CCT Cardiac Monitoring & Emergency Response 4 — Questions and Answers
Question 1: A patient's monitor alarm triggers for a heart rate of 42 bpm with narrow QRS complexes and visible P waves before each QRS. What rhythm does this most likely represent?
- Third-degree AV block
- Junctional escape rhythm
- Sinus bradycardia (Correct answer)
- Accelerated idioventricular rhythm
Correct answer: Sinus bradycardia
A slow rate with a consistent 1:1 P-to-QRS relationship and narrow complexes indicates sinus bradycardia, where the SA node is simply firing slowly.
Question 2: Which ECG pattern is associated with Wolff-Parkinson-White (WPW) syndrome during normal sinus rhythm?
- Prolonged QT interval and U waves
- Short PR interval and delta wave (Correct answer)
- Right bundle branch block pattern and ST changes
- Peaked T waves and tall QRS voltages
Correct answer: Short PR interval and delta wave
WPW is identified by a short PR interval (<0.12 s) and a delta wave (slurred upstroke of the QRS) caused by ventricular pre-excitation via an accessory pathway.
Question 3: The cardiothoracic technician notices ST elevation in leads V1–V4 with reciprocal depression in II, III, and aVF. Which coronary artery is most likely occluded?
- Right coronary artery (RCA)
- Left circumflex artery (LCx)
- Left anterior descending artery (LAD) (Correct answer)
- Posterior descending artery (PDA)
Correct answer: Left anterior descending artery (LAD)
The LAD supplies the anterior wall and septum; its occlusion causes ST elevation in precordial leads V1–V4 with reciprocal inferior changes.
Question 4: When a patient's transcutaneous pacemaker is capturing at 70 bpm but the patient's pulse is absent, the most appropriate next action is:
- Increase the pacing rate to 100 bpm
- Resume CPR immediately as pacemaker capture alone does not ensure perfusion (Correct answer)
- Decrease the output milliamps and reassess
- Document successful pacing and continue monitoring
Correct answer: Resume CPR immediately as pacemaker capture alone does not ensure perfusion
Electrical capture on the monitor does not guarantee mechanical contraction; the absence of a pulse means CPR must continue while the underlying cause is treated.
Question 5: Hyperkalemia most commonly produces which ECG change as an early sign?
- Prolonged QT interval
- Tall peaked T waves (Correct answer)
- ST elevation in multiple leads
- Delta waves
Correct answer: Tall peaked T waves
Elevated potassium first manifests as tall, narrow, peaked (tent-like) T waves before progressing to PR prolongation, wide QRS, and sine wave pattern.
Question 6: What does a negative QRS deflection in lead I combined with a positive QRS in lead aVF indicate about the cardiac axis?
- Normal axis
- Left axis deviation
- Right axis deviation (Correct answer)
- Extreme axis deviation
Correct answer: Right axis deviation
A negative QRS in lead I and positive QRS in aVF places the electrical axis in the right axis deviation range (between +90° and +180°).
Question 7: A patient with an implanted pacemaker shows pacemaker spikes on the monitor but no following QRS complex. This finding is called:
- Oversensing
- Failure to capture (Correct answer)
- Failure to sense
- Rate hysteresis
Correct answer: Failure to capture
Failure to capture occurs when the pacemaker delivers an electrical impulse that does not depolarize the myocardium, resulting in a spike without a subsequent QRS.
CCT Cardiac Monitoring & Emergency Response 4
A patient's monitor alarm triggers for a heart rate of 42 bpm with narrow QRS complexes and visible P waves before each QRS.
What rhythm does this most likely represent?