Pacemaker Patient Information Glossary of Terms Atria- The two upper chambers of the heart   AV node- Part of the electrical pathway between the atria and the ventricles   ECG- An Electrocardiogram (ECG) records the electrical activity within the heart   Ventricles- The two lower chambers of the heart, providing most of the pumping force   Heart block- Electrical impulses are slowed or blocked as … Continue reading Pacemaker