AFib Fall 2023 2

Atrial Fibrillation (AF) Study Notes

Overview

  • Definition: Atrial fibrillation is the most common sustained cardiac arrhythmia.
  • Incidence and Prevalence: Increases with age. Individuals with AF are at high risk for:
    • Cerebrovascular accidents (CVA)
    • Pulmonary emboli

Characteristics of Atrial Fibrillation

  • Key Features:
    • Disorganized, very rapid atrial impulses (rate of 350 to 600 times per minute).
    • Irregular atrial rhythm resulting in an irregular ventricular rhythm.
  • ECG Features:
    • Unidentifiable P waves
    • Immeasurable PR and QT intervals
    • Irregular rhythm

Atrial Fibrillation Pathophysiology

  • Comparison with Normal Heart Function:
    • Typical heart: Sinus node generates impulses that create organized heart contractions.
    • Heart with AF: Chaotic atrial signals pass through the AV node leading to rapid ventricular impulses.

Causes of New Onset Atrial Fibrillation

  • Pulmonary Issues:
    • Pulmonary embolism (PE)
    • Chronic Obstructive Pulmonary Disease (COPD)
    • Pneumonia (PNA)
    • Pericarditis
  • Iatrogenic Causes:
    • Digoxin toxicity
    • Myocardial ischemia (MI, CAD)
  • Rheumatic Heart Disease:
    • Mitral regurgitation
  • Additional Factors:
    • Alcohol, anemia, advanced age
  • Thyroid Conditions:
    • Hyperthyroidism
  • External Factors:
    • Endocarditis, electrocution, elevated blood pressure
  • Systemic Issues:
    • Sick sinus syndrome, sepsis, sleep apnea

Other Etiologies of Atrial Fibrillation

  • Cardiac Causes:
    • Hypertensive heart disease
    • Valvular heart disease causing left atrial stretch
    • Ischemic heart disease, myocardial infarction
    • Cardiomyopathy, heart failure
    • Pericarditis, congenital heart disease
    • Post-cardiac surgery complications
  • Non-Cardiac Causes:
    • Pulmonary causes: pneumonia, COPD, pulmonary embolism
    • Hyperthyroidism
    • Excess catecholaminergic/sympathetic activity
    • Alcohol and drug usage
    • Digitalis toxicity
    • Significant electrolyte imbalances

Lone Atrial Fibrillation (Idiopathic)

  • Characteristics:
    • Typically seen in younger patients (<60 years)
    • No identifiable underlying cause
    • Minimal symptoms
    • Normal heart structure, no co-morbidities

Atrial Fibrillation with Rapid Ventricular Response

  • Significance:
    • This presentation requires special attention due to potential for complications.

Physical Assessment

  • Vital Signs Evaluation:
    • Pulse: Irregular (hallmark feature)
    • Blood Pressure: Typically lower than normal
  • Symptoms Due to Decreased Cardiac Output:
    • Shortness of breath
    • Altered mental status
    • Angina
    • Altered level of consciousness
    • Dizziness
    • Exercise intolerance
    • Generalized weakness
    • Syncope
    • Decreased or increased heart rate

Clinical Features of Atrial Fibrillation

  • Palpitations:
    • Sensation of an accelerated and irregular heartbeat
  • Dyspnea:
    • Shortness of breath during exertion
  • Fatigue:
    • Physical tiredness impacting daily activity
  • Syncope:
    • Episodes of fainting
  • Dizziness:
    • Light-headedness often correlated with arrhythmia
  • Angina:
    • Retrosternal chest pain and discomfort

Diagnostic Evaluation

  • Initial Presentation:
    • History, especially social factors (e.g., alcohol consumption)
    • Electrocardiogram (EKG)
    • Physical examination findings
    • Blood workup including electrolyte panel
  • Cardiac Workup:
    • Echocardiogram (ECHO) to assess heart structure and function
    • Stress tests to evaluate cardiac response to exertion
    • Holter monitor may be utilized once the patient is stabilized in rhythm

Holter Monitoring and ECG

  • Definition: Continuous ECG monitoring typically for 24-48 hours