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Ann Thorac Surg 2001;71:S114-S115
© 2001 The Society of Thoracic Surgeons
Presented at the Fifth International Conference on Circulatory Support Devices for Severe Cardiac Failure, New York, NY, Sept 15–17, 2000.
DR ROLAND HETZER (Berlin, Germany):
I would like to ask what you as a surgeon do with a patient who is unconscious. This is one of the most difficult situations to decide upon, whether to implant an assist device and which device, and also whether there are any means to define whether the patient has significant cerebral damage or not.
DR MEHMET C. OZ (New York, NY):
I will give you our philosophy. The first is we do not look for any objective neurologic examination issues. We just look to see if they move spontaneously and how long after their arrest did they move. If it is a postcardiotomy support patient, we would lighten sedation, make sure they wake up a little bit. If they had a cardiac arrest, which prompts many physicians to have called us to begin with, we look to see they move. The movement does not have to be purposeful, just not decerebrate moving.
On the other hand, the second point that you bring up is a good one. Is there a bridge technique we use to waken these patients? No. It is a binary decision: Either they are salvageable or they are not. Once we decide to put a device in them, we put the device that they are going to end up with. We would not insert a bridge device and then later on if they wake up transition them. Because that is a use of resources and plus it reduces the chance of their long-term survival.
DR ALY EL-BANAYOSY (Bad Oeynhausen, Germany):
It depends on where the cardiopulmonary resuscitation (CPR) occurs. When the resuscitation occurs in our hospital in which case we can look at the period of resuscitation, that might mean we can go on to support the patient with a Thoratec or a similar device. But in the case of resuscitation outside the hospital and an unclear period or effectiveness of the resuscitation, we put a femorofemoral bypass in these patients and wait until we can reevaluate the neurological status and decide for other device.
DR JACK G. COPELAND III (Tucson, AZ):
We also would use femorofemoral extracorporeal membrane oxygenation (ECMO) and wait for some sign of neurologic function in a comatose patient, either in-house or not, we have had unconscious cardiac arrest patients who are put immediately on an ECMO device and it may take a day or two for them to develop significant neurologic signs or to clear neurologically.
DR FRANK SCHOLL (Nashville, TN):
This is directed to Dr Copeland. Have you looked at patient size in relation to outcome? Did larger patients do poorer than smaller patients with regard to adequacy of flow? And was there any difference in cannulation in terms of ventricular cannulation versus atrial cannulation?
DR COPELAND:
We did not, but I can tell you my impression, which is that the larger patients fared worse.
We looked at the configuration of the 26 Thoratec devices in those patients. Eighteen patients had biventricular assist devices (BiVADs) from the beginning, with 50% survival. There were 3 who underwent left ventricular assist device (LVAD) to BiVAD switches, with 1 of those surviving. And 1 of the 5 into whom we put an LVAD survived. These results speak for the severity of illness.
One of the patients who was chronically in right heart failure and had a BiVAD was fairly large, and we struggled with the decision of whether we should go to a total artificial heart or not. He eventually wound up being taken out of consideration for transplantation and was eventually sent home to die on his BiVAD because of chronic multiple organ failure, probably due to inadequate flow in a large patient over a long period of time.
DR ALAIN J. PAVIE (Paris, France):
Jack, on the same subject, you said that 3 patients developed biventricular failure while they were on biventricular support. In such a case do you use biventricular cannulation?
DR COPELAND:
That is one of the reasons we started doing biventricular cannulation, because we felt that often the atrial cannulation technique is tenuous. And we do find that seems to give us higher flows in the Thoratec group.
DR J. DAVID VEGA (Atlanta, GA):
This is a question directed to Dr Oz.
What percentage of your transferred patients do you find are not salvageable? And what do you do with those patients then?
DR OZ:
David, we divide the transferred patients into three categories. About half of them are suitable for long-term support devices and receive them.
About a quarter of those patients can be resuscitated without a device. And actually we remove devices, whatever they came with. They went home, and did well.
And about a quarter of the patients do not do well. Now, the last time we reviewed these data in detail, which was about a year ago, every single one of those patients had had a neurologic injury.
DR VEGA:
Can you determine on arrival that they are not salvageable, for whatever reason, and that you are not going to do anything else with those patients?
