ECG Interpretation Questions for the Prometric Nursing Exam 2026: 15 Rhythm and 12-Lead MCQs with Answers for Nurses, ECG Technicians and Paramedics

Every nursing, ECG technician and paramedic Prometric paper includes ECG questions, usually described in words rather than shown as a strip: "the rhythm is irregularly irregular with no P waves" or "ST elevation in leads II, III and aVF". Candidates who can translate the description into a diagnosis and an action collect five to ten easy marks. This set covers the rhythms and patterns that recur.

The five-step method

1. Rate: 300 divided by the number of large squares between R waves, or count R waves in 6 seconds and multiply by 10 for irregular rhythms.
2. Rhythm: regular or irregular; if irregular, regularly irregular or irregularly irregular.
3. P waves: present, upright in II, one before every QRS?
4. PR interval: 0.12 to 0.20 seconds (3 to 5 small squares); constant or lengthening?
5. QRS: narrow (under 0.12 seconds) or broad; then look at ST segments and T waves.

Rhythm questions

Question 1

A regular rhythm has 5 large squares between R waves, an upright P wave before every QRS, a PR of 0.16 seconds and a narrow QRS. The rhythm is:

1. Sinus bradycardia
2. Normal sinus rhythm at 60 per minute
3. Junctional rhythm
4. Atrial flutter

Answer: B. 300 ÷ 5 = 60. Sinus rhythm with a rate of 60 to 100 is normal; below 60 is sinus bradycardia.

Question 2

A rhythm is irregularly irregular with no discernible P waves, a wavy baseline and narrow QRS complexes at about 130 per minute. The rhythm and the nurse's priority are:

1. Sinus tachycardia; give fluids
2. Atrial fibrillation with rapid ventricular response; assess the patient for haemodynamic compromise, obtain a 12-lead, and anticipate rate control and anticoagulation assessment
3. Ventricular tachycardia; defibrillate
4. Normal variant; no action

Answer: B. Irregularly irregular with absent P waves defines AF. An unstable patient needs synchronised cardioversion; a stable one needs rate control and stroke-risk assessment.

Question 3

A regular narrow-complex rhythm at 150 per minute shows a sawtooth baseline best seen in leads II, III and aVF. The rhythm is:

1. Atrial flutter with 2:1 conduction
2. Sinus tachycardia
3. Ventricular fibrillation
4. Third-degree heart block

Answer: A. Flutter waves at about 300 per minute conducting 2:1 give a ventricular rate near 150. A regular tachycardia at exactly 150 should always prompt a search for flutter waves.

Question 4

The PR interval lengthens progressively with each beat until a QRS is dropped, then the cycle repeats. The rhythm is:

1. First-degree AV block
2. Second-degree AV block Mobitz type I (Wenckebach)
3. Mobitz type II
4. Complete heart block

Answer: B. Wenckebach is usually benign and often asymptomatic. Mobitz type II has a constant PR with sudden dropped beats and can progress to complete block, so it needs monitoring and often pacing.

Question 5

P waves and QRS complexes occur regularly but independently of each other, with an atrial rate of 80 and a ventricular rate of 35 with broad complexes. The rhythm and action are:

1. Sinus bradycardia; observe
2. Third-degree (complete) heart block; assess for instability, give atropine as a bridge if symptomatic, prepare for transcutaneous pacing and urgent cardiology review
3. Atrial fibrillation; anticoagulate
4. Normal; no action

Answer: B. AV dissociation with a slow escape rhythm is complete heart block. Atropine is often ineffective for infranodal block; pacing is definitive.

Question 6

A patient is unresponsive and pulseless. The monitor shows a chaotic, irregular waveform with no identifiable QRS complexes. The rhythm and immediate treatment are:

1. Asystole; adrenaline only
2. Ventricular fibrillation; immediate unsynchronised defibrillation and CPR
3. Artefact; check leads only
4. Atrial fibrillation; cardioversion

Answer: B. VF and pulseless VT are shockable rhythms. Defibrillate, resume CPR for two minutes, reassess, and give adrenaline after the third shock with amiodarone.

Question 7

A monitor shows a regular broad-complex tachycardia at 180 per minute in a patient who is conscious with a blood pressure of 110/70. The rhythm and action are:

1. Supraventricular tachycardia; carotid massage
2. Ventricular tachycardia with a pulse; 12-lead ECG, continuous monitoring, call the doctor and prepare for amiodarone or synchronised cardioversion if the patient deteriorates
3. Ventricular fibrillation; defibrillate
4. Sinus tachycardia; give fluids

Answer: B. A broad-complex regular tachycardia is treated as VT. Stable patients receive amiodarone; adverse features trigger synchronised cardioversion.

