Left atrial enlargement induced by pure mitral regurgitation: time frame in a new swine model.
BACKGROUND
Atrial enlargement occurs in patients with significant mitral regurgitation. However, the time frame of the development of atrial enlargement induced by mitral regurgitation remains unknown.


METHODS
Fourteen Lanyu miniature pigs (age = 6.6 ± 0.9 months) were studied. Mitral regurgitation was created by placing a predefined hole on the middle scallop of the posterior mitral leaflet under cardiopulmonary bypass. The parasternal long-axis atrial dimension was measured by transthoracic echocardiographic examinations.


RESULTS
All animals exhibited grade 3 mitral regurgitation immediately after surgery. Seven pigs expired within 2 weeks after the operation [technical complications (n = 1), acute cardiac tamponade (n = 1), and acute and subacute heart failure (n = 5)]. Seven pigs remained alive at a mean follow-up of 7.7 ± 2.1 months. The left atrial diameter indices of the 7 pigs increased significantly at 1 month (33.1 ± 8.6 mm, p = 0.018) and 3 months (41.3 ± 12.6 mm, p = 0.018) after surgery compared with baseline values (22.8 ± 5.2 mm), and the left atrial diameter index increased significantly at 3 months compared to 1 month (p = 0.018).


CONCLUSIONS
Left atrial enlargement develops rapidly and progresses after the creation of significant pure mitral regurgitation.
Chang
J-P
JP
Division of Cardiovascular Surgery, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung, Taiwan, ROC. chenmien @ ms76.hinet.net
Tsai
T-H
TH
Chen
Y-L
YL
Wang
Y-H
YH
Ho
W-C
WC
Yu
G-H
GH
Chen
M-C
MC
D000818:Animals; D006332:Cardiomegaly / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D018618:Echocardiography, Doppler, Color; D005260:Female; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008944:Mitral Valve Insufficiency / Q000150:complications* / Q000503:physiopathology; D013552:Swine; D013556:Swine, Miniature; D013997:Time Factors