I have had a few heart "events" in the past. I have heart failure,
and have had atrial fibrillation. A couple of weeks ago the Afib
stopped, but a "flutter" remained. They say the upper part of my
heart is beating faster than the remaining part, which I don't
really understand. They talk like I will be getting a Cardioversion
in the near future. I understand that they will put me to sleep,
put a scope down my throat to get images of my heart, and use
electrical paddles or pads to shock my heart out of the irregular
heartbeat and back into normal rhythm. Doesn't sound to me
like a fun way to spend a day, and was just wondering if anyone
has had the procedure, and tell me about the experience.
Your heart has its own "electrical system", which under normal circumstances causes it to beat in a regular pattern. The nervous system (Vagus Nerve) can stimulate it to speed up and slow down, as well as chemical mediators in your body (Epinephrine, also called Adrenalin) and others. The natural "pacemaker" in the system is the SA node (sinoatrial node) in the right atrium of th heart. This is the right upper chamber, and receives blood from the rest of the body. The SA node initiates the heartbeat by creating an electrical stimulus that causes both atria to contract, which pumps the blood through the tricuspid valve from right atrium to right ventricle, at the same time through the mitral valve from left atrium (which received freshly oxygenated blood from the lungs) to left ventricle. This electrical signal is picked up by the AV node (atrioventricular), delayed for less than a second to allow the ventricles to fill completely, then sends the signal though the Bundle of His and into the right and left Bundle Branches. These bundles are specialized cardiac tissue, sort of like rapid conduction cables, that send the signal to the far ends of the ventricles faster than they could travel through the heart muscle. These "cables" end in small "wires" called Purkinje fibers, which then stimulate the ventricles to contract very forcibly and rapidly, ejecting the blood within them either to the lungs (right ventricle) to pick up oxygen, or out to the body (left ventricle). This whole process occurs about once a second at a normal resting rate (60 beats/minute).
If the SA node goes haywire, it starts firing randomly and irregularly, and other areas of the atria can also start giving off their own stimuli. This is atrial fibrillation. Not all the stimuli reach or stimulate the AV node, so the ventricular rhythm is both slower and also irregular. In atrial flutter, there are usually a couple of points in the atria that fire regularly and very rapidly, and again, only part of those signals are picked up and passed on by the AV node. The SA node can completely fail; if it does, the AV node can pick up the task of setting the heart rhythm, but it does it at a slower rate and is less influenced by the nervous system or naturally occurring drugs. In these cases, your resting rate is usually slower, (40's) and when you exercise, your heartrate may not increase as much, or sufficiently, and you get tired and out of breath faster. If the AV node can't or doesn't take over, the ventricles can establish their own rhythm, but at an even slower rate. Both of those circumstances call for an artificial pacemaker.
A cardioversion is what is done to override and hopefully end those irregular atrial electrical activities. They are rarely done without some sort of drug therapy to try keeping the natural rhythm going afterwards. The big danger is atrial fibrillation, because the blood flow in the heart is disrupted somewhat, and small clots can form within the atria. Small pieces can separate and travel to different parts of the body and lodge in the vessels there, with varying effects. If they lodge in the small vessels (or even larger ones) of the legs, you get deep vein thrombosis, or DVT's. If they lodge in vessels of the lungs, you get Pulmonary Embolus, which can be fatal. If they lodge in the vessels of the brain, you have a Stroke, with all kinds of bad things, from paralysis, to loss of memory and body functions, to death. Anticoagulation therapy ("blood thinners") is used in patients with A-Fib, to control or decrease the amount of clots that form. That can be as simple as a baby aspirin per day to quite a few choices of heavier duty anticoagulants, as the physician determines necessary.
I hope this was not too elementary or long-winded an explanation. It's difficult to describe A-Fib/Flutter without knowing what normally goes on in the heart, and what I gave was a very basic description.
I do already have a Meditronix pacemaker/defibrillator, and it saved my
bacon last August. Thank you all for the well wishes.
I was a Registered Nurse for 37 years, and for 5 of those years worked for Medtronic as a Cardiac Pacing Specialist. I attended pacemaker implants and advised the cardiologists or surgeon when they implanted the devices, and also helped with followup treatment, when patients came in for checkups. When I was working for them (more than 25 years ago), implantable defibrillators were still in the developmental stages and were just beginning to get implanted beyond investigational use. The technology in these things is incredible and amazing; I'm happy they have improved your life.
It's 
