EP IMAGES: FROM CELL TO BEDSIDESection Editor: David S. Rosenbaum, M.D.

Respiration and Initiation of Atrial FibrillationPEI-HONG LIN, M.D., JIN-LONG HUANG, M.D., CHIH-TAI TING, M.D., PH.D.,

and SHIH-ANN CHEN, M.D.*

From the Division of Cardiology, Department of Medicine, Institute of Clinical Medicine, National Yang-Ming University, andVeterans General Hospital-Taichung and *Veterans General Hospital-Taipei, Taiwan, Republic of China

A 67-year-old man without organic heart disease wasnoted to have several episodes of paroxysmal atrial � bril-lation (AF) documented by surface ECG. Transthoracicechocardiography revealed mild dilation of the left atrium(4.3 cm). Transesophageal echocardiography showed nointracardiac thrombus. The 24-hour Holter ECG showedfrequent monomorphic atrial premature contractions(APCs), repeated bursts of nonsustained AF, and sustainedAF. Simultaneous recordings of respiration movement andECG are shown in the � gure. Upper tracing of panels A andB is respiratory movement with positive wave for inspira-tion and negative wave for expiration. Repetitive bursts ofAF occurred during regular respiration (panel A). AF wasconverted to sinus rhythm after forced expiration andbreath-holding (panel B).

This laboratory showed that autonomic function canmodulate the initiation and termination of focal AF.1 ,2 In-crease of parasympathetic activity mediated by phenyleph-rine infusion with barore� ex can suppress spontaneous ec-topic beats and AF from pulmonary veins.2 In this patient,initiation of AF was considered a focal mechanism becausethe Holter ECG showed frequent monomorphic APCs thathave a contour similar to the P waves during initiation ofAF. Because a change in vagal input was associated withexpiration and breath-holding, this type of paroxysmal AFcan be suppressed. Temporal factors involved with therespiratory phase and vagal activation, and increase of ve-nous return with stretch of pulmonary vein, which caninitiate AF from the pulmonary vein, should be considered.

References

1. Chen SA, Hsieh MH, Tai CT, Prakash VS, Yu WC, Hsu TL, Ding YA,Chang MS: Initiation of atrial � brillation by ectopic beats originatingfrom the pulmonary veins. Electrophysiological characteristics, phar-macological responses, and effects of radiofrequency ablation. Circu-lation 1999;100:1879-1886.

2. Tai CT, Chiou CW, Wen ZC, Hsieh MH, Tsai CF, Lin WS, Chen CC,Lin YK, Yu WC, Ding YA, Chang MS, Chen SA: Effect of phenyl-ephrine on focal atrial � brillation originating in the pulmonary veinand superior vena cava. J Am Coll Cardiol 2000;36:788-793.

Supported in part by grants from the Yen Tjing Ling Medical Foundation(CI-88-7-3).

J Cardiovasc Electrophysiol, Vol. 12, p. 979, August 2001.

Address for correspondence: Shih-Ann Chen, M.D., Division of Cardiol-ogy, Veterans General Hospital-Taipei, 201 Sec. 2, Shih-Pai Road, Taipei,Taiwan, Republic of China. Fax: 886-2-2873-5656 or 2873-5875; E-mail:sachen@vghtpe.gov.tw

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