Recent interest has focused attention on a type of ectopic ventricular rhythm which appears to have unique characteristics that distinguish it from the more rapid ventricular tachycardia discussed in the preceding two ECG analyses. These features include the manner in which the arrhythmia begins and ends, as well as the relatively slow rate and usually benign course.
The manifest onset of this arrhythmia is generally gradual (non-paroxysmal) rather than sudden and occurs when the rate of ectopic ventricular discharge exceeds the sinus rate or the rate of whatever supraventricular rhythm is dominant. This may happen in a variety of ways; for example, when the supraventricular rate slows or the supraventricular impulse is blocked (S-A or A-V block) in transit to the ventricles, the ectopic ventricular rhythm may escape and assume pacemaker control for a series of cardiac cycles (Fig 1 and 2). The ectopic mechanism may also begin with a
Zipes DP, Fisch C. Accelerated Ventricular Rhythm. Arch Intern Med. 1972;129(4):650-652. doi:10.1001/archinte.1972.00320040126017