J Point

www.circ.ahajournals.org/cgi/content/full/98/18/1937

The J point in the ECG is the point where the QRS complex joins the ST segment. It represents the approximate end of depolarization and the beginning of repolarization as determined by the surface ECG. There is an overlap of 10 milliseconds. The J point may deviate from the baseline in early repolarization, epicardial or endocardial ischemia or injury, pericarditis, right or left bundle-branch block, right or left ventricular hypertrophy, or digitalis effect. The term J deflection has been used to designate the formation of the wave produced when there is a large, prominent deviation of the J point from the baseline. The J deflection has been called many names, including camel-hump sign, late delta wave, J-point wave, and Osborn wave.