This is the second installment of our interview with Dr. Russ Bailey. Read the first story here.

Can you explain what a defibrillator is?

An (implantable cardioverter) defibrillator is smaller than a deck of cards and less than an inch in thickness. It is placed under the skin beneath the collarbone, and one or more wires are passed into a vein beneath the collarbone to the heart to allow the device to monitor the rhythm.

If it ever detects a life-threatening rhythm problem, it will promptly recognize that and treat it. In many cases, that means it will deliver an electrical shock to return the heart to normal. The device has some opportunity to deliver pacing, at a rapid burst, and that may interrupt the rhythm as well – and without any symptoms to the patient. (The defibrillator is different from the more commonly known pacemaker, which sends electrical impulses to maintain a proper heart rate.)

We don't get second chances with about 95% of patients who experience sudden cardiac arrest. So, waiting for that event is not the correct approach.

If we assess a patient and conclude they are at higher risk for sudden death, we have an opportunity to protect them by implanting a defibrillator.

How many people who have a defibrillator survive sudden cardiac arrest with no long-term impacts?

The vast majority. If they have an event, the device is very good at terminating that and returning them to baseline function in a matter of seconds.

Does the person realize they've had an event?

If they have a shock, they know. It causes no damage to them, and – as I tell my patients – it beats the alternative.

After a patient who has a defibrillator has this event, do they need to see a doctor or get to the ER?

Dr. Russ Bailey

Not necessarily. The device has a memory capacity; it saves the event that it sees and treats. Almost all implanted devices currently have the ability, through a little transmitter the patient has either in their home or as an app, to transmit that data.

We can see it on our end. You know within a day or two, if not the same day. And as long as the patient who had a shock feels they are back to their usual self, they don't need to go to the ER. The device did what it was designed to do, and we congratulate them. (Laughs.)

If they have repeated shocks, at the same setting or in the same day, they do need to go to an emergency room to determine what has changed.

The device is an insurance policy if they have a nasty rhythm that would otherwise have been a fatal event.

And does that device keep working even after it’s given a shock?

Yes, it’s capable of lasting eight to 10 years and potentially longer.

How do patients know if a defibrillator is an option they should consider?

The only way for potential patients to know they need a defibrillator is to get assessed. The vast majority of those patients are those with low heart function, either due to a previous heart attack or other causes that lead to heart muscle weakness.

There is a smaller group of patients who have normal function, who have potential for abnormal rhythms based on genetic abnormalities that predispose them to electrical instability. Fortunately, those are infrequent. Those folks generally come to our attention because they've had prior symptoms – palpitations or recurrent passing-out spells.

Anytime a doctor tinkers with your heart, it’s a big deal for a patient. But it’s just another day at the office for you, right?

From a risk standpoint, implanting a defibrillator is a lower-risk procedure.

We implant a lot of these. In many cases, patients will go home the same day. It takes an hour or so to implant one of these. It’s just a small skin incision, roughly 2 inches long, beneath the collarbone.

You mentioned in part one of this story that people can have a heart attack and not know it, and that seems strange. The word “attack” makes you think of something sudden and violent. How could you not know?

It's not necessarily as dramatic as it sounds. The classic symptoms are feeling like an elephant is sitting on the chest, pain going down the arm, shortness of breath, nausea.

But it could be subtler than that. It can be, and is, misinterpreted as indigestion. It can be just not feeling well for a day or two … or some chest discomfort that's rather nonspecific.

Women are more notable for having atypical symptoms – fatigue, back pain, shortness of breath. There are folks who have those and don't get evaluated, or they don't get evaluated till late in the game.

Some guys are notoriously stoic and won't go to a doctor unless something dramatic is happening.