L46 Cardiomyopathy Flashcards
What is a cardiomyopathy?
Primary abnormality of the myocardium in which the dysfunction is not attributable to pressure or volume overload.
What are the three types of cardiomyopathy?
- Dilated
- Hypertrophic
- Restrictive
What is the most common type of cardiomyopathy?
Dilated
What is caused by dilated cardiomyopathy?
Contractile (systolic) dysfunction; four chamber dilation, heart is often 2-3x normal weight
Describe the gross changes to the heart in dilated cardiomyopathy.
Lots of dilation, some hypertrophy
What are the non-genetic causes of dilated cardiomyopathy?
- Myocarditis
- Peripartum
- Toxic (alcohol)
- Idiopathic
- Iron overload
- Stress-provoked
___% of dilated cardiomyopathy is genetic.
25-50
Broadly, describe the genetic causes of dilated cardiomyopathy.
Various proteins are mutated leading to defects in force generation/transmission and/or myocyte signaling.
What is the phenotype of dilated cardiomyopathy?
Hypertrophy, dilation, fibrosis, intracardiac thrombi
What are the clinical outcomes of both dilated and hypertrophic cardiomyopathy?
Heart failure, sudden death, atrial fibrillation, stroke
Discuss the hypertrophic sarcomere changes that occur in response to volume overload.
New sarcomeres are added in series (increases myocyte length and cavity volume)
Discuss the hypertrophic sarcomere changes that occur in response to pressure overload.
New sarcomeres are added in parallel, increasing myocyte thickness, decreases cavity volume
What happens as a result of dilated cardiomyopathy?
Progressive systolic CHF –> heart failure symptoms, arrhythmias, and mural thrombi with embolic complications
How is dilated cardiomyopathy treated?
Medical therapy and heart transplantation
What causes hypertrophic cardiomyopathy (HOCM)?
Marked left ventricular myocardial hypertrophy
Describe the gross changes to the heart in hypertrophic cardiomyopathy.
The septum hypertrophies more than the free wall, creating a banana-shaped left ventricular cavity; this causes abnormal diastolic filling.
What can happen as a result of hypertrophic cardiomyopathy?
LV outflow obstruction (septal hypertrophy, anterior mitral valve leaflet contacts ventricular septum)
Describe the histology of hypertrophic cardiomyopathy.
Hypertrophied myocytes, disorganized myocytes, interstitial fibrosis
What are the primary causes of hypertrophic cardiomyopathy?
Genetic (autosomal dominant)
What happens when there are mutations in genes that encode sarcomeres (regarding hypertrophic cardiomyopathy)?
Increased myofilament function and myocyte hypercontractility
What are the most frequent mutations seen in hypertrophic cardiomyopathy?
Beta-myosin heavy chain (most common), also myosin binding protein C and troponin T
What are the clinical manifestations of hypertrophic cardiomyopathy?
Diastolic heart failure, exertional dyspnea, harsh systolic ejection murmur, anginal pain, intractable heart failure, arrhythmias
What is the classic story related to hypertrophic cardiomyopathy?
Sudden death in young athletes
How is hypertrophic cardiomyopathy treated?
Medical therapy that enhances ventricular relaxation, surgical excision of muscle
What causes restrictive cardiomyopathy?
Primary decrease in ventricular compliance leading to impeded LV filling during diastole (systolic function is preserved)
Describe the gross changes to the heart in restrictive cardiomyopathy.
The left atrium is dilated with a firm stiff myocardium, limiting the expansion ability; the cavity itself is normal
What are some of the causes of restrictive cardiomyopathy?
- Idiopathic
- Radiation fibrosis
- Amyloidosis
- Sarcoidosis
- Inborn errors of metabolism
- Endocardial fibroelastosis (thickening of endocardium)
- Loeffler endomyocarditis (thickening of endocardium + eosinophilic infiltrate)
- Iron overload
What are amyloids?
Misfolded proteins deposited in extracellular spaces that cause tissue damage
What are common features of amyloid deposits?
