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Ann Thorac Surg 1996;61:287-290
© 1996 The Society of Thoracic Surgeons
Minneapolis Heart Institute, Minneapolis, Minnesota
Abstract
Background. The data presented are a brief summary of The International Registry for Mechanical Ventricular Assist Pumps and Artificial Hearts and a summary of the personal experience of the Minnesota Thoracic Associates at the Minneapolis Heart Institute with the use of the Sarns centrifugal pump from May 1985 to September 1994.
Methods. Ventricular support with the use of centrifugal pumps for postcardiotomy shock consisted of cannulation of the left atrium and aorta for left ventricular support and the right atrium and pulmonary artery for right ventricular support, or the combination of the two for biventricular support.
Results. The average survival and discharge rate recorded by the National Registry for postcardiotomy syndrome was 25.3%. Our experience at Minnesota Thoracic Associates was 54%. The National Registry reported 45.7% of the patients being weaned from the device or receiving transplants and 25.3% of the patients ultimately discharged from the hospital. Sixty-five percent of the patients in our experience either were weaned from the device or received a transplant for an overall discharge rate of 42%. The average effective hospital cost per survivor was almost $400,000.00.
Conclusions. It is our belief that when considering the cost analysis of temporary devices, one must conclude that a more economical approach for the treatment of end-stage cardiac disease would be aggressive development of a permanent ventricular assist device.
Multiple devices have been used for cardiac support of patients who could not be weaned from the cardiopulmonary bypass machine. The first and perhaps still the most frequently used technique is merely prolongation of cardiopulmonary bypass to rest the heart. The length of time that this form of support can be maintained without irreversible detrimental effects to other organs is limited, and for that reason attention has been turned to other types of devices. Of the generally available devices, the most frequently used is a centrifugal pump.
The International Registry for Mechanical Ventricular Assist Pumps and Artificial Hearts has been maintained by the University of Pennsylvania since 1983 and is a voluntary registry that records data on all types of devices. The data that are being presented here were provided by Tom Aufiero, MD. This Registry report is published periodically [1].
The majority of the cases in the Registry include patients who have used either the Bio-Medicus or the Sarns centrifugal pumps. The Minnesota Thoracic Associates experience consists exclusively of the use of the Sarns centrifugal pump.
The hemodynamic criteria for instituting the use of a ventricular assist device as well as the cannulation technique and patient management protocols have been previously published [2, 3]. Cannulation for left ventricular support consisted of the left atrium for venous drainage and the aorta for return flow. For right ventricular support, the technique consisted of cannulating the right atrium and the pulmonary artery for inflow and outflow, respectively. Biventricular support consisted of the combination of the two techniques.
Results
The Registry's most frequent indication for the use of a ventricular assist device has been postcardiotomy cardiogenic shock (Table 1
). There were 1,297 patients voluntarily recorded as of 1983, with 45.7% of the patients either being weaned from the device or receiving a transplant and 25.3% of those patients ultimately being discharged from the hospital.
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. The 13 postcardiotomy patients consisted of individuals who initially were weaned from cardiopulmonary bypass after an elective surgical procedure but had development of cardiogenic shock in the intensive care unit and were taken back to the operating room for ventricular assist device support. Twenty-one patients failed to be weaned from cardiopulmonary bypass after a definitive surgical procedure without ventricular support. Four patients with acute cardiogenic shock secondary to acute myocardial infarctions were resuscitated in the catheterization laboratory and taken directly to the operating room for revascularization, but were then unable to be weaned from cardiopulmonary bypass. Three transplant recipients failed to be weaned from cardiopulmonary bypass. These individuals were supported with ventricular assist devices to give the donor heart time to recover.
