Incidence and Factors Predicting Skin Burns at the Site of Indifferent Electrode during Radiofrequency Catheter Ablation of Cardiac Arrhythmias

Radiofrequency catheter ablation (RFA) has become a mainstay for treatment of cardiac arrhythmias. Skin burns at the site of an indifferent electrode patch have been a rare, serious, and likely an underreported complication of RFA. The purpose of this study was to determine the incidence of skin burns in cardiac RFA procedures performed at one institution. Also, we wanted to determine the factors predicting skin burns after cardiac RFA procedures at the indifferent electrode skin pad site.Methods.A retrospective case control study was performed to compare the characteristics in patients who developed skin burns in a 2-year period.Results.Incidence of significant skin burns after RFA was 0.28% (6/2167). Four of the six patients were female and all were Caucasians. Four controls for every case were age and sex matched. Burn patients had significantly higher BMI, procedure time, and postprocedure pain, relative to control subjects (p< 0.05, one-tailed testing). No one in either group had evidence of dispersive pad malattachment.Conclusions.Our results indicate that burn patients had higher BMI and longer procedure times compared to control subjects. These findings warrant further larger studies on this topic.

Monophasic action potential recordings: which is the recording electrode?

The aim of this article is to provide an overview of current debate on the monophasic action potential (MAP) recording technique, specifically whether the depolarizing or the reference electrode is responsible for recording the MAP waveform. A literature search was made using key words including monophasic action potential, MAP, electrophysiological basis, recording electrode, depolarizing electrode, contact electrode, indifferent electrode, and reference electrode. References from articles were screened for additional relevant papers. Articles published by the different experimental groups claim that depolarizing electrode, but not reference electrode, records MAPs from the myocardium. This can be more accurately described when considering biophysical theory, which states that MAP is a bipolar signal with contributions from not only the depolarizing electrode but also remote activation at the reference electrode. It is not meaningful to claim that one is the recording electrode because potential differences must be measured between two points in space. Nevertheless, the MAP technique is useful for assessing the local electrical activity of the myocardium in contact with the depolarizing electrode. It is important to have the recording electrode in close proximity with the reference electrode to minimize contamination from far-field signals.