12.4 : 徐脈

Bradycardia is the medical term for decreased heart rate. It occurs when the sinus node produces an impulse rate slower than normal.

An adult is considered to have bradycardia when the pulse rate decreases to 60 beats or less per minute.

A bradycardia episode can reduce the oxygen supply to organs and tissues, causing the heart to insufficiently pump blood to the brain and other body parts.

Bradycardia may not always have symptoms or complications, but it can lead to stroke or even cardiac failure if left untreated.

The signs and symptoms of bradycardia include tiredness during physical activity, chest pain, lightheadedness, confusion, and shortness of breath.

Also, bradycardia is more likely to occur in old age and individuals with a history of high blood pressure, or an underactive thyroid gland.

Sleep apnea, low body temperature, poor oxygenation, certain medications like calcium channel blockers, and exercise can cause bradycardia.

These factors ultimately affect the heart rhythm resulting in arrhythmias.