What are the causes of sudden cardiac arrest in a post-ECMO (Extracorporeal Membrane Oxygenation) child?

Causes of Sudden Cardiac Arrest in Post-ECMO Children

The most common causes of sudden cardiac arrest in post-ECMO children include arrhythmias (particularly from underlying cardiac abnormalities), post-ECMO myocardial dysfunction, pulmonary hypertensive crisis, persistent underlying pathology, and complications related to ECMO therapy itself. 1

Primary Cardiac Causes

• Arrhythmogenic disorders - Children with genetic or congenital cardiac abnormalities are at high risk for ventricular fibrillation/pulseless ventricular tachycardia, including:

  • Hypertrophic or dilated cardiomyopathy
  • Inherited channelopathies (long-QT syndrome, Brugada syndrome)
  • Right ventricular cardiomyopathy
  • Catecholaminergic polymorphous ventricular tachycardia
  • Wolff-Parkinson-White syndrome
  • Congenital heart disease 2

• Post-ECMO myocardial dysfunction - Cardiac dysfunction persisting after ECMO decannulation due to:

  • Reperfusion injury
  • Inflammatory response
  • Prolonged hypoxemia during initial event 2, 3

Pulmonary Vascular Causes

• Pulmonary hypertensive crisis - Common in children with congenital heart disease and can be triggered by:

  • Pain or anxiety
  • Tracheal suctioning
  • Hypoxia
  • Acidosis
  • Withdrawal of pulmonary hypertension-specific therapy 2

• Right ventricular failure - Secondary to pulmonary hypertension, leading to:

  • Systemic hypotension
  • Myocardial ischemia
  • Cardiac arrest 2, 1

ECMO-Related Complications

• Bleeding complications - Occur in up to 70% of ECMO patients and can lead to:

  • Cardiac tamponade
  • Hypovolemic shock
  • Hemodynamic instability 2, 4

• Thrombotic events - Patient-related clots occur in approximately 13% of ECMO cases:

  • Pulmonary embolism
  • Coronary thrombosis
  • Cerebral thrombosis 4

• Acquired von Willebrand syndrome - Develops in most ECMO patients:

  • Loss of high-molecular-weight multimers
  • Contributes to bleeding risk 2

• Arrhythmias after ECMO - Associated with higher hospital mortality 3

Neurological Complications

• Post-cardiac arrest brain injury - Leading cause of morbidity and mortality:

  • Hypoxic-ischemic brain injury
  • Cerebral edema
  • Seizures 2, 5

• Intracranial hemorrhage - Occurs in approximately 16% of ECMO patients 4

Systemic Complications

• Systemic ischemia/reperfusion response - Characterized by:

  • Oxidative stress
  • Free radical-mediated cell injury
  • Inflammatory cascade 2, 5

• Persistent precipitating pathology - The original condition that necessitated ECMO may recur or worsen 1, 6

Metabolic and Respiratory Causes

• Electrolyte abnormalities - Particularly:

  • Hypokalemia
  • Hypomagnesemia
  • Hypocalcemia 1

• Respiratory failure - Can occur due to:

  • Atelectasis
  • Pulmonary edema
  • Pneumothorax
  • Ventilator-associated pneumonia 1, 5

Risk Factors for Poor Outcomes

• Abnormal neurology during or after ECMO support 3
• Bleeding complications requiring significant transfusion 3, 4
• ECMO duration >168 hours 3
• Need for renal replacement therapy during ECMO 3
• Cardiac arrest after ECMO decannulation 3

Clinical Approach to Post-ECMO Arrest

• Immediate high-quality CPR while simultaneously identifying potential causes 1
• Bedside cardiac ultrasonography to identify treatable causes 1
• Address hypotensive shock immediately as it significantly impacts survival 1
• Consider rapid re-initiation of ECMO (ECPR) for refractory cardiac arrest 1, 7
• Implement comprehensive post-cardiac arrest care if ROSC is achieved 1

Understanding these diverse causes is essential for prevention, early recognition, and effective management of sudden cardiac arrest in post-ECMO children to improve survival and neurological outcomes.