1465

ARRHYTHMIA ROUNDSSection Editor: George J. Klein, M.D.

“A Bird in Hand or Two in the Bush?”BOBBY JOHN, M.D., D.M., YASH Y. LOKHANDWALA, M.D., D.M.,

PURENDRA KUMAR PATI, M.D., D.M., and V. JACOB JOSE, M.D., D.M.

From the Department of Cardiology, Christian Medical College, Vellore, Tamil Nadu, India

Case Presentation

A 37-year-old man presented with a 6-year history of re-current paroxysmal palpitations. The episodes occasionallywere accompanied by presyncope and terminated by intra-venous verapamil. Symptoms persisted despite amiodaronetherapy. The patient underwent electrophysiology (EP) study.Baseline ECG (Fig. 1A) showed preexcitation. Decrementalatrial stimulation via the coronary sinus revealed the patternshown in Figure 1B. What is the diagnosis?

Commentary

Baseline ECG (Fig. 1A) shows submaximal preexcitation.The tall R wave in lead V1 suggests a left-sided accessorypathway (AP). Coronary sinus (CS) pacing elicits maximal

J Cardiovasc Electrophysiol, Vol. 15, pp. 1465-1466, December 2004.

Address for correspondence: Bobby John, M.D., D.M., Department ofCardiology, Christian Medical College, Vellore 632 004, Tamil Nadu, India.Fax: 91-416-2232035; E-mail: bobeck@cmcvellore.ac.in

doi: 10.1046/j.1540-8167.2004.04367.x

Figure 1. A: Baseline ECG. B: Decremental left atrial pacing via the coronary sinus. The paced cycle length decreases toward the right half of the figure.

preexcitation by engaging the AP early. Intriguingly, two pat-terns of preexcitation are seen, with the abrupt change occur-ring from the 11th QRS complex onward (Fig. 1B). The firstpattern suggests a left posterior location. The second patternis more consistent with a left anterolateral location, consider-ing the negative QRS complex in lead aVL and the S wavesin leads V5–V6. The change in activation pattern is due to thedecreased pacing cycle length, which becomes shorter thanthe refractory period of the left posterior pathway.

During EP study, initially orthodromic AV reentrant tachy-cardia (AVRT) was easily and repeatedly inducible usingprogrammed ventricular extrastimuli. Retrograde earliest ac-tivation was in the left anterolateral region. A similar retro-grade activation was seen during right ventricular stimulation(Fig. 2). This activation was mapped and successfully ablatedin the left anterolateral region. Radiofrequency (RF) energywas delivered during orthodromic AVRT at a site where an-tegrade and retrograde AP conduction was the earliest. Oncareful scrutiny, the retrograde activation sequence revealssimilar activation time in the distal three adjacent bipolarCS electrograms (Fig. 2). Because the CS bipoles are 8 mmapart, such a wide area of earliest retrograde atrial activationsuggests the presence of more than one AP.

1466 Journal of Cardiovascular Electrophysiology Vol. 15, No. 12, December 2004

Figure 1. (Continued)

During application of RF energy, VA conduction seemedto change with continuing AVRT. Close scrutiny after RFenergy application revealed that earliest retrograde atrial ac-tivation during AVRT and during right ventricular stimulationnow was restricted to the left posterior region (CS5-6). Thelocal ventriculogram at this site preceded delta wave onsetby 21 msec. RF ablation at this location during atrial pac-ing eliminated preexcitation. Afterward, VA conduction wasnot present, and transient AV block was demonstrable withadenosine.

Multiple APs are present in 5% to 20% of patients withWolff-Parkinson-White syndrome.1 The APs should be at

Figure 2. Right ventricular pacing showing VAconduction and earliest A wave in the distal coro-nary sinus (CS1-2). The A wave in CS3-4 showsa similar early timing, but in CS5-6 the A wavefollows almost immediately after the A wave inCS12.

least 3 cm apart1 in order to be labeled as different APs.Ockham’s razor tells us to try and explain all symptoms byone pathology. However, at times you must look out for twobirds in the bush rather than be satisfied with the one inhand.

Reference

1. Chen SA, Hsia CP, Chiang CE, Chiou CW, Yang CJ, Cheng CC, TsangWP, Ting CT, Wang SP, Chiang BN, Chang MS: Reappraisal of ra-diofrequency ablation of multiple accessory pathways. Am Heart J1993;125:760-771.