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J Thorac Cardiovasc Surg 2006;132:1402-1403
© 2006 The American Association for Thoracic Surgery
Surgery for Acquired Cardiovascular Disease |
First, were these 100 consecutive patients and, if not, how were they selected? Second, did you encounter any dissected carotid arteries and, if so, how were those managed? Third, you note that there are only 2 patients with focal neurologic deficits postoperatively. Did you note any patients with more generalized temporary neurologic dysfunction? Last, was the right radial pressure the only means of monitoring adequacy of CP?
Dr Diegeler. Thank you, very much, Dr. Mitchell, for the excellent comments and the questions. Regarding the first question, the population does not include consecutive patients only. The patients became consecutive after January 2005. We started using this procedure in 2002 in a patient with a particular surgical condition. Because the approach went well and looked easy, we used it in some selected patients afterward. This selection within the first period was more related to very diseased patients or emergency patients. The first group of patients rather reflects a more sick patient population. Since we became more and more familiar with the approach, we use it now for every single patient.
Regarding the second question: Yes, we had 1 patient with a dissected carotid artery and in this patient our approach offered some advantages because we could address the dissection. We crossclamped the segment and performed an end-to-end anastomosis with the graft used for the perfusion line. There was 1 other patient with obstructive carotid disease in whom we used an additional femoral line, and of course we started the perfusion via the femoral artery retrogradely.
Third, you inquired about the role of radial artery pressure monitoring. We have the impression that right and left radial artery pressure monitoring can indicate cross-perfusion, but the supra-aortic artery has to be occluded during selective perfusion. For example, if you open the left subclavian artery, this pressure should drop to zero, and if you occlude it again, then it should rise again. You could test it with the contralateral side as well. I do not know what value this measurement has, but we feel a little bit safer with this maneuver if it is possible to work out.
Regarding temporary neurologic dysfunction, this is a population of very sick patients. Some of the patients had prolonged ventilation times. In those, it is very difficult to do sophisticated neurologic tests such as neurocognitive function. We could not detect a transient focal neurologic deficit in all of our patients, but of course we could miss some.
Dr Mitchell. Just one last question. After merely oversewing the stump of the graft, did you see any late neurologic events related to that left carotid?
Dr Diegeler. No. We just cut the graft down to its basis and performed a 2-layer suture. So far, we have not seen any thromboembolic problems. We have a follow-up of at least 30 days or 6 weeks after surgery, because most of our patients are discharged to our local rehabilitation center, and if a patient would have such a problem, he would be sent back to our hospital. We are very sure that there is no embolic event, at least during the early period after surgery.
Dr Tirone E. David (Toronto, Ontario, Canada). Dr Diegeler, I am a bit puzzled why you chose the left carotid instead of the right axillary artery. If you perfuse the axillary artery, you provide not only the carotid but also the right vertebral. So the chance for a better cross-circulation is almost doubled, and yet you picked the left carotid. What is the rationale to change from the right axillary artery to the left carotid?
Dr Diegeler. That is a very good question and you are right on that point. The left carotid is a very easy approach and we want to have it easy. To be honest, we had 1 patient with an absent left vertebral artery, and in this patient we used the right carotid artery and clamped the brachiocephalic trunk just above the aortic arch to provide additional flow through the right vertebral artery. However, if the brachiocephalic trunk is diseased, it should not be crossclamped. I do not think this situation makes a big difference. But in general, you are right on that point.
Dr David. It has been my experience that if we maintain the systemic temperature at 25°C, we have to pump more than a liter per minute to maintain a mean pressure of 50 or 60 mm Hg. I noticed your flow is only 0.9 L/min. What was the pressure in the radial artery?
Dr Diegeler. The mean pressure in the radial artery was around 30 mm Hg. The difference between the right and left sides was about 10 mm Hg. We followed the literature. The literature has mentioned a flow of 10 or 15 mL/kg weight. We increased it a bit. Usually we had 1000 mL, sometimes 1,200, but the mean was 800.
Dr Thoralf Sundt (Rochester, Minn). Maybe I missed this, but I am concerned about ipsilateral hyperperfusion. Did you put a needle in the carotid distal to the graft and measure the relative pressures in the body and in the distal carotid?
Dr Diegeler. This is a very important point. We do not have a pressure measurement distal to the graft. In a couple of cases, just to know what happens, we used an 8- or 10-mm Doppler probe for flow measurement. We estimate about 800 mL forward volume in the situation when we had a total of 5.5 L backward body perfusion, as you may have seen in the second or third slide. In some of our first patients who were not awakened the next day, we performed a CT scan the next day, and we never could detect signs of ipsilateral edema on the perfusion side. But you are right; you never can exclude an overflow on the ipsilateral side of the brain.
Related Article
J. Thorac. Cardiovasc. Surg. 2006 132: 1398-1403.
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