Journal of Cardiology Cases (2011) 3, e37—e39

avai lab le at www.sc iencedi rec t .com

journa l homepage: www.e lsev ier .com/ locate / j ccase

Case Report

Paradoxical ventriculophasic sinus arrhythmia during2:1 atrioventricular block

Tong Liua,b, Michael Shehataa, Xunzhang Wanga,∗

a Heart Rhythm Center, The Heart Institute, Cedars-Sinai Health System, Los Angeles, CA, USAb Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin, People’sRepublic of China

Received 5 August 2010; accepted 30 August 2010

KEYWORDSVentriculophasic sinusarrhythmia;

Summary Ventriculophasic sinus arrhythmia is a particular phenomenon commonly observedin patients with complete atrioventricular (AV) block. Typically, the PP intervals which containa QRS complex are shorter than the PP intervals which do not contain it. This phenomenon is

Paradoxical;Atrioventricular block

present in more than 40% of cases with complete AV block and less common in the setting ofsecond-degree AV block. We present a case with paradoxical ventriculophasic sinus arrhythmiaduring 2:1 AV block, in which the PP intervals containing a QRS complex are longer than the PPintervals without an intervening QRS complex. The possible mechanisms regarding this unusualphenomenon are also discussed.© 2010 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

Qi

C

A

Introduction

Ventriculophasic sinus arrhythmia is a particular phe-nomenon commonly observed in patients with completeatrioventricular (AV) block. Typically, the PP intervals whichcontain a QRS complex are shorter than the PP intervalswhich do not contain it. This phenomenon is present in more

than 40% of cases with complete AV block and is less commonin the setting of second-degree AV block [1—3]. We presenta case with paradoxical ventriculophasic sinus arrhythmiaduring 2:1 AV block, in which the PP intervals containing a

∗ Corresponding author.Tel.: +1 310 423 4856; fax: +1 310 423 6795.

E-mail address: Xunzhang.Wang@cshs.org (X. Wang).

ocdwe4Tsdf

1878-5409/$ — see front matter © 2010 Japanese College of Cardiology.doi:10.1016/j.jccase.2010.08.005

RS complex are longer than the PP intervals without anntervening QRS complex.

ase report

56-year-old woman was referred for further evaluationf type II Mobitz AV block by her primary physician. Sheomplained of chest discomfort and shortness of breathuring walking and denied syncope or near-syncope. Sheas not receiving any medications with AV node-blockingffects. Blood pressure was 120/62 mmHg, heart rate was

0 beats per minute, and the oxygen saturation was normal.he 12-lead electrocardiogram (ECG) (Fig. 1) demonstratedinus rhythm with second-degree AV block and 2:1 AV con-uction. Paradoxical ventriculophasic sinus arrhythmia wasound during 2:1 AV block. Note that the PP intervals con-

Published by Elsevier Ltd. All rights reserved.

e38 T. Liu et al.

F ith seN than

tno

D

Vpcwfisiod

phtwa

iiaei

igure 1 The 12-lead electrocardiogram shows sinus rhythm wote that the PP intervals containing a QRS complex are longer

aining the QRS complex are longer than the PP intervalsot encompassing the QRS complex, which are completelypposite to the typical ventriculophasic sinus arrhythmia.

iscussion

entriculophasic sinus arrhythmia is a common finding in theresence of complete heart block. The PP intervals whichontain a QRS complex are shorter than the PP intervalsithout an intervening QRS complex. This phenomenon was

rst described by Erlanger and Blackman in an experimentaltudy of chronic AV block in dogs in 1910 [4]. Later, othernvestigators also observed this phasic variation in over 40%f patients with complete AV block [1—3]. It has been alsoescribed in the setting of second-degree AV block [2] and

c

ibt

cond-degree atrioventricular (AV) block and 2:1 AV conduction.the PP intervals not encompassing a QRS complex.

atients with ventricularly paced rhythms [5]. In a compre-ensive review, Rosenbaum and Lepeschkin [1] also proposedhat a paradoxical effect was seen in 3.5% of the patientsith complete AV block, in which the PP intervals containingQRS complex are longer than those not containing one.Although the potential mechanism of this phenomenon

s still not fully understood, the most plausible explanations two-phase chronotropic effects proposed by Rosenbaumnd Lepeschkin [1]. The positive chronotropic (accelerating)ffect is related to early appearance of a P wave follow-ng a QRS complex and shortening of the PP interval which

ontains a QRS complex.

Two potential mechanisms have been proposed regard-ng the positive chronotropic effect. First, atrial stretchy the mechanical effects of ventricular systole may has-en the discharge of normal sinus node impulses. Second,

iove

mec

R

[

[

[

[

[

[

Paradoxical ventriculophasic sinus arrhythmia during 2:1 atr

ventricular contraction may increase sinus node blood sup-ply and improve the perfusion of sinus node [6,7], whichleads to an earlier sinus node discharge and a P wave fol-lowing a QRS complex. Rosenbaum and Lepeschkin [1] alsofound the maximum positive chronotropic effect appearedduring the relatively shorter QP intervals (between 0.3 and0.4 s). On the other hand, a negative chronotropic (decel-erating) effect may result in the next longer PP intervalwithout an intervening QRS complex. A possible mechanismthat explains the negative chronotropic effect involves arte-rial baroreceptor-mediated changes in vagal tone. In detail,elevated arterial blood pressure caused by ventricular ejec-tion activates the arterial baroreceptors, which produce avagal reflex to slow the firing of sinus node and lengthen thefollowing PP interval without a QRS complex. The maximumnegative chronotropic effect occurs during the relativelylonger QP intervals (between 0.6 and 1.0 s) and slow ven-tricular rate.

Paradoxical ventriculophasic sinus arrhythmia during 2:1atrioventricular block has not been described in the litera-ture thus far. Our particular case can also be explained by

two-phase chronotropic effect mechanisms. In general, theinterplay of these two-phase effects determines whetherthe PP intervals containing a QRS complex will be shorteror longer than those not containing one. Note that the QPinterval is relatively long (620 ms) (Fig. 1) in our case. This

[

ntricular block e39

ay represent a more negative than positive chronotropicffect, which causes the paradoxical effect observed in ourase.

eferences

1] Rosenbaum MB, Lepeschkin E. The effect of ventricular systoleon auricular rhythm in auriculoventricular block. Circulation1955;11:240—61.

2] Parsonnet AE, Miller R. Heart block: the influence of ventricularsystole upon the auricular rhythm in complete and incompleteblock. Am Heart J 1944;27:676—87.

3] Roth IR, Kisch B. The mechanism of irregular sinus rhythm inauriculoventricular heart block. Am Heart J 1948;36:257—76.

4] Erlanger J, Blackman JR. Further studies in the physiology ofheart block in mammals. Chronic auriculo-ventricular block inthe dog. Heart 1910;1:177—230.

5] Chung EK, Jewson DV. Ventriculophasic sinus arrhythmia in thepresence of artificial pacemaker induced ventricular rhythm.Cardiology 1970;55:65—8.

6] Hashimoto K, Tanaka S, Hirata M, Chiba S. Responses of the sino-atrial node to change in pressure in the sinus node artery. Circ

Res 1967;21:297—304.

7] de Marchena E, Colvin-Adams M, Esnard J, Ridha M, CastellanosA, Myerburg RJ. Ventriculophasic sinus arrhythmia in the ortho-topic transplanted heart: mechanism of disease revisited. Int JCardiol 2003;91:71—4.