Was doing hill intervals yesterday. It was about an 8th of a mile climb, relatively steep. Really hammered up the hill after a 2 hr ride.
On the way down, my chest started really thumping oddly. Two to four normal beats followed by a stiff beat which felt like someone was punching my chest from the inside out. Got off the bike. Took my pulse. BEAT- BEAT- THUMP- BEAT- BEAT- THUMP. During the THUMP - no pulse, so it felt like my pulse was skipping.
Had my ride partner take my pulse. He felt the same thing. This went on for about 4 or 5 minutes. Luckily we were close to home at that point. He went and grabbed is car and we went to the emergency room about 10 minutes away.
By the time I got there, the THUMPING had stopped and my heart rate was in normal recovery mode. The docs hooked me up to a monitor, did an EKG, and took a blood test. Heart rate monitor turned out normal results after an hour. The EKG showed nothing abnormal. Blood test showed nothing abnormal. Blood pressure was normal.
DOC said it sounded like a PVC which, as he explained to me, occurs in the lower portion of the heart. He said this would explain the THUMP without the pulse. He said that during excessive athletic activity sometimes the heart can get confused and fire off electric impulses which causes the bottom to beat (for lack of a better word). This beat doesn't result in a pulse.
He said that this can occur in perfectly healthy individuals BUT usually doesn't last 3-4 minutes. This seemed to concern him a bit and he scheduled me for a cardio appt this Thursday.
not a doctor, but have studied arrhythmias. premature vent contractions do occur in totally healthy individuals more often than people realize, but yeah they are usually confined to a few beats, not 3-4 minutes. since the beat is "premature" the atria (top part of the heart) haven't had time to fire yet and squeeze blood into the ventricles, so when the vents beat early they don't have any blood to pump, hence no pulse (the thump)
Good luck on your tests, they might put you through stress tests, to see if they can get it to happen again, and record it on the ECG. I know lots of people with arrhythmias who are fine athletes, so hopefully it's not serious in your case.