The CardioWest total artificial heart as a bridge to transplantation

The CardioWest total artificial heart (TAH), formerly known as the Jarvik-7 and then the Symbion heart, is the only TAH in current clinical use. A new study, approved by the Food and Drug Administration (FDA), was initiated in 1993 with the goal of approving this pump for commercial release. Since then, 145 CardioWest TAHs have been implanted, including 37 pumps in 36 patients at our center. Our 36 patients were studied prospectively according to the investigational device exemption protocol approved by the FDA. Clinical and hemodynamic data obtained upon patients' entry into the study identified this group as mortally ill. After receiving a CardioWest TAH, 29 of the 36 patients (81%) survived to heart transplantation, and 26 (72% of the total group and 90% of the transplant recipients) have survived for up to 7 years (average, 24 months). Multicomponent anticoagulation, based on readily available tests, and the intrinsic properties of the TAH have resulted in a low linearized stroke rate of 0.48 event per patient-year. There have been no device-related mediastinal infections. In dying patients with nonexistent or severely compromised biventricular function, the CardioWest TAH has proved safe and effective, allowing a 72% survival rate for an average of 24 months.     

Less invasive Thoratec LVAD insertion: a surgical technique

Left Ventricular Assist Device (LVAD) implantation is historically a complicated, invasive operation performed on critically ill patients and is often associated with bleeding and multiorgan morbidity. The purpose of this investigation was to devise an LVAD insertion technique, utilizing the concepts of less invasive cardiac surgery, that would be a less complicated operation, with low morbidity, and still meet all the goals of the standard procedure. We describe the technical details of a "less invasive" LVAD implantation.     

The use of an artificial pericardium with a total artificial heart

Postoperative adhesions following open heart surgery enhance the risks and increase the time of subsequent reoperation. When possible, primary closure of the natural pericardium is recommended, particularly in those cases that are more likely to be reoperated upon. The use of a total artificial heart (TAH) as a bridge to transplantation makes reoperation mandatory. If the pleura is left open to accommodate the ventricles, the risk of adhesion is considerable. To address this question, gluteraldehyde-fixed pericardial allografts were evaluated in calves undergoing TAH replacement. Eight animals were implanted with 3 different types of TAHs and survived from 12 to 108 days (mean 52.8 +/- 14.5). The pericardial substitute was wrapped around the TAH and the vascular grafts and cuffs. Two different surgical techniques were evaluated. At the time of autopsy, the presence of adhesions and gross epicardial reaction was macroscopically characterized and classified according to a standardized scale. Bacterial cultures were taken and tissue submitted for histology. The animals implanted with pericardial allografts for periods greater than 3 weeks were observed to have greater adhesions than those implanted for periods less than 3 weeks (p = 0.006). Pericardial cultures were negative in all cases and neovascularization and fibroplasia of the underlying tissues occurred in all cases. Leukocyte infiltration was minimal in the shorter term implant animals. Degeneration of a portion of the pericardium occurred in only 2 cases after 90 days. Minor calcification of the artificial pericardium was noted, but only in the longer term implant animals. The artificial pericardium reduced adhesion, thus facilitating reoperation in implants lasting up to a month.(ABSTRACT TRUNCATED AT 250 WORDS)     

