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Biomedical subjects

R K Jarvik

Publications and source records attributed to R K Jarvik.

At least 19 recordsLinked to original sources
PubMed2001

Research and development of an implantable, axial-flow left ventricular assist device: the Jarvik 2000 Heart.

Advances in technology and increased clinical need have led to the development of a new type of blood pump. The Jarvik 2000 Heart is an electrically powered, axial-flow left ventricular assist device that has been developed during the past 13 years. Unlike first-generation left ventricular assist devices, which were developed in the 1970s and were designed to totally capture the cardiac output, the Jarvik 2000 is designed to normalize the cardiac output by augmenting the function of the chronically failed heart for extended periods. Design iterations have been tested in 67 animals, and clinical trials have recently begun. Three patients have received the Jarvik 2000 as a bridge to transplantation, and 1 patient is being supported permanently outside the hospital. All 4 patients have improved from New York Heart Association functional class IV to class I, and 2 of them have been discharged from the hospital after heart transplantation. The experimental and clinical results indicate that the Jarvik 2000 can provide physiologic support with minimal complications and is reliable, biocompatible, and easy to implant.

Animals↗
PubMed1997

Development of an implantable ventricular assist system.

BACKGROUND: This study describes the present state of progress in the development of the Jarvik 2000 ventricular assist system. METHODS: Designed for implantation in the human thorax, the system consists of a small (25 cm3, 90 g) intraventricular axial-flow blood pump that transmits power and data via internal electronics and a transcutaneous energy transfer system. The pump is powered by portable internal and external polymer lithium ion batteries. The only moving part, the pump rotor, contains a permanent magnet of a brushless direct-current motor that mounts an axial-flow impeller and partial magnetic thrust support, with blood-immersed radial and thrust bearings. The motor uses a redundant coil and electric lead design, which permits continued operation in case of wire breakage. RESULTS: Seven calves have been supported for an average of 107 days (range, 40 to 162 days) with prototypes of the Jarvik 2000 ventricular assist system. No physiologic complications have occurred. When its user is at rest, the pump produces flows of 5 to 6 L/min with a decreased arterial pulse contour. Renal and hepatic functions have remained normal throughout the duration of all studies. Mean plasma free hemoglobin levels ranged from 4.3 to 11.4 mg/dL (mean, 6.3 mg/dL) for each study. Pathologic analyses of the heart and kidneys revealed no damage related to the device. CONCLUSIONS: These studies indicate that the Jarvik 2000 ventricular assist system is feasible in animals and holds promise for long-term support of patients.

Animals↗
PubMed1997

The Jarvik 2000 Oxford system: increasing the scope of mechanical circulatory support.

METHODS: We developed a system for mechanical circulatory support based on the Jarvik 2000 intraventricular axial flow impeller pump (Jarvik Research, Inc., New York, N.Y.) and percutaneous electric power. The adult pump provides flow at a rate up to 10 L/min with an energy requirement of 7 to 10 watts. The device was implanted into the apex of the left ventricle through a left thoracotomy without cardiopulmonary bypass. A Dacron graft conveyed blood to the descending thoracic aorta. In patients, we will use a skull-mounted carbon pedestal to transmit fine electric wires through the scalp skin. Being highly vascular, the scalp skin is resistant to infection. RESULTS: We tested 16 adult systems and one pediatric system in 17 adult ewes weighing between 60 and 90 kg. Five died of perioperative complications. Twelve survived between 3 and 198 days (mean 44 days) with a functioning device. None of the sheep could receive adequate anticoagulation with warfarin (INR 1.0 to 1.5). Acute thrombotic occlusion occurred after a 3-hour power loss in one device (46 days) but was cleared with streptokinase. In a second animal with endocarditis, the pump inflow became occluded with vegetations. No other device-related problems or important hemolysis developed despite pump speeds between 10,000 and 18,000 rpm. Renal function remained normal in all animals. Autopsy studies showed no pannus ingrowth at the device inflow despite the restrictive left ventricular cavity size. No sign of thromboembolism could be detected in the brains or kidneys. CONCLUSION: Our findings indicate the Jarvik 2000 Oxford System to be a safe and effective circulatory assist device. Potential uses include permanent circulatory support, bridge to transplantation, or bridge to myocardial recovery in acute or chronic left ventricular failure.

