Can AFib make you pass out?
The answer to that is yes, I’ve seen three different ways in which atrial fibrillation can make a patient pass out. The first one is if your AFib is going too fast, your heart rate can be going 170-180, and it can cause poor circulation to your brain and cause you to pass out. Now typically this is the least common way that I have seen atrial fibrillation make you pass out. Although people feel terrible when their heart’s going extremely fast 170-180 close to 200, they feel short of breath, dizzy, chest pain but don’t frequently pass out. Most of the time that I’ve seen somebody passed out, purely because the heart is going too fast, those are typically older patients who also have existing other heart conditions like maybe they have a bad heart valve or they’ve had blockages in the arteries of their neck called carotid artery disease. In those type of patients it is possible that they could pass out purely because it was going too fast.
Now more commonly is a reason why people pass out from atrial fibrillation because their heart rate is going to slow. Now you may say “well atrial fibrillation makes your heart go fast how can you make how can it also go too slow?” Well, there’s a couple of ways in which it can go slow, which is the second reason, which is that the ventricle could also pause. Now atrial fibrillation, the upper chambers of your heart are going very fast, over 300 to 600 beats per minute but the pulse comes from the ventricle and ventricle sometimes can slow down or even pause, even despite the fact that you are in atrial fibrillation. I tell my patients that their heart needs to catch their breath for a second from being constantly sent signals from the atrial fibrillation. So the heart rate may pause, or the pulse may pause for 3 to 5 seconds, and that can certainly make people get dizzy, lightheaded or even pass out.
Now the third way in which you can pass out is not because of atrial fibrillation, but because atrial fibrillation stops, this is called a conversion pause. Episodes of afib can come and go, but when the afib stops your natural heartbeat can take several seconds to start kicking in. It’s like your natural heartbeat so tired of being atrial fibrillation. It takes several seconds to start kicking in again and start having a natural heartbeat, which can lead to pauses that can last three four or five long seconds. That is the most common reason that I have seen people passing out from atrial fibrillation. These actual pauses that happen are when the afib stops and your natural heartbeat is too slow to kick back in again. So what can you do for these times that you pass out because your heart rate is too slow?
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