cardiology question

[IM05]

Could anyone answer this question for me please ?

How significant is supraventricular arrhthmias in assymptomatic patients who have no previous cardiac events ?

Is it a predictor of subsequent cardiac pathology ?

Do you routinely treat them ? and which group of medications are better ( beta blocker / ca channel blocker/ adenosine)

thanks heaps.

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[Kalel]

I just had a patient with a supraventricular tachycardia today. We gave her adenosine because we thought that she might be in flutter, but we couldn't make out the P waves. This was after we attempted vagal maneuvers and carotid massage. She was refusing anticoagulation, so we wanted to send her to electrophysiology for radioablation (even though she would still need to be anticoagulated for some period after that, even after ruling out for thrombus with a TEE). Anyways, I was told today that any kind of tachy-rhythm is associated with ventricular myopathy and eventual failure, so any long-term tachy-rhythm should be attempted to interrupted, whether that be through medical therapy or interventional therapy. Some of the medicines used to control supraventricular tachycardia include medicines like digoxin, which increases the vagal effect on the AV node slowing down conduction, calcium channel blockers (non-dihyropiridines), and beta blockers which slow conduction as well. Adenosine is given intravenously and is often just used to help establish a diagnosis, like it was in our case. Anyways, the complications and treatment depend on the cause, so here are some good articles I was able to find on the subject:
http://www.emedicine.com/med/topic1762.htm
http://www.vh.org/adult/provider/familymedicine/FPHandbook/Chapter03/02-3.html

 

[ERMudPhud]

I think there may be some confusion here between the rythym the OP was asking about and the one Kalel is answering about. I think Kalel is talking about atrial fib/flutter which although technically an SVT is usually considered seperately from PSVT since the treatments are quite different. For PSVT the rhythym is usually terminated with adenosine being the drug of choice. B-blockers, CCB, or Dig can then be use to prevent recurrence but events are usually so infrequent that patients are often on nothing or just get the reentrant circuit ablated so that the PSVT stops happening. I'm not aware of any correlation with subsequent heart(coronary) disease

atrial fib/flutter cannot be terminated with adenosine although adenosine does sometimes help with the diagnosis. The heart rate is controlled with B-blockers, CCB, or Dig until the patient can be chemically or electrically cardioverted. This is often done electively after a period of anticoagulation. If the patient can't be kept in sinus after cardioversion they will sometimes be on antiarrthmics to keep them in sinus or they may be left in fib/flutter with anticoagulation and rate control(B-blockers etc...) Radioablation can sometimes be used for fib/flutter but I've seen it done much less than with PSVT. fib/flutter is often but not always associated with underlying coronary disease.

 

[punjabiMD]

Originally posted by Kalel
Anyways, I was told today that any kind of tachy-rhythm is associated with ventricular myopathy and eventual failure,

I don't see how that's possible.

 

[ERMudPhud]

Originally posted by sardarg89
I don't see how that's possible.

Sustained, untreated severe tachycardia can lead to problems. You generally don't see it now because we don't leave people in afib at rates of 180-200 for months.

 

[punjabiMD]

Originally posted by ERMudPhud
Sustained, untreated severe tachycardia can lead to problems. You generally don't see it now because we don't leave people in afib at rates of 180-200 for months.

no, I was talking about the statement that any type of dysrrhythmia being associated with ventricular myopathy. it doesn't make sense.

 

[Kalel]

Originally posted by sardarg89
no, I was talking about the statement that any type of dysrrhythmia being associated with ventricular myopathy. it doesn't make sense.

Thanks for the correction ERMudPhud. I was responding to the question of any supraventricular tachyarrhythmia, which can be caused by atrial flutter or fib. Some sources (emedicine) actually do classify a flutter and fib as causes of PSVT, as technically, they are, because the definition of PSVT is just any sort of supraventricular tachycardia that occurs from time to time (paroxysmally). Here is an article from e-medicine about the other causes:
http://www.emedicine.com/med/topic1762.htm
The OP probably was referring to PSVT that ERMudPhud wrote about, which occurs in "asymptomatic" patients, is technically called either "true paroxysmal atrial tachycardia" or "atrioventricular nodal reentrant supraventricular tachycardia", a condition known to occur in otherwise healthy, young individuals (and is not associated with any short-term morbidity):
http://www.merck.com/mrkshared/mmanual_home2/sec03/ch027/ch027d.jsp

Regarding the cardiomyopathy question, if you read what I wrote in my original statement, it states that any "tachy" arrhythmia, or anything that keeps the heart going at a fast rate for abnormally prolonged periods of time is associated with cardiomyopthy. I think this kind of makes intuitive sense, because the heart will be overworked if it is forced to beat at a faster rhythm. It's probably a similar mechanism to CHF developing secondary to hypertension, it's just forcing the heart to do more work. Here is an article about PSVT which lists CHF as a long term complication:
http://www.nlm.nih.gov/medlineplus/ency/article/000183.htm

Actually, even an increased resting "normal" heart rate in anybody is an independent risk factor for overall mortality, probably partly due to the strain of the heart too. This kind of makes sense too, because athletes, who have trained their heart to be more efficient, have a lower resting heart rate, and a lower cardiovascular risk of dying.
http://www.blackwell-synergy.com/links/doi/10.1046/j.1365-2796.2000.00602.x/abs/

 

[IM05]

Thanks to all who shared your views, kalel you are amazing, don't know how you found those articles on the web so easily since I have been searching for them for atleast a week now.

This is about the findings on holter monitoring on some assymptomatic patients and quite a lot of them happen to have what appears to be PSVT much more prevelant than expected. I am really surprised and actually there is not a lot written about the long term sequele of PSVT without therapy, I guess everybody assumes subjects just grow out of it since they are comparatively young.

 

[asm3]

kalel,

i agree that you are awesome in finding all these articles. I would caution you, though, to actually read more than the abstract. The article you site for the baseline heartrate actually showed that it is based on blood pressure and injured myocardium. If you take a group of twenty-year-olds with a baseline rate of 100, most of them would just be found to have a highly active adrenergic system. The article also showed that by the time you adjust for age, cholesterol, diabetes, etc, you will not have a statistically significant value.

asm

 

[Kalel]

Originally posted by asm3
kalel,

i agree that you are awesome in finding all these articles. I would caution you, though, to actually read more than the abstract. The article you site for the baseline heartrate actually showed that it is based on blood pressure and injured myocardium. If you take a group of twenty-year-olds with a baseline rate of 100, most of them would just be found to have a highly active adrenergic system. The article also showed that by the time you adjust for age, cholesterol, diabetes, etc, you will not have a statistically significant value.

asm

Thanks for the correction. I didn't even think to look the actual article up since I had assumed that there was an overall consensus that an elevated resting heart rate was associated with an increase in cardiovascular mortality, but upon reading the article, I do see that this is one of those studies out there that questions the usage of resting heart rate as an independent predictor of cardiovascular mortality. I still think that resting heart rate is an independent risk factor for overall mortality though; although this particular article seems to suggest that the independent increase may be secondary to "nonmalignant disease" in men. I do have to admit that I am a frequent abstract browser though, but I agree that it's important to read the actual article of those abstracts that would change our management decisions. Thanks again!