Dysrhythmia Cardiac Rhythm Interpretation

Question 1

What is the defining characteristic of atrial fibrillation on an ECG?

Accepted Answer

Irregularly irregular rhythm with no P waves

Answer

Atrial fibrillation (AFib) is definitively characterized on an ECG by an 'irregularly irregular' ventricular rhythm and the absence of distinct, organized P waves. Instead of clear P waves, chaotic fibrillatory waves are often seen, reflecting the uncoordinated electrical activity within the atria. This distinct pattern helps differentiate AFib from other arrhythmias.

Question 2

Which cardiac rhythm is characterized by a prolonged PR interval greater than 0.20 seconds?

Accepted Answer

First-degree AV Block

Answer

First-degree AV block is characterized by a consistent prolongation of the PR interval beyond the normal upper limit of 0.20 seconds. This indicates a delay in electrical conduction from the atria to the ventricles through the AV node, but every atrial impulse still reaches the ventricles. The prolonged PR interval is the defining diagnostic criterion for this specific type of heart block.

Question 3

What is the key ECG feature of ventricular tachycardia?

Accepted Answer

Wide QRS complexes with a fast rate

Answer

Ventricular tachycardia (VT) originates from the ventricles, leading to abnormal, wide QRS complexes (typically >0.12 seconds) as ventricular depolarization is delayed. The 'tachycardia' aspect means the heart rate is fast, usually between 100-250 bpm. This combination of wide QRS and a rapid rate is the hallmark ECG feature distinguishing VT from supraventricular tachycardias.

Question 4

Which rhythm is described by a sawtooth pattern of P waves on an ECG?

Accepted Answer

Atrial Flutter

Answer

Atrial flutter is characterized by a rapid, regular atrial rhythm, typically between 250-350 bpm, caused by a re-entrant circuit in the atria. On an ECG, this manifests as distinct, uniform 'flutter waves' that resemble a sawtooth pattern, especially prominent in leads II, III, and aVF. These flutter waves represent the rapid atrial depolarization.

Question 5

Which of the following rhythms is considered a medical emergency due to its lack of cardiac output?

Accepted Answer

Ventricular Fibrillation

Answer

Ventricular fibrillation (VF) is a chaotic electrical activity in the ventricles that results in ineffective quivering rather than coordinated contractions. This completely prevents the heart from pumping blood, leading to an immediate cessation of cardiac output and collapse. Without immediate defibrillation, VF is rapidly fatal, making it a critical medical emergency.

(DC) Dysrhythmia Certification Practice Test

(DC) Dysrhythmia Certification Practice Test

Dysrhythmia Cardiac Rhythm Interpretation