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Heart & Cardiology/second deg I heart block in heat stroke?


Hello Doctor,

I am a fellow expert (first aid/ EMT category), I was attempting to research a call I had today and found very little (human anyways) to answer my question. I had a call for a healthy 22yo African American male. His only history at all was a slight "heart murmur", and when asked specifically, he had felt an irregular pulse in the past but his PCP said not to worry about it.

While working as a paramedic on the ambulance in 80 deg. weather with 70-80% humidity I cam across a patient who had been helping a family member move and admittedly hadn't drank much water or eaten. He was sweaty, hyperventilating, nauseous, and his arms and legs were cramping. We put him in the air-conditioned ambulance, put him on an ECG, started IV fluids and started off to the hospital. As we transported the patient began feeling better, his heart rate of 90+ began to come down at which time I notices a pretty classic second degree type 1 heart block. I asked him about any "irregular heart beat" in the past and he said he had one once but his doctor checked him and said not to worry about it.

I had thought this might be related to an electrolyte shift causing irritation in the myocardium (as it had in his arms and legs)? I have looked on line about arrhythmias related to heat illness but little came up other than some veterinary studies dealing with pugs.  The other possibility is that he just developed a heart block at 22 for no good reason at all?

What are your thoughts on this? Is it possibly related to his heat injury? (We don't have great follow-up with hospitals and my medical director isn't as available an asking on line. (just curious).


Hi Marc,
Not enough information for an opinion in this patient, but abnormal electrolytes, calcium, and magnesium levels may certainly have played a role. To confirm, you would have needed another EKG once corrected with rehydration.
Hope this helps,
Dr T

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