The following article presents an unusual case of atrial tachycardia, initially misdiagnosed due to a lack of clear P waves. The diagnosis was eventually confirmed using the atrial electrogram from the patient’s pacemaker

Hanon, Sam

Schweitzer, Paul

Shapiro, Michael

English

PubMed

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An Unusual Tachycardia

The following article presents an unusual case of atrial tachycardia, initially misdiagnosed due to a lack of clear P waves. The diagnosis was eventually confirmed using the atrial electrogram from the patients pacemaker

Sam Hanon

Michael Shapiro

Paul Schweitzer

Directory of Open Access Journals

Indian Pacing and Electrophysiology Journal

Cognitive Sciences ePrint Archive

 
www.ipej.org 152
Case Report
An Unusual Tachycardia
Hanon, Sam MD, Shapiro, Michael DO, Schweitzer, Paul MD, FACC
Division of Cardiology of Beth Israel Medical Center, University Hospital and Manhattan
Campus for the Albert Einstein College of Medicine New York, NY.
Address for correspondence: Sam Hanon, M.D.  Division of Cardiology, Beth Israel Medical
Center, 1st Avenue at 16th Street, New York, NY 10003. Email: shanon@bethisraelny.org
Abstract
           The following article presents an unusual case of atrial tachycardia, initially misdiagnosed
due  to  a  lack  of  clear  P  waves.  The  diagnosis  was  eventually  confirmed  using  the  atrial
electrogram from the patient’s pacemaker.
Key words: Atrial tachycardia, P wave, atrial electrogram.
Case report
            An  eighty-four  year  old  Dominican  man  presented  to  the  Emergency  Department
complaining of “dizziness.” He had a past medical history significant for aortic stenosis, status
post aortic valve replacement, paroxysmal atrial fibrillation and sick sinus syndrome, for which a
DDD pacemaker was placed. Two days prior to admission he noted light-headedness,  which
began while walking.
            Initial electrocardiogram (ECG) (Figure 1), revealed a wide complex tachycardia at 170
bpm with LBBB morphology. The differential diagnosis included ventricular tachycardia with
exit  block,  atrial  tachycardia,  atrial  flutter,  and  A-V  nodal  reentrant  tachycardia.  Previous
tracings had shown a preexisting LBBB.
            The  tachycardia  terminated  spontaneously  but  recurred.  After  the  resolution  of
symptoms, the ECG was repeated (Figure 2). This ECG showed a QRS morphology similar to
the admission tracing with a ventricular rate of 85 bpm and no clear P wave activity. 
            Because the follow up ECG was at a rate exactly half the initial one, an underlying atrial
tachycardia was suspected. The pacemaker was interrogated to assist in analysis of the rhythm
(Figure 3). The interrogation revealed atrial tachycardia with 2:1 block, with an atrial rate of 170
bpm and a ventricular rate of 85 bpm. The patient was treated with metoprolol and his symptoms
resolved after normalization of his rhythm.
Indian Pacing and Electrophysiology Journal (ISSN 0972-6292), 4(3): 152-154 (2004)
Sam Hanon, Michael Shapiro, Paul Schweitzer, “An Unusual Tachycardia”                     153
Figure 1. Initial ECG on presentation: Wide complex tachycardia at 170 bpm with LBBB
morphology
Figure 2. Repeat ECG after resolution of symptoms: LBBB morphology with a ventricular
rate of 85 bpm and no clear P wave activity
Discussion
            P wave size and morphology are determined by the location of the ectopic pacemaker and
the sequence of atrial activation, which may be influenced by atrial disease.1 As a result,  the
correlation between atrial activity and cardiac rhythm can be difficult  to establish by surface
ECG alone. Specifically, in cases of atrial tachycardia, identification of the underlying rhythm
can be problematic, as P waves may be small or hidden in the QRS complex. Occasionally, as in
the  present  case,  no  P  waves  may  be  detected  from  the  ECG  while  the  atrial electrogram
Indian Pacing and Electrophysiology Journal (ISSN 0972-6292), 4(3): 152-154 (2004)
Sam Hanon, Michael Shapiro, Paul Schweitzer, “An Unusual Tachycardia”                     154
 
Figure  3. Pacemaker  interrogation  demonstrating  sensed  atrial  activity  at  170  bpm  and
conduction to the ventricle 2:1 resulting in a ventricular rate of 85 bpm, confirming a diagnosis
of atrial tachycardia
demonstrates  clear  atrial  activity.  Consequently,  the  rhythm may be  mistaken  for  junctional
tachycardia  or  A-V nodal  reentrant  tachycardia.  This  case  illustrates  that  the atrial  wire  can
facilitate elucidation of atrial activity during an arrhythmia.
References
1. Zipes  DP,  DeJoseph  RL:  Dissimilar  atrial  rhythms  in  man  and  dog.  Am  J  Cardiol
1973;32:618-628.
Indian Pacing and Electrophysiology Journal (ISSN 0972-6292), 4(3): 152-154 (2004)


RL: Dissimilar atrial rhythms in man and dog.

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An Unusual Tachycardia

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