In a typical heart rhythm, electrical signals travel from the heart's upper chambers (atria) to the heart's lower chambers (ventricles), causing the ventricles to contract and pump blood. In ventricular fibrillation, rapid, irregular electrical signals cause the ventricles to quiver uselessly instead of pumping blood.
Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission.
Check out these best-sellers and special offers on books and newsletters from Mayo Clinic Press.
Mayo Clinic researchers drive discoveries that improve detection, diagnosis and treatment. Your quick message to them means so much.