Disorders of the Heart, Rhythm & Conduction Flashcards
What is normal cardiac rhythm called?
Normal cardiac rhythm is called sinus rhythm, typically 60-100 beats per minute, initiated by the sinoatrial (SA) node.
What is the role of the SA node in cardiac rhythm?
The SA node acts as the heart’s pacemaker, generating electrical impulses that set the heart’s rhythm.
What is bradyarrhythmia?
Bradyarrhythmia refers to a heart rhythm disorder where the heart rate is slower than normal, typically below 60 beats per minute.
What is sinus bradycardia?
Sinus bradycardia is a slow heart rate (<60 bpm) that originates from the SA node and follows normal conduction pathways.
What is AV block?
AV block is a conduction disorder where the electrical signal from the atria to the ventricles is delayed or blocked at the AV node.
What is first-degree AV block?
First-degree AV block is characterized by a prolonged PR interval (>0.20 seconds) but every atrial impulse still reaches the ventricles.
What are supraventricular tachyarrhythmias (SVT)?
SVT refers to fast heart rhythms originating above the ventricles, including atrial fibrillation, atrial flutter, and AV nodal reentrant tachycardia.
What is atrial fibrillation (AF)?
Atrial fibrillation is a type of SVT where the atria beat irregularly and rapidly due to disorganized electrical activity.
What is atrial flutter?
Atrial flutter is a type of SVT characterized by a regular, fast atrial rhythm, often with a sawtooth pattern on ECG.
What is AV nodal reentrant tachycardia (AVNRT)?
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.
What is ventricular tachycardia (VT)?
Ventricular tachycardia is a fast heart rhythm (>100 bpm) that originates from abnormal electrical activity in the ventricles.
What is torsades de pointes?
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.
What is ventricular fibrillation (VF)?
Ventricular fibrillation is a life-threatening arrhythmia where the ventricles quiver instead of contracting effectively, leading to cardiac arrest.
How do early afterdepolarizations (EADs) cause arrhythmias?
EADs occur during repolarization, prolonging the action potential and potentially leading to arrhythmias like torsades de pointes.
What is the main mechanism of re-entry in arrhythmias?
Re-entry occurs when an electrical impulse reactivates tissue that has already been excited, leading to a self-perpetuating loop of electrical activity.
What are the four classes of antiarrhythmic drugs?
The four classes are:
Sodium channel blockers (Class I)
Beta-blockers (Class II)
Potassium channel blockers (Class III)
Calcium channel blockers (Class IV)
How do potassium channel blockers (Class III) work in treating arrhythmias?
Class III drugs (e.g., amiodarone) prolong the action potential by delaying repolarization, which helps suppress arrhythmias.
What is the role of beta-blockers (Class II) in arrhythmia management?
Beta-blockers reduce heart rate and contractility by blocking the effects of adrenaline on the heart, decreasing automaticity and conduction.
What is the mechanism of Class I antiarrhythmic drugs?
Class I drugs (e.g., flecainide) block sodium channels, slowing depolarization and reducing excitability of cardiac tissue.
What are the two main types of pacemakers?
The two main types are single-chamber pacemakers (stimulate either the atrium or ventricle) and dual-chamber pacemakers (stimulate both atrium and ventricle).
What is the role of calcium channel blockers (Class IV) in arrhythmia treatment?
Calcium channel blockers (e.g., diltiazem, verapamil) slow AV node conduction, making them effective in rate control for SVTs like atrial fibrillation.
What is adenosine used for in arrhythmia management?
Adenosine is used for acute termination of certain SVTs by temporarily blocking AV node conduction, leading to a brief period of asystole.
How does a pacemaker help treat bradyarrhythmias?
A pacemaker generates electrical impulses that stimulate the heart to contract, maintaining an adequate heart rate when the natural conduction system is too slow.
What is the function of an implantable cardioverter-defibrillator (ICD)?
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.
What are the indications for an ICD?
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.
How is catheter ablation used to treat atrial fibrillation?
In AF ablation, catheters are used to create lesions around the pulmonary veins or other areas to block abnormal electrical signals that trigger AF.
What is catheter ablation?
Catheter ablation is a procedure that destroys small areas of heart tissue responsible for abnormal electrical signals, effectively treating certain arrhythmias.
What is the success rate of catheter ablation for atrial fibrillation?
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.
What complications can arise from catheter ablation?
Complications from catheter ablation include bleeding, infection, cardiac tamponade, and damage to the esophagus or surrounding structures.
What is the difference between pacemakers and ICDs?
Pacemakers treat bradyarrhythmias by generating electrical impulses to maintain heart rate, while ICDs treat tachyarrhythmias by delivering shocks to restore normal rhythm.
