Ventricular complexes, especially when they occur in couplets, triplets, or higher, are very often morphologically altered by fusion with other waves and complexes. The fusion can occur with previous P or T waves or with other complexes of ventricular origin. The fusion of ventricular complexes is typically caused when a supraventricular complex is partially conducted at the same time that a ventricular complex is occurring. The net result is that the complexes morphologically resemble the two parents (Figure 30-18) and are known as a fusion complex.
Figure 30-18 Complex 1 is a supraventricular complex being normally transmitted to the ventricles. This complex would give rise to a nice, tight QRS complex. Complex 2 originates in an ectopic ventricular focus and will give rise to an aberrant, wide QRS complex. The ECG machine translates these bits of electrical information into the fusion complex below. Note that the resulting complex resembles each parent complex slightly.
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DescriptionFusion complexes are critical to understand and diagnose in the more complex ventricular arrhythmias. They are a critical diagnostic point for accelerated idioventricular rhythms and, especially, ventricular tachycardia.
ARRHYTHMIA RECOGNITION
Premature Ventricular Contractions
| Rate: | Single complexes (may occur in sequence) |
| Regularity: | Regular with events |
| P wave:
Morphology: Upright in II, III, and aVF: |
Variable
Inverted No |
| P:QRS ratio: | Not applicable |
| PR interval: | Not applicable |
| QRS width: | Wide |
| Grouping: | None |
| Dropped beats: | None |
DIFFERENTIAL DIAGNOSIS
Premature Ventricular Contractions
This list is not inclusive, as the causes of PVCs are extensive. Normally, PVCs are benign and cause no hemodynamic compromise. However, hemodynamic compromise can rarely occur.