Implantable Cardiac Devices: Medical Technology for Heart Problems

Implantable cardiac devices figure among the very expensive and highly sophisticated equipment now in existence because of the advancement of medical technology. People with heart problems would do well to not only follow the dietary instructions given to them by their doctors, but also to educate themselves on some of the implantable cardiac devices available. Most people have heard about the pacemaker and have some concept of how it works. However, few are familiar with the automatic implanted cardiac defibrillator (AICD) or the left ventricular assist device (LVAD). The AICD can range in size from that of a 9-volt battery to the size of a wallet. Yes, it's usually very easy to palpate it through the skin. The upper left chest is the typical area of placement, but it could also be implanted into what's known as the left upper abdominal quadrant. The job of the device is to sense abnormal heart rhythms that are life-threatening; these rhythms are known as ventricular fibrillation (VF) and ventricular tachycardia (V-tach). The heart has its own natural pacemaker and electrical system to ensure it continues to pump. V-tach is a condition in which the heart is beating fast--sometimes too fast to even allow the its chambers enough time to properly fill with blood before contracting. This, in turn, means that not enough oxygenated blood reaches the rest of the body, including the brain.

Ventricular fibrillation, another dysrhythmia, can be loosely thought of as a quivering heart instead of a pumping one. Although the heart could have strong electrical activity during VF, that activity is taking place haphazardly. Just as an automated external defibrillator (AED) was developed to detect these rhythms and attempt to correct them through the delivery of an electrical shock, so an AICD, which might also contain a pacemaker, is designed to do the same. If a person is shocked while conscious, he or she will experience great discomfort. Other people near or even touching him or her will not be shocked. People with heart problems tend to stay in close contact with their doctors if anything out of the ordinary occurs; it's no different when they receive a shock from an AICD. They're usually instructed to phone their physician even if all appears fine after a shock; however, if they experience certain symptoms such as shortness of breath or the device shocks them more than twice in a 24-hour period, they're advised to call 911 or go to the hospital.

One of the newer provisions of medical technology in the area of implantable cardiac devices is the left ventricular assist device. The heart contains four chambers, the two lower ones are the ventricles. The left ventricle is unique in that it contains the most muscle, is the strongest, and works the hardest. When functioning properly, it pumps oxygenated blood to the aorta, the largest artery in the body, for system-wide distribution. Severe left ventricular heart failure could leave a patient waiting for a donor for transplant. Meanwhile, the left ventricular assist device might be able to sustain him or her until that time.

The LVAD is designed to move blood, via a tube, from the failed left ventricle to an artificial pump implanted into the abdomen which takes the place of the left ventricle. Once pressurized, that blood is then pumped to the aorta for distribution to the entire body. Some of the complications that patients with heart problems using the LVAD can experience include leakage of air and the battery could fail requiring immediate transport to the emergency room. These implanted cardiac devices now on the scene through medical technology, as amazing as they are, still present problems and risks. This should be a forceful reminder of the need to remember that nothing artificial, however technologically advanced it might be, can compare with good health, usually achieved by treating the body right to prevent problems.

Source:
EMT training (Lecture/Text): Emergency Care (11th Edition) by Daniel Limmer, Michael F. O'Keefe, Medical Editor: Edward T. Dickinson MD FACEP