PREMATURE VENTRICULAR CONTRACTIONS (PVCs) PVCs are due to impulses originating from single or multiple areas in the ventricles. The ECG characteristics of PVCs are as follows:
1. There is a premature and wide QRS complex.
2. There is no preceding P wave.
3. The ST segment and T wave of the PVC are directed opposite the major QRS deflection.
4. Most PVCs do not affect the sinus node, so there is usually a fully compensatory postectopic pause or the PVC may be interpolated between two sinus beats.
5. Many PVCs have a fixed coupling interval (within 0.04 s) from the preceding sinus beat.
6. Some PVCs are conducted into the atria, producing a retrograde P wave (Fig 24:16).
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