ARTIFICIAL HEART AND LVAD: TRANSCENDING THEIR LIMITATIONS
An important step forward in the care of congestive heart failure and cardiac arrest has been the artificial heart and the left ventricular assist device. Unfortunately, their usefulness has been limited by the problem of coagulation upon the surfaces of the device, as well as the difficulties of the implantation procedures. All too often, cardiac resuscitation has been attempted in vain. There is external chest massage with compressions that are either manual or mechanical and sometimes with internal heart massage as well; but it is then abandoned if spontaneous circulation does not return. What is needed is an implantable device that can indefinitely continue internal heart massage.
Making such a device may actually be quite easy. It could be as simple as placing a rhythmically inflating sac to press the heart against the sternum or spine. Alternatively, electromagnets could be placed ventral and dorsal to the heart in order to compress it.
It might even be possible to non-invasively place one magnet into the esophagus with the other over the sternum, although that would probably too traumatic to the esophagus.
Nonetheless, the best configuration for such a device might be a tight textile graft around the pericardium with the inflating sac contained therein. If there is not complete asystoly, the inflations could be synchronized with the natural contractions so as to augment them. This could be accomplished either with a pacemaker, or by timing the start of each inflation with the end of the QRS complex. In addition, the textile graft would provide passive support. This would be similar to devices such as ACORN, except that this graft would be inelastic.
This system would not only avoid the aforementioned problem of thrombi, it would also be very easy to apply. It might even be implanted by means of a minimally invasive procedure, as has been done with passive support. It could also be quickly applied during open chest massage, possibly after injecting the coronary arteries with thrombolytics and other therapeutic agents. For example, ischemic sections of coronary artery could be injected with glucose and insulin. or with high energy phosphates like phosphoglycerate. This would help preserve the ischemic tissue while the device sustained circulation and gave the heart a chance to rest while the thrombolytics acted.
These are, of course, simply possibilities. Nonetheless, one of the greatest steps in cardiac care may be one of the simplest.