Ischemic Heart Disease: Clinical Manifestations and Pathophysiology

00:00 So other symptoms of ischemic heart disease, and basically, this has to do with a dysfunctional heart.

00:08 So if the heart is not squeezing appropriately.

00:10 It's got systolic dysfunction because of ischemia, you're going to have low flow and you will have symptoms of dyspnea.

00:14 you're going to have low flow and you will have symptoms of dyspnea.

00:17 So you will be short of breath.

00:19 You may have abnormal conduction through the heart.

00:22 That will give rise to palpitations.

00:24 You may have inadequate perfusion of the rest of the vasculature.

00:29 So you get dizziness. You can even have syncope.

00:33 There is a sense of restlessness and anxiety.

00:35 A feeling of doom and gloom, particularly, if you're having an acute myocardial infarct.

00:40 This is probably due to activation of a neurohumoral axis, but you actually feel like, "I'm going to die." Sometimes, you're right.

00:50 And then you can have other autonomic symptoms.

00:53 So diaphoresis, sweating, nausea and vomiting.

00:56 Those are typically associated with posterior wall ischemia, so that we are activating the vagal nerve. You can also have syncope.

01:04 If you activate the vagal nerve enough, you can go into bradycardia.

01:07 Alright. So some other interesting pathophysiology of atherosclerotic ischemic heart disease.

01:14 So this is just showing you a progression over years of an atherosclerotic plaque.

01:20 On the left-hand side is a normal coronary artery with a nice normal media and no intimal hyperplasia.

01:28 And you can grow that atherosclerotic plaque for a long time.

01:31 Up to that point shown there on the fourth circle where the luminal diameter hasn't changed.

01:40 It's the same blood flow through that vessel, even though I got more and more and more atherosclerotic plaque.

01:46 That's because there's outward remodeling of the vessel.

01:50 So even though I'm getting a thicker intima and the wall is getting thicker locally, the vessel is dilating and adapting. That's the Glagov phenomenon.

01:59 Now, there's an upper limit to this adaptation, and it occurs kind of right around when you have 70% stenosis.

02:07 At that point, the atherosclerotic plaque wins, and the ability of the vessel wall to expand is inadequate to keep up.

02:14 So now, with that critical stenosis, the 70% stenosis, you could potentially start becoming symptomatic.

02:21 And actually, if the atherosclerotic plaque progresses, you can develop now, anginal symptoms, even without an infarct, even at rest.

02:30 So the last one on the right is just showing you a very small pinpoint lumen, and that may be limiting even at rest in terms of providing adequate nutrition and oxygenation to the heart muscle.

02:43 So let's think about this looking in a slightly different way.

02:48 We're going to look at the lumen of a coronary artery, and over the course of decades as indicated at the top, you can have a progressive evolution of atherosclerosis.

03:02 Atherosclerosis has a very long timeline.

03:05 It doesn't in most people occur within weeks or months. It takes years and decades.

03:12 So you can have up to six decades before it begins to be a significant occlusion.

03:18 At that 70% stenosis, that's critical.

03:21 That will give - that critical stenosis will give you stable angina.

03:25 So running around the block pretty reliably gives you chest pain.

03:29 And then you can have plaque rupture.

03:32 And within minutes, you go from whatever degree of occlusion you had, to now, a completely occluded vessel.

03:39 Manifesting as an acute coronary syndrome, unstable angina and remember that the majority of such plaque ruptures occur on vessels that are less than critically stenotic.

03:53 So that are 20%, 30%, 40%, 50% chronically stenotic, alright? With that thrombus formation and complete occlusion of a vessel, then you can have a myocardial infarct.