New implantable device to prevent sudden cardiac arrest

Aug 13 2010

It's a familiar scene on most TV medical dramas: a patient is unconscious; CPR didn't work; someone yells, "All clear!" and the defibrillator paddles are applied to the person's chest in hopes the electric current shocks the heart back into action. In real life 350,000 Americans die of sudden cardiac arrest every year because they don't have implantable devices or defibrillators nearby at the time of the cardiac arrest.  Northwestern Memorial Hospital heart rhythm specialists recently gave a 34-year-old man a makeshift paramedic—who's always on duty—inside of his chest by implanting a device that did not require X-ray assistance and the usual snaking of wires leading to the heart. In fact, the innovative device rests just beneath the surface of the skin and its components are positioned using the patient's own anatomical landmarks.

"One of the greatest innovations about this new technology is that there are no leads touching the heart," said Bradley Knight, MD, director of cardiac electrophysiology at Northwestern Memorial Hospital.  "That's a huge divergence from conventional defibrillators, where with every contraction of the heart the lead wires can bend. Bending can cause a wire fracture that could potentially send false signals to the defibrillator, causing the delivery of unnecessary shocks."

Knight explained that the electric shockwaves of a defibrillator can stave off or stop sudden cardiac arrest. He added that patients liken the electric impulse to getting kicked in the chest by a horse.  When unnecessary shocks are delivered, they not only give patients severe discomfort, they could also trigger life-threatening arrhythmias.

Knight added that in some cases the false signals could also cause the defibrillator not to pace or shock when it's most crucial, frightening news to the 100,000 Americans who are implanted with defibrillators every year. Time is of the essence to these patients, whose abnormal heart rhythms require urgent treatment to prevent sudden death.

"This device's wires sit in the middle of the chest, and don't lead directly to the heart, so the chance of the wire's getting fractured or dislodged and not working as they should is reduced," said Knight.  

Cameron Health's S-ICD system device handed Rosario Ahon the peace of mind that had eluded her for more than a year.  Her husband Carlos was diagnosed in 2009 with cardiomyopathy, a disease affecting 50,000 Americans which causes the heart to become enlarged and its muscles to weaken, decreasing the heart's ability to pump blood efficiently to the body.  This disease put Carlos at an increased risk for sudden cardiac arrest, and Rosario feared her husband would be taken from her without warning.

"My husband is a machine operator, and I was always frightened I'd get a phone call from his job telling me he collapsed and died," said Rosario.  "I'm not so scared anymore."

In June Carlos became Northwestern Memorial's first subject to be implanted with the Cameron Health S-ICD device.  The device implantation takes less than an hour and is far less invasive than implantation of traditional defibrillators.  Knight and his team made an incision on the left side of Carlos' chest, next to his rib cage, and a pocket was formed under the skin for the placement of the pulse generator.  Two small incisions were made to the left of the breastbone to place the electrode under the skin, and then the electrode and generator were connected by wires.  

"He only needed a few weeks of rest and recovery, and he's already back to work," said Rosario.

Cameron Health representatives visited Carlos' job site to detect any electrical interference to the device from the machines he works with so that Carlos and his physicians could make adjustments accordingly.  Carlos will continue to be monitored by Northwestern Memorial physicians every three months.

"I feel like I've been given an opportunity of life," said Carlos.  "Compared to the horror stories I've heard about other models, this device is a big improvement and very comfortable.  It is designed to prevent sudden cardiac death and not give me shocks unnecessarily, so that I should be able to have a more normal life."

SOURCE Northwestern Memorial Hospital