drugs for vetricular tachycardia

Re: drugs for vetricular tachycardia

Clive Ansell — Fri, 28 Mar 2014 16:04:11 GMT

[quote user="Martin Atkinson"]

I'm sure I took hydrochlorothiazide with me to combat altitude sickness when climbing Killimanjaro.

[/quote]

I've not come across that? only acetazolamide (Diamox). Did you have to use it?

Re: drugs for vetricular tachycardia

John Flynn — Thu, 27 Mar 2014 18:56:45 GMT

[quote user="Mike Martin"]As regards studies on propafenone - I don't recall a significant vet clinical paper and had a search in PubMed with no joy - if you can find it that would be great.[/quote]

Therapy of cardiac arrhythmias in dogs with propafenone. Gabriel, A.; Kersten, U. Kleintierpraxis 1993 Vol. 38 No. 8 pp. 485-495

ABSTRACT:

Results are given from experiments on 61 dogs using propafenone (Rytmonorm) for treatment of cardiac arrhythmias supraventricular or ventricular in origin, including their special forms or atrial fibrillation. For oral therapy 3 mg propafenone/kg was given 3 times daily to 34 dogs. For parenteral (i.v.) application 1 mg propafenone/kg was used, either administered over 3 min in 30-100 ml isotonic full electrolyte solution or by a permanent infusion with 0.008 mg/kg/min. 31 of 34 patients with supraventricular or ventricular ectopic beats given oral long-term therapy showed a complete or partial reduction of the arrhythmia 1 week after beginning the therapy. Simultaneously, the clinical behaviour of these dogs improved. However, in 14 dogs with atrial fibrillation propafenone therapy had no influence on the arrhythmia. In most of 13 hospitalized dogs studied for a short-term effect of oral propafenone therapy a reliable reduction of the arrhythmia was seen in about 3 to 5 days. Of 15 dogs given propafenone i.v. 11 dogs showed a partial or complete elimination of the arrhythmia immediately after the application, but the antiarrhythmic effect decreased 30 to 90 min after the application. Administration of propafenone as a permanent infusion in 3 dogs eliminated the ectopic beats successfully. Side effects were observed in single cases. It is concluded that propafenone may represent an advantageous alternative in the long-term and emergency therapy of supraventricular and ventricular ectopic beats in the dog.

Only other paper specifically from a veterinary journal (re dogs) that I can find, in case of interest:

Pharmacokinetics of propafenone in the dog after single-dose intravenous administration. Puigdemont, A.; Lligoña, L. L.; Arboix, M.; Mora, F. de; Fernandez, J. Journal of Veterinary Pharmacology and Therapeutics 1987 Vol. 10 No. 4 pp. 351-353

ABSTRACT:

Six adult male Beagle dogs with a mean weight of 13.8 kg were given propafenone (2′-(3-(propylamino)-2-(hydroxy)-propoxy)-3-phenyl-propiophenone hydrochloride) by rapid i.v. injection at 2 mg/kg. The plasma concentrations from 5 to 210 minutes after injection declined from a mean of 824 ± 257 to 82 ± 18 ng/ml, and were described in all 6 dogs as a mono-exponential curve. The half-life was 65.9 ± 13.6 minutes, the apparent volume of distribution 2.7 ± 0.6 litre/kg, systemic clearance 25 ± 5.4 litre/hour and the area under the curve 69.8 ± 17.6 µg minutes/litre. It is suggested that for emergency ventricular tachyarrhythmia propafenone could be given as an infusion followed by oral maintenance. An appropriate daily dose may be 7 mg/kg/day in divided doses.

But there's a number of experimental studies and such-like from which useful clinical inferences can potentially be drawn also.

e.g.:

http://circ.ahajournals.org/content/66/6/1190.full.pdf

http://onlinelibrary.wiley.com/doi/10.1002/jps.2600801203/abstract

http://europace.oxfordjournals.org/content/6/5/384.full

Re: drugs for vetricular tachycardia

Mike Martin — Thu, 27 Mar 2014 17:53:20 GMT

[quote user="Martin Atkinson"]What is the risk of hypokalaemia with this combination, do you routinely monitor potassium?[/quote]

K issues is not a common significant clinical problem in dogs, but we do seen it, but much more common in cats. We recommended routine regular monitoring of renal function and electrolytes in animals on anything more than mild doses of diuretics. The amiloride is K-sparing, although the thiazide and frusemide are not.

[quote user="John Flynn"]anyone else preferring torasemide for bid dosing in preference to furosemide?[/quote]

Torsemide is an interesting drug with additional potential benefits. We use it when we believe there is resistance to frusemide in the chronic case. It is quite powerful, and the switch over from fruse to torse is tricky, but we do use it.

