Korean Circ J.  2007 May;37(5):208-215. 10.4070/kcj.2007.37.5.208.

Effect of Left Atrial Decompression by Percutaneous Balloon Mitral Commissurotomy on the Atrial Electrophysiologic Properties

• Kim HJ
• Shin DG
• Hong GR
• Park JS
• Kim YJ
• Shim BS
• Kim W
• Lee SH

• KMID: 2227066
• DOI: http://doi.org/10.4070/kcj.2007.37.5.208

Abstract

BACKGROUND AND OBJECTIVES: Atrial dilatation contributes to the inducibility of atrial fibrillation (AF) by changing the atrial electrophysiological properties. There has been no report regarding the electrophysiologic data of the left atrium (LA), where the most significant electrophysiological impact might be expected to occur in case of mitral stenosis (MS). We investigated the electrophysiological changes after reduction of the LA pressure in patients who were undergoing percutaneous balloon mitral commissurotomy (PBMC).
SUBJECTS AND METHODS
We studied 26 patients (21 women, age range: 50+/-12 years) with MS, including 7 sinus rhythm (SR) patients. The effective refractory period (ERP), the monophasic action potential duration (MAPD90), and the conduction time (CT) were measured simultaneously in both atriums at 600, 500, 400 and 300 ms of drive cycle length (DCL). The restitution slope (RS) was also calculated by the S1S2 method. The atrial fibrillation cycle length (AFCL) and dominant frequency (DF) for the cases of AF were also calculated. All the measurements were repeated after PBMC.
RESULTS
The mean LA pressure was significantly reduced after PBMC in both the AF and SR patients (17.0+/-5.5 mmHg vs 10.4+/-4.0 mmHg, respectively, p<0.01, 17.6+/-7.1 mmHg vs 9.0+/-2.8 mmHg, respectively, p<0.01). A significant increase of ERP was observed in the LA after PBMC, but not in the right atrium (RA). The increase of MAPD90 after PBMC was significant in the LA at all the tested DCLs, but not in the RA. The CT was also significantly decreased at all the tested DCLs after PBMC. The RS of the LA decreased from 1.71+/-0.82 to 0.76+/-0.33 after PBMC (p=0.056). However, no significant changes of the AFCL or DF after PBMC were observed in the AF group.
CONCLUSION
Chronic atrial stretch altered the atrial electrophysiological milieu, especially in the LA, which was partially reversible in SR patients. This result supports the theoretical basis for the beneficial effects of early intervention to reduce the atrial pressure overload in MS patients.

Keyword

Atrium; Arrhythmia; Mitral stenosis; Electrophysiology

MeSH Terms

Action Potentials
Arrhythmias, Cardiac
Atrial Fibrillation
Atrial Pressure
Decompression*
Dilatation
Early Intervention (Education)
Electrophysiology
Female
Heart Atria
Humans
Mitral Valve Stenosis

Figure

• 

  Fig. 1 ERP change after left atrial decompression. A significant increase of ERP was observed in the LA after PBMC, but not in the RA. ERP: effective refractory period at 600 ms drive cycle length, LA: left atrium, PBMC: percutaneous balloon mitral commissurotomy, RA: right atrium, NS: not significant.

• 

  Fig. 2 Conduction time change after left atrial decompression. The CT decreased significantly at all the tested DCLs except 600 ms DCL after PBMC. CT: conduction time, DCL: drive cycle length, PBMC: percutaneous balloon mitral commissurotomy. *: p<0.05.

• 

  Fig. 3 MAP90 change after left atrial decompression. The increases of MAP90 after PBMC were significant in the LA at all the tested DCLs, but not in the RA. MAP90: 90% monophasic action potential duration at 600 ms drive cycle length, PBMC: percutaneous balloon mitral commissurotomy, LA: left atrium, RA: right atrium, DCL: drive cycle length, NS: not significant. *: p<0.05, †: p<0.01.

• 

  Fig. 4 Change of maximal APD restitution slope after PBMC decompression. APD: action potential duration, PBMC: percutaneous balloon mitral commissurotomy, RA: right atrium, LA: left atrium, NS: not significant.

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  Fig. 5 Dominant frequency change after left atrial decompression. Empty bar means DF at both atrium before PBMC, and Filled bar, after PBMC. PBMC: percutaneous balloon mitral commissurotomy, DF: dominant frequency in Hz, RA: right atrium, LA: left atrium, NS: not significant.

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  Fig. 6 Atrial fibrillation induced by single atrial stimulation. AF induced by a single atrial stimulation (600/230 ms) in a patient with sinus rhythm during pre-PBMC. AF induction was abolished after PBMC. AF: atrial fibrillation, PBMC: percutaneous balloon mitral commissurotomy.

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