DR OZ:
Usually this was not evident on arrival, but it became evident within the first 24 to 48 hours. At least half of those patients had intracerebral events while on support devices.
I remember one particularly tragic case who arrived at 10 o’clock at night, wide awake. By the next morning he had a massive intracerebral hemorrhage. So these are patients who come to us in tenuous condition and often will develop neurologic injuries. Some of them came to us with a question mark. And as we waited the first 24 to 48 hours, it became evident they had irreversible neurologic injury and we did not proceed with those cases.
DR VEGA:
Did you move progressively toward the withdrawal of support?
DR OZ:
I felt some trepidation about moving aggressively toward withdrawal of support. We had a paper in The Annals of Thoracic Surgery about 3 years ago on the ethics of devices continuation. Legally in this country—this is true for ventilators also—every new impulse of an air jet into your lung, for example (and this has been lobbied for by the AIDS patient populations) is a reinstitution of CPR. So legally, every time that pump pushes blood into the heart or up into the aorta is a renewed CPR impulse. So when you discontinue LVAD support, you are discontinuing CPR, and that is completely within your rights.
Now, obviously, we are not going to walk into the room and turn off the pump and then go out and tell the family we decided to do this. There is a dialogue. But you do not have to burden them with the decision. We do not have them sign papers telling us to turn off the pump. We inform them that there is nothing else for us to do, that we are going to turn the pump off. And unless they have a big problem with that decision, which we work through with them, we go in and do that.
DR COPELAND:
I think this is such an important topic for the field of devices that we should spend a few minutes discussing it before we go to lunch.
DR O. HOWARD FRAZIER (Houston, TX):
I have appreciated these presentations. I presented our recovery data in the idiopathics in Venice in 1993, and I was gratified that the Berlin group followed up on this research, because we have certain limitations of doing a study of this nature in the United States.
There is no question that in every instance the myocardium improves with prolonged unloading. This was part of Burch’s observations, and it was a method of therapy in the 1930s and 1940s for heart failure.
I think we have to look at that, because with mechanical unloading we can give this benefit to these patients, particularly young patients, and we will be able to spare many of them from heart transplantation. I think that obvious lack of data is the chief limiting factor now. We have one center with 2 patients and one with 5, and ours with 14. We need a cooperative center study to enroll, particularly the young idiopathic myopathies, and hopefully spare many of these patients from transplantation.
DR LOUIS E. SAMUELS (Philadelphia, PA):
I want to understand something and make sure I have this right. You are leaving the inflow and outflow cannulas completely intact and just disconnecting the cannula from the pump and putting the patients on Coumadin?
DR HETZER:
Yes.
DR SAMUELS:
My second question is, in the unloading phase, what is the duration of complete unloading, how many months? And then for the loading part, what is the retraining phase? Do you have a set regimen, or is this an individual thing? How do you modify when it is time to start working that ventricle again? And how do you assess, other than just hemodynamics with your histological staining, how do you assess that this ventricle is ready for explantation?
DR HETZER:
As I showed in my slides, when we see on echoes that recovery has taken place, then we perform pump-off studies for about 20 minutes or half an hour with one beat every minute to determine the ejection fraction and the left ventricular end-diastolic diameter. We are looking for valves approaching normal—the ejection fraction more than 45% and the left ventricular diastolic diameter less than 55 mm. We would say this is a candidate for later-on pump explantation. Once these values are reached, we set the pump at a fixed rate mode in order to put some extra load on the heart, because I think it is important that we do not abruptly explant the pump from a completely unloaded state to full work. We set this latter period at about 3 or 4 weeks, and then explant the pump. As I mentioned, I think it is important not to harm the heart because it is still vulnerable.
We had some problems afterwards in the 1 patient who had apex infection about whom we were discussing whether it would have been wise to explant the retained cannula at an earlier time. But I think this is a valid concept to just open the pump pocket and not to open the chest.
DR EL-BANAYOSY (Bad Oeynhausen, Germany):
I have one question on hemodynamic exercise data. Do you have any exercise data, hemodynamic or echo, from the successfully recovered patient and the other patients before explantation of the devices on pump to help identify recovering patients?
DR HETZER:
I think this would be a very good idea to do studies as the Munster group has suggested with the DeBakey pump.
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