[Heart transplantation and long-term lvad support cost-effectiveness model]. / Szívtranszplantáció és muszívkezelés költséghatékonysági elemzési modellje.

Heart transplantation is a high priority project at Semmelweis University. In accordance with this, the funding of heart transplantation and mechanical circulatory support also constitutes an important issue. In this report, the authors discuss the creation of a framework with the purpose of comparing the cost-effectiveness of heart transplantation and artificial heart implantation. Our created framework includes the calculation of cost, using the direct allocation method, calculating the incremental cost-effectiveness ratio and creating a cost-effectiveness plane. Using our model, it is possible to compare the initial, perioperative and postoperative expenses of both the transplanted and the artificial heart groups. Our framework can possibly be used for the purposes of long term follow-up and with the inclusion of a sufficient number of patients, the creation of cost-effectiveness analyses and supporting strategic decision-making.

Rapid Speed Modulation of a Rotary Total Artificial Heart Impeller.

Unlike the earlier reciprocating volume displacement-type pumps, rotary blood pumps (RBPs) typically operate at a constant rotational speed and produce continuous outflow. When RBP technology is used in constructing a total artificial heart (TAH), the pressure waveform that the TAH produces is flat, without the rise and fall associated with a normal arterial pulse. Several studies have suggested that pulseless circulation may impair microcirculatory perfusion and the autoregulatory response and may contribute to adverse events such as gastrointestinal bleeding, arteriovenous malformations, and pump thrombosis. It may therefore be beneficial to attempt to reproduce pulsatile output, similar to that generated by the native heart, by rapidly modulating the speed of an RBP impeller. The choice of an appropriate speed profile and control strategy to generate physiologic waveforms while minimizing power consumption and blood trauma becomes a challenge. In this study, pump operation modes with six different speed profiles using the BiVACOR TAH were evaluated in vitro. These modes were compared with respect to: hemodynamic pulsatility, which was quantified as surplus hemodynamic energy (SHE); maximum rate of change of pressure (dP/dt); pulse power index; and motor power consumption as a function of pulse pressure. The results showed that the evaluated variables underwent different trends in response to changes in the speed profile shape. The findings indicated a possible trade-off between SHE levels and flow rate pulsatility related to the relative systolic duration in the speed profile. Furthermore, none of the evaluated measures was sufficient to fully characterize hemodynamic pulsatility.

Future Prospects for the Total Artificial Heart.

A total artificial heart (TAH) is the sole remaining option for patients with biventricular failure who cannot be rescued by left ventricular assist devices (LVADs) alone. However, the pulsatile TAH in clinical use today has limitations: large pump size, unknown durability, required complex anticoagulation regimen, and association with significant postsurgical complications. That pump is noisy; its large pneumatic driving lines traverse the body, with bulky external components for its drivers. Continuous-flow pumps, which caused a paradigm shift in the LVAD field, have already contributed to the rapidly evolving development of TAHs. Novel continuous-flow TAHs are only in preclinical testing or developmental stages. We here review the current state of TAHs, with recommended requirements for the TAH of the future.

Use of an inexpensive blue band during ventricular assist device and total artificial heart placement facilitates and expedites explantation during heart transplant.

Ventricular assist devices and total artificial hearts are now being used routinely as a bridge to heart transplantation. Reoperation is often weeks to months from implantation. Difficulty dissecting mediastinal and cardiac structures is often encountered due to adhesion formation that prolongs operative time. A temporary, flexible, rectangular-shaped polyisoprene blue band is used to encircle major vascular structures. We have found that this facilitates identification, reduces adhesion formation, and expedites device removal at the time of heart transplantation.

Current status of the total artificial heart.

Although heart transplantation remains the gold standard for patients who remain in advanced heart failure despite optimal medical therapy, limited donor supplies allows for just >2000 transplant each year in the United States. Recent enthusiasm has developed for the role of mechanical circulatory support for this ever-growing population of sick patients. Although much attention has been directed toward ventricular assist devices, less information is available regarding the role of the total artificial heart. Indeed, efforts in this latter technology have allowed the relatively recent deployment of a variety of complete circulatory assist devices. The purpose of this article is to review the historical development, current use, and future role of total artificial hearts.

"He knows that machine is his mortality": old and new social and cultural patterns in the clinical trial of the AbioCor artificial heart.

The clinical trial of the AbioCor artificial heart, initiated in July 2001 and still in process, has taken place within a matrix of social and cultural patterns that are both "old" and new. The old patterns--those that have accompanied previous clinical trials of other vital artificial organs and transplantation in the United States--include "experiment perilous," and courage, heroism, and pioneering themes; "right stuff" motifs; "Americana" symbols; allusions to the meaning of the human heart; connections with a for-profit corporation; and the occurrence of moratoriums. New patterns--those more particular and distinctive to the AbioCor trial--involve the restrictions imposed on releasing information about the post-operative clinical status of the implant recipients; the quasi-institutionalization of a patient advocacy system to represent patient-subjects and their families; and the "crises of success" that were encountered when several of the AbioCor recipients survived longer than expected. In certain instances, old and new patterns have been combined--for example, in some of the idiosyncratic features of the AbioCor-associated lawsuit that has resulted in part from the problem of the "therapeutic misconception," the belief that an experimental intervention is actually intended to be a treatment.

AbioCor totally implantable artificial heart. How will it impact hospitals?

Although heart transplantation remains the most effective treatment for severe heart failure, there are far fewer donor hearts available than there are patients who could benefit from them. One approach to addressing this shortfall is the total artificial heart, or TAH. To date, however, no TAH design has been able to achieve one of the ultimate goals of heart replacement: to allow a patient to live a reasonably normal life without being connected to external machinery. A new design, the AbioCor TAH developed by Abiomed Inc., may make this goal achievable. Thanks to a power system that transfers energy through the skin without the aid of wires, the AbioCor--currently undergoing clinical trials in the United States--allows the patient to be completely mobile. The lack of transcutaneous wires also eliminates the primary source of the infections that have plagued TAH patients in the past. Though it is not without drawbacks, the AbioCor could represent a crucial advance in TAH technology. In this Technology Overview, we describe the operation of the AbioCor and discuss its likely impact on hospitals if it is approved for marketing in the United States. We also discuss a related cardiac-support technology: ventricular assist devices (VADs), which may also be used for permanent cardiac support someday.

That giant whirring sound you hear is either an artificial heart or Louisville's Jewish Hospital cashing in on being first.

For Jewish Hospital in Louisville, Ky., a modest-looking device made of titanium and plastic could be the ticket to healthcare's big leagues. Earlier this summer the hospital was the first to implant the AbioCor artificial heart, and it's been riding a wave of media acclaim ever since. Hospital President Doug Shaw hopes the facility can cash in on its successes.