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A majority of the patients who received centrifugal ventricular assistance recorded by the Registry were treated with left ventricular assistance (Table 3). This group of patients also had the best chances of being weaned (51.2%) and discharged from the hospital (28%). Minnesota Thoracic Associates' experience is somewhat different (Table 4), with the largest percentage of patients treated with biventricular support. This group of patients had the best chance of being weaned (65%) and discharged (48%) as well as a somewhat longer life expectancy, with 35% of those patients being alive at the time of this presentation. I do not believe this represents a different group of patients, but rather reveals the difference in our philosophies for ventricular support. We tend to be very aggressive with biventricular support if there is any indication of biventricular failure rather than stressing either the left or the right ventricle to the degree of allowing other complications to develop.
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The average number of days of support in the Registry for patients with the use of centrifugal assist devices was 2.9 days. Our average was slightly longer at 3.6 days. As expected, those patients who were able to be weaned but died while hospitalized had a longer support time than those who were ultimately discharged. This clearly demonstrates the difference in the state of the underlying myocardium in these two patient groups.
Figure 1 shows the number of patients supported for a particular number of days versus the chances of the patient being weaned and discharged. The majority of the patients fall within the first 4 to 5 days [2, 3]. We attempt to decide over the first 3 days if it appears that the patient is salvageable, and by the fifth day we have usually convinced the family that if the situation looks promising we should continue support somewhat longer. On the other hand, if the chances of recovery look slim, the family is prepared for considering discontinuation of the device. Using this protocol, the salvage rate is still quite good in patients who have been kept on the device for as long as 10 days.
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). The data confirm this expectation; however, 40% of the patients who had preoperative ejection fractions less than 0.25 were able to be weaned and ultimately discharged after ventricular support.
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Cause of death has not changed over the past several years (Table 5). The most frequent cause of death is multiple organ failure. We believe this reflects the prolonged resuscitative efforts and delay in inserting the device as well as the terminal effects of ventricular failure. The failure of the ventricle is the determinate factor in the ultimate demise of most of the patients. Brain deaths include a few patients who have had cerebrovascular accidents secondary to emboli, but a majority of these patients had neurologic events in the operating room and never regained consciousness. Again, this is probably a reflection of prolonged attempts at resuscitation before the insertion of a device for full support.
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Although the success with the use of the centrifugal pumps for postcardiotomy cardiogenic shock remains suboptimal, we do believe that we have learned a few things over the last 9 years. First of all, we know that patients can show clinical improvement with continuous flow (nonpulsatile) support. These patients are awake, all organs can function normally, and there appears to be no detrimental effect from short-term continuous flow support. Some centers ambulate their patients; however, we do not do that on a routine basis.
We know that with temporary support it is the state of the myocardium rather than the level of technology that determines survival. That is not to say that there is not room for improvement in the devices that we presently use, and certainly there is still room for improvement in the cannulation techniques, the cannulas used, and patient selection. However, it is the state of the myocardium that remains most important.
The time on the device is no longer as significant a determining factor for survival as we once believed. Perhaps we are improving our patient management techniques to allow longer periods of support without detrimental effects.
In considering the International Registry data as well as our data, it appears that only 30% to 40% of the patients are able to be discharged from the hospital with the short-term support devices described, and the cost is extremely high. One must ask the question: Can we afford short-term support when an appropriate permanent device may save more lives for fewer dollars spent? We evaluated the cost of our patients in 1994 dollars and figures were available on 42 of the 43 patients. More than 7 million dollars was spent to support those 42 patients at an average of $167,000 per patient. The average hospital charge for each of the 18 discharged patients was $223,600 per patient. None of these figures reflect physician costs. The effective cost is even more: if we divide the 7 million dollars by 18 survivors, almost $400,000 was spent to get 1 patient out of the hospital successfully.
We certainly believe that a human life is worth $400,000, but with the reimbursement situation in Minnesota, this is becoming a very real factor. Over the years, the average reimbursement for support in Minnesota was 47% (range, 0% to 80%). A typical example of the present situation is that of a 17-year-old child who was admitted to the emergency room in cardiogenic shock and resuscitated with the use of a biventricular assist device. The resuscitation was not successful and the patient died. The hospital bill was more than $180,000. The third-party payer paid $544 for the entire hospital stay.
