Ventricular Rhythms: General Overview
The ventricular rhythms occur either as a result of an escape mechanism or due to increased automaticity. Some ventricular rhythms actually occur as a result of reentry loops. In this section, we will be reviewing the most important ventricular rhythms. These include ventricular escape beats, ventricular premature depolarizations, idioventricular rhythm, accelerated idioventricular, ventricular tachycardia, ventricular flutter, and ventricular fibrillation (Figure 29-11). At the end of this section, Chapter 36, Wide-Complex Tachycardias: Criteria, discusses the differential diagnosis of the wide-complex arrhythmias. It will be worth your while to review and thoroughly understand this particular chapter. Finally, we will take a look at the agonal rhythms and asystole (complete absence of ventricular activity).
Figure 29-11 The spectrum of the ventricular rhythms. In addition, there are the agonal rhythms and asystole (which is considered the absence of any ventricular rhythm). Notice that in previous chapters, the bar had sections that were green, to symbolize some level of stability. In the ventricular rhythms, there is no such luxury, as any of them can be life-threatening.
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DescriptionAs mentioned previously, the intrinsic rate of the ventricular pacemakers ranges from 30 to 45 BPM. The ventricular pacemakers are the last fail-safe mechanism for the heart. Their failure signifies death. In addition, the hemodynamic status of the body is completely dependent on the ventricular rate and their appropriate contraction. Take every ventricular rhythm that you encounter very seriously. Wide-complex rhythms are generally dangerous and should be treated with extreme urgency and care.
Additional Information
Josephson’s Sign
Josephson’s sign refers to the presence of a notch in the downstroke of the S wave present in many complexes of ventricular origin (Figure 29-12). The presence of the notch is very useful in distinguishing a ventricular complex from an aberrantly conducted supraventricular complex or a complex with an underlying LBBB or RBBB.
Figure 29-12 Josephson’s sign.
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Additional Information
Brugada’s Sign
Brugada’s sign refers to a distance of at least 0.10 seconds from the onset of the QRS complex to the very bottom (or nadir) of the S wave that is present in many complexes of ventricular origin (Figure 29-13). The presence of this distance interval is a very useful sign in distinguishing a ventricular complex from an aberrantly conducted supraventricular complex or a complex with an underlying LBBB or RBBB.
Figure 29-13 Brugada’s sign.
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