Intraoperative Cardiac Arrhythmias Cause, Recognition, and Treatment

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Intraoperative Cardiac ArrhythmiasCause,
Recognition, and Treatment

• R4 Park Sung-Wook

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• Occurrence 15-85
• Rare complication resulting from cardiac
  arrhythmia in the healthy patients
• Life-threatening arrhythmia during surgery
• Fewer than 1 of patients
• Almost all have cardiac disease

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Physiology

• The Action Potential

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Physiology

• The Action Potential
• Spontaneous diastolic depolarization
• Resting potential not stable in conductive tissue
  cell
• Slow spontaneous depolarization until the
  threshold potential is reached

Slope is controlled by ANS
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Physiology

• The Action Potential
• Excitability depolariztion to specific stimulus
• Increased excitability
• depolarization to a lesser stimuls or an
  exaggerated response to normal stimulus
• Refractoriness
• Absolute refractory period phase 0,1,2
• Relative refractory period late phase 3, early 4
• Susceptable to strong stimuli

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Physiology

• The Conduct System

Control ventricular response to increased supra
ventricular rates
most rapid conduction
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Physiology

• Electrophysiology of Arrhythmias
• Disturbance of SA nodal rate
• Reentry-associated arrhythmias
• Alternate pathways
• One-way or unidirectional block in one pathway
• An area of slow conduction in the other pathway

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Diagnostic Criteria

• Supraventricular Arrhythmias
• Rate
• 150 - atrial flutter with 21 AV block
• gt200 - accessory AV pathway
• Regularity
• AF irregular rhythm
• Regular SVT with variable AV block may be
  misleading

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Diagnostic Criteria

• Supraventricular Arrhythmias
• P waves
• Presence of P wave before QRS atrial origin
• No P wave with regular tachycardia AV node or
  below
• QRS width
• lt0.12 ms supraventricular source
• Wider QRS BBB, aberrant conduction, accessory
  path

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Diagnostic Criteria

• Supraventricular Arrhythmias
• QRS axis
• Severe LAD ventricular origin
• Paroxysmal SVT
• Sinoatrial node reentry normal P
• Atrial tachycardias upright but abnormal
  appearing P
• Atrioventricular node reentry no P or inverted
• Accessory pathway delta wave
• AF irregular narrow QRS
• A-flutter atrial rate 300 with AV block

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Diagnostic Criteria

• Ventricular Arrhythmias
• Frequent PVCs, couplets or brief runs of VT
• Healthy persons benign
• Presence of cardiac dis or LV dysfunction
  dangerous
• Frequent PVCs(gt 6/min) after MI increased
  mortality risk

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Cause and Significance

• Congenital
• Mostly benign
• Accessory pathway tachycardia compromise
  hemodynamic stability
• Congenital prolonged Q-T interval predispose to
  vetricular arrhythmia

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Cause and Significance

• Acquired
• Vetricular arrhythmia
• IHD., aortic stenosis, dis. associated with LVH
• Atrial fibrillation
• IHD., related to aging, distened aorta (MS, CHF)
• Acquired prolonged Q-T interval
• IHD., electrolyte abnormality, drug side effect
• Progress polymorphic ventricular tachycardia
  (torsades de pointes)
• CNS dis, ICH, stroke all types of SVT and
  vetricular arrhythmia

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Cause and Significance

• Electrolyte Imbalance
• Low potassium may trigger dangerous vetricular
  arrhythmia
• Low magnesium produce primarily SVT
• Acute changes in pH
• Anesthesia
• Calcium antagonistic properties
• Halothane sensitize the heart to catecholamines

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Treatment

• Class I
• Block the fast Na channel decrease the rate of
  rapid depolarization
• Class IA
• Vagolytic action, decrease contractility,
  ?-adrenergic blockade
• Quinidine, disopyramide, procainamide,
  diphenylhydantoin

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Treatment

• Class I
• Class IB
• Lidocaine
• Used in all types of vetricular arrhythmia
• Except vetricular arrhythmia d/t prolonged Q-T
  interval
• Toxic effect CNS activation
• Class IC
• Suppressor of phase 0 sodium conductance
• Increased mortality risk

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Treatment

• Class II
• ß-adrenergic receptor blockers
• Effective in all tachyarrhythmias
• Perioperative management of congenital prolonged
  Q-T interval
• Toxicity related to bronchoconstriction

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Treatment

• Class III
• Prolong reploarization
• Increase action potential duration the
  effective refractory period
• Bretylium
• Facilitation of ventricular defibrillation
• Effective in bupivacaine-induced arrhythmias

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Treatment

• Class III
• Amiodarone
• Effective all arrhythmia
• Long onset half-life
• Side effect photosensitivity, abnormal skin
  pigmentation
• Ibutilide
• Effective in converting A-flutter AF
• Side effect hypotension, prolongation of Q-T
  interval

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Treatment

• Class IV
• Calcium channel antagonists
• Supraventricular tachyarrhythmias useful
• Ventricular tachycardias ineffective, severe
  cardiac dysfunction
• Potentiate the myocardial effects of anesthetics
• Contraindication AF with WPW syndrome

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Treatment

• Adenosine
• Effective in acutely converting reentrant nodal
  SVT accessory pathway SVT
• Digoxin
• Perioperatively maintain rate control in
  A-flutter AF
• Magnesium ion
• Useful in the period around CPB operations

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Conclusion

• Tx only associated with hemodynamic compromise
  and potential to progress to life-threatening
  arrhythmias
• Must be familiar with only selective drug