Si. Riva et al., VALUE OF ANALYSIS OF ST SEGMENT CHANGES DURING TACHYCARDIA IN DETERMINING TYPE OF NARROW QRS COMPLEX TACHYCARDIA, Journal of the American College of Cardiology, 27(6), 1996, pp. 1480-1485
Objectives. Repolarization changes during narrow QRS complex tachycard
ia were analyzed to differentiate the tachycardia mechanism and to gui
de the preliminary location of the accessory pathway. Background. Noni
nvasive determination of the mechanism of tachycardia is becoming incr
easingly important in view of the role of catheter ablation techniques
for the cure of supraventricular tachycardia. Methods. We analyzed 15
9 12-lead electrocardiograms during narrow QRS complex tachycardia to
evaluate 1) the tachycardia cycle; and 2) ST segment depression or T w
ave inversion, or both. Each patient underwent a complete electrophysi
ologic evaluation, Results. There were 13 atrial tachycardias, 57 atri
oventricular (AV) node reentrant tachycardias and 89 AV reciprocating
tachycardias. The mean RR cycle did not differ among types of tachycar
dia. ST segment depression >2 mm or T wave inversion, or both, was pre
sent more often in AV reciprocating tachycardia (57%) than in AV node
tachycardia (25%). The magnitude of ST segment depression was greater
in AV reciprocating tachycardia than in AV node tachycardia (mean +/-
SD 1.3 +/- 1.6 vs, 0.7 +/- 0.8 mm, p < 0.005). In AV reciprocating tac
hycardia distinct patterns of repolarization changes and P wave config
uration,were associated with different sites of the accessory pathway.
Conclusions. The presence of ST segment depression >2 mm or T wave in
version, or both, during narrow QRS complex tachycardia suggests that
AV reentry using an accessory pathway is the mechanism of the tachycar
dia. The phenomenon may be the consequence of a distinct pattern of re
trograde atrial activation, Analysis of repolarization changes can gui
de preliminary localization of the accessory pathway even in the absen
ce of ventricular preexcitation.