EKG certification Certification EKG Arrhythmias & Dysrhythmias 1 — Questions and Answers
Question 1: A rhythm strip shows a regular rhythm at 60 bpm with a PR interval of 0.28 seconds that remains constant throughout. QRS complexes are narrow. What is the most likely interpretation?
- First-degree AV block (Correct answer)
- Second-degree AV block Type I (Wenckebach)
- Third-degree AV block
- Junctional rhythm
Correct answer: First-degree AV block
First-degree AV block is defined by a consistently prolonged PR interval (>0.20 seconds) with every P wave followed by a QRS complex and no dropped beats. The rhythm remains regular and the QRS is typically narrow.
Question 2: A patient's EKG shows progressive lengthening of the PR interval over several beats, followed by a non-conducted P wave (dropped QRS), then the cycle repeats. Which dysrhythmia does this describe?
- First-degree AV block
- Second-degree AV block Type I (Wenckebach) (Correct answer)
- Second-degree AV block Type II (Mobitz II)
- Complete heart block
Correct answer: Second-degree AV block Type I (Wenckebach)
Mobitz Type I (Wenckebach) is characterized by progressively lengthening PR intervals until a P wave is not conducted and a QRS is dropped. The pattern then resets and repeats cyclically.
Question 3: On a 12-lead EKG, a patient shows a short PR interval (<0.12 seconds) and a slurred upstroke at the beginning of the QRS complex (delta wave) with a widened QRS. The patient complains of palpitations. What is the most likely diagnosis?
- Right bundle branch block
- Wolff-Parkinson-White (WPW) syndrome (Correct answer)
- Left ventricular hypertrophy
- Accelerated idioventricular rhythm
Correct answer: Wolff-Parkinson-White (WPW) syndrome
Wolff-Parkinson-White syndrome presents with a short PR interval, delta wave (slurred initial QRS deflection), and widened QRS due to an accessory pathway (Bundle of Kent) bypassing the AV node and pre-exciting the ventricles.
Question 4: You observe a rhythm strip with no discernible P waves, a regular ventricular rate of 38 bpm, and wide, bizarre QRS complexes. The patient is hemodynamically unstable. What rhythm is this?
- Accelerated junctional rhythm
- Idioventricular rhythm (Correct answer)
- Third-degree AV block with junctional escape
- Atrial flutter with aberrant conduction
Correct answer: Idioventricular rhythm
Idioventricular rhythm originates in the ventricles, producing wide and bizarre QRS complexes at a rate of 20–40 bpm. The absence of P waves and the slow ventricular escape rate distinguish it from junctional rhythms, which produce narrow QRS complexes.
Question 5: A patient's rhythm strip shows a regular P-to-P interval and a regular R-to-R interval, but the PR intervals vary with no consistent relationship between P waves and QRS complexes. The ventricular rate is slower than the atrial rate. What is this rhythm?
- Second-degree AV block Type II
- Atrial tachycardia with variable block
- Third-degree (complete) AV block (Correct answer)
- Accelerated idioventricular rhythm
Correct answer: Third-degree (complete) AV block
Third-degree (complete) AV block occurs when no atrial impulses conduct to the ventricles. The atria and ventricles beat independently (AV dissociation), resulting in regular but unrelated P waves and QRS complexes, with the ventricular rate slower than the atrial rate.
Question 6: A patient presents with a sudden-onset regular tachycardia at 170 bpm. The EKG shows narrow QRS complexes and retrograde P waves buried in or just after the QRS. Vagal maneuvers terminate the rhythm abruptly. What is the most likely diagnosis?
- Atrial flutter
- Atrioventricular nodal reentrant tachycardia (AVNRT) (Correct answer)
- Multifocal atrial tachycardia
- Accelerated junctional rhythm
Correct answer: Atrioventricular nodal reentrant tachycardia (AVNRT)
AVNRT is the most common paroxysmal supraventricular tachycardia (SVT). It results from a reentrant circuit within the AV node, producing a regular narrow-complex tachycardia with retrograde P waves very close to or hidden within the QRS. It characteristically terminates with vagal maneuvers or adenosine.
EKG certification Certification EKG Arrhythmias & Dysrhythmias 1
A rhythm strip shows a regular rhythm at 60 bpm with a PR interval of 0.28 seconds that remains constant throughout.
QRS complexes are narrow.
What is the most likely interpretation?