Myocardium diseases Flashcards
LVEF in dilated cardiomyopathy
<40%
LVEF in hypertrophic cardiomyopathy
50-80%
LVEF in restrictive cardiomyopathy
45-90%
Mechanism of HF in dilated cardiomyopathy
Impairment of contractility –> systolic dysfunction
Mechanism of HF in hypertrophic cardiomyopathy
Impairment of compliance –> diastolic dysfunction
Mechanism of HF in restrictive cardiomyopathy
Impairment of compliance –> diastolic dysfunction
Causes of dilated cardiomyopathy
Genetic
Alcohol
Peripartum
Myocarditis
Hemochromatosis
Chronic anemia
Doxorubicin (Adriamycin) toxicity
Sarcoidosis
Idiopathic
Causes of hypertrophic cardiomyopathy
Genetic
Friedreich ataxia
Storage disease
Infants of diabetic mother
Causes of restrictive cardiomyopathy
Amyloidosis
Radiation-induced fibrosis
Idiopathic
Indirect myocardial dysfunctions in dilated cardiomyopathy
IHD
Valvular heart disease
HTN heart disease
Congenital heart disease
Indirect myocardial dysfunctions in hypertrophic cardiomyopathy
HTN heart disease
Aortic stenosis
Indirect myocardial dysfunction in restrictive cardiomyopathy
Pericardial constriction
Characterized by ventricular chamber enlargement with impaired systolic contractile function.
Dilated cardiomyopathy
Genetic mutations that cause dilated cardiomyopathy
Mutations in proteins for sarcolemma, cytoskeleton, and nuclear envelope (laminin)
Mutation in TTN –> encodes titin
Inheritance of genetic dilated cardiomyopathy
Autosomal dominant
Takotsubo cardiomyopathy falls under what cardiomyopathy type?
Dilated
Causes of excess catecholamine production that can result in dilated cardiomyopathy
Pheochromocytoma
Cocaine or dopamine use
Intense autonomic stimulation
Emotional duress –> Takotsubo
Complications of dilated cardiomyopathy
Secondary mitral regurgitation
Abnormal cardiac rhythms
Embolism from intracardiac thrombi
Microscopy of heart in dilated cardiomyopathy
Hypertrophied with enlarged nuclei
Interstitial and endocardial fibrosis of a variable degree
Abnormally thickened ventricular wall with abnormal diastolic relaxation. Due to sarcomeric alterations, defective energy transfer, and/or exaggerated response of myocardial fibroblasts.
Hypertrophic cardiomyopathy
Inheritance of genetic causes of hypertrophic cardiomyopathy
Autosomal dominant with variable penetrance
Genetic mutations associated with hypertrophic cardiomyopathy
Sarcomeric proteins –> missense
Beta-myosin heavy chain
Cardiac TnT
Alpha-tropomyosin
Myosin binding protein C (MYBP-C)
Affect of sarcomeric alterations in hypertrophic cardiomyopathy
Abnormal cardiac contraction causing a secondary compensatory hypertrophy
Affect of myofiber disarray in HOCM without outflow obstruction
Ventricular arrhythmias
Myocyte hypertrophy
Complications of ventricular arrhythmias in HOCM without outflow obstruction
Syncope
Sudden cardiac death
Complications of myocyte hypertrophy in HOCM without outflow obstruction
Ventricular hypertrophy
Increased stiffness and impaired relaxation –> diastolic dysfunction
Elevated LVEDP
Dyspnea, exertional
Cause of outflow obstruction of blood flow to aorta in HOCM with obstruction
Abnormal motional of anterior mitral valve leaflet to cover the LV outflow tract
Also results in mitral regurgitation
Harsh systolic ejection murmur heard best at the L lower sternal border. Intensity increases with decreased preload and decreases with increased preload and increased afterload.
HOCM
Major clinical complications in hypertrophic cardiomyopathy (HOCM)
A fib
Mural thrombi embolization
Intractable cardiac failure
Ventricular arrhythmias
Sudden death
One of the most common causes of sudden, otherwise unexplained, death in young athletes
HOCM
Transthoracic echo findings in hypertrophic cardiomyopathy (HOCM)
Reduced LV cavity size
LA enlargement
Normal or increased LVEF
Overall increase in LV mass
Asymmetric LV wall thickness
Microscopy of heart in hypertrophic cardiomyopathy
Massive myocyte hypertrophy
Asymmetric septal hypertrophy –> septum to free wall ratio of 3:1
Myofiber disarray –> irregular myofibers with surrounding collagen
Interstitial and replacement fibrosis
Abnormally stiffened myocardium, because of fibrosis or infiltrative process, leading to impaired diastolic relaxation. Causing a primary decrease in ventricular compliance resulting in impaired ventricle filling.
Restrictive cardiomyopathy
Peripheral eosinophilia and eosinophilic infiltrates in multiple organs, including heart, release major basic protein. Causes endomyocardial necrosis in the heart. May develop in restrictive cardiomyopathy.
Loeffler endomyocarditis
Fibrosis of the ventricular endocardium and subendocardium that primary affects children and young adults in Africa and other tropical areas. May result in restrictive cardiomyopathy.
Endomyocardial fibrosis
Fibroelastic thickening of the LV endocardium, most comment in first 2 years of life. A complication of mumps exposure in utero. May develop into restrictive cardiomyopathy
Endocardial fibroelastosis
Most common recognized cause of restrictive cardiomyopathy in non-tropical countries
Cardiac amyloidosis
Small, semi-translucent nodules (resembling drips of wax) may be seen on the atrial endocardial surfaces.
Cardiac amyloidosis
Stain for amyloid fibrils that causes them to appear apple-green under polarized light
Congo red stain
Effect of rigid myocardium in restrictive cardiomyopathy
Increased diastolic ventricular pressure –> venous congestion
Decreased ventricle filling –> decreased CO
Major viral causes of myocarditis
Coxsackie virus B
Adenovirus
Parvovirus B19
HIV
HHV-6
Major parasitic causes of myocarditis
Trypanosoma cruzi –> Chagas
Toxoplasma gondii
Major bacterial causes of myocarditis
Borrelia burgdoferi
Mycoplasma pneumoniae
Major toxins causing myocarditis
CO poisoning
Black widow venom
Drugs that can cause myocarditis
Doxorubicin
Cocaine
Autoimmune disease that can cause myocarditis
SLE
Kawasaki disease
Complications of myocarditis
Sudden death
Arrhythmias
Heart block
DCM
Mural thrombi with embolization
Microscopy finding in myocarditis caused by Chagas disease
Myofiber distended with trypanosomes
Microscopy findings in myocarditis caused by toxoplasma
Toxoplasma pseudocyst in myocardial cell that contains bradyzoites