Animals↗
PubMed1996

Miniature axial flow pump for ventricular assistance in children and small adults.

We investigated the efficacy of the Jarvik 2000 intraventricular assist device (Jarvik Research, Inc., New York, N.Y.) in an ovine model. The device is an axial flow pump measuring 1.8 cm in diameter by 5 cm long, has a displacement volume of 12 ml, and can deliver flow from 2 to 7 L/min. Seven devices were implanted through a left thoracotomy into the left ventricle with an outflow graft to the descending aorta. Animals were treated with warfarin sodium and aspirin to maintain prothrombin times approximately 1.5 times control. Animals were followed up for 3 to 123 days. Two animals died of operative complications at days 3 and 5. One device failed at 58 days because of thrombus formation at the inflow side of the impeller. The remaining four animals were killed at days 19, 42, 42, and 123, respectively, because of broken electric power cables. Hematocrit values rose significantly higher than preoperative levels (22.8% +/- 3.8% to 30.5% +/- 3.4%); premortem elevations of values higher than baseline values of plasma free hemoglobin (10.4 +/- 7.8 mg/dl to 17.1 +/- 7.4 mg/dl) and lactate dehydrogenase (391.5 +/- 113.7 units/L to 771.2 +/- 370.8 units/L) were statistically insignificant. Serum creatinine and bilirubin levels were normal. No end-organ dysfunction arising from long-term support was evident clinically or at postmortem examination, nor was there any evidence of embolism or damage to intracardiac structures. We found the Jarvik 2000 intraventricular assist device to be easily implantable, safe, nonhemolytic, and able to provide physiologic flow with power requirements under 10 watts.

Adult↗
PubMed1995

System considerations favoring rotary artificial hearts with blood-immersed bearings.

Hydrodynamic blood pumps provide such advantages as not requiring an air vent or compliance chamber as well as a great reduction in mechanical complexity with the potential for very long durability. The detailed design of their bearings is emerging as the single most important determinant of long-term success. Three categories of bearings include remote force, such as magnetic suspension; blood-isolated, which require a shaft seal; and blood-immersed using either mechanical or hydrodynamic support. Blood-immersed bearings permit maximum simplification and miniaturization of the entire system, require no flush fluid, and require no electronics as with magnetic suspension. The Jarvik 2000 heart represents an example of their potential. The intraventricular titanium pump (25 mm diameter, 25 cc, 85 g), uses blood flow through the motor air gap with blood-immersed bearings. The longest in vitro bearing durability test is ongoing at 20,000,000,000 revolutions with minimal wear (3 years at 15,000 rpm). In vivo results include 5-month calf survival, no thromboembolism, plasma Hb 2-5 mg%, and power under 10 W.

Blood Flow Velocity↗
PubMed1984

Clinical use of the total artificial heart.

We report here our first experience with the use of a total artificial heart in a human being. The heart was developed at the University of Utah, and the patient was a 61-year-old man with chronic congestive heart failure due to primary cardiomyopathy, who also had chronic obstructive pulmonary disease. Except for dysfunction of the prosthetic mitral valve, which required replacement of the left-heart prosthesis on the 13th postoperative day, the artificial heart functioned well for the entire postoperative course of 112 days. The mean blood pressure was 84 +/- 8 mm Hg, and cardiac output was generally maintained at 6.7 +/- 0.8 liters per minute for the right heart and 7.5 +/- 0.8 for the left, resulting in postoperative diuresis and relief of congestive failure. The postoperative course was complicated by recurrent pulmonary insufficiency, several episodes of acute renal failure, episodes of fever of unidentified cause (necessitating multiple courses of antibiotics), hemorrhagic complications of anticoagulation, and one generalized seizure of uncertain cause. On the 92nd postoperative day, the patient had diarrhea and vomiting, leading to aspiration pneumonia and sepsis. Death occurred on the 112th day, preceded by progressive renal failure and refractory hypotension, despite maintenance of cardiac output. Autopsy revealed extensive pseudomembranous colitis, acute tubular necrosis, peritoneal and pleural effusion, centrilobular emphysema, and chronic bronchitis with fibrosis and bronchiectasis. The artificial heart system was intact and uninvolved by thrombosis or infectious processes. This experience should encourage further clinical trials with the artificial heart, but we emphasize that the procedure is still highly experimental. Further experience, development, and discussion will be required before more general application of the device can be recommended.

