Cardiac Complications: Atrial Fibrillation

Jun 13, 2024

Cardiac Complications: Atrial Fibrillation

Overview of Atrial Fibrillation (Afib)

  • Definition: Common heart arrhythmia affecting up to 1% of the population.
  • Mechanism: Atria (top chambers of the heart) beat or quiver abnormally (400-600 bpm).
  • Pathophysiology: Increased pressure and dilation of the left atrium.
    • Common causes: Aging, left ventricular hypertrophy (LVH), high blood pressure, sleep apnea.
    • Post-Operative State: High circulating catecholamines.

Importance in Surgical Context

  • Post-Operative Risk: Especially common in thoracic, cardiac, or vascular surgeries and in elderly patients.
  • Implications: Often indicates other potential post-operative complications.

ECG Characteristics of Afib

  • Rate: Tachycardic
  • P Waves: Absent; replaced by fibrillatory waves.
  • Rhythm: Irregularly irregular.

Post-Operative Causes of Afib

  • High Catecholamine Surge:
    • Infection (wound, intra-abdominal, pneumonia).
    • Bleeding (surgical site).
    • Hypoxia/Hypercarbia (e.g., PE, sleep apnea, anesthesia recovery).
    • Volume Status (hypovolemia or fluid overload).
    • Electrolyte Abnormalities (hypokalemia, hypomagnesemia).
    • Other Factors:
      • Thyroid disease (hyperthyroidism).
      • Substance withdrawal (e.g., alcohol).

Workup and Management

Initial Assessment and Orders

  1. Vitals: Check BP, respiratory rate, O2 saturation.
  2. Immediate Orders:
    • ECG
    • Labs: CBC, BMP, Magnesium, Troponin (trending), Thyroid studies, Blood gas, Lactate (if needed).
  3. Patient History & Physical Exam:
    • Symptoms: Chest pain, shortness of breath, dizziness, altered mental status.
    • Volume Status: Lung auscultation, jugular venous pressure, peripheral edema.

Imaging Studies

  • Case-dependent: CT for abdominal concerns, imaging for PE if hypoxic, etc.

When to Consult Cardiology

  • Case-specific, generally after initial stabilization and assessment.

Management Highlights

  1. Stabilizing the Patient:
    • If unstable: Follow ACLS protocol (consider DCCV).
    • If stable: Focused history, physical exam, and specific labs.
  2. Underlying Cause: Essential to identify and correct underlying cause to prevent recurrence.
  3. Rate Control Medications:
    • Beta Blockers: Metoprolol (first-line).
    • Calcium Channel Blockers: Diltiazem (use with caution in heart failure patients).
    • Amiodarone: Reserved for cases with heart failure or hypotension.
    • Digoxin: Less effective in high sympathetic tones.
  4. Heart Failure Consideration: Use EF from recent echo to guide medication choice.

Long-Term Management

  • Anticoagulation:
    • CHADS-VASc Score: Assesses stroke risk.
    • HAS-BLED Score: Assesses bleeding risk.
    • Discuss anticoagulation with patient and family considering risks.

Summary

  • Afib is a common complication in post-operative patients, especially the elderly or those undergoing major surgeries.
  • Key to management: Stabilizing, identifying, and correcting the underlying cause, and appropriate use of rate control medications.
  • Long-term management includes anticoagulation based on stroke and bleeding risk assessment.