Pacemaker Malfunctions

DR HIMANSHU GUL MIRANI

EMERGENCY PHYSICIAN

With increasing number of patients walking home with a pacemaker for their cardiac care, it has become quite a common scenario to encounter a bizarre ECG strip with a symptomatic patient and maybe a malfunctioning pacemaker! It’s extremely vital to sense a pacemaker malfunction so as to coordinate with the cardiology team and the manufacturer for further evaluation and management.

In this article I have tried to highlight some very common pacemaker malfunction phenomena and the possible patient presentation to the ER along with a simplified scheme to approach such patients and concluded it with some handy tips for the patients on pacemakers.

Common errors and their causes:-

1. Self tampering

Called as Twiddler’s Syndrome, it’s due to fiddling of the device by the patient themselves. These patients need more counseling to understand the implications of such acts.

2. Runaway

Rare, but seen in case of low battery nearing replacement, especially in patients who have irregular follow up. Low battery causes low amplitude pulses and inadequate stimulus. There is non-physiological erratic heart stimulation with rate up to 2000 bpm!

It needs deactivation of the pacemaker using a magnetic field but definitive treatment is replacement of the battery.

3. Endless loop tachycardia

It s caused due to retrograde conduction of ventricular impulse into the atria leading to a vicious endless loop producing pacemaker mediated tachycardia. This high heart rate may induce ischemic changes in the heart muscle. Magnetic inhibition is warranted to terminate the tachycardia.

4. Sensing issues

Under-sensing may occur when the pacemaker would not detect the inherent cardiac activity and hence fire asynchronously. It may occur due to lead dislodgement or insulation breach or programming error.

Over-sensing would occur when some non-cardiac activity is detected as cardiac electrical impulses leading to malfunction. Over-sensing stimuli may be from muscle activity of diaphragm or pectoralis or from external sources like MRI.

5. Failure to capture

When the pacemaker stimuli are not followed by atrial or ventricular depolarization, it’s referred to as failure of capture by the pacemaker. It can be due to numerous causes like circuit failure, dyselectrolytemia, infarction or fibrosis under the pacemaker tip etc.

Such patients need temporary pacing till the definitive management is done by correcting the device setting or treating the pathology like electrolyte imbalances.

6. Pacemaker syndrome

Seen in ventricular pacing, where due to asynchrony, atria may contract when the ventricles are in systole from pacemaker impulse. Hence the atria contract against closed AV valves, leading to worsening of patient symptoms rather than improvement.

Such patients need Dual Chamber Pacemakers rather than just ventricular stimulation.

Patient presentation:-

·         Worsening of symptoms.

·         Chest pain.

·         Engorged neck veins.

·         Shortness of breath.

·         Palpitations.

·         Manipulation marks over the site of pacemaker insertion indicating tampering.

·         Dizzy feeling.

·         Lightheadedness.

·         Racy pulse.

How an ER physician should proceed:-

·         Take the vitals.

·         Give supplemental oxygen.

·         Give a fluid challenge for low BP, may need inotropic support.

·         Get a 12 lead ECG.

·         Send blood samples for electrolytes, ABG – correct any imbalances.

·         Send cardiac enzymes to detect any fresh insult to the heart.

·         Send drug levels of medicines which the patient is on and which can alter the conduction (eg – flecainide).

·         External pacing may be needed.

·         Do a chest x-ray as a lot of clues like lead dislodgement/ lead fracture etc can be noted on the x-ray. Ask for an over penetrated film. A CT-Scan is more conclusive.

·         Ask for regularity of follow up with the cardiologist and the last check date, note the model type and pacemaker code and get in touch with the cardiologist and electro-physiologist for a possible recalibration or battery change.

·         Magnet application – it helps to convert the pacemaker to asynchronous mode and thus detect low battery or failure to capture.

·         Always keep cardiologist, CTVS surgeon and electro-physiologist in the decision making loop.

Tips for patients:-

·         In case patients sense any of the symptoms as enlisted above – they must seek medical help immediately at the nearest centre.

·         Be regular in follow up – it would ensure proper care of the pacemaker and it’s various components like leads, generator, battery etc. Malfunction of any component can lead to device failure.

·         Always carry with you a laminated card mentioning the pacemaker type, model, manufacturer’s name and contact, treating doctor’s name and contact number, list of current medications, any known allergies & names and contacts of people to be informed case of emergency.

·         Don’t manipulate/ fiddle with the pacemaker.

·         In case external hindrance to pacemaker function is expected as in case of MRI – inform the doctor/ attendant about it.

·         The manufactures give a list of possible conditions which interfere with the pacemaker – avoid these conditions always.

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