cardiolab — Interactive Cardiac Rhythm Training

Normal Sinus Rhythm

normal

Lead II

25 mm/s10 mm/mV

Heart rate

72bpm

RR

833ms

QT

338ms

RR

833ms

PR

162ms

QRS

105ms

QT

338ms

QTc

359ms

Controls

Heart Rate72 BPM

Noise Level0.03 mV

Normal Sinus Rhythm

The heart's normal electrical rhythm. The SA node fires at 60–100 bpm, impulses conduct normally through the atria, AV node, and ventricles.

Recognition· 4

Regular rhythm
P wave before every QRS
PR interval 120–200 ms
Narrow QRS (<120 ms)

Mechanism

SA node fires normally at 60–100 bpm, impulses conduct through normal pathways

The sinoatrial (SA) node in the right atrium acts as the heart's natural pacemaker. It generates electrical impulses that spread through the atria, pause briefly at the AV node, then rapidly conduct through the ventricles via the His-Purkinje system.

Findings· 5

Regular rhythm.
Upright P wave before every QRS.
PR interval 120–200 ms.
Narrow QRS (<120 ms).
Each P followed by a QRS.

Clinical Impact

Normal finding — no treatment needed