Determining heart rateThe number of QRS complexes per minute; note that HR may not equal perfused pulse rate. See also: - Step 1 Heart Rate - Rate - Rule of 300s (Triplicate Method) - Six Second Count - The Caliper Method 1.... of complexA collection of waveforms (i.e. QRS complex and the ECG complex). 1. Six Second ECG Guidebook (2012), T Barill, p. 194 rhythms can be challenging. Within complex rhythms is an underlying rhythmWhile a rhythm as a whole may be irregular, segments may be regular. These regular periods are often referred to as the underlying rhythm. Apply the three step method to the underlying rhythm first. When naming a rhythm, the underlying... (i.e. sinus rhythmAlso known as regular sinus rhythm or sinus rhythm, this cardiac rhythm is not a dysrhythmia; sinus rhythm originates in the sinoatrial (SA) node with a rate of 60-100/minute; P waves are upright in most leads and the QRS is...) and possible extra ectopicA depolarizing wave that originates anywhere outside of the SA node. 1. Six Second ECG Guidebook (2012), T Barill, p. 196 beats (i.e. PACEarly QRS complexes (usually narrow) make the ECG rhythm pattern irregular. Atrial impulses are preceded by abnormal P waves, often biphasic, but always distinct from the P waves generated by a sinus node. Premature atrial complexes (PAC) are typically benign,..., PJCA narrow QRS complex that arrives distinctly earlier than expected can be a premature atrial complex or a premature junctional complex (PJC). A PJC can be preceded by an inverted P wave, no P wave (timing places the inverted P..., PVCA wide QRS complex that arrives early is called a premature ventricular complex (PVC). A PVC has a width of 0.12 seconds or longer. The elongated period of ventricular depolarization is caused by an abnormal, less efficient pathway of ventricular...). A dynamic heart rateHeart Rate; calculated by counting the number of QRS complexes in six seconds and multiplying by 10; rate is also determined by measuring the number of large squares between two R waves; i.e. –1 large square = heart rate of 300/minute. on a cardiac monitor often adds all QRSThe electrical representation of ventricular depolarization; the atrial repolarization is also a part of the QRS. ECG interpretation relies heavily on the QRS complex. The QRS complex represents the depolarization of the ventricles. The repolarization of the atria is also... complexes within a time frame and then extrapolates to heart rate/minute. This is essentially a cumulative heart rate.