Florida State Paramedic Practice Exam

What rhythm is most commonly assumed when there are no P-waves observed on an EKG?

1. Atrial flutter

2. Atrial fibrillation

3. Sinus rhythm

4. Ventricular tachycardia

The correct answer is: Atrial fibrillation

When P-waves are not observed on an EKG, atrial fibrillation is most commonly assumed. In atrial fibrillation, the electrical signals in the heart become disorganized, leading to a chaotic rhythm and the absence of distinct P-waves. The condition is characterized by irregularly irregular R-R intervals, which can also signify the loss of effective atrial contraction. This lack of organized atrial activity prevents the formation of the typical P-wave that represents atrial depolarization. It’s important to differentiate between the other rhythms as well. Atrial flutter can occasionally present without visible P-waves, but it typically has a characteristic "sawtooth" pattern that can sometimes be detected. Sinus rhythm is defined by the presence of P-waves preceding each QRS complex, which rules it out when there are no P-waves present. Ventricular tachycardia usually shows wide and abnormal QRS complexes but may also lack P-waves, yet it typically indicates a more serious condition. The absence of P-waves primarily points towards atrial fibrillation as the likely rhythm in such scenarios.