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possible SVT misdiagnosis by event monitor?
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possible SVT misdiagnosis by event monitor?

I have a 20 year history of high resting heart rate and periodic
panic attacks, which I have always felt was consistent with a
diagnosis of andrenaline sensitivity, Inappropriate Sinus Tach, or
some form of Dysautonomia - which are all  known to be accompanied
by anxiety/panic in many cases.

After a recent flare-up of my panic attacks, which always center on
heart anxiety, I saw a cardiologist for the first time in my life.
He had me wear a 30 day event monitor. On the 30th day of monitoring, the monitor caught
one of  fairly infrequent panic attacks, during which, the cardiologist
informed me, I went into Supraventriclar Tachycardia of 182BPM for
several minutes.

I was shocked by this. My tachycardias during panic do not seem to conform to the presentation
of SVT as it is usually described:  a heart rate that goes from normal to 160BPM+
instanatenously, and then returns to a normal rate within one heartbeat, also instantaneously.

My extreme tachycardias (such as the one that the event monitor captured), occurring during
anxiety/panic attacks tend to build up over several minutes as anxiety ramps up to a peak,
and then the heart rate resolves to within normal range over many minutes, as the anxiety
gradually subsides.

Is it possible that, as I have read elsewhere, event monitors simply interpret any
heart rate over 160 as "SVT"? Could my cardiologist have been wrong in his diagnosis of SVT?
When I asked my my cardiologist if adrenaline during
an anxiety attack could have accounted for the 182BPM tachycardia, he said "adrenaline
can't cause your heart rate to beat that quickly," which is nonsense. People in panic are frequently
known to have Heart Rates near 200.

My cardiologist is very inattentive and non-communicative toward me. He basically
annonced that I have SVT over his shoulder, as he was leaving the exam room, and then referred me
to his cardiology group's EP, before i could ask him any questions.

Now I am terrified.
3 Comments Post a Comment
I found it! Sinus Tachycardia is a form of SVT. Supra means above, so Supra Ventricular Tachycardia is a Tachycardia that originates above the Ventricles. Sinus Tachycardia is the heart rate being driven by the heart's natural pacemaker, not a re-entrant tachycardia. The following link discusses this aspect.

Interestingly, at the following link, they give an example of a man brought to the hospital manifesting what appeared to be SVT, but after hydration, changes occurred in the EKG that revealed he was, in fact, in Sinus Tachycardia.

I think you make some good points, perhaps an evaluation by another cardiologist would be of some value. See the Wiki link for maximum Sinus Tachycardia rates, you're in the ball park for Sinus Tachycardia.

Hope this helps.

"While we are discussing this, we should be clear about our terminology. Sinus tach is one of the Supraventricular Tachycardias. "SVT" is an umbrella term that represents a group of tachydysrythmias that originate above the ventricles. They will generally be narrow tachycardias, unless aberrant conduction is present. Some of the other types of SVT are AVNRT, AVRT, A-Flutter, A-Fib, junctional tachycardias and atrial tachycardia. Not only is sinus tach one of the SVTs, it is by far the most common SVT!"


Thank you so very much for those links, Artaud (I like your moniker, by the way). I appreciated it.

There seems to be some  terminological confusion surrounding SVT
and sinus tachycardia. My concern is that there also seems to be this notion that "normal" sinus tachycardia is anything between 100-180, and that any heart rate > 180 is generically diagnosed as probable abnormal/non-sinus SVT.

According to wikipedia, an ECG allows a cardiologist to diagnose the specific form of SVT (re-entrant, etc) that is occurring. So theoretically, if I call my cardiologist's office tomorrow,  they will be able to tell me exactly which form of bona fide SVT I experienced. Diagnosis: case closed.

However,  wikipedia also says "diagnosis is usually apparent on the EKG, but if heart rate is above 140 bpm the P wave may be difficult to distinguish from the previous T wave and one may confuse it with a paroxysmal supraventricular tachycardia"

While other medhelp posters have posted things such as:
"a fast heart beat looks the same on the ekg as an accessory pathway svt."

So I don't know where I stand. If my diagnosis was made on the basis of some clear-cut finding on the EKG monitor, that is one thing. But if it has been made on the basis of some algorithm which states that one beat over 180BPM = abnormal SVT, I'm not sure what I should do.

I guess I will call tomorrow and ask for clarification. I am so scared that I will have one of these SVT attacks where my heart rate goes into the 200s and "locks" in at that rate. I just know I would go into such a panic at that point that I would  likely drop dead. SVT + massive panic cannot be easy on the heart.
Actually the link I provided demonstrated an EKG that seemed to show SVT, but saner circumspect minds prevailing, the EGK eventually showed the underlying Sinus Tachycardia, so not treating it as SVT, being patient, paid off.

I'll never be able to find it, but I saw a fascinating EKG once. Seemingly showing a specific fast rhythm, the Cardiologist did a carotid artery massage, which slowed the Heart Rate sufficiently for an underlying rhythm, the true issue with the patient, to be seen. My wife worked for a cardiologist, he treated patients for SVT, I'm not sure why they are sending you to an E.P.


"Supraventricular tachycardia (SVT) includes a variety of types of reentrant fast heart rhythms originating in any part of the heart’s conduction system above the ventricles. The major types of SVT include: atrioventricular nodal reentrant tachycardia, atrioventricular reciprocating tachycardia, atrial tachycardia, inappropriate sinus tachycardia, and atrial flutter. Physiologically atrial fibrillation is also a type of SVT, but typically discussed outside of other SVT rhythms because of the complex differences between it and other SVT rhythms. Atrioventricular nodal tachycardia is the most common type of SVT, representing 50% to 90% of all SVT cases. This type of SVT, along with inappropriate sinus tachycardia, has a higher prevalence in women. Atrioventricular reciprocating tachycardia is the second most prevalent type of SVT, accounting for approximately 33% of all SVT. Atrioventricular reciprocating tachycardia and atrial flutter are seen more frequently in men. Other details of the mechanisms and clinical manifestations of SVT rhythms have been described elsewhere."

If your fast rhythm is from sinus tachycardia (or, as the above paragraph indicates, Inappropriate Sinus Tachycardia, since sinus tachycardia may simply be an appropriate response to exertion), a Beta Blocker may help to hold the rhythm at a slower rate.

I'll be interested to see what your doctor says, keep us updated.
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