Rhythm InterpretationQuestion 32 of 100
Which premature ventricular contraction pattern is considered most dangerous because it can trigger ventricular tachycardia or fibrillation?
a.A unifocal PVC that is late in the cycle
b.An interpolated PVC between two normal beats
c.A PVC followed by a full compensatory pause
d.A PVC that lands on the T wave of the preceding beat
Explanation
A PVC falling on the T wave, called the R-on-T phenomenon, arrives during the vulnerable relative refractory period of repolarization and can precipitate ventricular tachycardia or fibrillation. Unifocal PVCs that arrive later in the cycle are the least worrisome type. An interpolated PVC does not disturb the underlying rhythm, and a compensatory pause is a normal feature of most PVCs rather than a warning sign.
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