Sometimes Atrial fibrillation can be a little tricky to identify. To look at it, it looks simple enough however you can almost see an even rhythm and your eyes may trick you to make you think you see P waves when in essence there are none. Afib is characterized by its irregularity and the fact they are no P waves before each QRS. We note that the QRS is narrow so we know where the QRS signal is coming from. If the signal is from above the AV node; the QRS is narrow and from below the AV node; the QRS complex is widened. With a wide QRS we have watch out for Ventricular tachycardia so to be safe it always good practice to treat it like it is until it is ruled out. By knowing the rate is another way to figure out what rhythm we are in. Atrial fibrillation is at a rate of 120 to 140 beats per minute.
Now we know what rhythm you are in; what do we do about it? If we know how long you have been in the rhythm for we know what to do. This is where having a cardiac examination comes in handy. For Afib that is chronic (long time) we don’t use cardioversion or drugs to convert (Diltiazem or Procainamide). All we are interested in is controlling the rate so your symptoms disappear, so we use Metoprolol or some other Beta blocker. Conversely, if your Afib is acute (new onset) and less than 3 hours, we will use cardioversion (low level shock) especially if the patient is unstable. An unstable patient is one with chest pain and/or any vital sign that is severely out of the normal range (i.e. Blood pressure 90/50 too low) and cardioversion should be considered as first line of defense. The shock itself is not scary as we use conscious sedation to knock you out, but not to put you to sleep, just so you don’t remember the shock. If the doctor deems it to be too risky to use cardioversion then they may opt for conversion using drugs, then Diltiazem or Procainamide may be used. Using drugs to convert can take up to 1 hour, so it is not recommended for unstable patients only patients that are deemed stable. A stable patient is classified as someone that has normal vital signs and is not in any distress.
Atrial fibrillation can be caused by a heart attack or M.I. (myocardial infarction) that occurs over and around the SA node. It could even be caused by bad wiring by genetics as in Wolfe Parkinson white syndrome. It is a re-entry rhythm meaning it goes around and around and re-enters the AV node over and over again causing the ventricles to respond over and over, even if the ventricles don’t feel like responding. The AV node stops most of the signals from the SA node hence why the rhythm is irregular. Atrial fibrillation is dangerous due to the fact that the top part of the heart known as the Atria quivers like a bowl full of jelly. Since the Atria doesn’t squeeze the blood into the ventricles like they should, the quivering causes a whirlpool in the heart and this whirlpool is where blood clots can form. Any stagnant blood will clot and Afib causes stagnant blood. That is why if you have AFib for a long time your doctor will put you on “blood thinners” like Coumadin (warfarin) to prevent these clots from entering your blood stream and wrecking more havoc. If the doctors tried to cardiovert a person in chronic Afib the blood clots could be released into the blood stream causing a stroke or embolism.