Sinus Tachy related to Hypothyroidism?

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Hi all,

I work days on a busy med/surg tele unit. Yesterday I was caring for a patient who was on tele and began taching away between 160-185 without breaking the rhythm for approximately 2 minutes. This occurred twice within about 10 minutes of each event. When I called the MD the first time, she ordered Synthroid for the patient, stating that hypothyroid could be the cause of the tachy (and some of her other symptoms). This patient had a slew of other issues, biggest being a critical Hgb of 6.4 (could not transfuse because she is Jahova Witness). When I called about the second event, she then proceeded to order Metoprolol IV Push and a large cardiac workup.

All said and done, the patient broke the rhythm on her own after about 2 minutes of a sustained HR of 180 or so. But my question is, does anyone know the mechanism of why the MD would think it was caused by hypothyroidism? I understand that the extremely low Hgb would most likely be the culprit, but in general has anyone ever heard of hypothyroid causing extreme sinus tachy?

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Specializes in Neuro, Telemetry.

Kind of veering off as I do not know the answer to your question. But I do have a question. I thought it was only sinus tachy up to 150 BPM. After that it would be SVT or some other rhythm that is tachy. Is this incorrect?

And I am not trying to be snarky. I am a new grad and am truly curious.

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Specializes in SICU, trauma, neuro.
Kind of veering off as I do not know the answer to your question. But I do have a question. I thought it was only sinus tachy up to 150 BPM. After that it would be SVT or some other rhythm that is tachy. Is this incorrect?

And I am not trying to be snarky. I am a new grad and am truly curious.

http://www.ems12lead.com/2013/04/30/the-trouble-with-sinus-tachycardia/

OP, I did a bit of digging, because I didn't know either. Thyroid Disease and the Heart | Circulation Interesting!

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I failed to mention that the MD had ordered labs including a thyroid work up earlier in the day, but I was just curious as to the mechanism between thyroid and tachy

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Very interesting couple of articles!

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Specializes in Neuro, Telemetry.
The Trouble with Sinus Tachycardia | EMS 12 Lead

OP, I did a bit of digging, because I didn't know either. Thyroid Disease and the Heart | Circulation Interesting!

Thanks for the article link. It pointed out the exact reason why I thought over 150 was SVT. I never learned that SVT is actually a category of rhythms and not a dysrythmia in and of itself. I'll chalk it up to nursing school world for testing purposes vs. real world nursing.

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Specializes in Family Nurse Practitioner.

I don't think hypothyroidism would cause tachycardia. It's usually hyperthyroidism (everything is sped up) which causes the tachycardia. This sounds very much like a hypoxic response to the low hemoglobin. I would put this patient on some oxygen if they are not on it already and see if there are any medicinal options other than a blood transfusion. How were the electrolytes? Did you get an EKG during the event? Does the patient have baseline a-fib?

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Specializes in Adult Nurse Practitioner.

A patient in severe Hashimoto's hypothyroidism can develop tachycardia as a results of either/both extremely decreased free T3 or the histamine response associated with elevated TPO/TG antibodies. Do some research...you will find the thyroid quite an interesting gland :)

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