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New device keeps heart beating without touching heart

On April 4, 2014 at Experts agree that insurance policies should be kept in a safe, secure place in the event of an emergency. Jeremiah Timmons has taken that advice to heart

 Medical Center of the Rockies, University of Colorado Health cardiologist and board-certified electrophysiologist Dr. Tim Johnson inserted a different kind of insurance policy, a device called a Subcutaneous Implantable Defibrillator (S-ICD), under Timmons’ left armpit. The potentially life-saving piece of equipment protects Timmons against deadly heart rhythms by providing a shock when those rhythms are detected, rapidly resetting the heartbeat to normal.

“The left side of my heart only pumps at 30-percent capacity, and I have an enlarged heart due to high blood pressure for most of my life,” Timmons said. “They wanted to put in the device in case I had a heart attack because my heart muscle is so weak.”

After suffering from debilitating dizzy spells, weakness and chronic malaise, the 33-year-old Johnstown resident was diagnosed in 2013 with cardiomyopathy, a condition in which the heart muscle becomes enlarged from being overworked, and is at some risk for developing life-threatening arrhythmias, or irregular heartbeats.

Because Timmons has already had one minor heart attack, his regular cardiologist referred him to Johnson, one of only four physicians in the state currently trained in S-ICD procedures. In Colorado, only electrophysiology-certified cardiologists are allowed to perform the procedures.

University of Colorado Health cardiologist and board-certified electrophysiologist Dr. Tim Johnson, pictured here, is one of only four physicians in the state currently trained in S-ICD procedures.

 Board-certified electrophysiologist Dr. Tim Johnson, pictured here, is one of only four physicians in the state currently trained in S-ICD procedures.

Automatic vs. Subcutaneous

The implantable defibrillator is not new. Cardiologists have been successfully using the Automatic Implantable Cardioverter Defibrillator (AICD) since the 1980s. But the S-ICD, approved by the U.S Food and Drug Administration in September 2012, has the advantage of being a considerably less invasive and thus potentially safer option.

The concept is the same for both defibrillators. A small generator with a battery pack detects potentially lethal arrhythmias that originate in the lower portion of the heart. Then, like a small-scale model of the paddles you see on television, the defibrillator sends a shock to the heart muscle within 15 to 20 seconds, resetting it to a normal rhythm. And that’s where the two devices diverge.

With the AICD, the wire is tunneled upward to the left subclavian vein en route to its ultimate destination, the right ventricle. A tiny extendable corkscrew anchors it to the inside of the heart muscle. This approach carries a high risk of bleeding and damage to the blood vessels, heart, and lungs.

“The wire,” Johnson said, “is the weak link in the system.”

Additionally, if bacteria clamp onto the wire inside the heart or blood vessels or onto the generator under the skin, antibiotics can’t be used to eradicate the infection. The only option would be to remove the wire entirely, which is, according to Johnson, “not a low-risk procedure.”

With the S-ICD, all components remain safely outside the chest wall. The generator, which is about the size of an iPhone 4, is implanted under the skin in the left side of the chest below the armpit. The wire that performs the defibrillation is tunneled under the skin, from the generator around the front of the chest wall toward the lowest point of the sternum, avoiding the need for incisions to the chest cavity or vital blood vessels. The physician makes three small incisions: one on the side of the chest to implant the generator; another at the base of the sternum where the wire is anchored with a stitch; and a third to anchor the wire’s tip as close as possible to the heart tissue. The procedure takes 60 to 90 minutes, and the device also is easier to remove than the AICD, Johnson said.

“There’s not a lot of anatomic variabilities when you’re just placing it (S-ICD) outside the chest,” said Dr. Duy Nguyen, UCHealth cardiologist at the University of Colorado Hospital in Denver who has implanted seven S-ICDs since December 2013. “You are fairly certain how long it will take. The AICD placement depends on anatomy, and could take as long as a few hours.”

Generally, any patient who is at high risk or already has irregular heartbeats may be an appropriate candidate for the S-ICD, Nguyen said. The most common candidates are those with a high likelihood of sudden death because of a prior heart attack or a history of cardiomyopathy. Other likely candidates are people with vascular access problems and those who are at significant risk of infection. Nguyen suggests that patients who benefit the most are ones who can’t tolerate having a foreign substance in their bloodstream or inside their heart. His youngest patient was 17 and suffered from a congenital defect that precluded him from having an AICD placed.

“It was perfect timing,” Nguyen recalled. “We saved him from open-heart surgery.”

One drawback of the S-ICD, Nguyen said, is that unlike the traditional ICD, it doesn’t have the dual capability of functioning as a pacemaker. For patients with certain arrhythmias that could cause the heart to beat either too slow or too fast on a regular basis, Nguyen said that the standard ICD is the better option.

For young patients like Timmons with severe cardiomyopathy, treatment options are typically limited to medications and lifestyle modifications such as losing weight and lowering blood pressure. Still, there’s no guarantee of reversing cardiac muscle damage, and the risk of a death remains high.

“I didn’t want it because of how young I am, but I guess with my heart condition it’s necessary,” Timmons said. “You hope it doesn’t have to work.”


Other than basic discomfort, Timmons’ recovery was smooth.

“The first week, I felt where he fished the wires through my body, and when I was lying down and moving around, I felt the wires tugging on the tissues around it,” he said. “Otherwise, I don’t really notice it too much. I’m not too worried about it, especially knowing it’s not wired through my heart.”

Johnson said he feels that the S-ICD has a promising future. “This will probably be performed by every electrophysiologist in Colorado within a short period of time. It really does open up the technology to patients who in the past may not have had any other alternative.”

And even though the S-ICD lies just below the skin, for Timmons, its benefits reach far deeper.

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