J point

In ECG, the J point (also: junction point) marks the intersection of QRS complex and ST segment. It represents the transition from phase I to phase II of the action potential.

The J point may deviate from the baseline in pathologic conditions: I is often depressed in the case of cardiac ischemia, and in ergometry if coronary artery disease is present. Elevations of the J point are seen e.g. in cases of Brugada syndrome.

References

• J. W. Hurst (1998) Naming of the Waves in the ECG, With a Brief Account of Their Genesis. Circulation. 1998;98:1937-1942.
• D. Scherr. Überlebter plötzlicher Herzkreislaufstillstand bei einem Patienten ohne strukturelle Herzerkrankung: das Brugada-Syndrom. Journal für Kardiologie 2003; 10 (Supplementum B - Forum Rhythmologie): 8-10