- Emergency
- Coronary heart disease.
- Symptoms.
- Risk factors.
- Complications of CHD and myocardial infarction.
- Necessary investigation methods (diagnosis).
- Treatment of coronary heart disease
- Valvular heart disease.
- Diseases of the thoracic vessels.
- Arrhythmias.
- Transplantation.
Jarvik 2000 as long-term assist device and alternative to cardiac transplantation
In Germany about 400 patients receive a heart transplant annually but several thousand patients would need this treatment. There are also large numbers of patients who cannot be given priority for cardiac transplantation for reasons of age and because of their frequent additional diseases (diabetes, impaired kidney, lung and liver function) and on account of the listing criteria.
Implantation of the Jarvik 2000 left heart assist device can be a possible solution. Only a few LVADs have so far been used long-term because of the frequent complications such as infections, thromboembolism and mechanical failure. The Jarvik 2000 is an innovative LVAD, which has been generally approved in Europe only since May 2005. It is intended to offer the possibility of permanent, lifelong support for the left heart.
Fig.1: The Jarvik 2000 is a roughly thumb-sized pump that is implanted in the left ventricle directly through the apex of the heart. The current volume weighs 90g and occupies a volume of 25 ml. These dimensions make it the world’s smallest system.
The Jarvik 2000 was developed in the USA by Dr. R. Jarvik in collaboration with the Texas Heart Institute, Houston. The aim was to develop a pump that would assist the failing heart by partially relieving the left ventricle. It would not replace the heart completely. The blood passes through the pump to the descending aorta (Fig. 1) or ascending aorta (Fig. 3 on left). The natural heart continues to pump so that the blood also reaches the systemic circulation physiologically through the aortic valve. The special feature of this system is that a mode runs that lets the heart beat on its own for 9 seconds in every minute. This has a certain training effect for the diseased heart and allows recovery at the same time. Thrombus formation is reduced. This mode is something completely new and up to now has been a feature only of the Jarvik 2000. Two models of energy transmission were developed, one with a cable emerging from the abdomen as in most conventional systems and one with a retroauricular cable (emerging behind the ear, see right of illustration). The pump is located directly in the heart and reduces the risk of thromboembolism as no inflow prosthesis is required, which is otherwise the main source of thrombus. The risk of thromboembolism is thus markedly reduced with this system, and so is the risk of infection due to the connection in a well-perfused area behind the ear (Fig. 2). It is a new system with high quality of life as it is completely silent, unlike other systems, and it can be carried in a small bag. The costs are very high but the operation is paid for by all health insurance companies.
Fig. 2: The energy for the pump is supplied by batteries that the patient wears on his belt together with a controller (left). There are two different battery packs that can be attached, depending on need. A Jarvik patient has portable lithium batteries that last about 7 hours and so can be worn during the day, and a battery in the home console with energy for up to 48 hours, to which the system can be attached at night. The power and data cables are connected through a small and inconspicuous plug behind the ear so that the otherwise frequent infections at the cable exit sites can be virtually ruled out.
Fig. 3: Other advantages of the Jarvik 2000 are that it can be implanted in the beating heart without a heart-lung machine and can be connected to both the descending aorta and the ascending aorta (left). The latter procedure has been employed twice in our clinic in combination with aortic valve replacement and bypass surgery. Long-term use for 6 years has been achieved in the USA (right).
The Jarvik 2000 can be used in patients for bridging until cardiac transplantation. Quality of life and organ function should thus be markedly improved by the time of the operation. The disadvantage of the system is that it is intended especially for NYHA class III patients and not for NYHA IV patients with biventricular heart failure, who require complete heart replacement. Right ventricular pump function should still be adequate (RV-EF > 40%).
In elderly patients who cannot have a transplant due to their comorbidities, the Jarvik 2000 is a good alternative to cardiac transplantation in Germany. It is the only pump system with which a few patients have already lived well for 6-7 years (Fig. 3 shows the first patient in the USA who used the Jarvik 2000 as an alternative to cardiac transplantation).