An animal model for ectopy-induced cardiomyopathy.
BACKGROUND
Ectopy-induced cardiomyopathy is an increasingly recognized cause of reversible left ventricular (LV) dysfunction. The underlying mechanisms remain unknown. Our goal was to create an animal model for ectopy-induced cardiomyopathy.


METHODS
Eleven mongrel dogs underwent the implantation of a dual-chamber pacemaker. Four dogs served as the control group and seven as the paced group. In the paced group, the pacemaker was connected to two endocardial right ventricular leads, one inserted into the atrial port and the other one into the ventricular port with an atrioventricular delay adjusted to ensure the presence of coupled pacing simulating ventricular bigeminy. Echocardiographic measurements of LV size (LV end-diastolic diameter [LV-EDD], LV end-systolic diameter [LV-ESD]), LV ejection fraction (LVEF), and mitral regurgitation (MR) were obtained at baseline and after 4 weeks of monitoring or pacing in all dogs except one who had lead dislodgement.


RESULTS
In the control group (n = 4), no significant changes in LV dimensions or function were noted. In the paced group (n = 6), LV-EDD and LV-ESD increased from 3.58 ± 0.65 cm and 2.47 ± 0.55 cm to 4.15 ± 0.59 cm and 3.21 ± 0.47 cm, respectively (P < 0.01). In addition, LVEF decreased from 60 ± 7% to 46 ± 9% (P < 0.05). No changes in MR were noted.


CONCLUSIONS
We have shown that coupled pacing simulating ventricular bigeminy was feasible and resulted in increased LV dimensions and decreased LV function. By controlling the percentage of pacing, the coupling interval and the location of the pacing lead, this new model will allow the assessment of the relative roles of these variables in the development of ectopy-induced cardiomyopathy.
Nora Eccles Harrison Cardiovascular Research and Training Institute, Salt Lake City, Utah, USA.
Nazem W
NW
Akoum
Marcos
M
Daccarett
Stephen L
SL
Wasmund
Mohamed H
MH
Hamdan
D000818:Animals; D009202:Cardiomyopathies / Q000209:etiology* / Q000503:physiopathology; D004195:Disease Models, Animal; D004285:Dogs; D004562:Electrocardiography; D006801:Humans; D018487:Ventricular Dysfunction, Left / Q000209:etiology* / Q000503:physiopathology*; D018879:Ventricular Premature Complexes / Q000150:complications* / Q000503:physiopathology