New Toys for the Electricians

Electrophysiology is the subspecialty of cardiology that deals with the electrical problems of the heart.  At times the heart develops rhythms that break down into the fast rhythms, the slow rhythms and the lethal rhythms.  I have blogged in the past about the development of ICDs or implantable defibrillators and now we are seeing the next generation of these devices.

This paper was published online at the NEJM website and presented at the Heart Rhythm Society Meeting in May.  It was presented by Dr. Bardy who is the founder of the company as well as one of the inventers of the device.  Dr. Bardy  works at the Cleveland Clinic in Cleveland Ohio.

A conventional ICD is implanted by placing a wire into the right top chamber of the heart known as the atrium and a “shocking catheter” into the right lower chamber of the heart known as the ventricle.  There are other ways to do this but the descriptions are outside the scope of this blog.  To do this, the wires are in contact with the blood of the body and special equipment and x-ray is need.  This new device uses a generator that is implanted in the top part of the chest underneath the skin as in a standard ICD.  The new part is an array shocking catheter which is placed under the skin near the heart alongside the sternum.  It is not in actual contact with the heart and is not in the blood stream.

The procedure requires no x-ray and can be done in any suitable surgical location.  This device requires much more energy to work, almost twice as much, and the device is capable of delivering an astounding 80 joules of energy.  Most ICDs deliver shocks in the range of 18 joules.

The study encompassed 55 patients followed for a short 10 months.  One hundren and thirty seven bouts of induced rhythm were terminated.  Twelve episodes of spontaneous rhythms were successfully treated by the device.  For one patient the device would not successfully work in the lab and the patient received a standard ICD.  One patient died of renal failure unrelated to the study.

This is an exciting advance but not ready for prime time.  The device lacks many of the standard features of ICDs; perhaps the most important one is that of tiered therapy.  What is meant by that is that the device delivers therapy in many ways and often terminates the rhythm without delivering a full shock.  In addition the ICDs often function as backup pacemakers for patients.

Not quite ready, but an exciting advance and I applaud the thought leaders here. 

Next: A new device for atrial fibrillation…

Tags: Electrophysiology, Heart Rhythm, Heart Rhythm Society, ICD, implantable defibrillator
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