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Question 1

Ordinary myocardium

Answer 1

One type of cardiac tissue responsible for the heart’s contraction.

Question 2

Specialised cardiac conduction system

Answer 2

Includes the sino-atrial node, atrio-ventricular node, His bundle, right and left bundle branches, and Purkinje network.

Question 3

What is automaticity?

Answer 3

The ability of cardiac tissue to generate electrical impulses without neural stimulation.

Question 4

What are cardiac myocytes?

Answer 4

Electrically excitable cells that contract and relax to pump blood.

Question 5

What initiates the electrical impulse in the heart?

Answer 5

The sinoatrial node (SA node), known as the heart’s pacemaker.

Question 6

How does electrical discharge occur in cardiac cells?

Answer 6

Through ionic movement into and out of the cardiac cell, resulting in an action potential.

Question 7

What is the phase 0 of action potential in cardiac cells?

Answer 7

Rapid depolarization due to the inflow of Na+ (sodium ions).

Question 8

What is the phase 1 of action potential in cardiac cells?

Answer 8

Partial repolarization with outflow of K+ (potassium ions) and deactivation of inward Na+ current.

Question 9

What occurs during phase 2 of action potential?

Answer 9

A plateau phase marked by slow inward calcium current.

Question 10

Describe phase 3 of action potential.

Answer 10

Repolarization phase when calcium current inactivates and K+ flows out.

Question 11

What happens in phase 4 of action potential?

Answer 11

Pacemaker potential characterized by slow Na+ inflow and slowing of K+ outflow.

Question 12

What is the refractory period in cardiac cells?

Answer 12

Phases 1 to 3 during which the cells cannot be re-excited.

Question 13

What does ECG stand for?

Answer 13

Electrocardiogram, a recording of the electrical activity of the heart.

Question 14

What is the P-QRS-T pattern in an ECG?

Answer 14

P - atrial depolarization; QRS - ventricular depolarization; T - ventricular repolarization.

Question 15

What is normal sinus rhythm?

Answer 15

A heart rate of 60 to 100 beats per minute originating from the sinoatrial node.

Question 16

How does the autonomic nervous system affect heart rate?

Answer 16

The parasympathetic system decreases heart rate while the sympathetic system increases it.

Question 17

Define bradycardia.

Answer 17

A slow heart rate, typically less than 60 beats per minute.

Question 18

Define tachycardia.

Answer 18

A fast heart rate, typically exceeding 100 beats per minute.

Question 19

What mechanisms can produce cardiac arrhythmias?

Answer 19

Abnormal pacemaker activity, ectopic pacemakers, and re-entry circuits.

Question 20

What is class I antiarrhythmic drug action?

Answer 20

They block sodium channels and are further divided into subclasses based on their effects on action potential.

Question 21

Name a class IA antiarrhythmic drug.

Answer 21

Quinidine, procainamide, disopyramide.

Question 22

What effects do Class IB antiarrhythmic drugs have on action potential?

Answer 22

They decrease the action potential duration.

Question 23

Name a class IC antiarrhythmic drug.

Answer 23

Flecainide or Propafenone.

Question 24

What is the mechanism of action of Beta-blockers?

Answer 24

They block beta-adrenoceptors, which reduces heart rate and contractility.

Question 25

Class III antiarrhythmic agents

Answer 25

Only K+ channel blockers that prolong the action potential and refractory period.

Question 26

Name one Class III antiarrhythmic drug.

Answer 26

Amiodarone.

Question 27

What class of drugs primarily affects calcium channels?

Answer 27

Class IV antiarrhythmic drugs.

Question 28

What is adenosine used for in cardiology?

Answer 28

It is used for the termination of supraventricular tachycardia.

Question 29

Mechanism of action of digoxin?

Answer 29

It increases inotropy (contractility) and decreases chronotropy (heart rate).

Question 30

What is the half-life of Amiodarone?

Answer 30

20 to 100 days.

Question 31

Adverse effects of Amiodarone include:

Answer 31

Pulmonary fibrosis, hypo/hyperthyroidism, hepatic dysfunction, and peripheral neuropathy.

Question 32

Define supraventricular tachycardia (SVT).

Answer 32

A rapid heart rhythm originating at or above the atrioventricular node.

Question 33

What causes Atrial Flutter?

Answer 33

It results from reentrant circuits in the atria.

Question 34

What can cause Sinus Arrest?

Answer 34

Conditions such as myocarditis, myocardial infarction, or digitalis toxicity.

Question 35

What impact does verapamil have?

Answer 35

It slows conduction through the SA and AV nodes.

Question 36

What is the heart rate like during Ventricular Tachycardia (V-tach)?

Answer 36

Typically ranges from 100 to 220 beats per minute.

Question 37

What causes Ventricular Fibrillation (V-fib)?

Answer 37

Often results from acute myocardial infarction.

Question 38

Which antiarrhythmic class is contraindicated in patients with a history of seizures?

Answer 38

Class IB drugs, specifically lidocaine, due to its CNS effects.

Question 39

What is the primary use of Class IA antiarrhythmic drugs?

Answer 39

They are used to treat atrial fibrillation and ventricular tachycardia.

Question 40

What class does Sotalol belong to?

Answer 40

It is both a non-selective beta-blocker and a Class III antiarrhythmic.

Question 41

What are the key side effects of Quinidine?

Answer 41

Cinchonism, hypotension, and hypersensitivity reactions.

Question 42

What heart condition can lead to Atrial Fibrillation?

Answer 42

Conditions like chronic obstructive pulmonary disease (COPD) or congestive heart failure (CHF).

Question 43

What is the mechanism of action of Class IV drugs?

Answer 43

Calcium channel antagonists impair impulse propagation in the heart.

Question 44

Name an indication for digoxin.

Answer 44

It is used for heart failure and atrial fibrillation.

Question 45

What classification of antiarrhythmic does lidocaine belong to?

Answer 45

It is a Class IB antiarrhythmic drug.

Question 46

How does the sympathetic nervous system affect heart rate?

Answer 46

It increases heart rate through beta-1 receptors.

Question 47

What effect does reducing automaticity have?

Answer 47

It decreases the risk of arrhythmias.

Question 48

Define arrhythmia.

Answer 48

An abnormality of the heart rhythm, including irregular rates and rhythms.

Question 49

What role does K+ play in cardiac action potentials?

Answer 49

K+ outflow is crucial for repolarization of cardiac cells.

Question 50

What is a unique feature of the cardiac conduction system?

Answer 50

It has specialized tissues that ensure the synchronized contraction of the heart.

Question 51

Name the components of the cardiac conduction system.

Answer 51

Sino-atrial node, atrio-ventricular node, His bundle, bundle branches, and Purkinje fibers.

Question 52

What effect does amiodarone have on action potential duration?

Answer 52

It prolongs the action potential duration and the refractory period.

Question 53

What can increase the risk of proarrhythmia with antiarrhythmics?

Answer 53

Coronary artery disease (CAD) or chronic heart failure (CHF).

Question 54

Describe Vaughan Williams classification of antiarrhythmic drugs.

Answer 54

It categorizes antiarrhythmic drugs into Class I, II, III, and IV based on their mechanisms.

Question 55

What defines the refractory period in cardiac cycles?

Answer 55

It is the time during which a cardiac cell cannot initiate a new action potential.

Question 56

What is the primary use of Class II antiarrhythmic agents?

Answer 56

They are used for controlling arrhythmias associated with sympathetic activity.

Question 57

Phases 1-3 in cardiac cells are characterized as what period?

Answer 57

The refractory period where the cells cannot respond to new stimuli.