ACLS: Bradycardia and Tachycardia

Introduction

• Advanced Cardiac Life Support (ACLS) is a structured approach to the rapid recognition and management of life-threatening cardiac events during the perioperative period.
• Tachycardia and Bradycardia are common arrhythmias that occur during the perioperative period and can lead to cardiac arrest if not recognized and treated promptly.
• Scientific reviews estimate approximately 3-6 cardiac arrest events in the perioperative period per 10,000 anesthetic events, with increased occurrences noted in patients with a higher American Society of Anesthesiologists (ASA) physical status and old age.¹
• When comparing perioperative cardiac arrests with arrests occurring at other locations in the hospital, researchers found substantially higher patient survival rates, with survival to discharge approximately 33-42% for intraoperative events compared to 18-26% of ward cardiac arrests.
• Long-term outcomes also favor perioperative events, with 4-year survival of 59.9% for perioperative in-hospital cardiac arrest (IHCA) versus 33.0% for ward IHCA.^2-4
• This is likely attributable to the combination of continuous monitoring, readily available airway and vascular access, and the presence of trained Anesthesia personnel, which enables rapid recognition and prompt intervention.

Bradycardia With a Pulse

• Bradyarrhythmia is defined as a heart rate of less than 50 beats per minute.
• Common causes of this in patients in the perioperative period include increased vagal tone, neuraxial anesthesia, hypoxia, or medications. Identifying these possible factors is a critical first step.
  • Common medication causes include beta blockers, non-dihydropyridine calcium channel blockers, antiarrhythmics, anesthetic agents (propofol), opioids, succinylcholine, clonidine, dexmedetomidine, digoxin, etc.⁵
  • Certain procedures have also been notorious for inducing bradycardia and include
    • Peritoneal insufflation during laparoscopic surgery
    • Maxillofacial surgeries, carotid endarterectomies, and spinal or dural manipulation that induce the trigeminal cardiac reflex or activate the vagus nerve
• Patient-related risk factors include age (older than 60 years), higher ASA classification, baseline heart rate less than 60 beats per minute, and use of beta-blockers or renin-angiotensin system blockers.⁵
• Patients with bradycardia can be further categorized as stable or unstable. Signs that a patient is unstable include the following:
  • Hypotension
  • Altered mental status
  • Shock
  • Ischemic chest pain
  • Acute heart failure
• For symptomatic bradycardia that is resistant to correction of reversible causes, atropine is the first-line treatment.
  • Atropine blocks muscarinic acetylcholine receptors, thereby removing parasympathetic inhibition of the heart, thereby enhancing sinus node automaticity and atrioventricular nodal conduction.
  • Intravenous dose: Initial 1mg bolus. Repeat every 3-5 minutes. The maximum dose is 3mg.
• If atropine is ineffective, dopamine and epinephrine infusions should be considered
  • Dopamine has mixed adrenergic effects that are noted to be dose dependent. At the higher doses used in ACLS, dopamine induces beta-adrenergic stimulation, increasing both heart rate and contractility.
  • Infusion rate: 5-20 mcg/kg/min
  • Epinephrine causes both alpha-adrenergic and beta-adrenergic stimulation to increase heart rate, heart contractility, blood pressure, and myocardial oxygen consumption
  • Infusion rate: 2-10 mcg/min with titration based on hemodynamic response
• If the patient remains unstable or unresponsive to pharmacological interventions, transcutaneous pacing should be initiated. Analgesia and sedation are encouraged for awake patients undergoing pacing.

Tachycardia with a Pulse

• Tachycardia is defined as a heart rate greater than or equal to 150 beats/minute
• In the perioperative period, tachycardia is usually a transient insult and can include hypoxemia, cardiac ischemia, catecholamine excess, hypovolemia, sepsis, anemia, and pulmonary embolism.⁶
• Management is based on hemodynamic stability and QRS width.
• Initial assessment should include prioritizing resuscitative measures if necessary and obtaining a 12-lead electrocardiogram to assist with rhythm classification
  • Ensure the airway is patent and provide supplemental oxygen if the patient is hypoxic
  • Obtain adequate intravenous access
• If there are signs of instability, the patient requires immediate intervention with synchronized cardioversion. Adenosine may also be considered if the QRS complexes are regular and narrow.
  • Unstable signs include hypotension, altered mental status, signs of shock, ischemic chest pain, and acute heart failure
  • Adenosine activates A1 receptors to ultimately block atrioventricular nodal conduction and slow the heart rate
  • Intravenous dose: Initial 6mg bolus. If there is no response, repeat with 12 mg bolus.
• If the patient is evaluated as stable, management is based on the QRS complex duration.
• If the QRS complex is less than 0.12 seconds, it is defined as a narrow complex tachycardia
  • For regular rhythms, vagal maneuvers are first line treatment; however, it can be followed by adenosine administration if unsuccessful
  • Consider a beta blocker or calcium channel blockers for rate control
• If the QRS complex is equal to or greater than 0.12 seconds, it is defined as a wide complex tachycardia
  • Adenosine is recommended only if the rhythm is noted to be regular and monomorphic
  • Antiarrhythmic infusions may be considered and are as follows:
  • Amiodarone
    • Amiodarone exhibits multi-class antiarrhythmic effects to slow atrioventricular nodal conduction, prolong refractoriness and reduce automaticity
    • Initially, administer 150mg over 10 minutes. Then, a maintenance infusion should be started at 1mg/min for 6 hours
  • Procainamide
    • Procainamide is a class I sodium channel blocker that increases the refractory period in cardiac tissue
    • Avoid in patients with congested heart failure or prolonged QT syndrome
    • Administer 20-50mg/min until the following criteria have been met:
    • Arrhythmia is suppressed, the patient becomes hypotensive, QRS duration increases by more than 50% or the maximum dose of 17mg/kg is given
    • Maintenance infusion at 1-4mg/min
    • Sotalol
• Sotalol is both a class II and class III antiarrhythmic
• Avoid in patients with prolonged QT syndrome
• Administer 100mg over 5 minutes
• If refractory or recurrent tachycardia is appreciated, consult a cardiologist and electrophysiology specialist early. Also consider increasing synchronized cardioversion energy or adding additional antiarrhythmic therapy.