Tachycardia: Atrial Fibrillation: Pathogenesis

00:01 Continue our discussion of dysrhythmia and conduction system diseases.

00:06 Remember once again with arrhythmias, we'll do two different categories or two major etiologic backgrounds.

00:14 One would be conduction system issues, the other one was vascular.

00:18 So for under conduction disease, we have looked at bradyarrhythmias.

00:23 Our topic now will take us into tachyarrhythmias.

00:27 And with tachyarrhythmias, we will focus upon SVT's at first, supraventricular tachycardias above the ventricles.

00:35 And we will then divide this into part one and part two.

00:38 In part one, we'll take a look at atrial fibrillation and atrial flutter.

00:42 Let's begin.

00:44 Now with AFib, exceedingly common rhythm especially in elder patients.

00:51 So as we get older - well, a number of things start slowing down.

00:55 In this case, things start speeding up.

00:58 And by that, I mean that the normal physiology as we get older unfortunately starts losing its effect, maybe the kidneys will start decreasing GFR.

01:08 You end up developing or end up accumulating more creatinine.

01:11 As we get older, our ability to protect our cell membrane from free radicals starts diminishing.

01:17 The ability to have proper conduction, remember for your entire life, when you had this inherent pacemaker in the heart known as the SA node, it continues - I mean you would expect at some point when you get older that perhaps, it's not as efficient and effective as it once was.

01:34 And so in elderly people, well, there's every possibility that atrial fibrillation might be taking place.

01:40 And anytime there's an AFib, what are you worried about? Well, you're worried about that increased turbulence within the atrium and so therefore may result in stasis.

01:51 And with that stasis, you're worried about Virchow's triad.

01:56 One of the components of Virchow's triad referring to formation of a clot is what you are truly worried about.

02:05 With that clot formation, of all the sequelae of your clot formation and the embolization of the thrombus moving forward through the left atrium specifically.

02:15 Which one are you worried about the most? Through the carotid artery and you're worried about a cerebral vascular accident such as a stroke.

02:23 Now keep in mind that you could have an embolization and might end up in the SMA; superior mesenteric artery, resulting in ischemic and bowel disease that is also an emergency.

02:35 Isn't it? Or it may result in renal artery resulting in renal artery stenosis.

02:40 All that you're doing is following the pathway of a clot or thrombus from the left atrium and distally into whatever organ system.

02:50 So what do you wanna give to this patient prophylactically? A blood thinner such as warfarin.