"This thing keeps kicking me," the man says, pointing to his chest, where he has a small, hard object in the place where a cardiac pacemaker usually resides.

Attack One was dispatched in the middle of the afternoon for a "cardiac problem," so the crew is prepared for a cardiac emergency of some type. But before they can ask any further questions or begin to apply their cardiac monitor, the man winces again, screams and yells, "Stop kicking me like that!"

He's lying on the couch and seems to be uncomfortable. Quickly, the Attack One crew places the three-lead cardiac monitor and matches a monitor appearance of normal sinus rhythm with a regular, full pulse in both wrists.

"It's already kicked me five times, and I called my heart doctor," the man relates. "He told me I had to call you guys. I don't feel bad, and I told him I think I was too close to the microwave oven, and it set this thing off!"

The man and his wife can answer all the crew's questions about the device. It is an automatic implantable cardioverter defibrillator (AICD), which the man has had in place for the last six months, following a severe heart attack. It has not functioned before. The patient has no symptoms of chest pain, shortness of breath, irregular heartbeat, passing out, nausea or vomiting. His medicines have not changed recently. He says he feels fine, except when the defibrillator discharges, and then he feels like he's being kicked inside his chest.

His vitals are stable, and his monitor now shows a continuous sinus rhythm. He is preparing to move from the couch to the ambulance stretcher when his rhythm suddenly changes to a ventricular tachycardia, and the device discharges and cardioverts him back to a sinus rhythm again. Just like before, the man screams and yells, "Ouch! Stop kicking me like that!"

The Attack One crew asks him to lie back down and repeats the same questions as before. The patient confirms he has no pain anywhere, especially in his chest. He is back in a sinus rhythm and appears to be perfusing very well. The paramedic advises the patient that his device is operating properly, and has just saved him from a rhythm that otherwise would have resulted in him going unconscious and forced the Attack One crew to defibrillate him externally.

"Sir," the paramedic says, "this isn't from you being too close to the microwave oven. Something is wrong that is causing your heart to suddenly develop a life-threatening rhythm, and the device is saving you."

The paramedic phones online medical direction and reports the sequence of repeated discharges of the implanted device in a patient who is asymptomatic except for the pain when he is shocked. He reports that the patient had one episode while on the monitor, and at that time he'd had sudden-onset ventricular tachycardia. His perfusion, blood pressure, pulse oximetry and mental status were all normal.

Medical control asks that the crew initiate therapy with procainamide, starting with a bolus and then continuing a drip. The crew starts an IV line, mixes the appropriate dose and begins the 30-minute infusion. They explain to the patient that this older medicine has regained favor in the past year, since the American Heart Association's 2010 emergency cardiac care guidelines were published. They advise him to let them know if he feels poor in any way, and that they will monitor him closely as they transport him to the cardiac center where he received his prior heart care and had his IACD implanted.

Hospital Course

Transport time to that hospital is about 25 minutes, and the infusion of procainamide is about complete on arrival. The emergency physician who delivered medical direction is there to greet the patient. No further dysrhythmias have occurred, and the device has not discharged again. The crew shares the rhythm strip showing the cardioversion.

The emergency physician examines the patient and places a call to the hospital's heart center. A cardiac technician comes to the emergency department with a monitor that "interrogates" cardiac devices that have been placed in patients. Placing the monitor's wand over the top of the patient's chest provides a reading of all the heart rhythms the patient has demonstrated over the last days. This technician collects the data, interprets the information and tells the patient, "Sir, you have been in very bad heart rhythms over the past few hours. Once you were dead."

He calls the emergency physician to the bedside and shares this information with the patient and physician at the same time. The physician asks the Attack One crew to join him to learn about the patient's illness. The cardiac technician produces a paper report on the activity of the defibrillator in the patient's chest. The monitor strip shows the patient developing multiple episodes of ventricular tachycardia, each triggering the internal defibrillator to deliver an electric shock. Once, the patient had quickly gone from ventricular tachycardia to ventricular fibrillation, which was converted by another shock from the defibrillator. The rhythm had finally stabilized over the last 20 minutes, as the paramedics were treating the patient.

Subsequent evaluation of the patient finds his potassium level was very low, and that likely was the cause of his repeated dysrhythmias. His rhythm stabilizes on the procainamide, and he develops no more problems in the ED. He receives doses of potassium by mouth and intravenously to raise his level as quickly as safely possible. He is admitted to the hospital for several days but experiences no further problems, and is sent home on a potassium supplement.

Case Discussion

It is now common for patients to leave hospitals with all types of devices in place to address a broad range of medical problems. A growing number of these are cardiac devices. EMS providers have a long history of managing patients with cardiac pacemakers, and in the last 10 years have managed patients with implanted cardiac defibrillators. In the last few years, ventricular assist devices, cardiac pumps and combination devices have been introduced in hospitals and placed on patients going home.

Automatic implantable cardioverter defibrillators (AICDs) are indicated for patients with malignant ventricular arrhythmias that have been refractory to other therapies. A popular combination now is the AICD with a built-in rescue pacemaker. This device will cardiovert or defibrillate any lethal rhythms, then monitor the resulting cardiac rhythm. If the patient's heart rate is below a certain threshold, it will provide emergency pacemaking. Some patients are not aware of this combination of rescue technologies, so may not be able to help EMS providers regarding the unexplained presence of a pacemaker rhythm.

Another new device is a ventricular assist device. A VAD is a mechanical circulatory device used to partially or completely replace the function of a failing heart. It is a pump, and has at least some part of the mechanism outside the body. There are catheters that carry blood into one or more chambers of the heart using the assist pump to power them. These catheters would be torn away or displaced by activity such as CPR. Based on input from the cardiology community, some EMS agencies have written protocols that direct emergency providers not to perform chest compressions on patients with these devices in place until instructed by medical control.

It is nearly impossible for emergency personnel to keep up with the blizzard of new devices and technologies they may come across. Therefore, EMS providers should be comfortable asking patients, families, primary physicians or online medical direction for assistance in dealing with these devices. The experienced EMS provider can apply basic principles of supportive care to manage emergencies until someone familiar with the device can provide definitive care.

Basic principles for dealing with emergencies involving cardiac assist devices:

• Note their presence, and ask the patient or family what they are. In some cases those persons may have to provide explanatory documentation.
• Apply cardiac monitor devices as per usual protocol.
• Apply pulse oximetry to assist in determining if any cardiac device is providing cardiac output that perfuses the entire body, including the extremity where the pulse oximeter probe is placed.
• Keep the patient and any device in the position of most comfort.
• If the device is supposed to be providing an electrical intervention that is available to the rescuer but is not doing it, the rescuer will need to provide that intervention. That applies to defibrillation, cardioversion or electrical pacing.
• Let the patient or family contact their source of care for their device and handle its routine care if they are comfortable doing it.
• Contact online medical direction in crisis situations where medical protocols do not provide immediate guidance.

James J. Augustine, MD, FACEP, is medical advisor for Washington Township Fire Department in the Dayton, OH, area. He is director of clinical operations at EMP Management in Canton, OH, and a clinical associate professor in the Department of Emergency Medicine at Wright State University in Dayton. Contact him at jaugustine@emp.com.