Microangiopathic Hemolytic Anemia: Etiology

by Carlo Raj, MD

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    00:01 What if you’re inside your blood vessel and you’re an RBC and you end up hitting an obstructive and your head was chopped off? That’s not very nice.

    00:10 Welcome to micro- and macroangiopathic hemolytic anemia, and what we’re going to do with our head being chopped off with an RBC, referring to a schistocyte, hence you should wear helmets.

    00:22 Helmet cells.

    00:23 Let’s continue.

    00:24 So what we have here is inside my blood vessel, and we’ll begin by looking at micro and macroangiopathic.

    00:30 It’s a mechanical damage.

    00:32 Meaning to say that this is not a problem within the RBC, so therefore you would then refer to this being an extrinsic problem.

    00:40 And by extrinsic, we mean that the issue is taking place outside the RBC.

    00:44 Where are you? In your blood vessel.

    00:47 So what is the difference between micro- and macroangiopathic? All it is quite simple.

    00:52 If it’s macroangiopathic, then it is your common, common diseases in our society secondary to hypertension or diabetes mellitus, in which, well, the larger blood vessels are undergoing obstruction or hyaline arteriolosclerosis, and there’s every possibility that an RBC might then get hurt and form a schistocyte.

    01:14 Or you can have little blood vessels that are undergoing thrombotic diseases where our focus shall be.

    01:21 So our focus, ladies and gentlemen, in this lecture series, will be in the format of microangiopathic.

    01:27 However, keep in mind, if it’s macroangiopathic type of hemolytic anemia, it only means that your patient has a systemic type of disease, either hypertension or diabetes mellitus, resulting in the same type of consequence where the RBCs are extrinsically becoming hurt.

    01:46 And the next question that you want to ask yourself is, well, would this be primarily a intravascular or extravascular type of disorder? It will primarily be an intravascular disorder, which means your patient is going to show up with hemoglobinuria.

    02:01 Now, you can have mechanical or stenotic heart valves known as Waring Blender effect, in which for example, if you have an RBC passing across, let's say, a stenotic mitral valve or the patient was experiencing something like an Austin Flint murmur, which is a very, very severe form of aortic regurgitation.

    02:23 And you needed to replace that valve , and when you do so, you replaced it with a mechanical structure in which now it causes increased resistance or destruction to your RBC.

    02:34 Are we clear? Forming some type of micro and macroangiopathic hemolytic anemia.

    02:39 Ultimately, this RBC in which it has been sheared will form a schistocyte, you may also call this a helmet cell.

    02:49 The other one that we just referred to here is in terms of your malignant hypertension in which there’s enough pressure within your blood vessel here once again causing damage in RBC, resulting in a type of anemia.

    03:01 Keep this in mind because you have systemic diseases in which ultimately you’ll have blood vessels that are then compromised and when they are, it’s only the RBCs that are going to become hurt.

    03:11 So therefore, this angiopathic hemolytic anemia is actually a pretty big deal because you would see it in many conditions.

    03:20 Continuing, so let’s say that you’re in a little blood vessel and in the little blood vessel, you are then forming a thrombus.

    03:28 Why? Well, that thrombus formation is not homeostatic in terms of it wasn’t dissolved quickly and you have excess thrombi in your microvasculature.

    03:41 Well, same consequence.

    03:43 We talked about hypertension maybe or mechanical type of issues with heart valves.

    03:48 But then if you have a little thrombi in which it offers resistance to an RBC to the point it’s actually causing extrinsic damage to the RBC, here once again, the RBC will get sheared.

    03:58 It will look like a schistocyte.

    03:59 You call this a helmet cell.

    04:02 The three conditions that often are associated with thrombotic disorders include DIC, TTP, and HUS.

    04:12 A couple things real quick, if it’s DIC, it’s devastating.

    04:15 If this patient, when you see this patient, with DIC rolling into your room, then this is not good because this is as close to death as you shall see with the patient.

    04:27 There’s bleeding that’s taking place in every single orifice.

    04:30 Every single platelet has been consumed.

    04:33 Every single coagulation factor has been consumed.

    04:37 So therefore you’re going to find an increase in PT, PTT, and bleeding time.

    04:41 You’ll find a decrease in platelet count.

    04:44 And so therefore, you have all this thrombi up and down the body, guaranteed, your patient with DIC is going to have what kind of anemia? It will be a normocytic hemolytic type of microangiopathic hemolytic anemia.

    04:59 Clear? Now, the triggers for DIC are quite unique.

    05:04 Maybe, maybe it was a acute myelogenous leukemia type III.

    05:10 How many letters in DIC? One, two, three.

    05:13 M3.

    05:15 Maybe it was amniotic fluid emboli.

    05:18 Maybe it was sepsis.

    05:19 Sepsis is a big one.

    05:21 Maybe it was some type of venom, maybe perhaps some snake venom.

    05:26 So the origin or the true etiology of DIC, it’s a little peculiar.

    05:31 But when it takes place and you have that trigger, oh, it’s really dangerous.

    05:35 Really dangerous, close to death, if not, already.

    About the Lecture

    The lecture Microangiopathic Hemolytic Anemia: Etiology by Carlo Raj, MD is from the course Hemolytic Anemia – Red Blood Cell Pathology (RBC).

    Author of lecture Microangiopathic Hemolytic Anemia: Etiology

     Carlo Raj, MD

    Carlo Raj, MD

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