There are some realistic alternatives on the horizon that we believe are worth considering. Today, we spend between $70,000 and $150,000 for cardiac transplantation, and the annual follow-up cost is $12,000 to $20,000 per year. Thermo Cardiosystems, Inc is estimating the implantation cost of their HeartMate (which should be more costly than a centrifugal pump or a continuous flow pump) to be $75,000 to $100,000 (information gathered via personal communication with Thermo Cardiosystems, Inc, Woburn, MA) with an annual maintenance cost perhaps as low as $2,000 per year. If $100,000 could be spent for the implantation of a permanent ventricular assist device with the same success rate as transplantation (90%), the $7 million could have cared for 63 survivors, rather than the 18 reported above.
Our conclusion is philosophical: At a time when healthcare reform is trying to stop the development of new technology, the best economical approach for the treatment of end-stage cardiac disease would be to aggressively develop a permanent ventricular assist device that could return productive patients to society.
Footnotes
Presented at The Third International Conference on Circulatory Support Devices for Severe Cardiac Failure, Pittsburgh, PA, Oct 28-30, 1994.
Address reprint requests to Dr Joyce, 920 E 28th St, Suite 440, Minneapolis, MN 55407.
References
This article has been cited by other articles:
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  S. Osaki, N. M. Edwards, M. R. Johnson, and T. Kohmoto A novel use of the implantable ventricular assist device for isolated right heart failure Interact CardioVasc Thorac Surg, August 1, 2008; 7(4): 651 - 653. [Abstract] [Full Text] [PDF]
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 E. C. McGee Jr., P. M. McCarthy, and N. Moazami Temporary Mechanical Circulatory Support Card. Surg. Adult, January 1, 2008; 3(2008): 507 - 534. [Full Text]
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S. Aggarwal, F. Cheema, M. C. Oz, and Y. Naka Long-Term Mechanical Circulatory Support Card. Surg. Adult, January 1, 2008; 3(2008): 1609 - 1628. [Full Text]
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 A. A. Pitsis, A. N. Visouli, D. Burkhoff, P. Dardas, N. Mezilis, G. Bougioukas, and G. Filippatos Feasibility Study of a Temporary Percutaneous Left Ventricular Assist Device in Cardiac Surgery Ann. Thorac. Surg., December 1, 2007; 84(6): 1993 - 1999. [Abstract] [Full Text] [PDF]
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N. Moazami and P. M. McCarthy Temporary Circulatory Support Card. Surg. Adult, January 1, 2003; 2(2003): 495 - 520. [Full Text]
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 A K Mahmood, J M Courtney, S Westaby, M Akdis, and H Reul Critical review of current left ventricular assist devices Perfusion, September 1, 2000; 15(5): 399 - 420. [PDF]
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J. R Pepper Surgery for heart failure: options and outcomes Perfusion, July 1, 2000; 15(4): 287 - 293. [PDF]
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H. B. Hangler, J. O. Bonatti, H. Antretter, P. Mair, and L. C. Muller Isolated right ventricular assist for postcardiotomy myocardial infarction Ann. Thorac. Surg., December 1, 1999; 68(6): 2326 - 2328. [Abstract] [Full Text] [PDF]
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J. J. Curtis, J. T. Walls, C. C. Wagner-Mann, R. A. Schmaltz, T. L. Demmy, C. A. McKenney, and F. A. Mann Centrifugal pumps: description of devices and surgical techniques Ann. Thorac. Surg., August 1, 1999; 68(2): 666 - 671. [Abstract] [Full Text] [PDF]
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 N. G. Smedira, C. C. Hlozek, and P. M. McCarthy Mechanical Support After Cardiac Surgery Seminars in Cardiothoracic and Vascular Anesthesia, March 1, 1998; 2(1): 66 - 77. [Abstract] [PDF]
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