[quote user="John Flynn"]There was a study years ago in dogs that found: "31 of 34 patients[/quote]

As regards studies on propafenone - I don't recall a significant vet clinical paper and had a search in PubMed with no joy - if you can find it that would be great. There was an interesting paper on on amiodarone out of Liverpool - a good paper.

Re: drugs for vetricular tachycardia

John Flynn — Thu, 27 Mar 2014 17:18:54 GMT

[quote user="Martin Atkinson"]What is the risk of hypokalaemia with this combination, do you routinely monitor potassium?[/quote]

I don't routinely monitor potassium when using coamilozide alongside furosemide for ascites if that's any help.

I'd probably stop the spironolactone if starting on coamilozide, but that's possibly unnecessary?

As an aside (seeing we're covering so many cardiac drugs in one thread!), anyone else preferring torasemide for bid dosing in preference to furosemide?

Re: drugs for vetricular tachycardia

John Flynn — Thu, 27 Mar 2014 17:18:47 GMT

[quote user="Martin Atkinson"]What is the risk of hypokalaemia with this combination, do you routinely monitor potassium?[/quote]

I don't routinely monitor potassium when using coamilozide alongside furosemide for ascites if that's any help.

I'd probably stop the spironolactone if starting on coamilozide, but that's possibly unnecessary?

As an aside (seeing we're covering so many cardiac drugs in one thread!), anyone else preferring torasemide for bid dosing in preference to furosemide?

Re: drugs for vetricular tachycardia

Martin Atkinson — Thu, 27 Mar 2014 15:03:48 GMT

[quote user="Mike Martin"]We commonly add co-amilozide in these cases with chronic ascites when the dose of frusemide reaches 3mg/kg bid[/quote] What is the risk of hypokalaemia with this combination, do you routinely monitor potassium?

I'm sure I took hydrochlorothiazide with me to combat altitude sickness when climbing Killimanjaro.

Re: drugs for vetricular tachycardia

John Flynn — Wed, 26 Mar 2014 10:28:21 GMT

[quote user="Mike Martin"]Hope this helps?[/quote]

Yes. Thanks for additional info.

[quote user="Mike Martin"]Propafenone I have tried for re-entrant SVTs with no significant response. There are mixed reports from my colleagues on its use, but no consistent or universal consensus. [/quote]

There was a study years ago in dogs that found: "31 of 34 patients with supraventricular or ventricular ectopic beats given oral long-term therapy showed a complete or partial reduction of the arrhythmia 1 week after beginning the therapy."

I've never used it, but just wondered how it compared to amiodarone (which I've also never used) as on paper at least it sounded similarly promising as an alternative to mexilitine for ventricular tachycardias and it is a more similar class of antiarrhythmic to what I'm familiar with (mexilitine).

For both amiodarone and propafenone, I'm guessing that the summation of personal experiences of use in clinical canine cases by cardiologists far out-weighs the very limited case data that has been published.

Re: drugs for vetricular tachycardia

Mike Martin — Wed, 26 Mar 2014 10:21:16 GMT

[quote user="Martin Atkinson"]elected to just increase frusemide to control the ascites a little better[/quote]

We commonly add co-amilozide in these cases with chronic ascites when the dose of frusemide reaches 3mg/kg bid. See 'Co-amilozide' Information sheet on our website

Also, some of these CKCS develop pulmonary hypertension, resulting in chronic ascites, so might be worth a re-scan to check that, if not already done?

Good luck.

Re: drugs for vetricular tachycardia

Mike Martin — Wed, 26 Mar 2014 10:16:00 GMT

Mexitiline was a wonderful drug and I wish a generic was produced. Boehringer stopped manufacturing mexilitine in 2008. IDIS then took it on for selling the world's remaining stock-piles and as the stock piles have become less and less, the cost has risen exponentially. They have imported these stock pile from all corners of the earth. At some point none will be available. It has not been listed in the BNF for some years now. Most cardiologists therefore moved away from mexilitine some time ago now, but still not found something as good, for dogs.

Propafenone I have tried for re-entrant SVTs with no significant response. There are mixed reports from my colleagues on its use, but no consistent or universal consensus.

Digoxin is primarily only used for heart rate control in AF in both man and animals.

Hope this helps?

Re: drugs for vetricular tachycardia

Martin Atkinson — Tue, 25 Mar 2014 18:06:30 GMT

[quote user="Mike Martin"]

The general consensus is to treat arrhythmias when they are causing symptoms. If this CKCS is amazingly bright and active, then I'm not sure I would rush to add another drug too quickly. VT is unusual in a CKCS too. I wonder if this is persistent or intermittent and maybe more monitoring is needed, eg prolonged ECG or even a Holter?