Question 8

The monitor shows a flat line. Before declaring asystole, the nurse should:

1. Start compressions without any checks
2. Check the patient for responsiveness and pulse, check lead connections and gain, and confirm in a second lead, then start CPR if confirmed
3. Defibrillate immediately
4. Wait one minute

Answer: B. Disconnected leads and low gain mimic asystole. Asystole and pulseless electrical activity are non-shockable; CPR with adrenaline every 3 to 5 minutes is the treatment.

12-lead questions

Question 9

ST elevation of 3 mm in leads V1 to V4 with reciprocal depression in II, III and aVF indicates infarction of the:

1. Inferior wall
2. Anterior (anteroseptal) wall, usually the left anterior descending artery
3. Lateral wall
4. Right ventricle

Answer: B. V1 to V4 look at the septum and anterior wall. Anterior STEMI carries the highest risk of heart failure and cardiogenic shock; activate the cath lab pathway.

Question 10

ST elevation in leads II, III and aVF with ST elevation in V4R indicates:

1. Anterior STEMI
2. Inferior STEMI with right ventricular involvement; avoid nitrates and give fluids for hypotension
3. Pericarditis
4. Pulmonary embolism

Answer: B. Right ventricular infarction makes the patient preload-dependent; nitrates and diuretics cause profound hypotension. Record right-sided leads in every inferior STEMI.

Question 11

Widespread concave (saddle-shaped) ST elevation in most leads with PR segment depression and no reciprocal changes, in a young patient with sharp chest pain relieved by sitting forward, suggests:

1. STEMI
2. Acute pericarditis
3. Hyperkalaemia
4. Left bundle branch block

Answer: B. Pericarditis is diffuse and concave with PR depression; STEMI is territorial and convex with reciprocal change. Pericarditis is treated with NSAIDs and colchicine, not thrombolysis.

Question 12

Tall, peaked, narrow-based T waves with a widening QRS in a dialysis patient who missed a session suggest:

1. Hypokalaemia
2. Hyperkalaemia; obtain an urgent potassium level and prepare intravenous calcium, insulin with dextrose and nebulised salbutamol, and arrange dialysis
3. Digoxin effect
4. Normal variant

Answer: B. Peaked T waves progress to loss of P waves, QRS widening and a sine wave before arrest. Hypokalaemia causes flattened T waves and U waves.

Question 13

A QRS duration of 0.16 seconds with a broad notched R wave in V5 and V6 and a deep S wave in V1 indicates:

1. Right bundle branch block
2. Left bundle branch block; a new LBBB with chest pain is treated as a STEMI equivalent
3. Normal conduction
4. Ventricular fibrillation

Answer: B. "WiLLiaM MaRRoW" is the mnemonic: W in V1 and M in V6 for LBBB, M in V1 and W in V6 for RBBB. LBBB also masks ST changes, so compare with old ECGs.

Question 14

A regular rhythm at 70 per minute shows a sharp vertical spike immediately before every QRS complex. This indicates:

1. Artefact from a loose lead
2. A functioning ventricular pacemaker with capture; a spike without a following QRS would indicate failure to capture
3. Atrial flutter
4. Hyperkalaemia

Answer: B. Pacing spikes are recognised by their sharp, narrow shape. Failure to capture and failure to sense are the common pacemaker problems tested.

Question 15

When recording a 12-lead ECG, lead V4 is placed at the:

1. Fourth intercostal space, right sternal border
2. Fifth intercostal space in the mid-clavicular line
3. Fifth intercostal space in the anterior axillary line
4. Second intercostal space, left sternal border

Answer: B. V1 and V2 are at the fourth intercostal space either side of the sternum, V4 at the fifth space mid-clavicular, V3 between V2 and V4, V5 anterior axillary and V6 mid-axillary at the level of V4. Misplaced chest leads cause false anterior changes.

How to practise

• Learn the normal numbers: PR 0.12 to 0.20, QRS under 0.12, QTc under about 0.44 to 0.46 seconds.
• Memorise territories: II, III, aVF inferior; V1 to V4 anterior; I, aVL, V5, V6 lateral; V1 to V2 depression with tall R waves for posterior.
• Pair each rhythm with its first action, because that is how the paper asks.

Nurses find more ECG and critical care items in the Registered Nurse bank; ECG technicians and technologists have their own banks (ECG Technician, ECG Technologist, guide); paramedics use the Paramedic bank. Related sets: nursing sample questions, drug calculations and cardiology specialist questions.

Frequently asked questions

Are ECG strips shown in the Prometric nursing exam?

Some forms include images, but most ECG questions describe the rhythm in words. Practise translating descriptions into diagnoses.

How many ECG questions are in the nursing exam?

Usually five to ten, within the critical care and medical-surgical domains; more in ECG technician and paramedic papers.

Which rhythms come up most?

Sinus rhythms, atrial fibrillation, the heart blocks, VT and VF, asystole and PEA, and STEMI territories.

What is the normal PR interval?

0.12 to 0.20 seconds, three to five small squares.

Do assistant nurses get ECG questions?

Occasionally, at the level of recognising a life-threatening rhythm and calling for help.