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Atrial Fibrillation

I recently saw a 14 year old Havanese with Mitral and Tricuspid endocardiosis that was in congestive

heart failure.

I did an EKG and Boots also had Atrial Fibrillation.

I had been treating Boots with Enalapril, Furosemide and Pimobendan.

Because it was the end of the day I referred Boots to the local Blue Pearl for hospitalazation and

management of his CHF and Atrial Fibrillation.

They kept Boots on the triple therapy for CHF and added Diltiazem.

I have a couple of questions for you would be cardiologists:

 

I recently saw a 14 year old Havanese with Mitral and Tricuspid endocardiosis that was in congestive

heart failure.

I did an EKG and Boots also had Atrial Fibrillation.

I had been treating Boots with Enalapril, Furosemide and Pimobendan.

Because it was the end of the day I referred Boots to the local Blue Pearl for hospitalazation and

management of his CHF and Atrial Fibrillation.

They kept Boots on the triple therapy for CHF and added Diltiazem.

I have a couple of questions for you would be cardiologists:

 

1. Is diltiazem safe to use when a dog is in CHF?

2. Could I use Digoxin if needed and would I have to stop the Pimobendan?

My local Blue Pearl does a good job for me and I have no complaints- this case just made me consider my options

 

Thanks

 

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3 responses to “Atrial Fibrillation”

  1. I’ve always believed tx the

    I’ve always believed tx the volume overload first and then see what the rhythm does ( in valve dogs not boxers or dobies for example that have arrhythagenic disease based pathology) but in this overloaded valve case nothing more than more lasix and maybe some effect from spironolactone or TID pimo would help. The a-fib will also cause further volume overload from systolic failure/poor function induced by the arrythmia.Just look at the mmode during sinus rhythm compared to one in a-fib.

    So at this point you have to deal with the arrhythmia because volume reducers for long term management are an empty space on the shelf at least in the US. Diltizem is a solid choice if myocardial insufficiency is not an issue… (i.e. stage C-D valve disease with fs% < 40% +/- is myocardial insufficiency for valve dogs) because diltiazem is a negative inotrope so you will lose a few points of fs% when using it technically. However, if its effective in controlling the a-fib then the fs% lost by the a-fib is actually gained back so there is a sum increase in function and secondary reduiction of volume overload because it has better rhythm… i.e. Starling is looking to come home form his vacation away from the patient:)… key point “if its effective.” So you can back door into better function this way even with a negative inotrope by controlling the arrythmia.

    So what I would do is do the ECG again in a few days and the echo and see how the function is. Holyter would be great here and we have them (info@sonopath.com) if need be read by Keith or Maggie our cardiologists.

    Mexilitine is another option.

    Digoxin and Pimo can be used together. Dig is not a very effective inotrope even though we used it as such for years…but in this case its a solid choice for a-fib. Pimo is much more effective as inotrope than good ol Digoxin.

    A-fib in these cases is always high maintenance and a tightrope of medicine to manage. Glad Im behind the computer:)

    Let me see if Peter is available on this as I’m a ham & egger cardio-fanatic… I won’t say “wanna-be” because I don’t want to be a cardiologist lol… but I do play one virtually:)

  2. Hi!
    In the ACVIM consensus

    Hi!

    In the ACVIM consensus statement it’s mentioned that some panelists use digoxine if there is no contraindication (increased creatinine, GI signs, ventricular ectopy, abnormal potassium levels), some favor diltiazem.

    What I usually do is:

    In congestive heart failure the heart rate can be considerably high (for compensation reasons). I usually treat CHF first and then decide if I have to reduce the ventricular response rate. Some patients (usually large breed dogs) can have a quite slow afib and do not need any rate reduction. Most small breed dogs have tachycardic afib. I use digoxine as first choice additionally to standard therapy (including pimobendan).Then I check the digoxine plasma level 8 days later (8 hrs after drug administration) and change the doseage if needed. I let the owners check the heart rate at home (they can use a stethoscope) and decide if I have to add diltiazem (usually if the heart rate exceeds 120-140/min at rest (but this is not evidence based, though). (I would never add betablockers instead of diltiazem!!! Betablockers are contraindicated). In my personal experience I hardly need more than digoxine. If there are contraindications (as mentioned above) I use diltiazem if rate reduction is needed starting at 0.5 mg/kg tid.

    Digoxine has hardly any positive inotropic action but it is not negative inotropic. That’s why I go for digoxine first. Still, I think that diltiazem in the lower range does not have a clinically relevant negative inotropic effect that would outweigh it’s effect on the heart rate. 

    Summarizingly, you can use both drugs or combine them if necessary. I would still be very cautious if a patient is in CHF. If you drop the heart rate in a CHF patient from 180 to 100 you could potentially kill the patient. In the very rare cases where the heart rate is 240 and the patient is in CHF I would still try to reduce the heart rate because this would be too high to be only compensatory and diastolic function/cardiac output  would be significantly impaired.

     

    I hope I could help!

     

    Best regards!

     

    Peter

  3. Thank you both. I will

    Thank you both. I will bookmark and print out this advice.

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