globecanvas

This came up in another conversation and it seems to deserve its own thread.

There are many causes for irregular or rapid heart rates. Obviously if you have heart issues you should see a cardiologist. But I can share some specifics about SVT, specifically PSVT (paroxysmal supraventricular tachycardia), which I have had my whole life. This is qualitatively different from atrial fibrillation, which is another common cause of rapid heartbeat.

SVT is essentially an electrical short circuit in the heart tissue that causes one heartbeat signal to trigger multiple beats. This manifests as distinct episodes of very fast, but regular, heart rate. In my case when an episode starts, heart rate doubles immediately, like flipping a switch, and hammers away at that rate until the episode "breaks" and heart rate drops back to half (that is, normal) just as if the switch was flipped back. The distinguishing characteristics are the extreme rapidity and regularity of the heartbeat. Atrial fibrillation is more of a fluttering sensation, and heart palpitations are more irregular.

According to my cardiologist, the episodes are not dangerous per se, as long as they are consistently breakable. The risk from SVT is if the episodes don't break on their own. A hyper-fast heart rate is very inefficient and you can eventually black out.

This is from a garmin HRM during an episode. This was on the bike, just after a hard effort. The episode is from about 3:33 to 3:39, so 6 minutes or so. My normal max HR is about 180.



I have had these episodes since I was a kid, 2-3 times a year, and I never knew it was unusual until I started riding bikes seriously and it became bothersome. For me, episodes will always break within few minutes if I stop whatever I am doing and lie down flat on my back and get calm. Nothing else will make the episode stop.

A few years ago I had an episode on the bike and tried to softpedal it out. 10 minutes later, heartrate still doubled, I started to black out (actually, red out), so I got off the bike and laid down, which broke the episode as usual. I have had maybe 3 episodes on the bike, in total, never in a race, but I'm sure that day will come eventually.

SVT is not known to be hereditary, but my father, and one of my sons both have it in different degrees. My son now knows to lie down and get calm, and his episodes go away just like mine do. His are much more frequent than mine, maybe 1-2 times per month. His cardiologist told me that the condition can change as he grows older, for better or worse.

My dad (who is an MD) doesn't handle it so well, he starts to panic which makes the episode persist. He has had to be defibrillated in the ER to break an episode, and is permanently on medication to slow his heart rate and prevent episodes, which is detrimental to his quality of life.

At the advice of my cardiologist, I quit coffee for a few years, thinking that might be correlated, but it didn't affect the frequency of the episodes. Episodes are much more likely when I am exerting myself while poorly rested. That state was much more common in my teens and 20s better than in my 40s, so the episodes have become less frequent over time.

For somebody who has very infrequent episodes, an occurrence could be terrifying, because it feels like your heart is going to blow up. The most important thing is just to get still and get calm. Panicking, or any exertion at all, will prolong the episode.

MDcatV

Thanks for sharing GC.

I posted in the other thread, but copying to here:

I had what I have had (by a cardiologist) called supraventricular tachycardia (SVT) events, two of them, one on a saturday and one on the following tuesday during 2013. the saturday episode was during a long road race, about mid way through. It was the first warm race of the year and I'm pretty confident I was dehydrated. i was pedaling along in the group at a hard pace, when it felt like my heart flipped in my chest and I couldnt breath. I knew one of my cycling buddies was in the pack further back, so I started drifting back to him to tell him something was wrong and by the time I got to the part of the group he occupies, it was over. I continued (probably stupid) was fine, and even broke away from the bunch on the last lap in a secondary break that lasted to the end.

The second episode was 3 days later during a hard workout, I was on the 3rd 8 minute rep of the pacing workout when boom, same sensation. I stopped immediately and soft pedaled home. I was not wearing an HRM during either, so no HR #s or durations, they were both perceived as a feeling like my heart flip flopped in my chest, that my HR raced momentarily, then returned to normal. It scared the **** out of me and I have hypochondriac tendencies perpetuated by being present at two races where very experienced elite racers died of cardiac arrest (one was a teammate who was in his late 20s and was miraculously resuscitated) so I started seeing a cardiologist. We did stress test, I wore a HR monitor for a week including training and racing trying to duplicate what occurred, and everything tested "normally" so it was written off as likely dehydration induced episode, and the cardio told me to do what I do. I've done tons of research on the topic, none really cheered me up on the matter.

