On April 25, the first of four planned preclinical tests with Real Heart ™ was performed on calves at the laboratory in Belgium. The outcome of the tests was better than expected both in terms surgical technique and the principle function of the pump.
As a preparation for the calf test, we have done some changes to the heart pump. The pump capacity has been increased to approximately 9.5 liters per minute compared to the previous 5 liters per minute, and the size has at the same time been reduced. We have also changed to using materials that are tolerated by the human body and are approved for permanent implantation (known as biocompatible materials). The new pump is now completely built in biocompatible materials, which is a major step forward. This is very important in order to facilitate future certification of the pump for human use. In addition, we have developed a new way of connecting the heart pump to the blood vessels of the thoracic cavity by developing a new type of connection. This is a kind of quick connector that significantly facilitates implantation of the pump.
The first calf test in Belgium on April 25, was designed to be an acute test. The goal of the first calf test was to try out the connection of the heart pump, the surgical technique and adjustment of the heart pump in the thorax. The intention was not to wake up the animal from anesthesia. At the test we could connect the pump without any problems. The new connection significantly facilitated the operation. The pump could easily be inserted, and the heart-lung-machine could without problems be disconnected so that the animal was supported only by the heart pump. The animal had very good oxygenation (98-100%), good blood pressure (about 150/110) and a normal low pressure in the left atrium, which is a sign that the flow of blood from the lungs to the heart works physiologically well. The most remarkable was that the connection could be done without any bleeding at all. It was completely dry which is very encouraging. In summary, the result was both in terms ease of connection and surgical technique better than expected. The principal pump function of the artificial heart was once again impressive.
However, there are always challenges. The implant was this time performed between the 4th and 5th ribs on the left side of the thorax, instead of dividing the sternum and opening up the entire chest along the midline as we have done in previous trials. This technique has both advantages and disadvantages. The advantage is that it is less extensive for the animal in particular if the animal is to be woken up later. The downside is that you have a smaller operating field. Unfortunately, during this surgery, we did not have enough space to comfortably adjust the heart pump inside the chest. There should theoretically be enough space if you do the implantation a bit lower – between the 5th and 6th ribs. We will do the next surgery in this way and hopefully improve the heart pump’s fit in the chest. Another challenge is the de-airing of the system. We need to redesign the de-airing valve and adapt the location to the new operation technique.
The final result of this calf test is thus very encouraging and much better than expected for a first test. We already have three more calf tests planning in Belgium before midsummer. The next calf test will be performed on May 9 and will be designed as an additional acute test before we switch to chronic survival tests. The goal for the next calf test is to carry out some adjustments and fix some of the problems so that we may be able to carry out survival tests, already with the third or fourth calf. If we then manage to wake up the animal the aim is that the animal should be able to live with heart pump for a few days.