Blood Pressure↗
PubMed1983

Electrical energy converters for practical human total artificial hearts--an opinion in support of electropneumatic systems.

Until recently, most artificial hearts have served as research tools to acquire further knowledge necessary ultimately to design practical systems for human use. Transcutaneous systems or percutaneous systems utilizing permanently implanted energy converters, batteries, and electronics packages have a number of substantial problems that would not exist if most system elements were kept outside the body. These problems include physiologic control, fit and fixation, foreign body infection, hermetic sealing, cable insulation and fatigue, inherent system complexity, stringent requirements for maintenance-free operation with long-term high reliability, and high cost. Percutaneous systems, particularly those in which only the blood pump is implanted, are an attractive choice for practical systems in the near future. A wearable, battery-powered electropneumatic total heart system should be developed.

Assisted Circulation↗
PubMed1983

Response of the human body to the first permanent implant of the Jarvik-7 Total Artificial Heart.

The success of the first permanent total artificial heart implant would have been more obvious had the patient been able to be transferred from the hospital to an outlying home care setting. Nevertheless, several major achievements were realized. First, we were able to demonstrate that the total artificial heart will fit within an adult male chest without causing obstruction to inflow or outflow channels. Second, we were able to demonstrate that the total artificial heart would sustain life on a long-term basis (at least up to 112 days) without any evidence of systemic or local infection and without any untoward systemic effects. Third, we were able to demonstrate that the patient was able to tolerate a total artificial heart without complaint of the noise or the bulk of the drive system to which he required permanent attachment and that the patient could be comfortable and totally free of pain. An additional finding, which could not be assessed in the animal experimentations, was the fact that the patient was able to maintain higher CNS activity on an undisturbed basis following the implant of the total artificial heart. It is for these reasons that the entire University of Utah Medical Center staff feel great indebtedness to the patient and his family for demonstrating to the world the feasibility and the necessity for pursuing this device as a new therapy for end-stage heart disease.

Adolescent↗
PubMed1981

Determinants of pannus formation in long-surviving artificial heart calves, and its prevention.

In a group of 76 calves maintained with Jarvik-5 and Jarvik-7 artificial hearts, pannus formation in the atrial location was evaluated retrospectively using a grading system based on measurement of the pannus tissue. Pannus was present in 87% of the calves surviving one to 7 mos with an old-style inflow quick-connect design utilizing polyester felt surfaces. This design had a suboptimal hemodynamic flow path. Using a new design of quick-connect with an improved hemodynamic flow path and a Biomer blood-contacting surface, pannus occurred only in 17% of calves surviving one to 9 mos. Furthermore, the pannus formation with the new design was mild in the 2 cases where it occurred, whereas the pannus formation in animals with the old cuffs was frequently severe. One calf survived 9 mos with no pannus formation utilizing our new quick-connect system, and we conclude that pannus is no longer a problem in our experiments. We also reviewed the relation of pannus to anticoagulant regimens and found that Persantine, Coumadin, and aspirin were not effective in preventing pannus when the inflow cuff design was conducive to its development.

Animals↗
PubMed1979

Six-month survival of a calf with an artificial heart.

A pneumatically powered artificial heart, constructed primarily from a polyurethane, was implanted in the chest of a calf and supported the calf for more than 6 months. The heart, which was designed to fit in the chest of a 90 kilogram calf, was able to suppor the animal when it weighed 180 kilograms. During the first 105 days the calf remained strong and healthy. The animal grew progressively weaker after day 106, and by day 160 right heart failure became apparent. The principal cause of the right heart failure was an obstructive growth between the right atrium and the right ventricle. An attempt to correct the problem on day 184 with an artificial heart resulted in the animal's death.

Animals↗
PubMed1978

The beat goes on: status of the artificial heart, 1977.

After two decades of continuous research on the artificial heart, survival times of experimental animals indicate that clinical application of such a device is definitely feasible. However, a number of problems remain to be solved. Durability of the device, infection, pannus formation at the interface between the device and natural tissue and thrombosis within the device appear to be the major problems. Development of an implantable power source is also an area of important research. Questions of efficiency, cosmetic and psychological acceptability and cost are just beginning to be considered.

Animals↗