Left atrial pressure reduction for mitral stenosis reverses left atrial direction-dependent conduction abnormalities.
OBJECTIVE
Left atrial (LA) stretch-associated electrophysiological changes in patients with mitral stenosis (MS) predispose to atrial fibrillation. We hypothesized that the normalization of the pressure gradient by percutaneous transvenous mitral balloon valvotomy (PTMV) affects LA but not right atrial (RA) conduction, depending on the site of stimulation. Because direction-dependent (asymmetric) changes of conduction may contribute to arrhythmogenesis, we assessed conduction symmetry in MS patients and tested whether it is restored by PTMV.


RESULTS
In nine patients with MS, atrial effective refractory period and local activation times (ATs) were determined during stimulation before and after PTMV, with up to four decapolar catheters (LA and RA). Eight patients with ventricular pre-excitation served as controls. ATs at basic cycle length were similar before and after PTMV. With stimulation from either atrium, they were about 45 ms in the ipsilateral atrium and about 115 ms in the contralateral atrium. With premature stimulation, ATs increased dramatically. The shortest ATs were found in the RA with RA stimulation (78 +/- 9 and 80 +/- 6 ns, before and after PTMV). PTMV caused a shortening in LA-ATs (following LA stimulation) from 118 +/- 14 to 82 +/- 5 ms (before and after; P < 0.05). Asymmetry in conduction properties was therefore normalized by PTMV. PTMV led to a decrease in RA-ATs (following LA stimulation) from 196 +/- 11 to 174 +/- 13 ms (P < 0.02). In addition, following RA stimulation, the dispersion in ATs in the LA decreased significantly by PTMV (from 66 +/- 10 to 34 +/- 7 ms; P < 0.02).


CONCLUSIONS
MS is associated with LA conduction delay, increased LA dispersion of conduction, and conduction asymmetry. These changes are immediately reversible by PTMV.
Coronel
Ruben
R
Experimental Cardiology Group , Center for Heart Failure Research, Academic Medical Center, rm K2-112, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. r.coronel@amc.uva.nl
Langerveld
Jorina
J
Boersma
Lucas V A
LV
Wever
Eric F D
EF
Bon
Laurens
L
van Dessel
Pascal F H M
PF
Linnenbank
André C
AC
van Gilst
Wiek H
WH
Ernst
Sjef M P G
SM
Opthof
Tobias
T
van Hemel
Norbert M
NM
D000328:Adult; D001281:Atrial Fibrillation / Q000503:physiopathology; D016279:Atrial Function, Left / Q000502:physiology*; D002304:Cardiac Pacing, Artificial; D002404:Catheterization; D004562:Electrocardiography; D005260:Female; D005471:Fluoroscopy; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008946:Mitral Valve Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy*; D012032:Refractory Period, Electrophysiological / Q000502:physiology; D017725:Ventricular Pressure / Q000502:physiology