Baylor University Medical Center Proceedings April 2014, Volume 27, Number 2 | Page 49
Irregular cardiac rhythm with wide QRS complexes
D. Luke Glancy, MD, and Manpreet Singh, MD
he patient is an 80-year-old woman
with a history of aortic valve replacement, chronic kidney disease, and a
left ventricular ejection fraction of
35%. The cardiac rhythm is atrial fibrillation,
which in her is permanent. A VVI pacemaker
senses and captures normally (Figure). The
pacemaker lead is in the right ventricle, and
consequently pacer-initiated QRS complexes
(the first QRS in the limb leads and the third
and fourth QRSs in the precordial leads) resemble left bundle branch block. The other
seven QRSs are the result of conduction down
the atrioventricular node and His bundle and
show left bundle branch block.
There is a difference between the QRSs
of the paced complexes and the QRSs of the
native complexes in addition to the presence
or absence of pacemaker spikes. In lead V1,
the paced QRS has a notch on its downstroke
making it slow, whereas the downstroke of the
native QRS has no notch and is quick. Kindwall et al described the differences between
lead V1 morphology in ventricular tachycardia
with a left bundle branch block-like morphology and in supraventricular tachycardia with
left bundle branch block aberration (1). With
ventricular tachycardia, V1 may show a wide
r wave and/or a notch on the downstroke of
Figure. Twelve-lead electrocardiogram in an 80-year-old woman with an electronic ventricular pacemaker.
the S wave, and from the beginning of the
QRS to the nadir of the S is > 0.06 s. In contrast, with left bundle branch block aberration, there is either
1. Kindwall KE, Brown J, Josephson ME. Electrocardiographic criteria for
a QS wave in lead V1 or the initial r wave is brief (≤0.02 s);
ventricular tachycardia in wide-complex left bundle-branch morphology
there is no notch on the quick downstroke of the S wave; and
tachycardia. Am J Cardiol 1988;61(15):1279–1283.
the time from the beginning of the QRS to the nadir is ≤0.06 s.
Although Kindwall et al described these differences in patients
with wide QRS tachycardias, they obviously would apply to
From the Sections of Cardiology, Departments of Medicine, Louisiana State
single premature complexes. As in our case, they also apply
University Health Sciences Center and the Interim LSU Hospital, New Orleans,
to right ventricular pacing which is not in a location that can
Louisiana.
replicate conduction that is normal except for left bundle branch
Corresponding author: D. Luke Glancy, MD, 7300 Lakeshore Drive, #30, New
Orleans, LA 70124 (e-mail: [email protected]).
block.
T
Proc (Bayl Univ Med Cent) 2014;27(2