Bh. Sarter et al., EFFECT OF BUNDLE-BRANCH BLOCK ON LOCAL ELECTROGRAM MORPHOLOGIC FEATURES - IMPLICATIONS FOR ARRHYTHMIA DIAGNOSIS BY STORED ELECTROGRAM ANALYSIS, The American heart journal, 131(5), 1996, pp. 947-952
Analysis of stored local ventricular electrogram recordings is a usefu
l diagnostic tool in the evaluation of patients with implantable cardi
overter defibrillators. Visual analysis of local electrogram morpholog
ic features has been demonstrated to be useful in distinguishing ventr
icular tachycardia from supraventricular rhythm. The effect of bundle
branch block (BBB) aberration during supraventricular tachycardia on l
ocal electrogram morphologic features is not entirely clear. Erroneous
diagnoses resulting from a change in electrogram morphologic features
with BBB may occur. To determine whether the development of BBB can p
roduce a change in local electrogram morphologic features and whether
this change is dependent on the site of recording, we retrospectively
reviewed local electrogram recordings from 23 patients who had intermi
ttent BBB during electrophysiologic evaluation of documented or suspec
ted supraventricular tachycardia. Local electrogram recordings from ca
theters placed in the right ventricular apex and coronary sinus during
supraventricular tachycardia with BBB aberrancy were compared with re
cordings during narrow complex supraventricular tachycardia or normal
sinus rhythm. Bipolar recordings were made with a 5 mm interelectrode
distance with filter settings at 40 to 400 Hz. Three independent blind
ed observers defined the paired electrograms as the same or distinctly
different. During right BBB a change in electrogram morphologic featu
res was demonstrated in 11 (85%) of 13 recordings from the right ventr
icular apex and in only 1 (8%) of 12 recordings from the coronary sinu
s. In contrast, during left BBB a change in electrogram morphologic fe
atures was seen in 6 (100%) of 6 recordings from the coronary sinus an
d in only 1 (8%) of 13 recordings from the right ventricular apex. The
se results demonstrate that when the described recording techniques ar
e used, a change in local ventricular electrogram morphologic features
during BBB is predominantly manifest in recording sites ipsilateral t
o the BBB, whereas recording sites contralateral to the BBB are relati
vely unaffected. This information may have implications regarding inte
rpretation of stored electrograms when an attempt is made to establish
a rhythm diagnosis leading to implantable cardioverter defibrillator
therapy.