CardioWest total artificial heart: a retrospective controlled study

The CardioWest total artificial heart (TAH) is a pneumatic device that is used as a bridge to heart transplantation and the only TAH available that totally replaces the failing ventricles. It has been utilized in selected centers in the U.S.A. with approval from the Food and Drug Administration. Strict criteria have been developed to select candidates to be bridged with the TAH. The patient must be a heart transplant candidate of age >18 and <59 years with a body surface area (BSA) > or = 1.7 m2, cardiac index (CI) <2.0 L/min/m2, and 2 inotropic agents or 1 plus an intraaortic balloon pump (IABP). A total of 24 heat transplant candidates (Group A) met the entry criteria and underwent placement of the TAH between January 1993 and July 1996. Group A consisted of 23 males; 16 patients had an IABP. The control group (Group B) consisted of 18 heart transplant candidates who met the TAH entry criteria but never received a TAH. Group B consisted of 15 males; 14 patients had an IABP. Preimplantation pulmonary vascular resistance (PVR) (Wood units), serum creatinine (mg/dl), and total bilirubin (mg/dl) were determined in both groups. The mean values for Groups A and B were, respectively, age: 47 and 47 years, BSA: 2.01 and 1.93 m2, CI: 1.5 and 1.8 L/min/m2, PVR: 2.88 and 2.47 Wood units, creatinine: 1.5 and 1.6 mg/dl, and bilirubin: 1.8 and 1.4 mg/dl. In Group A, 1 patient died on the TAH, 1 patient died after transplant, and 22 patients reached transplant and were discharged home for a survival rate of 91.7%. In Group B, 10 patients died while waiting for a heart transplant. Of the 8 patients transplanted, 7 survived and were discharged home for a survival rate of 38.9% (p = 0.0003). In summary the CardioWest TAH provided an excellent and successful method of bridging patients to heart transplantation with a reasonable risk.     

Early experience with the total artificial heart as a bridge to cardiac transplantation

There is no doubt that currently available biventricular pneumatic pulsatile devices placed orthotopically with transcutaneous drive lines can support life in patients who may then be successfully transplanted. For the most part, the world experience is with the Jarvik hearts. The current model of choice is the 70-cc device because it is smaller and may be implanted with less fear of "fit problems" than the 100-cc model. As Case 4 illustrates, a fit problem may cause a fatal outcome. But if special precautions in implantation are taken, these may be avoided (Case 6). The fears of excessive bleeding, hemolysis, embolism, and infection with the use of these devices are not as prohibitive as we suspected. Bleeding is always a threat in complex cardiac surgery with grafting. Hemolysis is not a problem if excessive transfusion can be avoided. Embolism and infection may be inevitable, but as our patient B.C. has proven, there is no need to rush immediately to transplantation. And if the implanted patient does not meet local transplant selection criteria, we have enough information now to recommend that they not be accepted for transplantation. Bleeding may be anticipated to be a major problem in any patient with dense reactive scar tissue. To avoid this, transplantation should be done within 3 weeks. We recommend patients who have previously been selected for orthotopic transplantation and begin an accelerated decompensation (our Cases 2 and 7) as the best candidates for temporary orthotopic mechanical support. In these patients, there is no question about whether recovery of the native heart is possible or whether a reversible myocardial insult is present. The plan to do an orthotopic transplant indicates that a cardiectomy is necessary. Case 5, who was in reasonable shape for transplantation, was also favorable. In cases of anticipated graft failure, early use of the Jarvik 7-70 is recommended. This type of device, when suitably placed, provides excellent control of the circulation. There is no requirement for intensive care of the native heart, since it is gone, along with toxic antiarrhythmic medications, risk of embolizing a mural thrombus, and the constant balancing of a univentricular device vis-á-vis the native heart. Further, if pulmonary edema is present with accompanying elevation in pulmonary vascular resistance, the biventricular device requires only an upward adjustment in right drive pressure. With a univentricular device one must worry not only about the pulmonary vascular resistance but also about the capacity of the right heart to pump at a normal output.(ABSTRACT TRUNCATED AT 400 WORDS)     

Experience with the symbion total artificial heart as a bridge to transplantation.

