ICD Data Predicts Ventricular Tachycardia, Ventricular Fibrillation


May 2, 2008

May 1, 2008 - High-amplitude electrogram T-wave alternans often precedes spontaneous ventricular tachycardia (VT) and ventricular fibrillation (VF) in humans, and can be detected by measuring stored data directly from implantable cardioverter-defibrillators (ICDs), according to a new study published in the May issue of HeartRhythm, the official journal of the Heart Rhythm Society,

ICDs deliver electrical pulses to stop VT/VF after it has started. Study findings may permit ICDs to warn patients who are about to have VT/VF and may ultimately permit ICDs to deliver sequences of electrical pacing pulses that prevent the onset of VT/VF.

Characterized by a very fast and abnormal heart rate, VT is a serious condition that warrants immediate treatment and can lead to VF and sudden cardiac arrest. T-wave alternans is a measure of cardiac electrical instability.

Previous studies have used advanced signal processing techniques to measure T-wave alternans from the routine surface electrocardiogram and predict whether patients are at sufficient long-term risk of VT/VF to warrant implantation of an ICD. Unlike previous studies, the new study led by Charles Swerdlow, M.D., FHRS, Cedars Sinai Medical Center in Los Angeles, CA, looks for short-term predictors of spontaneous VT/VF using electrical signals recorded from ICD electrodes. These electrodes are wires that are permanently implanted in the heart and attached to the ICD.

This is the first study to measure T-wave alternans in humans directly from ICD recordings. To make these measurements, Dr. Swerdlow's team first had to develop and validate a new simple averaging method, suitable for use in an ICD, to measure T-wave alternans from short segments of ICD electrical signals. "Using this method, we found that high-amplitude T-wave alternans occurs frequently just before the onset of spontaneous VT/VF and only rarely at other times,"? said Dr. Swerdlow.

Using this new method, T-wave alternans from ICDs can be measured continuously, enabling the detection of high-amplitude T-wave alternans, which could be used to predict the onset of VT/VF. According to Dr. Swerdlow, the long-term goal of this research is to develop ICD technology that continuously and automatically assesses T-wave alternans for the purpose of warning patients before the onset of VT/VF or even initiating pacing algorithms to prevent VT/VF.

For more information: www.heartrhythmjournal.com

The content of this field is kept private and will not be shown publicly.
Type the characters you see in this picture. (verify using audio)
Type the characters you see in the picture above; if you can't read them, submit the form and a new image will be generated. Not case sensitive.