Maybe you should look at that first. Echo-Doppler mouse with simulataneous EKG would demonstrate if there is atrial activation.

Try this paper (it is downloadable from PubMed): 

Ozcan C, Battaglia E, Young R, Suzuki G. LKB1 Knockout Mouse Develops Spontaneous Atrial Fibrillation and Provides Mechanistic Insights Into Human Disease Process. J Am Heart Assoc. 2015 Mar 15;4(3).

The article has ECG traces of murine AF.

Interesting that mice can get AF. Kids rarely do, and it's said to be due to small size of atria not encompassing the fibrillatory wavelength. Probably different wavelength in mice? Best definition would be using intraatrial recording I'd have thought, at least to define it, although not really practical for telemetry.

You could use our papers with arrhythmia in the mouse

Tuomi, J. M., Chidiac, P. and Jones, D. L. Evidence for enhanced M3 muscarinic receptor function and sensitivity to atrial arrhythmia in the RGS2 deficient mouse. Am. J. Physiol. (Heart Circ. Physiol.) 298(2): H554-H561, 2010.

Tuomi, J. M., Tyml, K. and Jones, D. L. Atrial arrhythmia in the connexin 43 G60S mutant mouse: A model of Oculodentodigital Dysplasia. Am. J. Physiol. (Heart Circ Physiol) Am. J. Physiol. (Heart Circ Physiol) 300:H1402-1411, 2011

Dear Douglas,

thanks. I was though looking for spontaneous atrial fibrillation in mice rather than induced and measure by telemetry. Do you have any reference for that?

Thanks.

Best Regards,

You could Email my colleague Michael Gollob at Ottawa heart, he has the transgenic mouse model we developed with human gene SNP inserted that he was assessing for arrhythmia using telemetry.

Thanks.

Best,

SG

My pleasure.

Good luck.

Doug