I've worn a HRM since for a bunch of reasons including if it happens I'll have record to show a doc., but thankfully it hasnt, but it's been in the back of my mind a few times and probably caused me to govern efforts on occasion.

this might end up being a 2 person thread until someone busts in and says to buy a powermeter :-), or if you have SVT, dont go to Europe.

globecanvas

I have a number of episodes captured on a HRM, but the cardiologist wasn't especially interested in them. In order to rule out rarer, but more dangerous conditions similar to WPW, they need to capture the tachycardia on a Holter monitor, which will show more information that just the coarse heart rate. I have never captured an episode that way.

Although I haven't met anyone else in real life with SVT (outside of my family), there are heart issues forums just like there are bike racing forums, and on one of those boards I chatted with a guy who was a former national level speed skater, who experienced very frequent and longer-lasting (10+ minutes) SVT episodes which occasionally messed up his races. He eventually opted for an ablation, which is a procedure where they insert a catheter and zap the heart tissue around the short-circuit. His decision was entirely based on wanting a quality of life that did not include SVT episodes, not due to any concern that he would have a heart attack or anything. I would not choose that procedure given the current frequency/duration of episodes that I experience.

TheKillerPenguin

I have a friend....when he goes too hard, his HR actually DROPS to ~20bpm until he eases up...this is because there is a hole in one of the chambers of his heart that isn't fixable. Says it feels very much like drowning, but he still races his bike, because he's bamf (and his doc gave him the OK).

carpediemracing 

I have something but it seems to have gone away. When I have an attack it's like my heart is racing in neutral, i.e. lots of pumping but no oxygen. I've counted my HR at 240 bpm or so, pretty consistently, since I first started noticing the episodes at 15 years old. I haven't had one in a while. I used to have them pretty much any time I ran up the stairs after being sedentary for a bit - I'd feel like my heart jumped into my throat and then bam, it'd happen. It's happened a couple times on rides but usually when I'm walking and do something sudden for a few seconds, like going up the stairs 2-3 steps at a time.

I've never captured anything electronically, it was way before HRM and all that.

Because of this and some other stuff (padding the bill? I don't know) I was given a stress test and other things. Ends up I have an inverted T wave (separate thing) but the racing heart thing is still a mystery.

tetonrider

sorry you have to deal with this.

what happens if an episode occurs when you're already near your (normal) max, say during a threshold or vo2 interview? looks like you had eased off just prior to the episode you showed above.

sounds like you are saying that the beat-to-beat variability is zero when you say "fast but regular."

on a separate note, i've been particularly curious about HRV and devices to measure it w/r/t athletic performance and recovery. there are some devices that are more sophisticated than a typical HRM but short of the inconvenience of a holter. we already carry the recording devices!

globecanvas

People have all kinds of triggers. For me it's almost the opposite, stopping suddenly after a hard effort can be a trigger. 3-4 of the episodes have occurred just after finishing a big hill. Some people can trigger episodes just by taking a deep breath, something about rapidly changing the volume of the chest cavity.

I don't think that's ever happened. Given that episodes are only 2-3 times per year, and given the small percentage of my life that I spend at max HR, it's an unlikely scenario.

It's not a big deal. Until a few years ago, I didn't even know it was unusual, I thought everybody experienced it. My intention in starting this thread is to put the information out there that this particular condition can be totally livable and not a scary thing.

Enthalpic

I know relatively little about the heart but my first thought was "can't they do a cath procedure to fix most electrical problems?"

If they don't have to saw open your chest why not consider it? Then again, if it really is benign doing nothing is the best action...

Zapdaba

I have Atrial Fibrillation which I hold off with Flecanide twice a day. It is caused, I believe, from a misfiring nerve cluster in an artery close to the heart. There is a procedure to isolate that cluster but since it doesn't occur unless I miss a dose, I'll wait until the procedure is more refined. I don't expect to skid into my grave with any resellable parts.

