Descriptions: Wide QRS, usually more than 120ms or 3 small squares, and wide S wave, caused by partial or complete blockage of signal along the right branch below the bundle of HIS.

Descriptions: PR interval progressively lengthens and leading finally to the dropout of QRS complex, also known as Wenkebach Phenomenon.

Descriptions: Normal beats, but triggered at an irregular interval from 60 to 100 BPM, causing varying R-R interval.

Descriptions: A sinus rhythm of less than 60 beats per minute.

Descriptions: The sinus node sends out electrical signals faster than usual, speeding up the rate. A sinus rhythm of more than 100 beats per minute.

Descriptions: Usually caused by reentry currents within the atria or between ventricles and atria producing higher heart rates of 140~250. (Sinus rhythm at 160 BPM.)

Descriptions: Complete lack of synchronism between the P wave and QRS complex. No signals reaching ventricles.

Descriptions: Every second beat is followed by a premature contraction (two normal QRS complexes followed by a PVC).

Descriptions: Two PVCs together. Also called a couplet.

Descriptions: (Extremely Serious-near death conditions) Irregular ventricular waveform.