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Cardiac Electrophysiology and Arrhythmias Quiz

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#1

Which of the following ions primarily contributes to the resting membrane potential of cardiac cells?

Potassium (K+)
Explanation

Potassium maintains the negative resting membrane potential.

#2

Which phase of the cardiac action potential represents rapid depolarization due to the opening of voltage-gated sodium channels?

Phase 0
Explanation

Phase 0 involves rapid depolarization due to sodium influx.

#3

Which ion plays a crucial role in the initiation and propagation of the action potential in cardiac pacemaker cells?

Calcium (Ca2+)
Explanation

Calcium initiates and propagates action potentials in pacemaker cells.

#4

Which phase of the cardiac action potential represents rapid repolarization due to the opening of voltage-gated potassium channels and closing of voltage-gated sodium channels?

Phase 3
Explanation

Phase 3 involves rapid repolarization due to potassium efflux.

#5

Which of the following is a characteristic feature of atrial fibrillation on an electrocardiogram (ECG)?

Irregular rhythm and wide QRS complexes
Explanation

Atrial fibrillation on ECG exhibits irregular rhythm and wide QRS complexes.

#6

Which phase of the cardiac action potential is characterized by the plateau phase where calcium influx balances potassium efflux?

Phase 2
Explanation

Phase 2 maintains a plateau due to balanced calcium influx and potassium efflux.

#7

Which ion is primarily responsible for the initial depolarization of pacemaker cells in the sinoatrial (SA) node?

Calcium (Ca2+)
Explanation

Calcium initiates initial depolarization in SA node pacemaker cells.

#8

During which phase of the cardiac action potential do voltage-gated calcium channels open, leading to the plateau phase?

Phase 2
Explanation

Voltage-gated calcium channels open during Phase 2, causing the plateau.

#9

Which component of the cardiac conduction system is responsible for delaying the impulse transmission from the atria to the ventricles?

Atrioventricular (AV) node
Explanation

The AV node delays impulse transmission from atria to ventricles.

#10

During which phase of the cardiac action potential do voltage-gated potassium channels open, leading to repolarization?

Phase 3
Explanation

Voltage-gated potassium channels open during Phase 3 for repolarization.

#11

Which arrhythmia is characterized by chaotic, irregular electrical activity in the atria resulting in an irregular ventricular response?

Atrial fibrillation
Explanation

Atrial fibrillation leads to irregular atrial activity and ventricular response.

#12

Which of the following ECG findings is indicative of a prolonged QT interval and an increased risk of ventricular arrhythmias?

Prolonged QT interval
Explanation

A prolonged QT interval increases the risk of ventricular arrhythmias.

#13

What is the typical heart rate range of a patient experiencing sinus tachycardia?

100-150 bpm
Explanation

Sinus tachycardia manifests as a heart rate of 100-150 bpm.

#14

Which arrhythmia is characterized by a widened QRS complex and irregular ventricular rhythm?

Ventricular tachycardia
Explanation

Ventricular tachycardia presents with widened QRS and irregular ventricular rhythm.

#15

What is the typical heart rate range of a patient experiencing sinus bradycardia?

Less than 60 bpm
Explanation

Sinus bradycardia involves a heart rate less than 60 bpm.

#16

Which arrhythmia is characterized by a regular atrial rhythm with a sawtooth appearance of the P waves on ECG?

Atrial flutter
Explanation

Atrial flutter features regular atrial rhythm with sawtooth P waves.

#17

What is the term for a cardiac arrhythmia characterized by rapid, irregular atrial depolarizations with a chaotic baseline pattern on ECG?

Atrial fibrillation
Explanation

Atrial fibrillation involves rapid, irregular atrial depolarizations.

#18

Which of the following ECG findings suggests an increased risk of sudden cardiac death due to the presence of a prolonged QT interval?

Prolonged QT interval
Explanation

A prolonged QT interval increases the risk of sudden cardiac death.

#19

What is the term for an abnormally fast heart rhythm originating from the ventricles and often associated with hemodynamic compromise?

Ventricular tachycardia
Explanation

Ventricular tachycardia is an abnormally fast ventricular rhythm.

#20

What is the mechanism of action of class III antiarrhythmic drugs such as amiodarone?

Prolongation of cardiac action potential duration
Explanation

Class III drugs prolong the cardiac action potential duration.

#21

Which of the following ECG findings is indicative of an accessory pathway between the atria and ventricles resulting in a short PR interval and a delta wave?

Wolff-Parkinson-White syndrome
Explanation

WPW syndrome shows short PR interval and delta wave due to an accessory pathway.

#22

Which of the following ECG findings is indicative of a complete heart block where the atria and ventricles beat independently?

Third-degree atrioventricular block
Explanation

Third-degree AV block shows independent atrial and ventricular contractions.

#23

What is the primary mechanism of action of class I antiarrhythmic drugs such as lidocaine?

Blockade of sodium channels
Explanation

Class I drugs primarily block sodium channels.

#24

What is the mechanism of action of class IV antiarrhythmic drugs such as verapamil?

Inhibition of calcium channels
Explanation

Class IV drugs inhibit calcium channels.

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