Basically, mechanical support systems can be used (artificial heart), only if the heart cannot fulfill its function and the replacement is not possible with a donor heart or a donor heart is not available. In this case, different scenarios are shown, which make necessary various types of mechanical support of the circulatory system.
During the end of a procedure, using a heart-lung bypass machine, the immediate recovery of the cardiac function is not possible. This means that the patient cannot be kept alive without a heart-lung bypass machine. So, in order to make possible the completion of such a procedure, a support system is needed. Accordingly, if both the ventricles are sufficient, either the left ventricle is supported or – in rare occasions – the whole of the heart and the lungs is bypassed. This is achieved with a system of centrifugal blood pump, which allows a blood flow of 6 liters per minute. Under specific conditions, the oxygenator can be incorporated in the system, which enriched the blood with oxygen.
Such a system is simple and safe. However, the disadvantage is that its use is limited to 7 – 8 days. Regularly, the recovery of the cardiac function is achieved during this interval, since the heart does not need to work during the function of the centrifugal blood pump and it is not burdened with work production.
In case of cardiac function recovery during the first week, the removal of the system can take place, without problems and the course of the further patients’ recovery is not different in comparison with the other cardiological patients.
In case of non-recovery of the cardiac function and if there is the possibility of future transplantation, the replacement of the system should take place.
Here we deal with the use of mechanical support systems as bridging until a graft is available. The question if only the left ventricle or the whole of the heart should be supported is of significant importance.
Mainly, it concerns patients who are already in the list for heart transplantation and their condition is worsening quickly. The second group concerns patients, of which the cardiac function worsened because of myocardial infarct or inflammation of the cardiac muscles and which are threatened with death.
In case of functional limitation of both the ventricles, an extracorporeal support system is used. Through two pumping chambers, which function with air, the pumping function of the ventricles is replaced and supported.
In case that the function of the left ventricle is significantly limited, then a very smaller pumping system can be implanted. This does not concern a pumping chamber but an axial-flow pump. The blood transportation is realized through an “Arichemedes Snail (Archimedes’ Screwpump)”. These devices are very small and they can be fully implanted. Here, Heartware system is available.Heartware.
With this support system, the mobilization of the patient is for sure easier and his discharge from the clinic is more possible.
Both the ways of supporting are functioning as a bridge until a cardiac graft is available. In rare cases middle-term recovery of the heart function can occur, so that these systems are removed successfully and the heart functions normally.
It concerns patients whose left ventricle function the is severely limited. For these patients, unfortunately there is no possibility for heart transplantation or they have contraindications for transplantations or they are aged. In order these patients to be helped and to assure their life quality, the above mentioned axial flow pumps are used. In this way, a sufficient function of the pump is assured and the patients can leave the clinics with these systems. However, their application is limited only to selective patients. Because of the lack of alternative solutions for these patients, the use of this method will continue in the future to gain importance.