Enlarged left-side heart. Advice?

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Enlarged left-side heart. Advice?

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    05-23-2011, 10:48 PM
Unhappy Enlarged left-side heart. Advice?

So I've posted on and off with my gelding's health saga over the past 6 months. Some background information: 11 yrs old, Canadian Warmblood, 17.3hh, used for dressage. First we suspected lymphoma then ruled it out when his cbc came back clear. Then this spring he perked up; his edemas disappeared, he maintained his temperature (which was always low) and gained back 200 lbs. He looks so healthy.

We knew he had an irregular heart beat (hoping it was AF and that I could take him to Washington University to get his heart 'shocked' back into a normal beat). I got a cardiologist from 5 hours away to come and perform a electrocardiogram and echocardiogram. He has Atrial Fibrillation, high blood pressure and an enlarged left side of his heart. Since there's an underlying heart issue and he's a large horse, shocking his heart isn't an option anymore. The vet is consulting with a few more teaching specialists to discuss the prognosis and plan of treatment options. I'll hear back later this week.

I'm pretty upset at the thought of not being able to ride him, and/or ultimately losing him. I think the plan of action will be putting him on lasix, digoxin and possible a potassium supplement.

Anyone out there have/had a horse with an enlarged heart (left side)? If so how did you and the horse manage it? Any, any, any advice will be appreciated. I love this gelding so much and he has so much potential this is devestating.
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    05-23-2011, 11:39 PM
I am really sorry to hear about your boy, he sounds like he is a very special boy.
I don't know if they would mention it to you as it might be a very risky option in his situation but another way to correct AF is with a drug called quinidine. Like I said though if the AF is due to underlying heart disease it may be too risky to attempt.
The edema you mentioned had cleared up, where was it? Along his breast or in his lungs?
    05-24-2011, 12:46 AM
Thank you, yes, he's very special to me. And where I keep him now, the couple have fallen in love with him too. He's just a lovely personality.

He had two ventral edemas which cleared up after about three months. His legs stopped stocking up too. And within another two months he has put on his weight. Until we did the ecg, the vet and I both thought right-sided heart failure. So this case is a bit tricky for everyone.

Yes they mentioned quinidine. One problem is his sketchy history, and it's an egg or chicken question as to whether the enlarged heart caused the AF, or vice versa. No one has listened to his heart before this year. So I believe they are questioning whether treating the heart might help the AF, if that's possible? I'm weary of quinidine but it might be a very valid option (factoring in all the hospital stay, treatment, etc it is about the same cost as the 'shock' treatment. Approx. $2500 I hear). Do you know of any horses successfully converted from AF with quinidine with an underlying heart issue?

The specialist also mentioned not treating him at all, which leads me to suspect it might be more advanced than I'd like it to be. I wasn't on the ball as I should've been yesterday morning.
    05-24-2011, 08:25 PM
Do you know of any horses successfully converted from AF with quinidine with an underlying heart issue?
I do not know of any but that certainly does not mean that it hasn't happened. I have only seen a few horses converted in the first place and they all happened to have AFib as the main issue.
I am so sorry to have to say this and I hope like hell that I am wrong but with what you have described it sounds like he has severe mitral regurgitation which has caused left sided enlargement resulting in AFib. Because the left ventricle is enlarged, contractility is decreased and the blood is not being pumped through to the body properly. Instead it gets backed up into the lungs and causes congestion in the right side of the heart cause there is nowhere for that blood to go which actually does lead to right sided heart failure as you suspected. He needs to have an echo to see exactly what you are dealing with.
The lasix will be to try to decrease and fluid that might be on his lungs or in his abdomen, the digoxin will help to increase contractility of his heart, and potassium is thought to be helpful in Afib and heart disease (but I don't actually know how it works other than cells need potassium and sodium to fire action potentials)
I know that that is not good news but I hope I have explained ok for you. I wish you the best of luck, I hope I am wrong and you have many more years with your beloved boy.
    05-25-2011, 03:26 PM
Thanks Masquerade. I kind of know where this is heading and hope I'm wrong too.

He had an echo done as well, that's how we know the left side is enlarged. All the valves are good as well as the right side of the heart (believe it or not!). Everything you explained makes a lot of sense and reminds me of what the vet had said (kind of overwhelmed for those two hours). The hypothesis is that he has had the left sided enlargement for a few years, then got sick with something in the fall which his heart couldn't cope with and it effected his right-side of the heart, causing the symptoms we saw. When he recovered from the secondary illness we saw an improvement but the left-sided heart issue and resulting AF remained.

It's so curious because he shows no signs of left-sided failure. He's never coughed, no breathing problems, works out normally (lower level dressage). Right now his only outward symptom is his slightly enlarged veins. Even in the pasture he's really active.

Anyhoo, the specialist took all the measurements and is getting a few opinions on how to proceed. The vet said I could walk/trot, but I'm uncomfortable with that (collapse - he's 1500lbs at least. And I suppose it's not like we're competing anymore). What do you think?
    05-25-2011, 07:39 PM
It's hard to say as this sounds like a very strange case! I am not sure how he could get left heart enlargment without any valve problems so I am curious to hear what the specialists say.
I would think that collapse or at least weakness would certainly be a real risk since the left ventricle is the main power pump of the heart. When it is enlarged it usually looses some of it's ability to contract so less blood gets out to the body, add on top of that the fact that he is in Afib which means his atria are contracting really fast without any kind of coordination resulting in varying amounts of blood being pushed into the ventricles. So less blood in ventricles in the first place then the ventricle not beating strong enough push it out to the body I would think that would make for a weaker horse with exercise intolorance with or without full collapse. Please let me know what they say as I am really rooting for your boy (he is so handsom!).

Ps Where in Canada are you from, I was born and raised in Saskatoon but my family now lives in Calgary (I am in Australia for school)
    05-25-2011, 08:00 PM
Masquerade, those are my sentiments exactly. Very strange. I think that's why the specialist said she 'needed a second, third and probably a fourth opinion'!

I'm in the Okanagan (BC), but I just moved back here after nine years of living in Australia (Melbourne). I'm a dual citizen and can't wait to go back eventually.

Thanks for the compliments on my boy. It adds to the heartbreak knowing how talented he is and un-replaceable.
    05-25-2011, 08:58 PM
Wow, small world! We are both Canadians who have lived in Australia!! I am just south of Perth.
    05-25-2011, 09:10 PM
Lovely! I did my uni studies in Australia too. Married a Kiwi. Enjoy your time over there. It goes too fast then you're back to the coooold. I'll keep you updated as to what the vet says:)
    06-12-2011, 10:34 PM
Just thought I'd update. The heart specialist says his heart looks fine for his massive size. There's no valve defects or regurgitation. Because he's had AF now for over 4 months and is so large, we're not going to try and convert him, since it's a low success rate at this point. They're not sure whether it was an illness that caused the right-sided heart failure symptoms in the past, or if there is an internal mass creating pressure, which doesn't really make sense as to why he's gotten better.

So I'm getting him a heart monitor and we're going to slowly condition him since he has no symptoms and his heart is in good nick. We're only doing lower level dressage. The internal medicine vet is coming up later this summer to do chest xrays and an abdominal ultrasound, but nothing in his blood work suggests an internal mass. He's a mystery. Hope everything stays sound. Fingers crossed.

enlarged heart, equine heart disease, horse, left-sided heart

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