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Atrial function during cardiac arrest caused by ventricular fibrillation.
Chest
|April 18, 2000
Summary
Atrial contractions persist for over 8 minutes during ventricular fibrillation (VF), generating significant blood flow. However, this flow fails to reach the systemic circulation, instead regurgitating into the atrium.
Area of Science:
- Cardiovascular Physiology
- Cardiac Electrophysiology
Background:
- Ventricular fibrillation (VF) typically leads to cessation of organized cardiac output.
- The role of atrial activity during VF remains incompletely understood.
Purpose of the Study:
- To investigate the persistence of atrial electrical and mechanical activity during VF.
- To quantify the blood flow generated by atrial contractions in the setting of VF.
Main Methods:
- Continuous atrial pressure recordings in rats.
- Atrial electrograms in isolated perfused rat hearts.
- Transesophageal echo-Doppler flow measurements in pigs following VF induction.
Main Results:
- Regular atrial pressure pulses and depolarizations were observed during VF in rats.
- Atrial contractions generated significant, albeit declining, stroke volumes in pigs.
- Forward flow into the left ventricle did not progress to the systemic circuit and showed diastolic regurgitation.
Conclusions:
- Atrial contractions and electrical activity are preserved for at least 8 minutes after VF onset.
- Atrial-generated flow during VF is largely ineffective for systemic circulation due to outflow obstruction and regurgitation.