Cardiac Rhythm and Electrophysiology Quiz

Cardiac Conduction and Rhythm Disorders

• Cardiac Conduction System:
  • Controls the rate and direction of electrical impulses in the heart.
  • Impulses originate in the SA node (sinoatrial node), which has the fastest firing rate.
  • Impulses travel to the Purkinje fibers in the ventricles.
  • Specialized myocardial cells form the conduction system in specific areas of the heart to ensure efficient pumping.

Electrocardiography

• Twelve Leads: Each provides a unique view of the heart's electrical forces.
• Diagnostic ECG: Diagnostic criteria are specific to each lead.
• Lead Placement: Improper placement significantly alters QRS morphology, potentially leading to misdiagnosis of arrhythmias and conduction defects.

Calculating Heart Rate from ECG

• Count the number of "R" waves in 6 seconds.
• Multiply by 10 to determine the heart rate per minute (6 large boxes = 1 minute).

Cardiac Electrophysiology

• P-Wave: Represents atrial depolarization (contraction).
• QRS Complex: Represents ventricular depolarization (contraction).
• ST Segment: Represents the heart's resting period.
• T-Wave: Represents ventricular repolarization (relaxation).
• PR Interval: Period between atrial and ventricular depolarization.

Continuous Bedside Cardiac Monitoring

• Improved from basic heart rate and arrhythmia monitoring to include:
  • Identification of ST segment changes
  • Advanced arrhythmia identification
  • Diagnosis
  • Treatment provision

ECG and Cardiac Muscle Contraction

• False: The ECG reflects electrical activity, not directly cardiac muscle contraction. Specific defects in muscle activity cannot be directly diagnosed by ECG.

Types and Causes of Cardiac Conduction System Disorders

• Types:
  • Rhythm disorders
  • Impulse conduction disorders
• Causes:
  • Congenital defects or degenerative changes in the conduction system
  • Myocardial ischemia and infarction
  • Fluid and electrolyte imbalances
  • Drug effects

Types of Arrhythmias #1

• Sinus Node Arrhythmias:
  • Sinus bradycardia
  • Sinus tachycardia
  • Sinus arrest
• Arrhythmias of Atrial Origin:
  • Paroxysmal supraventricular tachycardia
  • Atrial flutter
  • Atrial fibrillation

Types of Arrhythmias #2

• Junctional Arrhythmias
• Disorders of Ventricular Conduction and Rhythm
• Long QT Syndrome and Torsades de Pointes
• Ventricular Arrhythmias:
  • Premature ventricular contractions
  • Ventricular tachycardia
  • Ventricular flutter and fibrillation

Diagnostic Methods

• Signal-averaged electrocardiogram
• Holter monitoring
• Exercise stress testing
• Electrophysiologic studies
• QT dispersion

Pharmacologic Treatment of Arrhythmias

• Class I: Blocks fast sodium channels
• Class II: Beta-adrenergic-blocking drugs
• Class III: Extends action potential and refractoriness
• Class IV: Blocks slow calcium channels

Correction of Conduction Defects, Bradycardias, and Tachycardias

• Electronic Pacemaker:
  • Temporary
  • Permanent
• Cardioversion:
  • Defibrillation
  • Synchronized
• Ablation: Surgical interventions

Radiofrequency Ablation

Cardioversion

• Elective procedures: Client awake & frequently sedated
• Synchronization with QRS—50-200 Joules
• EKG monitor & consent form

Defibrillation

• Emergency procedures for V-fib & V-tach
• No cardiac output—Start with 200 Joules, up to 360 Joules
• Client unconscious & EKG monitoring

Question #2

• Correct answer: C. The sinus node directly stimulates the rest of the heart into a new rhythm, having a greater effect than atrial arrhythmias.

Test your knowledge on cardiac conduction systems and rhythm disorders. This quiz covers the generation of electrical impulses, electrocardiography techniques, and heart rate calculations. Perfect for students and professionals in the medical field.