Hypertrophic Cardiomyopathy Center

ICD & Pacemaker

Implantable Cardioverter Defibrillator (ICD)

An important part of the work up for patients with hypertrophic cardiomyopathy is an assessment of the risk of dangerous heart rhythms. Fortunately, for those patients at risk, there is now the option of protection in the form of an implantable cardioverter defibrillator. This is a device a few inches in diameter that is inserted under the collarbone on one side. Leads are passed through veins to the heart so that the heart rhythm can be monitored at all times.

If a dangerous rhythm is detected, the device will begin a series of treatments that culminate in an electrical shock aimed at jolting the heart back into normal rhythm. It is a much less powerful shock than those administered by external defibrillators.

Illustration of an ICD
Click Image to Enlarge

The operation to implant the device takes about one hour and is usually done using local anesthetic and sedation. However, every device is then tested under general anesthetic by putting you briefly into a dangerous rhythm to confirm that the device can shock you out of it. Some devices are also capable of pacing.

An implantable cardioverter defibrillator is the most effective means of managing the risk of sudden cardiac arrest. This device is recommended for patients with hypertrophic cardiomyopathy with:


A pacemaker can be implanted using a very similar procedure to how an ICD is placed. Early trials of pacemaker therapy in hypertrophic cardiomyopathy suggested a significant benefit from simply changing the activation sequence of heart contraction. Although the pressure build up was decreased in most studies, it turned out that this did not translate to benefit the patients, so pacing as a therapy is not routinely recommended. However, in certain subsets of patients, it can be helpful. Newer technologies may result in further trials of this approach.

Stanford Physicians

Marco Perez, MD

Marco Perez, MD

Instructor, Cardiovascular Medicine

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