Slow heartbeat & heart block, made clear.

The SA node starts the signal. It spreads through the atria, passes through the AV node, and travels to the ventricles. This lets the upper and lower chambers squeeze in sequence.

The natural pacemaker may fire too slowly or pause. With heart block, signals do not travel reliably from the upper to the lower chambers. Medicines can also slow the pulse.

A low pulse is not always dangerous. Symptoms and the type of rhythm matter.

An EKG or monitor helps connect symptoms with a slow rhythm. A pacemaker sends small electrical signals when needed to support the heartbeat. Not everyone with a slow pulse needs one.

A pacemaker treats selected slow rhythms; it does not fix every cause of dizziness or fainting.