Cardiomyopathies: Pathology review

00:00 / 00:00



Cardiomyopathies: Pathology review

Cardiovascular system

Cardiac tumors

Cardiac tumors




Cardiomyopathies: Pathology review

USMLE® Step 1 questions

0 / 3 complete


USMLE® Step 1 style questions USMLE

of complete

A 68-year-old woman comes to the clinic complaining of dyspnea on exertion, fatigue, and chest pain. She also states that she has to use 3 pillows at night when she sleeps. Past medical history includes carcinoma of the breast, for which she received surgery and adjuvant radiation therapy but no chemotherapy. Temperature is 37.2°C (98.9°F), pulse is 80/min, respirations are 20/min, and blood pressure is 100/68. Physical exam shows jugular venous distension and bilateral leg edema. Cardiac auscultation shows S3 and S4 heart sounds. Electrocardiogram (ECG) shows low amplitude signals. Which of the following is the most likely cause of this patient’s disease?  


Aman is a 60 year old male who came into the clinic with shortness of breath and lower limb edema for the past 3 months. He has a history of hypertension, hyperlipidemia and chronic alcohol use. On auscultation, an additional S3 sound is heard. An echocardiogram is performed, which shows dilated ventricular chambers and a reduced ejection fraction. Alexandra is a 23 year old professional volleyball player who came to the clinic after multiple episodes of “passing out” during her games. At first, she presumed it was due to dehydration, but she is now concerned. She has a family history of sudden cardiac death in multiple relatives. An echocardiogram shows asymmetric hypertrophy of the interventricular septum, and a normal ejection fraction.

Both Aman and Alexandra have cardiomyopathies. From outside to inside, the heart is made of the epicardium, myocardium, and endocardium. Diseases that affect the myocardium are called cardiomyopathies. The three main subtypes are dilated, hypertrophic and restrictive cardiomyopathy.

Let’s start with dilated cardiomyopathy, which is the most common one, accounting for almost 90% of all cases. Now, In dilated cardiomyopathy the ventricular walls become thin and weak. As a consequence, the ventricular chambers dilate. Because the ventricular wall is thinner, muscle contraction is weaker and the heart can’t pump blood efficiently throughout the body. So we have a systolic dysfunction with normal diastole.

Okay, when it comes to the etiology of dilated cardiomyopathy, the large majority of cases are idiopathic, meaning the cause can’t be identified. However, there are many secondary causes that must be excluded first. Examples include toxins like chronic alcohol or cocaine abuse, nutritional deficiencies like thiamine deficiency, also called beri-beri, or selenium deficiency. Another cause is myocarditis, which is inflammation of the heart muscle, usually caused by viruses like Coxsackie B, but can also be related to autoimmune diseases like lupus. Hemochromatosis is a disorder of iron overload in which excessive iron can be deposited in many organ sites, including the cardiac muscle. Too much intracellular iron can act as a toxic free radical, resulting in cellular damage.


  1. "Pathophysiology of Heart Disease" Wolters Kluwer Health (2015)
  2. "Rapid Review Pathology" Elsevier (2018)
  3. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  4. "Dilated cardiomyopathy" Lancet (2017)
  5. "2011 ACCF/AHA guideline for the diagnosis and treatment of hypertrophic cardiomyopathy: executive summary: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines" J Thorac Cardiovasc Surg (2011)
  6. "Differential diagnosis of restrictive cardiomyopathy and constrictive pericarditis" Heart (2001)

Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.