Question

An ECG strip of a patient in the ED reveals the following rhythm. Which feature would the healthcare provider interpret as indicating atrial fibrillation?

1) P waves are absent
2) QRS complexes are irregular
3) PR intervals are prolonged
4) T waves are inverted

Answer 1

The absence of P waves on an ECG strip indicates atrial fibrillation, characterized by disorganized atrial activity and irregularly irregular QRS complexes without identifiable P waves.

Step-by-step explanation:

The healthcare provider would interpret the absence of P waves as indicating atrial fibrillation. This is because during atrial fibrillation, the atrial activity is disorganized, leading to an irregular electrical pattern prior to the QRS complex, and is reflected in the ECG as either very fine fibrillatory waves or a totally irregular baseline without identifiable P waves. This results in an increase in the frequency between the QRS complexes, making them irregular, which is a hallmark of atrial fibrillation.

In addition to the absence of P waves, atrial fibrillation is characterized by irregularly irregular QRS complexes, meaning there is no consistent pattern to their occurrence. Contrary to other changes like prolonged PR intervals, inverted T waves, or abnormal QRS shape seen in different cardiac conditions, the absence of P waves and the unpredictability of the QRS complex timing distinctly signify atrial fibrillation.