Friday, June 08, 2007

Cheney to Have Routine Defibrillator Change

Vice President Dick Cheney is to have his implantable cardiac defibrillator (ICD) battery changed. Actually, he'll have the whole device changed, with the exception of the leads - those will likely be re-used. It is a common misconception by patients needing an ICD battery change that only the battery is changed. The battery is housed with the capacitors and computer logic circuitry in one hermetically-sealed titanium can, to which the leads that extend to the heart are attached with small fixation screws. As such, the whole defibrillator can will be exchanged in a smae-say procedure.

It has not been publically discussed if Vice President Cheney has had some heart failure, or how much he uses his device to pace his heart. No doubt his doctors have considered if his device should be upgraded to a biventricular pacing defibrillator which can "resynchronize" and re-coordinate the heart's muscular contraction to improve symptoms of heart failure, since this would be an ideal time to do so while his device is exposed.

But usually with politicians eager to make light of the circumstances at hand, they usually opt for as little as possible (i.e., get in and get out) to minimize possible risks and media exposure. Hopefully, this will be the right decision.

As to which device he'll receive? Since he's had Medtronic devices previously, it's likely he'll receive a Virtuoso ICD this time around (which is a dual-chamber ICD that can be interrogated wirelessly). If his doctors should decide to upgrade his device to a biventricular ICD, then it would likely be with a Concerto ICD.



Anonymous said...

Wouldn't it be better to keep the pacemaker and change Cheney? Just askin'.

Anonymous said...

There is no way that the wireless ability of the defib will be enabled. Any thoughts?

DrWes said...

Anony 07:14 -

During routine day-to-day use, the wireless feature of these ICD's is not enabled. A specific "handshake" between the programmer and the ICD (verified by the device's serial number) is initiated by Medtronic's programmer. Only then will wireless communication be enabled. The frequency used for these devices was licensed by Medtronic (405-412MHz) because they needed a bandwidth that could be used internationally for communicating w/these devices that would not interfere w/cellular services in varying countries. Additionally, there is an interesting way that the device can change frequency transmissions in realtime, should a specific tranmitting frequency become noisy while communicating w/the programmer. Th etransmitting distance of the telemetry system for the device is limited to about 20-30 yards, max, I believe, so a clandestine attempt to reprogram Mr. Cheney's device would (a) have to be done in the immediate vicinity of the device, and (2) only with a wirelessly-enabled programmer.