Ann Thorac Surg 2001;71:S183-S184
© 2001 The Society of Thoracic Surgeons
Presented at the Fifth International Conference on Circulatory Support Devices for Severe Cardiac Failure, New York, NY, Sept 1517, 2000.
DR J. DONALD HILL (San Francisco, CA):
I have a question for Laman Gray and Bill Pierce. The total heart is on its way. And since you began this work many years ago, many more things have happened. I was wondering what class of patients you are anticipating to use the total heart on?
DR LAMAN A. GRAY, JR (Louisville, KY):
The initial group of patients who will be candidates for a total artificial heart will be patients who are not transplant candidates and who have end-stage cardiomyopathy with a life expectancy of less than 30 days. There will be no alternative therapies for this group of patients.
But what about in terms of alternatives to other devices, you would see it crossing the line?
Initially the total artificial heart will be used in patients with biventricular failure rather than left ventricular failure. There are currently no other permanent implantable devices that can treat biventricular failure.
DR WILLIAM S. PIERCE (Hershey, PA):
I have the same comment. You simply cannot put in two pulsatile univentricular support pumps. You end up with too much gear; there may be great advantages in removing the heart to remove the clots and calcification. I am always impressed when we take the heart out at cardiac transplantation.
If you are going to use a device like this, you are looking for 5 years; however, the reality is with porcine valves in place, you are probably looking at a few years. And for other reasons we are not looking that long.
What is the likelihood with your pumps to be able to replace them in a fairly simple way, that is, reoperate and replace the pumps using the same cannulas? Does that possibility exist with each of these pumps?
DR WALTER E. PAE, JR (Hershey, PA):
You could replace any of the components with the LionHeart left ventricular assist device.
Would that be part of the strategy that you could replace them?
I do not worry about the cannulas, the valves, the compliance chamber. I do not know the length of time they will last. I do not think anybody does until we conduct adequate trials. The batteries and electronics are basically a pacemaker change, and the actuating mechanism should be good for 5 years.
Doctor Robbins, have you ever had a reason to change a Novacor pump? Is it possible? Is there a connector?
DR ROBERT C. ROBBINS (Stanford, CA):
I think Phil Oyer changed one of the early failures, but I do not have any other details.
DR PEER M. PORTNER (Stanford, CA):
Actually, there has been only a single pump change at Stanford. It was an encapsulation leak that was evident early, in less than 24 hours, an easy replacement. The problem is later when you have fibrous encapsulation and the implant is rock solid. I think all of these devices present a real challenge in terms of replacement. They will all have to be replaced at some time, with destination therapy. It is clearly one of the areas for future development, that is, not only putting it in but also taking it out. They are all going to have to come out or preferably modular components will have to be replaced.
In the Novacor experience, there has been a limited experience with replacement. Dr Robbins showed 8 cases of pump replacement at times up to 4 years. It has been done successfully, but it is tough.
DR O. H. FRAZIER (Houston, TX):
Walter, do patients with that compliance chamber have any trouble flying?
We have not tried it yet, but it should be possble.
So if they go suddenly to 10,000 feet, you do not anticipate any problems? Most peopleIm sure it will not occur in the patientsbut in most people it expnds.
That is an interesting consideration, but I was amazed at how forgiving the compliance chamber is.When we were doing the animal experiments, you could blow the thing up like a basketball and it had very little effect on the pumping. The worst thing that happens is if the compliance chamber loses all of its volume. We have not tried to subject any of these patients to elevation changes yet.
I think the compliance chambers loses about 1.5 to 2 cc a day, and it requires recharging. Now, it looks like it may be longer than 4 weeks of patients.
DR ALY EL-BANAYOSY (Bad Oeynhausen, Germany):
The amount of air loss is about 1 cc per day. In some patients needing long-term ventilation, the amount of air loss is more than in the patient with no ventilation.
As far as how frequently we have to refill the compliance chamber, it varied in our experience from 3 to 6 weeks. But we did not fly any patient with the compliance chamber at the high altitude.
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