What is the primary difference between atrial bigeminy and atrial trigeminy on EKG observation?

What is the primary difference between atrial bigeminy and atrial trigeminy on EKG observation?

• A. Atrial bigeminy includes two normal cycles before a PAB, while trigeminy has one
• B. Atrial trigeminy follows two normal cycles with a PAB, while bigeminy has one
• C. There is no difference; both look the same
• D. Both conditions are clinically insignificant

Answer: (B)

The primary difference between atrial bigeminy and atrial trigeminy lies in the pattern of normal cycles and premature atrial beats (PABs). In atrial bigeminy, the sequence consists of one normal heartbeat followed by one premature atrial beat, establishing a consistent pattern where these beats alternate. On the other hand, atrial trigeminy involves a pattern where two normal heartbeats precede each premature atrial beat. Therefore, in trigeminy, you will observe two regular beats followed by a PAB, while in bigeminy, there is only one normal beat before each PAB. Recognizing this pattern is crucial for understanding the underlying cardiac rhythms and their implications in patients.