The hemodynamic and atrial electrophysiologic consequences of chronic left atrial volume overload in a controllable canine model.
J Thorac Cardiovasc Surg
; 156(5): 1871-1879.e1, 2018 11.
Article
em En
| MEDLINE
| ID: mdl-30336917
ABSTRACT
OBJECTIVE:
The purpose of this study was to determine the effects of chronic left atrial volume overload on atrial anatomy, hemodynamics, and electrophysiology using a titratable left ventriculoatrial shunt in a canine model.METHODS:
Canines (n = 16) underwent implantation of a shunt between the left ventricle and the left atrium. Sham animals (n = 8) underwent a median sternotomy without a shunt. Atrial activation times and effective refractory periods were determined using 250-bipolar epicardial electrodes. Biatrial pressures, systemic pressures, left atrial and left ventricle diameters and volumes, atrial fibrillation inducibility, and durations were recorded at the initial and at 6-month terminal study.RESULTS:
Baseline shunt fraction was 46% ± 8%. The left atrial pressure increased from 9.7 ± 3.5 mm Hg to 13.8 ± 4 mm Hg (P < .001). At the terminal study, the left atrial diameter increased from a baseline of 2.9 ± 0.05 cm to 4.1 ± 0.6 cm (P < .001) and left ventricular ejection fraction decreased from 64% ± 1.5% to 54% ± 2.7% (P < .001). Induced atrial fibrillation duration (median, range) was 95 seconds (0-7200) compared with 0 seconds (0-40) in the sham group (P = .02). The total activation time was longer in the shunt group compared with the sham group (72 ± 11 ms vs 62 ± 3 ms, P = .003). The right atrial and not left atrial effective refractory periods were shorter in the shunt compared with the sham group (right atrial effective refractory period 156 ± 11 ms vs 141 ± 11 ms, P = .005; left atrial effective refractory period 142 ± 23 ms vs 133 ± 11 ms, P = .35).CONCLUSIONS:
This canine model of mitral regurgitation reproduced the mechanical and electrical remodeling seen in clinical mitral regurgitation. Left atrial size increased, with a corresponding decrease in left ventricle systolic function, and an increased atrial activation times, lower effective refractory periods, and increased atrial fibrillation inducibility. This model provides a means to understand the remodeling by which mitral regurgitation causes atrial fibrillation.Palavras-chave
Texto completo:
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Base de dados:
MEDLINE
Assunto principal:
Fibrilação Atrial
/
Potenciais de Ação
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Função do Átrio Esquerdo
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Remodelamento Atrial
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Átrios do Coração
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Frequência Cardíaca
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Insuficiência da Valva Mitral
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
2018
Tipo de documento:
Article