Jseis 

I suffered PVC's on and off for 20 years (I'm 59). After wearing a Holter monitor and various tests my doc (former NASA flight surgeon) suggested that I excersize harder (I walked a lot) but limit my bursts to no more than 18 seconds at max hr (about 170) and not push it beyond. So I cycle an hour everyday to alternate days and push myself constantly but not balls out, like say at 85%. After 4 years I've exercised myself right out of the PVC's. Diet played a huge roll as the PVC's always happened in the eve about 2 hours after eating and it was eventually discovered that I also have GERD. Given my history of an extremely high and nearly life threatening fever at age 3, I had been told that I likely suffered some nervous system/heart damage that led to a slight but chronic heart murmur that I had until my early 30's. I also got the GERD under control with the diet change & constant exercise & inclined sleeping (what a pita). Evidentally I've got something going on with the vagus nerve and as long as I stay with the diet, exercise, keep GERD at bay, I've been better than fine. I sleep pretty soundly but my wife admits to checking on me now and then just to make sure I'm in this world.

furiousferret

I get random chest pains for the past three years, it started when I did an Long Ultra Event and pushed myself too hard. Went to the ER twice about it, and in August had another battery of tests. The Cardiologist convinced me its a chest wall tear, and that my heart is healthy as an ox, at least pre bacon cheese wrap.

globecanvas

Interesting article about endurance training and cardiac issues:

Cycling to extremes - VeloNews.com

JerrySTL

Just read that last night. Very interesting. I had a minor heart attack in 2000 while riding my bike. I'd been doing century rides before that. I started doing even longer rides afterwards like double centuries. Now I'm wondering if that was such a good idea. Too much of a good thing.

globecanvas

"But, like many other medicines, more isn’t always better. Research is honing in on the issue of dosage in exercise. If you think of exercise as a drug, there is a certain threshold at which good becomes bad, when benefit becomes detriment."

Heathpack 

A friend of mind sent me a similar article when I mentioned that I was getting a TT bike. Ironically the guy who sent me the article is a very fast competitive ultra guy who was making the argument that a 20k TT was going to wreck my heart. But the point was well-taken, his concern was running at max HR for 30 min or 60 min or in my case maybe 90 min was worse than riding a 500 mile race I which you vary your HR and effort a little more and of necessity ride with lesser intensity.

Who knows what is right, but it's worth being aware of. I'm increasingly capable of pushing myself at high intensity for long periods of time. I enjoy riding like that, it's very "cleansing". Is it good for me? I honestly am not sure.

grolby

Just read that, too. One thing jumped out at me: I've occasionally experienced this sensation since before I was heavily involved in cycling. I've mentioned it to doctors a couple of times and they've never seemed concerned. I got the impression it was pretty normal. Seems like it can be a precursor to developing AT... or not.

I've never had an episode of tachycardia, but my wife has or rather had a congenital condition that had led to sporadic episodes since childhood. It had been dormant for a while, but acted up early on when we were dating. Doctors had been unable to collect good data and it had never been diagnosed but they thought it was WPW (it wasn't, it was more dangerous than that). She wasn't even super active at the time because she had a history of exercise inducing episodes of tachycardia, but due to stressful events in her life, she began experiencing episodes for no good reason and just suffering irregular heartbeat that was making her feel awful without her heart necessarily racing. In a way that was a good thing, because the ongoing problems made it easy for the doctors to determine that she had an electrical problem and to induce tachycardia when she went in for an ablation. Which was good because they ended up making three separate ablations before they weren't able to induce tachycardia anymore. Since then (four years) she's been clear and even been able to take up running.

So this stuff is definitely on my mind. I've figured for a long time that there's a time limit on how long I'm going to want to do this whole training and racing thing. Not for health reasons necessarily but because it is a lot of work. I'm not at the point of wanting to take a break yet, but this article has me thinking it'll probably be a good thing if I don't feel like pushing hard into late middle age. I would be surprised if I'm seriously racing after age 40, but who knows. That's a decade from now. I do think I'm going to remain pretty active on the bike, though, and probably won't stop entering all races ever, but training hard? There may well be a time limit on that.

Ygduf

It seems to take a lot for me to get the endorphin flood these days, but it's better than ever. The last race I won, I had awesome power for the last 12 minutes of solo break and it wasn't painful or unpleasant at all. Just felt pretty zoned out and pleasant.

I also have the sensation of skipped heartbeats often, mostly at night when I'm laying in bed before sleep. thunk, thunk, ... (oh am I dying) ... thunk