Recognition of ventricular fibrillation concomitant with pacing artifacts

Introduction. In pre-hospital settings recognition of underlying rhythm in patients with ventricular stimulation can be difficult especially when a 3-lead electrocardiogram (ECG) is analyzed. This fact is particularly important in patients with life-threa-tening cardiac dysrhythmias. The pacing spikes in the ECG of a patient with cardiac arrest due to ventricular fibrillation may be misdiagnosed as QRS complexes. 

Aim of the study. The aim of this study was to assess emergency medical care students’ accuracy in recognizing ventricular fibrillation when pacing spikes are present.

Material and methods. The study group consisted of 39 emergency medical care students, 16 males and 23 females, aged 21 - 23. Subjects were at the midpoint of their 3-year university healthcare professional education. Subjects were asked to interpret electrocardiograms presenting ventricular fibrillation with concomitant pacing artifacts, ventricular fibrillation and atrial fibrillation with ventricular pacing, respectively. Students were trained in recognition of ECG tracings presenting ven-tricular stimulation, atrial fibrillation and ventricular fibrillation. They were instructed that the duration of the QRS complex in adults is at least 0.06s and that pacemaker stimuli are shorter. Prior to the examination, an electrocardiogram similar to the abovementioned, with ventricular fibrillation and pacemaker stimuli, was not presented.

Results. Only one student (out of 39) recognized ventricular fibrillation with pacemaker stimuli present; the majority of stu-dents (92%) incorrectly interpreted the rhythm as atrial fibrillation or atrial flutter. The ECG with isolated ventricular fibrillation was correctly interpreted by all but two students who recognized polymorphic ventricular tachycardia and 62% of students correctly recognized ventricular pacing whereas none of them recognized atrial fibrillation.

Conclusions. 1. The skills of recognizing ventricular fibrillation in patients with concomitant ventricular pacing are poor among emergency medical care students.

2. The ECG tracing showing concomitant ventricular fibrillation and pacing stimuli should be included in teaching programs for emergency medical care students. An ongoing quality improvement program may reduce the rate of mistakes in ECG analysis in rare cases with life-threatening emergencies.

ventricular fibrillation, cardiopulmonary resuscitation, trai-ning, cardiac pacing

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