Well, after 8 months of relative calm, I got my first official defibrillation from the ICD yesterday while doing yoga. It didn't feel quite like the "horse kick to the chest" the doctors had described. Imagine bein electrocuted and the charge coming directly from your heart. As I moved into downward dog, it zapped me and moved up my neck and down my hand. You learn physics in school and know how these things go. The charge moves through your body and resonates everything in its path. It didn't knock me over but I definitely came out of downward dog fast.
An implanted cardiac defibrillator, or ICD for short, is a device that shocks your heart when the rhythm ceases to sustain you. That can mean your heart is racing an unable to form a normal pattern or that your heart rate is too slow and can similarly go off on its own tangent, sending your heart into ventricular fibrillation. Mine is programmed at 170bpm and 30bpm to shock me when the wave of my heart beat no longer has the ability to form a cohesive pattern.
I had been doing king pigeon pose, which cuts off your vagus nerve. Your vagus nerve runs along the back of your neck and controls the parasympathetic actions for the heart. The parasympathetic action that the vagus nerve provides is the "resting" state of your heart, or in simpler terms, recovery.
The heart gets aggravated or engaged by heightened activity, such as yoga, and the parasympathetic causes the relaxation of the heart muscle in order to continue the cycle of normal contraction and relaxation. The heart beats--contracting and pushing blood--followed by relaxation phase where the chambers refill. Without the recovery phase working, your heart goes into ventricular fibrillation, which is what I originally almost died from.
This was a clue from my body. Moving forward from a cardiovascular event, there is a lot of questions about what you should and shouldn't do physically. There are no catch all answers because every one has a different body, different control and different outcomes. The best we can do is keep living and keep discovering new ways to live healthy.