From December 1985 through January 1991, 9 patients underwent bridging to transplantation using a Symbion J-7-70 total artificial heart. There were 4 female and 5 male patients aged 31 +/- 14 years (range, 15 to 52 years). Five patients were supported on an intraaortic balloon pump before total artificial heart support, and 2 had biventricular assist devices as well. Total artificial heart support was maintained for 17 +/- 12 days (range, 4 to 44 days); all patients underwent transplantation. Three patients died after transplantation on day 0 (primary donor organ failure), 25 (acute rejection), and 256 (multiorgan failure). The remainder were discharged at 41 +/- 32 days (range, 13 to 101 days). One patient died 28 months after transplantation of late acute rejection. Actuarial 1-year and 3-year survival is 67% and 55%. There were no surgical wound infections. Problems encountered in the J-7-70 period and the period after transplantation were for the most part related to patient condition in the period before implantation. The Symbion J-7-70 total artificial heart is an effective device for total circulatory support in patients with end-stage cardiogenic shock when an organ donor is not available. Organ system failure and infection before implantation may persist into the transplantation period resulting in long-term complications, increased mortality, and prolonged hospital stay; therefore, early implantation of the device when indicated should be applied.     

Update on the total artificial heart

There has been a quest for an artificial organ that can replace the heart for decades. Remarkable advances were made in the second half of the twentieth century in the fields of medicine and engineering that led to the development of several devices with the intention of totally replacing the human heart. Some of these devices, like the Jarvik artificial heart, were utilized initially as a permanent replacement for the failing heart. It became more successful as a bridge to heart transplantation (BTT) in the years that followed its introduction. Currently the CardioWest total artificial heart (TAH) is the only device in clinical use with the intention of bridging patients to heart transplantation. Two new TAHs are being developed with the intention of being used as an alternative to transplantation (ATT) or on a permanent basis. The next 100 years will bring revolutionary new designs and advances in the field of end stage heart disease that may only be ideas at the present time.     

Progress in the control system of the undulation pump total artificial heart

The undulation pump total artificial heart (UPTAH) is a small implantable total artificial heart. As the UPTAH generates outflow and inflow at the same time, control of the UPTAH is very difficult. Therefore suitable control methods specifically for the UPTAH should be established. Various motor control, left-right flow balance control, and physiological control methods were examined and tried for the UPTAH control in this study. The control system is divided into seven categories. It has a hierarchical structure and all control modes work at the same time. The UPTAH with the newly developed control method has been implanted into the chest cavities of 48 goats. Until now, six goats survived for more than one month, including 63 days in the longest case. The good condition of the UPTAH implanted animal could be maintained with the newly developed control scheme, consisting of the 1/R control and several other additional controls.     

Proposal of a new electromechanical total artificial heart: the TAH Serpentina

A new type of energy converter for an electro-mechanical total artificial heart (TAH) based on the principle of a unidirectional moving motor is described. Named the TAH Serpentina, the concept consists of 2 major parts, a pendulum shaped movable element fixed on one side using a joint bearing and a special shaped drum cam. Pusher plates are mounted flexibly to the crossbar of the pendulum. A motor drives the special shaped drum cam linked to the pendulum through a ball bearing. The circular motion of the unidirectional moving brushless DC motor is transferred into the linear motion of the pendulum to drive the pusher plates. Using a crossbar with a variable length, the stroke of the pendulum and therefore the displaced blood volume is alterable. To achieve a variable length, an electric driven screw thread or a hydraulic system is possible. Comparable to the natural heart, cardiac output would be determined by frequency and stroke volume.     

Development of a flow-transformed pulsatile total artificial heart for total implantation

To realize a totally implantable total artificial heart (TAH), a new pulsatile TAH, the flow-transformed pulsatile TAH (FTPTAH), was developed. The system was composed of a single centrifugal pump (CFP) and two three-way valves. One port of each three-way valve was connected to the inlet and outlet of a CFP. The other two ports of each valve were connected to the right and left atrium, and the pulmonary artery and aorta. The CFP can perfuse the pulmonary and systemic circulation alternately with pulsatile flow by switching the two three-way valves. A prototype and the secondary model in which the solenoid valves and a spool valve were included, respectively, were connected to a mock circulatory unit with the results that a pulsatile TAH with physiological flow wave form could be obtained from a single CFP, about 5 L/min of pulsatile output could be obtained alternately on the right and left side by switching the solenoid valves or a spool valve, and flow balance between the right and left could be easily controlled by the switching duration. The system is feasible for a totally implantable TAH because it does not need a compliance chamber and can be miniaturized.