RE: Syncopal Boxer

AlanH — Thu, 19 Sep 2019 16:01:21 GMT

Hi Dave, Thanks for the above , I normally like ECGs but gotta admit this one had me puzzled as to what was going on, the wide QRS threw me and I hadn't considered the arrhythmia clearing on sedation I had just thought it had slowed with the sedation - but it makes sense that the conduction defect would remain and the QRS would be unchanged and the rate certainly dropped.

I'll see what we can do in terms of further tests & a Holter!

Thanks again!!

Alan

RE: Syncopal Boxer

Dave Dickson — Thu, 19 Sep 2019 15:09:24 GMT

Hi Alan

Interesting one.

[quote user="AlanH"]Echo showed enlarged LA and also RA, normal contractility and left ventricular chamber dimensions, small amount of left atrial regurgitation but not severe. [/quote] The LA doesn't look huge to me, especially on the short axis.

[quote user="AlanH"]The left atrial enlargement I put down to the MR and would consider pimobendan for this ( aortic outflow is normal so no evidence of SAS which would contraindicate pimo)[/quote] I'm not convinced. If LV size and function is good, it would be unusual for mild MR to enlarge the LA so I'd hold off for now until we know more.

[quote user="AlanH"] I'm struggling to explain the RA enlargement [/quote] I agree, the RA looks big, with what looks like increased right atrial pressure (on the long-axis, the RA bulges into the LA). Videos would be better for this but I agree it's big.

don't think just in terms of valve regurg causing atrial enlargement. The LA enlargement seen in mitral valve disease is due to both MR and the increased circulating fluid volume caused by the fall in cardiac output. In DCM, there is often no MR but the LA enlarges. In most cat diseases, there isn't MR but the LA enlarges. Why? Because systolic and/or diastolic dysfunction causes atrial enlargement.

So if the RA is big and there is no TR, it's because (probably) there is RV systolic and or diastolic dysfunction. This is much harder to appreciate on echo than LV dysfunction.

Finally - the ECG! It's a great one. To me, I think you have got two rhythms. On the ECG there is AV dissociation (or at least, profound first degree AV block). I wonder if there are extra p-waves buried in the QRS (so a 2:1 block). The PQ and RR intervals are also variable. Then, on the echo, the ECG shows sinus rhythm (hence the matching a waves). You gave butorphanol and the heart rate halved. So I think that either sedation, or random chance, resolved the arrhythmia. There is also a conduction block, as you noted, which suggests trouble in the ventricles somewhere.

I'd ignore the MR, it probably isn't relevant right now. I agree some form of cardiomyopathy is top of the list. I'd run some bloods including troponin and T4/TSH, check systemic BP and Holter this dog. Something odd is going on and with syncope in the history, I'd be worried. I wouldn't start any treatment until we have a diagnosis.

Dave