Sudden drop in heart rate during exercise

[jmambrose]

Since I began running 8 years ago, I have had periodic instances of a sudden drop in my heart rate. It always happens while I am running and my heart rate is up around 170 bpm. My heart rate drops to 80 bpm (counted by the treadmill and manual count) and does not climb back up. I am only able to walk after an episode because I feel as if I have no energy and I can't breathe any faster.

The episodes occur at any speed and after varying time and distance (also varying degrees of fitness). Sometimes exhalation or a cough precedes the incident, but not always. Right after I feel the first squeeze, I take a deep wheezing inhalation, as if I can't get enough air. I feel a deep squeezing sensation like my heart is beating at the base of my throat.

I have had an event monitor for 2 2-week periods previously (2005 and 2006), but failed to record anything. An ECG did not show anything abnormal.

What should my next steps be?? Any suggestions as to the problem?

Thank you.

[Jerry_NJ]

Sounds like you're getting accurate data.

Is new to me, there may have been some  past posts on this subject, but I can't recall anything specific.

Maybe you'll get more inputs....hope so.

[jmambrose]

I do not hold the hand grips while running. I periodically pause to measure bpm with the hand grips and also count manually for 6 seconds. I know by now that when I'm running I get up around 170. When these episodes happen, I have to immediately jump off the track because of the lack of energy. I immediately check my pulse on the machine then with my fingers. When walking at 3.5mph after it happens, I keep checking my pulse and it stays at 80.

[Jerry_NJ]

I do not clearly understand how you are measuring you pulse: "rate drops to 80 bpm (counted by the treadmill and manual count) "  Does that mean you were running to get up to 170 bpm (how did you get this measurement) then stopped and measured 8 bpm?

The reason I'm focusing on the measurement method is it you are holding the hand grips and running, there is a good chance you are not getting a good contact with the pulse counter.  I know the tread mills I've run on are set to resist giving bpm at speeds over 4 mph.  For me, well a few years ago, I'd have to be running at 7 mph to hit 170 bmp.  This is way too fast, I think, for obtaining an accurate pulse rate from a tread mill grip.

So, I'm not help, but maybe my questions will help us focus on the facts.