Most Likely Type of Cardiac Arrest in RV Failure from Amniotic Fluid Embolism
Pulseless electrical activity (PEA) is the most likely type of cardiac arrest in amniotic fluid embolism with right ventricular failure, though asystole, ventricular fibrillation, and pulseless ventricular tachycardia can all occur. 1
Cardiac Arrest Rhythms in AFE
The Society for Maternal-Fetal Medicine guidelines explicitly state that patients with amniotic fluid embolism may progress rapidly to cardiac arrest with any of the following rhythms 1:
- Pulseless electrical activity (PEA)
- Asystole
- Ventricular fibrillation
- Pulseless ventricular tachycardia
Why PEA is Most Common
The pathophysiology of AFE-related cardiac arrest explains why PEA predominates 1:
- Acute right ventricular failure occurs from massive pulmonary vasoconstriction and mechanical obstruction by amniotic fluid components 1
- Interventricular septal displacement to the left occurs from the severely dilated, failing right ventricle, which obliterates the left ventricular cavity and drastically reduces left-sided cardiac output 1
- Hemodynamic collapse results from right ventricular infarction and/or the mechanical effects of RV dilation on LV filling 1
This creates a situation where electrical activity persists but mechanical cardiac output is insufficient to generate a pulse—the definition of PEA 1.
Clinical Context and Implications
Bedside echocardiography during resuscitation is critical because it will demonstrate the characteristic findings of AFE 1, 2:
- Severely dilated, hypokinetic right ventricle (acute cor pulmonale) 1
- Interventricular septal deviation into the left ventricle 1
- This finding helps distinguish AFE from other causes of peripartum arrest 1, 3
The presence of RV dysfunction on echocardiography is associated with significantly increased risk of cardiac arrest (OR 3.66,95% CI 1.39-9.67) 2, making early identification crucial for mortality reduction.
Management Priorities
Regardless of the specific arrest rhythm, immediate management follows standard ACLS protocols 1, 3, 4:
- High-quality CPR must begin immediately without waiting for diagnostic confirmation 1, 3
- Emergent delivery should be considered in viable pregnancies during resuscitation 1
- RV-specific therapies including inotropes (dobutamine, milrinone) and pulmonary vasodilators should be initiated once return of spontaneous circulation is achieved 1, 4
Critical pitfall: Avoid excessive fluid resuscitation in the setting of severe RV failure, as this will worsen RV distention, increase risk of RV infarction, and further compromise left ventricular filling through septal displacement 1.