Q: How could a failing ICD kill someone? My idea is for the victim to be an older individual who has this kind of device implanted in him. The killer hacks the wireless device in a similar manner to this: www.secure-medicine.org/icd-study/icd-study.pdf. According to this paper, the two attacks that seem most dangerous are to turn off therapy or to administer a V-fib shock intended for test purposes during the implantation procedure. How long would these take to kill someone? How healthy would someone be that had a pacemaker? How would this change if the victim had a mechanical cardiac pump?
Adam High, Marysville, CA
A: An AICD (Automatic Implantable Cardioverter Defibrillator) is a fancy pacemaker that has a defibrillator built in to it. It is used in people who have very severe and dangerous cardiac arrhythmias such as ventricular tachycardia and ventricular fibrillation, both of which are typically immediately deadly. These rhythms can occur in anyone. but are very problematic in those with severe coronary artery disease and/or severely damaged heart muscles, which we call a cardiomyopathy. These people are highly prone to death from these dangerous arrhythmias, so these are the types of patients who receive these devices. These are also the types of patients that are candidates for cardiac transplants and artificial hearts, or what are called left ventricular assist devices (LVADs). Since people who receive these assist devices have extremely damaged heart muscles and are at a very high risk of dangerous arrhythmias, they will also often receive an AICD at the same time.
An AICD basically monitors the cardiac rhythm, and when a dangerous rhythm occurs, they fire an electrical impulse which shocks the heart back to a normal rhythm. Sometimes it stops the heart and if so the pacemaker portion of the device will kick in. Some people have these devices implanted as a precautionary measure and never use them, while others have significant problems with arrhythmias and the device discharges more frequently. What this means is that turning off the defibrillator portion of the device will leave the victim a jeopardy but will not in of itself cause death. If he is one of those individuals that never uses the device, or only rarely, then your killer would have to wait a long time, and maybe forever, before the victim had a lethal change in heart rhythm. And since these devices are frequently checked, typically every 1 to 3 months, it would be noted during the check that this portion of the device had been turned off. So that leaves a narrow window for something serendipitously to happen. Most killers want more assurance that their method will work.
A better method is to trick the device into firing an impulse in the hopes that it would start a dangerous arrhythmia. Again this is not assured. In the cardiac catheterization lab, after the device is implanted, it is tested by inducing one of these arrhythmias. But the heart doesn’t always cooperate. Sometimes the rhythm cannot be induced. That would be the same situation with your victim. That is hacking the device and causing it to deliver a shock that was an appropriate might or might not cause the desired effect––a deadly cardiac arrhythmia.
Neither of these methods are assured of working, but of the two, I would go with hacking the device and delivering an inappropriate jolt of electricity. This would have the greatest probability of causing the result your killer wants. If so, death would be immediate.