What it is
Heart rate describes speed; rhythm describes the timing pattern of beats.[1,2]
Why it matters
Arrhythmias are grouped by whether they are slow, fast, or irregular and by which heart chamber is affected.[1]
Root causes of abnormal values
- Effective beat timing: Heart rate changes cardiac output by changing how many effective beats happen per minute; rhythm changes whether those beats arrive in an organized sequence that can fill and eject blood.[3,1]
- Too fast, too slow, or disorganized: Very fast rates can shorten filling time, very slow rates can provide too few beats, and disorganized rhythms can make some beats mechanically ineffective.[1,4]
What it affects
- Resting bradycardia, tachycardia, premature beats, and atrial fibrillation have different meanings in context.[1]