Exam ECG, MANAGEMENT & ARRHYTHMIAS

Question 1

What is the correct order of the heart’s electrical conduction system?

Answer 1

SA node → AV node → Bundle of His → Bundle branches → Purkinje fibers
Mnemonic: “Some Aunts Bake Beautiful Pies”

Question 2

What is the duration of one large box on ECG paper?

Answer 2

0.2 seconds

Question 3

What is the duration of one small box on ECG paper?

Answer 3

0.04 seconds

Question 4

How do you calculate heart rate using large boxes between QRS complexes?

Answer 4

300 ÷ number of large boxes between R waves

Question 5

What does the P wave represent?

Answer 5

Atrial depolarization

Question 6

What does the QRS complex represent?

Answer 6

Ventricular depolarization

Question 7

What is Sinus Bradycardia?

Answer 7

SA node fires < 60 bpm
Causes: beta-blockers, hypothyroidism, hypothermia, athletes

Question 8

What is Sinus Tachycardia?

Answer 8

HR > 100 bpm due to stress, fever, or hypovolemia

Question 9

What is Atrial Flutter?

Answer 9

Rapid and disorganized atrial contractions leading to an irregular rhythm.
Characterized by its Saw Tooth shape and BPM of 250-300.

Question 10

What is Atrial Fibrillation?

Answer 10

Irregularly irregular rhythm, no P waves, chaotic atrial activity

Question 11

What are symptoms of dysrhythmias?

Answer 11

Palpitations, dizziness, chest pain, SOB, fatigue

Question 12

What arrhythmias are life-threatening?

Answer 12

Ventricular tachycardia, ventricular fibrillation, asystole

Question 13

You’re at a code blue. The monitor shows VF. What do you do immediately?

Answer 13

Deliver unsynchronized defibrillation (shock) — time is myocardium

Question 14

Your patient’s ECG shows a flatline. Is defibrillation going to help?

Answer 14

No — this is asystole. Begin CPR and give epinephrine immediately

Question 15

Are Ventricular Fibrillation and Pulseless VT shockable rhythms?

Answer 15

Yes — both are shockable. Immediate defibrillation is required

Question 16

Are Asystole and Pulseless Electrical Activity (PEA) shockable rhythms?

Answer 16

No — focus on CPR and epinephrine

Question 17

What is the action of Class I antiarrhythmics?

Answer 17

Sodium channel blockers (e.g., Lidocaine) — slows depolarization

Question 18

What is the action of Class II antiarrhythmics?

Answer 18

Beta blockers (e.g., Metoprolol) — reduce HR & AV node conduction

Question 19

What is the action of Class III antiarrhythmics?

Answer 19

Potassium channel blockers (e.g., Amiodarone) — prolong repolarization

Question 20

What is the action of Class IV antiarrhythmics?

Answer 20

Calcium channel blockers (e.g., Verapamil) — slow AV conduction

Question 21

Mnemonic for remembering antiarrhythmics?

Answer 21

“Some Block Potent Channels” (Sodium, Beta, Potassium, Calcium)

Question 22

You’re treating narrow-complex SVT. Which drug can reset the rhythm instantly?

Answer 22

Adenosine — short half-life, slows AV node conduction

Question 23

What does Digoxin do?

Answer 23

Slows AV node conduction, increases contractility (AF + CHF)

Question 24

Your patient is in Torsades de Pointes. What is the drug of choice?

Answer 24

Magnesium sulfate

Question 25

You see a wide QRS on ECG. What’s your immediate concern?

Answer 25

Bundle branch block or VT — monitor for instability

Question 26

ST segment is elevated in leads II, III, aVF. What does it mean?

Answer 26

Inferior MI — activate cath lab, give antiplatelets

Question 27

You see no P waves and an irregularly irregular rhythm. What is it?

Answer 27

Atrial fibrillation — high stroke risk

Question 28

A patient is in AF with a pulse and is stable. Should you defibrillate or cardiovert?

Answer 28

Use synchronized cardioversion to avoid R-on-T

Question 29

When should a pacemaker be used?

Answer 29

When SA or AV node fails (e.g., bradycardia or heart block)

Question 30

What ion influx triggers Phase 0 (depolarization) in a cardiac action potential?

Answer 30

Sodium (Na+) influx rapidly depolarizes the membrane.

Question 31

What electrolyte imbalance causes peaked T waves and widened QRS?

Answer 31

Hyperkalemia — can progress to sine-wave pattern and cardiac arrest.

Question 32

What is the effect of Atrial Fibrillation on cardiac output?

Answer 32

Decreased cardiac output due to loss of atrial kick and irregular ventricular filling.

Question 33

What is the role of beta-blockers after an MI?

Answer 33

Reduce myocardial oxygen demand by lowering heart rate and blood pressure — prevents arrhythmias.

Question 34

What are signs of reduced cardiac output in a patient?

Answer 34

Hypotension, cold extremities, low urine output, confusion, weak pulse.