SA Node, aka SinoAtrial Node (60-100 bpm).b) It conducts the electrical signal very rapidly as compared to other tissues.a) It possesses automaticity, i.e., it will spontaneously depolarize and repolarize without an external.The special electrical conduction system has two important unique properties: This stimulus is usually the adjacent Purkinje Cell or an adjacent myocardial cell in the active process of depolarizing.

The myocardium does not possess automaticity and subsequently will not depolarize until stimulated by an external stimulus. Important Note: The depolarization of the SA node (at 1) and the AV node (at 2) produce only a tiny voltage and will not be visible on the standard rhythm strip.Įlectrically speaking, the two tissue types are characterized as follows below: The resultant electrical signal on the ECG Rhythm is as follows: The myocardial tissues then recharge (repolarize) and the SA node discharges again the cycle then repeats itself. In a normal, healthy heart, the electrical signal initiates in the SA (sinoatrial) node, depolarizes the Atrial myocardium, depolarizes the AV (atrioventricular) node, propagates through the Bundle of HIS, and terminates in the Purkinje cells, depolarizes the Ventricular Myocardium (endocardium to the epicardium). Propagation of the electrical signal of the ECG Rhythmīefore discussing recognition of the different ECG Rhythms, it is important to correlate the anatomical region where the electrical signal is generated with the electrical signal generated on the ECG rhythm strip.

A flutter rhythm strips