As regards drugs we use, the most common are atenolol, sotalol and amiodarone. Procainamide and mexilitine (old favorites) are off the market now.

[/quote] Thanks for the advice all. I've discussed the ins and outs with the owner: that giving something to control the VT we may compromise the control of the CHF versus it going into VF spontaneously, and elected to just increase frusemide to control the ascites a little better. After all, the swollen belly was why she brought it in today, up to that time it was showing very few symptoms, I've just been following current status assessment with monitoring to stay ahead of the game and keep it in B1. I have some amiodarone on order if it goes more symptomatic and some lidocaine in the cupboard in case it goes tits up!

Re: drugs for vetricular tachycardia

John Flynn — Tue, 25 Mar 2014 11:58:37 GMT

[quote user="Martin Atkinson"]Who is still a fan of digoxin or has it had its day?[/quote]

I use it (or diltiazem) to slow the rate in cases of AF where it is reasonable to assume that the fast rate is leading to poor ventricular filling and reduced cardiac output.

I checked and it appears to be contraindicated for ventricular arrhythmias.

[quote user="Martin Atkinson"]I ran a single lead ECG for 60 seconds and there was a continuous run of V-tach, not one single normal PQRS so I think a halter is unnecessary. I realise a negative ionotrope may cause this dog to go into uncompensated CHF but I'm equally keen to prevent it going into ventricular fibrillation.[/quote]

I see your point, but I'm personally more hesitant about instituting antiarrhythmic therapy (I consider myself a non-interventionist at heart, but maybe I'm just a wimp!). As there are about 1500 minutes in a day, what the heart is doing for just one of those is quite a loose means of quantifying the severity of the arrhythmia; I'd use the anology of basing a decision on the stability of a diabetic on a single blood sugar check. Obviously, chances are that if you catch 60 secs of v-tach on the only stretch of ECG done, then by inference there's likely to be a lot more during the rest of the day, so perhaps it's not necessary to Holter, but then again, is it necessary to treat...? A Holter can only waste money, antiarrhythmics can shorten lifespan (as well as potentially increasing it).

I think it's very hard to know whether such an arrhythmia is likely to lead to VF, and a Holter (and expert interpretation) might help decide that. http://www.holtermonitoring.co.uk/ is very good service if there's no-one local. Is it even VF that kills such dogs with arrhythmias? When they die acutely, we rarely know what the terminal rhythm was, and I can think of other explanations to offer in such a case. My guess would be that decompensated CHF is a greater risk to this patient? I think there is little evidence that reducing the VT on paper is necessarily going to give an increased survival?

Can you post some of the ECG tracing out of interest to see if there are any other negative prognostic indicators visible?

What was the rate of the V-tach?

[quote user="Mike Martin"]mexilitine (old favorites) are off the market now.[/quote]

Still available through my wholesaler in Ireland (I have a couple of dogs still on this...), I must check where they're sourcing it from.......

[quote user="Mike Martin"]As regards drugs we use, the most common are atenolol, sotalol and amiodarone.[/quote]

Any reason for propafenone being less popular for (symptomatic) VT or just less clinical experience than others?

Re: drugs for vetricular tachycardia

Martin Atkinson — Tue, 25 Mar 2014 09:49:52 GMT

[quote user="John Flynn"]I'd Holter first perhaps depending on severity of v-tach?[/quote] I ran a single lead ECG for 60 seconds and there was a continuous run of V-tach, not one single normal PQRS so I think a halter is unnecessary. I realise a negative ionotrope may cause this dog to go into uncompensated CHF but I'm equally keen to prevent it going into ventricular fibrillation.

Who is still a fan of digoxin or has it had its day?

Re: drugs for vetricular tachycardia

Mike Martin — Tue, 25 Mar 2014 09:30:25 GMT

As regards drugs we use, the most common are atenolol, sotalol and amiodarone. Procainamide and mexilitine (old favorites) are off the market now.

Re: drugs for vetricular tachycardia

David Mills — Mon, 24 Mar 2014 21:05:07 GMT

[quote user="John Flynn"]On a pracitcal note, I'm assuming amiodarone is pretty cheap - comparable to sotalol and digoxin?[/quote]

100mg tablet (perfect for a CKCS) around 20p cost I believe - normally would start at 10-15mg BID f0r 7d then 5-10mg SID forever.

[quote user="John Flynn"] I guess the principle reason for this was lack of clinical experience and perceived high side effects, whereas now they've published their experience those hurdles are cleared a little better.[/quote]

Yes, I think so. Amiodarone has had a 'bad rep' for a while for side effects and the fact it lasts in the body for a while (about 3w) but this was due to experimental evidence. In the absence of mexitil, I think people are taking more interest in it. Whether it has protective effects in preclin MMVD would be a great study.

