How are rhythms classified when every other beat is identified as a PVC?

The classification of rhythms in this scenario, where every other beat is identified as a premature ventricular contraction (PVC), corresponds to the term "bigeminy." This term is used to describe a pattern where a PVC occurs after every normal beat, essentially creating pairs of beats: one normal beat followed by a PVC.

In bigeminy, the rhythm consists of alternating normal beats and PVCs, which can be visibly recognized in an electrocardiogram (ECG) by the regularity of this pattern. This alternation significantly impacts how the heart functions, as each PVC interrupts the normal rhythm, leading to variability in heart rate and potentially affecting cardiac output.

Understanding this classification is essential for the interpretation of arrhythmias in polysomnography, as it relates to the overall assessment of patient cardiac health during sleep studies.