Pacemakers and death

Here’s a morbid thought.  Take a walk through that part of a cemetery where new arrivals are housed and cast a glance around the grounds where the recently deceased have been laid to rest.  Beneath your feet are a half-dozen or so cardiac pacemakers quietly toiling away, providing unneeded electrical impulses to their owners sixty times per minute while their batteries slowly deplete and wind their way down to lifelessness.  The devices, like the faithful dog that stands watch on the doorstep of a deceased owner who will never return, continue to function flawlessly without the slightest clue that their effort will never again result in the pulsating blood of a living body.

This concept seems to come right out of a horror movie with lifeless zombies propelled through the night by the unceasing prodding of their artificial pacemakers.

The reality of the situation is not quite so morbid and much less exciting, despite the fact that there is truth in the premise: we don’t turn off pacemakers when patients die (and we don’t remove them, either).  Since people with pacemakers continue to have new batteries implanted whenever the old one gives out they will invariably be outlived by their pacemaker.  What happens when the rest of the body dies but the pacemaker keeps pacing?

Just last week I had a discussion with a relatively healthy patient who is a candidate for a pacemaker.  He and his wife were full of questions, having come to the appointment prepared with extensive information from the internet.  One question related to the man’s ability to actually die once he gets the device.  “If I’m on my deathbed with cancer will the pacer keep me alive even when I want to pass away?”

It was this line of questioning that prompted me to write on this topic.  I have had several other patients broach this subject and have likely had an even greater number wonder about it without working up the courage to ask me.  Surprisingly, a large number of doctors and nurses are also relatively naïve about the interaction between a functioning pacemaker and a nonfunctioning human.

The purpose of a pacemaker is simple: it prevents your heart beat from going too slow.  The device is attached to the heart via wires called leads and spends its life looking for native impulses arising from the cardiac muscle.  If your natural pulse rate drops below 60 (or whatever our programmed number is) the pacemaker will begin stimulating the heart with an imperceptible electrical shock once every second.  The current passes through the tip of the lead into the adjacent heart muscle, and then spreads to the entire ventricle by flowing from cell to cell at lightning speed.  The stimulus triggers a brief restructuring of proteins and results in contraction of the muscle fibers.  Within a fraction of a second the entire ventricle wrings out somewhere around a hundred milliliters of blood into the aorta.

To summarize this series of events:
Step 1. Pacer sends electricity to lead tip.
Step 2. Electrical impulse conducts to tissue at the point of contact and spreads throughout the heart.
Step 3. The electrical impulse causes the heart to contract.

Now let’s talk about what happens to the heart at the moment of imminent demise.  One thing that a healthy body does really well is eliminate waste products (and, no, I am not complimenting you on your talents in the bathroom): the lungs eliminate carbon dioxide and the kidneys and liver break down and eliminate unwanted metabolic byproducts.  As these important organs deteriorate your blood becomes saturated with metabolic detritus and becomes an inhospitable milieu for normal cellular function.  Most notably, the pH of the blood drops and the normally neutral serum slowly turns into a weak acid.  Once the pH falls more than a fraction of a point the heart muscle becomes incapable of propagating an electrical stimulus or mounting an effective ventricular contraction.

In other words, no amount of external electricity will trigger a contraction once the heart muscle becomes electrically inert and mechanically dormant.  Step 1 (in the cascade described above) doesn’t matter once steps 2 and 3 fail.  It’s for this reason that we don’t turn off pacemakers in dying patients—it just doesn’t make any difference.

Of course that doesn’t stop people from asking us to decommission implanted devices.  Every now and then a doctor or family member will request that we shut down a pacer on a patient who is dying and in the last stages of palliative care.  Since other lifesaving services are being rolled back—such as antibiotics, IV fluids, and artificial ventilation—why not remove cardiac pacing as well?

Here’s another concept I’d like to clarify.  The purpose of a pacemaker in most people is to improve the quality of life by increasing exercise capacity, preventing fainting, and providing more energy.  It is actually somewhat uncommon that a patient’s heart would simply stop beating without the services of a pacemaker.  In other words, for most pacemaker patients, their device is a quality-of-life rather than a life-or-death therapy.  I don’t have exact numbers on how many patients would simply die if their pacemakers were to shut down today, but I’d put it at no more than 20%.

Turning off a functioning pacemaker in a terminally-ill patient would most likely not lead to his or her rapid demise.  In a patient who is dying but not yet on the deathbed, such an intervention would quite possibly lead to a dramatic worsening in quality of life without hastening end of life, with the patient suffering even more fatigue and periodic falls or loss of consciousness.

The management of pacemakers in the terminally ill population is by no means straightforward and is frequently debated in the medical literature.  In the US there is no law against turning off a pacemaker in a dying patient (such laws exist in some countries) and the consensus among professionals is that artificial cardiac pacing is no different than artificial ventilation and can be removed upon consensus among the patient, family and caregivers.  The simple fact remains, however, that in most patients such a decision makes little difference to the patient’s ultimate outcome and may produce unwanted results prior to death.

This issue is distinctly different from subject of implantable cardioverter-defibrillators (ICDs) in this patient population.  This device differs from a pacemaker in its ability to deliver a jarring shock to the heart in the event of cardiac arrest.  In a patient dying of other causes, being able to pass away suddenly and without suffering from a sudden cardiac arrhythmia would be a blessing rather than a curse.  For patients such as these we routinely offer to deprogram the shock function of the ICD and allow them to pass away without the intrusion of a 35-Joule kick to the chest.

In summary, if you are a patient with a pacemaker you can stop worrying about your device keeping your body alive long after the rest of you departs this earthly existence.  There will be no escapees from cemeteries or zombies pacing the streets at night searching for edible brain tissue.  Your pacemaker will be a reliable, useful companion to you until your body decides it’s no longer needed.  After that your pacer will be no more alive than the fillings in your teeth or the artificial joint in your knee and will slowly and quietly drain its battery as you move on to better things.

Comments

  1. matt swanson says:

    My dear Dr. Van De Graaf, I am so relieved that my cardiologist is not only a heart expert but a leader in zombie research. Bravo!