Beta-pleated sheet configuration, congo red staining in tissue, apple-green under polarized light
What is one example of a common amyloid?
Transthyretin
What causes the signs and symptoms of restrictive cardiomyopathy?
Reduced myocardial compliance and SV
What is myocarditis?
Inflammatory process targeting the myocardium, resulting in myocyte injur
What are the infectious causes of myocarditis?
- Viruses
- Bacteria
- Parasites
What is the most common cause of myocarditis?
Enteroviruses
What is a common type of enterovirus that causes myocarditis?
Coxsakie A and B
What are 2 other viruses that can cause myocarditis?
Cytomegalovirus and HIV
What is the pathogenesis of myocarditis caused by viruses?
Directly cause cell death or immune response directed against virus results in myocyte injury
What are 2 bacteria that cause myocarditis?
Diptheria and B. burgdorferi (Lyme disease)
What are 3 parasites that cause myocarditis?
- Trypanasoma cruzi
- Trichinosis
- Toxoplasmosis
What is caused by Trypanasoma cruzi and where is it found?
Chaga’s disease; endemic in South America
What are some non-infectious causes of myocarditis?
- Immune-mediated (hypersensitivity reactions, RF, SLE)
2. Giant cell myocarditis
Describe the histological findings of myocarditis that is lymphocytic, hypersensitivity, giant cell, and Chaga’s.
Lymphocytic: lots of lymphocytes
Hypersensitivity: + eosinophils
Giant cell: giant cells
Chagas: parasite
What are the clinical manifestations of myocarditis?
- Can be asymptomatic, non-specific symptoms
- Acute CHF
- Arrhythmias
- Progression to dilated cardiomyopathy
What are the two layers of the pericardium?
- Visceral (touches endocardium)
2. Parietal
What types of fluid can be seen in a pericardial effusion?
Clear yellow serous fluid, blood, pus
What is the classic finding of a pericardial effusion on CXR?
Globular enlargement
What can happen with rapidly developing or large pericardial effusions?
Atria and vena cavae are compressed, followed by the ventricles; this restricts cardiac filling. It can end in cardiac tamponade.
What is pericarditis?
Inflammation of the pericardium, usually secondary to a cardiac, thoracic, or systemic process
What can cause pericarditis?
- Infections (any type of microorganism)
- Immune-mediated (RF, SLE, hypersensitivity, uremia, post-myocardial infarction/Dressler syndrome)
- Neoplasia
- Trauma
- Radiation
What is Dressler syndrome?
Complication of an MI that causes an autoimmune phenomenon
What are the 4 types of pericarditis?
- Fibrinous
- Suppurative (Fibrinopurulent)
- Hemorrhagic
- Caseous
Describe the appearance of fibrinous pericarditis.
Pericardial surface is irregular and shaggy
What can cause fibrinous pericarditis?
Acute viral pericarditis, uremia, and acute RF
What is a physical exam finding of fibrinous pericarditis?
Pericardial friction rub
What causes suppurative pericarditis?
Acute bacterial infection (can be extension or seeding)
Describe the appearance of suppurative pericarditis.
Pus, ya’ll
What can cause hemorrhagic pericarditis?
TB, malignancy
What can cause caseous pericarditis?
TB
How does pericarditis present (labs and symptoms)?
- Asymptomatic
- Chest pain (gets worse lying down)
- Systemic complaints
- Friction rub
- EKG changes (diffuse ST elevation)
Describe the healing seen in pericarditis.
Focal plaque-like thickening and mild adhesions, can lead to constrictive pericarditis in which the pericardial space is obliterated, the heart is surrounded by a dense scare, and diastolic expansion is limited (reduced CO)
How is constrictive pericarditis treated?
Pericardiectomy
When is cardiac transplantation indicated?
Intractable heart failure (dilated and ischemic cardiomyopathy)
What are complications of cardiac transplantation?
- Acute or chronic rejection
- Infection
- Post-transplant lymphoma (Epstein-Barr virus)
- Allograft arteriopathy (fibromuscular intimal hyperplasia)
What part of the heart is biopsied?
Septum
