Intraoperative arrhythmias

Learning objectives

• Define and classify arrhythmias
• Describe the patient, anesthetic, and surgical risk factors for developing intraoperative arrhythmias 
• Management of intraoperative arrhythmias 

Definition and mechanisms 

• Arrhythmias are accelerated, slowed, or irregular heartbeats caused by abnormalities in the electrical impulses of the myocardium
• 60% of patients may experience perioperative arrhythmias 
• The majority are benign, but rhythm disturbance can be associated with potentially serious adverse outcomes

Classification

Bradyarrhythmia (HR <60 bpm)

• Sinus arrhythmia: Sinus bradycardia
• Conduction defects
  • AV blocks
    • First-degree AV block
    • Second-degree AV block
    • Third-degree AV block
  • Intraventricular blocks
    • Right bundle branch block
    • Left bundle branch block
  • Fascicular block
    • Left anterior hemiblock
    • Right anterior hemiblock
  • Bifascicular block
  • Trifascicular block

Tachyarrhythmia (HR >100 bpm)

• Sinus arrhythmia: Sinus tachycardia
• Supraventricular arrhythmias
  • Premature atrial contraction
  • Supraventricular tachycardia
  • Atrial flutter
  • Atrial fibrillation
• Ventricular arrhythmias
  • Premature ventricular contractions
  • Ventricular tachycardia
  • Ventricular fibrillation
  • Torsade de pointes

Complications

• Blood clots (i.e., thromboembolism)
• Stroke
• Heart failure
• Sudden death

Risk factors

Patient factors

• Preexisting arrhythmias
• Coronary artery disease
• Hypertension
• Congestive heart failure
• Electrolyte disorders (especially potassium, magnesium, and calcium)
• Valvular heart disease
• Obstructive sleep apnea
• Medications:
  • β2-agonists
  • Theophylline
  • Tricyclic antidepressants
• Less common causes:
• • Thyroid disease (i.e., hypothyroidism, hyperthyroidism)
  • Cardiomyopathies (including alcoholic)
  • Myocarditis
  • Trauma (myocardial or intracranial)
  • Connective tissue disorders
  • Smoking
  • Drug and solvent abuse

Anesthetic factors

• Hypotension or hypertension (e.g., inadequate anesthesia)
• Hypoxia
• Hypercarbia
• Direct laryngoscopy and intubation
• Central nervous pressure lines (irritation by line tip; microshock hazard)
• Drugs
  • Volatile anesthetic agents
  • Local anesthetics
  • Suxamethonium
  • Pancuronium
  • Multiple drugs prolong the QT interval (e.g., volatile agents, macrolide antibiotics, butyrophenone antipsychotics, amiodarone, and ondansetron)
• 4Hs 4Ts
  • Hypovolemia, hypoxemia, hyper/hypokalemia (electrolyte disorders) and metabolic disorders (acidosis), and hypo/hyperthermia 
  • Tension pneumothorax, tamponade, toxins/drugs, thromboembolism (pulmonary/cardiac)

Surgical factors

• Catecholamines
  • Endogenous (from any surgical stimulus)
  • Exogenous (topical or infiltrated epinephrine)
• Autonomic stimulation
  • Peritoneal and visceral traction
  • Peritoneal insufflation
  • Trigeminovagal reflexes (oculocardiac reflex)
  • Laryngoscopy, bronchoscopy, esophagoscopy
  • Carotid artery and thyroid surgery
• Direct stimulation of the heart during cardiac or thoracic surgery
• Embolism
  • Thrombus
  • Fat
  • Bone cement
  • Air
  • Carbon dioxide
  • Amniotic fluid
• Other
  • Aortic cross-clamping
  • Limb reperfusion
  • Glycine intoxication

Treatment goals

• Prevent thromboembolism formation
• Control heart rate
• Correct the condition causing the arrhythmia
• Reduce other risk factors for heart disease and stroke

Management

• More than one factor is likely to contribute to the development of an intraoperative arrhythmia 
  • Identify the rhythm
  • Evaluate its significance (in the context of)
    • Coexisting medical problems and their treatment
    • Surgical condition
    • Operative procedure
    • Anesthetic drugs and technique
    • Hemodynamic effect of the arrhythmia and the risk of progression to a more serious arrhythmia
  • Identify and correct any precipitating factors 
• Take an ABC approach
• Treat the whole patient, not just the ECG 

Algorithm

Prevention

• Keep surgical manipulations that can precipitate arrhythmias to a minimum
• An adequate depth of anesthesia may prevent or control intraoperative arrhythmias
• Prevent hypoxia, hypotension, hypovolemia, and hypothermia during surgery

Suggested reading

• Noor ZM. Md. Life-Threatening Cardiac Arrhythmias during Anesthesia and Surgery. Cardiac Arrhythmias – Translational Approach from Pathophysiology to Advanced Care. 2021. doi: 10.5772/intechopen.101371.
• Pollard BJ, Kitchen G. Handbook of Clinical Anaesthesia. 4th ed. Taylor & Francis group; 2018. Chapter 30 Management problems, Shelton C.

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