Trials and (De)fibrillations

All downhill from here...summiting Mont Ventoux, before my heart went south.

It has been one year and three months since I last updated this blog. This negligence has been due to general health and well-being, coupled with hyper-activity in the rest of my life – my final year of architecture school, and all the panic and excitement of exiting academia into a crappy economy. In all that time my heart held steady, except for one fun moment...

Shock of the New

Late February 2010...I’m deep into my “thesis semester” and back to living the life of a proper architecture student – not enough sleep, not enough exercise, too much caffeine, too much sugar, computer-monitor-eyeballs and adhesive-coated finger tips – the usual cliché.

Through this I try for –but do not always succeed at – a few hours a week either riding or running. Since recovering from my multiple ablations of 2008 I have noted that my heart does best when I get regular, moderate exercise. If I go more than a day or two without, I get a ramp up of PVCs accompanied from time to time with some low grade chest-pain. Likewise, if I exercise too much too soon – without a slow increase in time and intensity- I also get PVCs and chest pain. The key seems to be staying consistent and loyal to a modest exercise program, which is hard in the studio environment.

The day my defibrillator went off I was well rested, fed, and fairly unstressed. After a morning meeting with my thesis advisor I had two hours free and headed out for a short ride. The previous few weeks I’d mostly been doing intermittent, early morning hour-long roller rides before heading into studio, but this day the roads were clear of snow and it was unusually warm. Ten minutes into the ride, with no warning and no clear reason -riding along at a modest endurance pace- I went into V-tach. I felt it right away and stopped the bike. There was no doubt this was a legitimate bout of VT, I started my routine of vasovagal maneuvers –coughing hard and thumping my chest. The combination of manic coughing and VT made me a bit lightheaded, sending stars shooting across my vision. After a few coughs and thumps I felt that the VT had passed, I got back on the bike and turned around to go home and call in the episode to my docs. About twenty seconds down the road the defibrillator went off.

It felt like getting hit in the chest with a flying hockey puck while someone is popping two large balloons next to both ears and simultaneously turning out the lights. Yes, that’s right, this hallucination has visual, audible AND sensible components. People pay a lot of money for drugs that can do that, and I get it all from a little box in my chest. The shock did not knock me off my bike, though I probably bobbled for a second. I was moving at maybe 15mph. I immediately stopped to process what had happened.

Cell phone call to my EP at U Penn: after what seemed to be a standard-issue post-shock debriefing, the nurse on duty told me not to get back on the bike but rather find a ride home. That seemed silly, as I felt fine at this point, more traumatized by the implications of being shocked than by the shock itself, which was really less of a big deal than I had been expecting. I rode home at a pedestrian pace.

My “Carelink” transmission revealed that I had been in VT in the mid 200s (my ICD monitors at 160 and shocks at 225) The ICD tried “Anti-Tachycardia Pacing” (ATP) before shocking and was unsuccessful. With ATP the ICD tries to take over the rhythm of the heart electronically by first speeding up the tachycardia and then bringing it down slowly. It seems that that was happening as I was simultaneously trying my own vasovagal maneuvers. Perhaps the two techniques clashed and neither worked. I’ve generally vasovagaled my way out of VT in the past, so I was somewhat surprised that it didn’t work this time.

So the shock was legitimate, not a device error, and it came out of the blue. No Herculean effort brought it on, no over-indulging in caffeine or other substances, no cataclysmic event, just a random and capricious bout of VT. Nothing indicated this might happen before, and there were no “after shocks” after the fact. Not even a ramp up of PVCs. I saw my EP a few weeks later, we both agreed that I could start exercising again, that I should be attentive, and come back for some more testing when I had the time.

At first I thought this might lead to another ablation, but the episode turned out to be a complete outlier. Resuming exercise went off without a hitch. When I had the time, I slowly increased my maximum heart rate until I was occasionally hitting a conservative outer limit of 90% of maximum heart rate.

Techie Testing Talk

When school wrapped up at the end of May I went back in for testing. The goal was to induce VT, first with a treadmill stress test, a standard “Bruce” protocol. Generally with these stress tests the doctors are happy with anything more than 12 minutes, however I like to get a new maximum heart rate out of it and try to stick it for as long as possible while in a safe, controlled environment. My last stress test, in December of 2008, three months after my third ablation, I went to 17 minutes. This time I felt much better at 17 minutes, but the HR had been pegged at 175 for the last two minutes and didn’t seem to be going any higher, so I called it at 17. By the Bruce formula for estimating VO2max (14.8 - (1.379 x T) + (0.451 x T²) - (0.012 x T³) that put me at an oxygen uptake of 62.74 ml/kg/min. This in itself is pretty satisfying, as my tested VO2 high point was 72 ml/kg/min back when I was racing full time. I also tend to do much better on a bike-based VO2 test as I have pretty poor running efficiency. To have lost only 10ml over the course of years and through all the heart surgery, with a substantial part of my heart not contributing to its pumping, was further vindication of my hunch that my heart condition has not been getting progressively worse.

The second test was a “Non-invasive Programmed Stimulation” aka NIPS test. This is where they knock you out and run your heart through the gears using the ICD and several heavy doses of Epinephrine. Again, I was uninducable.

The results were puzzling but satisfying. In consultation with my EP, we speculated that I may in fact be “healing” the scar tissue created by my prior ablations; in other words the tissue that originally created the arrhythmia and had been put out of service by the ablation might have had a glimmer of electrical activity. This could happen again, of course. My exercising might in some ways encourage this process, but it is not a process of degradation, it is more a process of simple change over time, of what is generally considered positive “training effect”. If one of these sites of scaring comes back online on a regular basis more ablation on that site may be needed.

Though my heart was not remapped in an EP study, my ICD reading from the VT episode indicated that the VT came from the same area that it had always come from, indicating no new sites of scaring. The occasional PVCs recorded on my stress test ECG also verified this. I was given another get out of jail free card.

The State of Things

So now, as of October 2010, two years after my last ablation, and 2 years five months sporting an ICD, all is well. My activity level is as high as ever, I ride without limit – apart from work, and life’s responsibilities – I take no drugs for my condition, no special vitamins, no nothing. I ride in the hottest and coldest of conditions without ill effect, indeed I tend to ride better the hotter it is. I continue to harbor notions of competing again some day (perhaps in the more tempered “age-graded” events), but realistically I know this is unlikely. I worry about breaking my ICD, I worry about pushing too hard, and I simply don’t have the time to devote to being competitive. Never a “natural”, I’ve always had to train harder than everyone else, and now my developing architecture career is my priority and training is a luxury. So I confine myself to the occasional weekend throwdown and maintenance rides.

If any of this changes, if my condition worsens, or my defibrillator speaks up, I will document it again. In the meantime, silence is golden.