84,589views
00:00 / 00:00
de completadas
de completadas
2024
2023
2022
2021
hypertrophic cardiomyopathy p. 315
hypertrophic cardiomyopathy p. 315
hypertrophic cardiomyopathy p. 315
hypertrophic cardiomyopathy p. 315
Pompe disease p. 85
systolic murmur in p. 295
Cardiomyopathy means “heart muscle disease,” so cardiomyopathy is a broad term used to describe a variety of issues that result from disease of the myocardium, or heart muscle.
When cardiomyopathy develops as a way to compensate for some other underlying disease, like hypertension or valve diseases, it’s called secondary cardiomyopathy; when it develops all by itself, it’s called primary cardiomyopathy.
Now, hypertrophic cardiomyopathy is when the walls get thick, heavy, and hypercontractile; essentially, the muscles grow a lot larger because new sarcomeres are being added parallel to existing ones.
Usually, the left ventricle is affected, and in most cases, this muscle growth is asymmetrical, meaning that the interventricular septum grows larger relative to the free wall.
These larger muscles do two things: the walls take up more room, so less blood is able to fill the ventricle; and they become more stiff and less compliant, so they can’t stretch out as much, again, leading to less filling. When the ventricles don’t fill as much, they don’t pump out as much blood, and so stroke volume goes down. Thus, the heart can fail to pump enough blood to the body; this is called heart failure. Because this is due to a dysfunction in filling, which happens during diastole, this is a type of diastolic heart failure.
In some patients, the muscle growth of the interventricular septum essentially gets in the way of the left ventricular outflow tract during systole, or ventricular contraction. This increases blood velocity through the smaller opening, and pulls the anterior leaflet of the mitral valve toward the septum. This is called the venturi effect, which further obstructs the left ventricular outflow tract. For this reason, hypertrophic cardiomyopathy is sometimes called hypertrophic obstructive cardiomyopathy.
An obstructed left ventricular outflow tract means blood is forced through a tiny opening, which tends to cause a crescendo-decrescendo murmur. A crescendo-decrescendo murmur gets louder as blood first rushes out, and then softer; this is very similar to the murmur in aortic valve stenosis.
Copyright © 2024 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.