of Willis in detail [14–16]. Most important data for this discussion should be the clinical results, namely neurological outcomes. Out of 181 patients, 4 had major neurological event and 1 of these was transient. Again all neurological events were acute dissection cases with one having neurological symptoms preoperatively and one having accidental massive air embolism at the termination of distal repair. Total and permanent neurological event rates in this series were 2.2 and 1.6%, respectively.
To further support the thesis of adequacy of unilateral perfusion, we measured neurocognitive functions of both right and left hemisphere pre and postoperatively on first week and second month postoperatively [15]. In terms of neurocognitive test results, between the preoperative and postoperative assessments, for both hemispheric cognitive functions no deterioration was detected.
Furthermore, we have evaluated the flow patterns of both middle cerebral arteries before, during and after low-flow antegrade selective cerebral perfusion with transcranial Doppler (TCD) measurements [16]. A reduction of blood flow at the left side was observed after the onset of ACP. Nevertheless, TCD revealed that the blood flow never stopped and this reduced flow as far as our neurological results concerned, is satisfactory to maintain the metabolism of the left hemisphere.
The ultimate test for deciding whether or not a satisfactory amount of contralateral perfusion exist, may be a surgical one. In our experience, at the initiation of antegrade perfusion, visual assessment of the returning blood through left common carotid and subclavian arteries has been the most valuable proof of contralateral hemispheric perfusion and its amount was always satisfactory.
For the elective patients, we routinely perform carotid artery duplex scanning. None of our patients had severe stenosis of right internal or common carotid artery; however, we may have a future patient with such carotid lesion. In that case, surgical strategy needs to be changed. In that situation cooling can be achieved with femoral artery cannulation and during the arch repair, antegrade flow can be administered via direct left common carotid artery cannulation.
Postoperative renal and hepatic function tests did show significant difference when compared with the preoperative values. Still the results were within normal limits and these changes were similar to the patients undergoing ordinary CPB for routine cardiac operations [24,25]. However, mean selective non-cerebral systemic arrest duration was 36±12min. A note of caution should be left here for longer durations of systemic arrest.
Additional femoral artery cannulation may still be an option for acute dissection cases with renal, visceral or lower extremity malperfusion especially when the surgeon expects a long arch repair time. In order to prevent further ischemia, during selective antegrade perfusion period, distal perfusion can be provided with femoral artery cannulation following the insertion of intraaortic balloon occluder to the proximal descending aorta.
The cannula that we insert to the brachial artery is trimmed according to patients' brachial artery size and is about 16–18F. A cannula of this size can provide up to 4L/min flow without causing much hemolysis. Although no clinical signs were observed, both LDH and free Hgb levels were significantly higher during postoperative measurements when compared with preoperative values. This may be partly due to CPB and the nature of the operation but one should be cautious and if long durations of CPB are expected arterial cannula may be switched to the aortic graft following the termination of the distal anastomosis. Technically, we feel that upper brachial artery cannulation is much simpler than cannulating subclavian or axillary artery. Brachial artery can be directly cannulated, there is no need for a graft anastomosis. In our experience, brachial artery cannulation is associated with fewer complications and if ever occurs repair is much easier. The small size of brachial artery has not been a major problem in our experience due to its elastic nature and we have not observed intraoperative right arm ischemia in any of our 181 patients most probably due to rich collateral blood flow of the arm.
In light of the findings of this and our previous complementary studies, aortic arch repair with unilateral perfusion is safe and effective. In our experience, this technique has converted the challenge of arch repair to an ordinary heart surgery operation by providing simplicity, better surgical exposure, longer safe-time periods, shorter cardiopulmonary bypass times, less risk of cerebral embolization, and lastly, excellent neurological results for the patient.
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Appendix A. Conference discussion |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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Dr Kucuker: In Turkey people's body surface area is a little less than the northern part of Europe maybe. But you are right, and in some patients we had the problem of acidosis during the rewarming period and the pressure did not go up, so we had to go to a higher flow, so we switched the cannulation site to the distal graft.
Dr Haverich: Then you should report that here when you present this paper.
Dr Kucuker: Yes. That only happened in one case, so I did not put it here, but you are right.
Dr M. Cotrufo (Naples, Italy): So in these consecutive patient reports, you didn't find any patient with obstructive lesions in the supra-aortic trunks?
Dr Kucuker: We had patients who had no pulse on the right arm. In that case we first cannulated the ascending aorta, cooled down the patient, then cannulated the innominate artery after cooling the patient.
Dr C. Hagl (Hannover, Germany): There are quite a fair number of pathology studies which have shown an insufficient Circle of Willis in post mortem analysis. Therefore I'm not sure that your method is sufficient enough to show that the blood supply or at least the distribution is adequate for the entire brain. For that reason it would be interesting to know if you used any kind of neuromonitoring, such as somatosensory evoked potentials or infrared spectroscopy?
Dr Kucuker: Yes. Actually this study is not designed for showing the anatomical variations, but you are perfectly right to ask this question. We did some transcranial Doppler examination. We did neurocognitive testing. Also I showed you that you can do a simple test in the operation by clamping the innominate artery and observing the blood returning from the left common carotid artery. This may also tell you about the patency of the circle of Willis.
Dr Hagl: But your tests were only performed in 20 patients.
Dr Kucuker: If you are not satisfied with the amount of returning blood, you can always add a Y-cannula, a Y-connector to the arterial line and cannulate the left common carotid artery.
Dr Hagl: That's true, but I am not sure what information you can get from the backflow. There is always the possibility of shunting. Therefore it is quite hard to say if the whole amount returning from the carotid artery comes from the brain.
Dr Kucuker: Well, this may be shunting blood, but you can also perform a transcranial Doppler examination to observe the middle cerebral artery flow during the operation, and this test also can tell you if there is circulating blood on the left side, as we did on this patient.
Dr J. Bachet (Paris, France): Of course you should expect that this paper would be highly questioned. My comments are really conceptual. Why do you choose to perfuse only one side when it is so easy and takes 3s to put a cannula into the left carotid artery through the arch and provide your patient with a very, very safe perfusion? As a matter of fact, the advantages you showed on your slide are related to antegrade cerebral perfusion but not to unilateral perfusion.
My second comment is that the brachial artery, as Axel Haverich said, is in many patients a very small artery. In my opinion, it is safer to cannulate the axillary artery just under the clavicle, or the innominate artery. In many patients we have there 5, 6 or 7cm of very fair, nice artery. So why do you choose systematically to put your patient at risk when it is not really necessary?
Dr Kucuker: I will try to answer both your questions at the same time.
As much as you deal with the arch vessels, you will get more and more thrombosis or emboli or debris which will go. If you use the brachial artery, it's usually dissection-free, it's usually atherosclerosis-free, it's very elastic, and it's much simpler than cannulating the axillary or subclavian artery. You don't need to put a graft. You can directly cannulate it. We find it technically much simpler. To the question of why we don't put a cannula into the left common carotid, we always see the amount of returning blood, we can do the transcranial Doppler examination on these patients, and we don't want to increase our cluttering in the surgical field. That's why we prefer not to do that cannulation.
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Footnotes |
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Presented at the joint 18th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 12th Annual Meeting of the European Society of Thoracic Surgeons, Leipzig, Germany, September 12–15, 2004. |
References |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix A. Conference...References |
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