In this chapter we will cover the ventricular escape rhythms and the idioventricular rhythms. We will begin by looking at individual ventricular escape complexes. Then, we will move on to the more complicated ventricular escape rhythms. When there are three or more ventricular escape complexes in a row, we call this an idioventricular rhythm.
Idioventricular rhythms, however, are a bit more complicated. They can occur as an escape rhythm, or they can occur due to the increased automaticity of a single ventricular ectopic pacemaker. This increased automaticity may lead to rates that are faster than the intrinsic rate of the upper pacemakers.
When the rate is faster than the intrinsic pacemakers, the ectopic pacemaker actually takes over the pacing function of the heart, and so they are not escape rhythms in these cases. These fast ventricular rhythms are known as the accelerated idioventricular rhythms. At this point, the line frequently gets blurred with another lethal arrhythmia, which we will cover in the next chapter, ventricular tachycardia.
A word of caution about treatment before we begin. The ventricular escape pacemakers are the last line of defense for the heart when it comes to maintaining function and a cardiac output. You need to be extremely careful in treating any ventricular escape or idioventricular rhythm. If you succeed in eradicating the ventricular response, you may be left without any electrical activity whatsoever. This is not a good thing!