Disorders of the Heart, Rhythm & Conduction

Question 1

What is normal cardiac rhythm called?

Answer 1

Normal cardiac rhythm is called sinus rhythm, typically 60-100 beats per minute, initiated by the sinoatrial (SA) node.

Question 2

What is the role of the SA node in cardiac rhythm?

Answer 2

The SA node acts as the heart’s pacemaker, generating electrical impulses that set the heart’s rhythm.

Question 3

What is bradyarrhythmia?

Answer 3

Bradyarrhythmia refers to a heart rhythm disorder where the heart rate is slower than normal, typically below 60 beats per minute.

Question 4

What is sinus bradycardia?

Answer 4

Sinus bradycardia is a slow heart rate (<60 bpm) that originates from the SA node and follows normal conduction pathways.

Question 5

What is AV block?

Answer 5

AV block is a conduction disorder where the electrical signal from the atria to the ventricles is delayed or blocked at the AV node.

Question 6

What is first-degree AV block?

Answer 6

First-degree AV block is characterized by a prolonged PR interval (>0.20 seconds) but every atrial impulse still reaches the ventricles.

Question 7

What are supraventricular tachyarrhythmias (SVT)?

Answer 7

SVT refers to fast heart rhythms originating above the ventricles, including atrial fibrillation, atrial flutter, and AV nodal reentrant tachycardia.

Question 8

What is atrial fibrillation (AF)?

Answer 8

Atrial fibrillation is a type of SVT where the atria beat irregularly and rapidly due to disorganized electrical activity.

Question 9

What is atrial flutter?

Answer 9

Atrial flutter is a type of SVT characterized by a regular, fast atrial rhythm, often with a sawtooth pattern on ECG.

Question 10

What is AV nodal reentrant tachycardia (AVNRT)?

Answer 10

AVNRT is a common type of SVT caused by a re-entry circuit within or near the AV node, leading to a rapid heart rate.

Question 11

What is ventricular tachycardia (VT)?

Answer 11

Ventricular tachycardia is a fast heart rhythm (>100 bpm) that originates from abnormal electrical activity in the ventricles.

Question 12

What is torsades de pointes?

Answer 12

Torsades de pointes is a type of polymorphic ventricular tachycardia characterized by shifting QRS complexes on ECG and is often caused by prolonged QT interval.

Question 13

What is ventricular fibrillation (VF)?

Answer 13

Ventricular fibrillation is a life-threatening arrhythmia where the ventricles quiver instead of contracting effectively, leading to cardiac arrest.

Question 14

How do early afterdepolarizations (EADs) cause arrhythmias?

Answer 14

EADs occur during repolarization, prolonging the action potential and potentially leading to arrhythmias like torsades de pointes.

Question 15

What is the main mechanism of re-entry in arrhythmias?

Answer 15

Re-entry occurs when an electrical impulse reactivates tissue that has already been excited, leading to a self-perpetuating loop of electrical activity.

Question 16

What are the four classes of antiarrhythmic drugs?

Answer 16

The four classes are:

Sodium channel blockers (Class I)
Beta-blockers (Class II)
Potassium channel blockers (Class III)
Calcium channel blockers (Class IV)

Question 17

How do potassium channel blockers (Class III) work in treating arrhythmias?

Answer 17

Class III drugs (e.g., amiodarone) prolong the action potential by delaying repolarization, which helps suppress arrhythmias.

Question 18

What is the role of beta-blockers (Class II) in arrhythmia management?

Answer 18

Beta-blockers reduce heart rate and contractility by blocking the effects of adrenaline on the heart, decreasing automaticity and conduction.

Question 19

What is the mechanism of Class I antiarrhythmic drugs?

Answer 19

Class I drugs (e.g., flecainide) block sodium channels, slowing depolarization and reducing excitability of cardiac tissue.

Question 20

What are the two main types of pacemakers?

Answer 20

The two main types are single-chamber pacemakers (stimulate either the atrium or ventricle) and dual-chamber pacemakers (stimulate both atrium and ventricle).

Question 20

What is the role of calcium channel blockers (Class IV) in arrhythmia treatment?

Answer 20

Calcium channel blockers (e.g., diltiazem, verapamil) slow AV node conduction, making them effective in rate control for SVTs like atrial fibrillation.

Question 20

What is adenosine used for in arrhythmia management?

Answer 20

Adenosine is used for acute termination of certain SVTs by temporarily blocking AV node conduction, leading to a brief period of asystole.

Question 21

How does a pacemaker help treat bradyarrhythmias?

Answer 21

A pacemaker generates electrical impulses that stimulate the heart to contract, maintaining an adequate heart rate when the natural conduction system is too slow.

Question 22

What is the function of an implantable cardioverter-defibrillator (ICD)?

Answer 22

An ICD monitors the heart’s rhythm and delivers shocks to restore normal rhythm if life-threatening arrhythmias, like ventricular tachycardia or fibrillation, are detected.

Question 23

What are the indications for an ICD?

Answer 23

ICDs are indicated for patients with a history of life-threatening ventricular arrhythmias or those at high risk for sudden cardiac death due to conditions like heart failure.

Question 24

How is catheter ablation used to treat atrial fibrillation?

Answer 24

In AF ablation, catheters are used to create lesions around the pulmonary veins or other areas to block abnormal electrical signals that trigger AF.

Question 24

What is catheter ablation?

Answer 24

Catheter ablation is a procedure that destroys small areas of heart tissue responsible for abnormal electrical signals, effectively treating certain arrhythmias.

Question 25

What is the success rate of catheter ablation for atrial fibrillation?

Answer 25

Catheter ablation has a success rate of 70-80% for paroxysmal AF and 50-70% for persistent AF, depending on patient factors and procedure type.

Question 26

What complications can arise from catheter ablation?

Answer 26

Complications from catheter ablation include bleeding, infection, cardiac tamponade, and damage to the esophagus or surrounding structures.

Question 27

What is the difference between pacemakers and ICDs?

Answer 27

Pacemakers treat bradyarrhythmias by generating electrical impulses to maintain heart rate, while ICDs treat tachyarrhythmias by delivering shocks to restore normal rhythm.