Which rhythm can precede blocks or Asystole?

Which rhythm can precede blocks or Asystole?

• A. Premature Atrial Complex
• B. Normal Sinus Rhythm
• C. Atrial Flutter
• D. Junctional Rhythm

Answer: (A)

Premature atrial complexes are early atrial impulses that can arrive at the AV node when it is in a relative refractory period. If the premature beat is not conducted to the ventricles, you get a non-conducted PAC and a compensatory pause. That pause can be long enough to look like a block or even a moment of no ventricular activity (asystole) until the next conducted beat occurs. So this rhythm can precede episodes of conduction block or temporary asystole on an EKG tracing. Normal sinus rhythm wouldn’t set up a block or asystole in advance; atrial flutter has a rapid atrial rate with variable conduction and isn’t described as preceding blocks or asystole in the same way; a junctional rhythm originates from the AV node and typically presents with a slower rate and different P-wave morphology, not as a precursor to blocks or asystole.

Premature atrial complexes are early atrial impulses that can arrive at the AV node when it is in a relative refractory period. If the premature beat is not conducted to the ventricles, you get a non-conducted PAC and a compensatory pause. That pause can be long enough to look like a block or even a moment of no ventricular activity (asystole) until the next conducted beat occurs. So this rhythm can precede episodes of conduction block or temporary asystole on an EKG tracing.

Normal sinus rhythm wouldn’t set up a block or asystole in advance; atrial flutter has a rapid atrial rate with variable conduction and isn’t described as preceding blocks or asystole in the same way; a junctional rhythm originates from the AV node and typically presents with a slower rate and different P-wave morphology, not as a precursor to blocks or asystole.