Personally, I think it's a fantastic drug.

Re: drugs for vetricular tachycardia

Andrew Kent — Mon, 24 Mar 2014 20:40:33 GMT

I would agree with David on this one - amiodarone would be my first choice with sotalol as second choice. Would avoid pure beta blocker due to risk of destabilising CHF. I don't think mexilitine is available over here anymore but can be imported under licence. Andy

Re: drugs for vetricular tachycardia

John Flynn — Mon, 24 Mar 2014 20:37:06 GMT

[quote user="David Mills"]

Numbers small but this is the only one I can find at mo (PM if you don't have access):

http://onlinelibrary.wiley.com/doi/10.1111/j.1748-5827.2011.01142.x/abstract;jsessionid=B1AF3E534322F73558B56F473D1453AF.f04t04

[/quote]

Thanks.

Looked it up and does sound interesting (I've not been aware of use of amiodarone in dogs before).

As you say numbers are small, but the theory sounds at least as reasonable as more widely used antiarrhythmics.

Re the numbers in the study, I count 5 cases of v-tach, and none in any of the 4 MVD cases treated. Just one CKCS too (MVD and AF, treated concurrently with digoxin). Also worth noting that the authors at the time were using this mainly as a second-line anti-arrhythmic and most of their relevant cases were on other anti-arrhythmics also, but I guess the principle reason for this was lack of clinical experience and perceived high side effects, whereas now they've published their experience those hurdles are cleared a little better.

On a pracitcal note, I'm assuming amiodarone is pretty cheap - comparable to sotalol and digoxin?

Re: drugs for vetricular tachycardia

David Mills — Mon, 24 Mar 2014 20:20:21 GMT

[quote user="John Flynn"]

[quote user="David Mills"]Amiodarone would be my choice. Far fewer side effects than originally thought - couple of JSAP papers on this. Widely used in humans for similar.[/quote]

Interesting. I'm guessing the negative inotropic effects might be considerably less than with sotalol? Would you use this generally in preference to sotalol? Is it considered safe in a dog with compensated congestive heart failure like this or is there any perceived risk of precipitating deconmpensation?

[/quote]

It is an 'all class' anti-a but mainly class III. Sotalol has more class II effects than amiodarone so yes less negative inotropic effects with latter. There is a perceived risk, but I think it's less than with sotalol. Usefully, it also has some class I actions which may help with e.g. ectopic focus.

Numbers small but this is the only one I can find at mo (PM if you don't have access):

http://onlinelibrary.wiley.com/doi/10.1111/j.1748-5827.2011.01142.x/abstract;jsessionid=B1AF3E534322F73558B56F473D1453AF.f04t04

Re: drugs for vetricular tachycardia

John Flynn — Mon, 24 Mar 2014 20:09:02 GMT

[quote user="David Mills"]Amiodarone would be my choice. Far fewer side effects than originally thought - couple of JSAP papers on this. Widely used in humans for similar.[/quote]

Re: drugs for vetricular tachycardia

John Flynn — Mon, 24 Mar 2014 20:02:34 GMT

[quote user="Martin Atkinson"]About to reach for the propranolol but would atenolol be better?[/quote]

EIther risks throwing the dog into (worse) chongestive heart failure due to negative inotropic effect.

Unless the tachydysrrhyhtmia is life-threatening, I'd stop and think very hard. If it is life-threatening, then I'd go iv lidocaine as 2mg/kg bolus and then set-up a CRI while I had time to digest and assess my options.

If money permits, mexilitine ("Mexitil") would probably be my drug of choice if indeed the V-tach required treating.

If it was just a matter of bringing the heart rate down a peg (such as sometimes in AF), then I use digoxin (cheap) on occasions, but I've never used this for V-tach and don't know if it might not be contraindicated (would have to check).

Sotalol (cheap) would be better than propanolol or atenolol (or bisopronol) I would have thought, but is still a negative inotrope and might send into CHF.

I REALLY think you want to stop and think before adding in a beta-blocker given the pulmonary oedema and ascites and the feact that is "still amazingly bright and active".

I'd Holter first perhaps depending on severity of v-tach?

Re: drugs for vetricular tachycardia

David Mills — Mon, 24 Mar 2014 20:00:59 GMT

Amiodarone would be my choice. Far fewer side effects than originally thought - couple of JSAP papers on this. Widely used in humans for similar.

Re: drugs for vetricular tachycardia

Timothy Miles — Mon, 24 Mar 2014 19:48:55 GMT

Lidocaine iV ?