The significance of notched upright T waves.

Cardiological texts yield scant information on the significance of notching of upright T waves. White (1948) states briefly: " The T wave is frequently diphasic but rarely notched ... A late notch or dip in a low T wave in lead II suggests the effect of heart position in an otherwise normal person." Katz (1947) points out that notching of the T wave is abnormal in the limb leads but may be observed in records ofnormal children in leads CF2 and CF4, rarely in CF5. Occasionally, notching of T occurs in lead CF2 of normal adolescents. Pathologically notching of T is associated with hyperthyroidism or acute pericarditis. Scherf and Boyd (1946) mention the occurrence of bifid T waves in cases of rheumatic heart disease and pericarditis. According to Burch and Winsor (1949), notched T waves are not uncommon in lead II in normal persons; deeply notched T waves in lead I are suggestive of myocardial disease. Ashman and Hull (1941) state that the normal T wave is never abruptly and sharply notched; slight notching of low T waves in the limb leads and notched T waves in lead IV F are occasionally observed in normals; in heart disease due to rheumatic fever, thyrotoxicosis, arteriosclerosis, or syphilis, sharp notching of the T wave may be present, especially in lead IV F. Pardee (1941) writes: " Notching ofT is rare in the limb leads. This wave is typically a smooth, rounded or peaked elevation, unless it should have a P wave superimposed on it ... Notching ofT is seen ... as a result of digitalis and. . . quinidine administration. A similar notching has been observed in records from certain patients suffering from hyperthyroidism. Nothing can be said as to the significance of this notching of T except that it is probably due to a toxic reaction of the myocardium. Notching of T is also found in records obtained by prxcordial leads. It is much more frequently seen in these leads than in the leads from the extremities. Its significance in the precordial leads is not understood but it is thought to be an abnormal finding.' The statements quoted from current textbooks convey the impression that notching of T is associated with few pathological conditions and that its meaning is still obscure. Within recent years we have become aware of the frequent incidence of notched T waves, especially since we made it a routine procedure to take full sets of chest leads. We decided to study systematically the incidence and significance of notched T waves correlating clinical and electrocardiographic data.