IUHS Student-2-Student USMLE Step 1 Recall
Cardiovascular
Cardiomyopathies/Myocarditis
Dilated
Cardiomyopathy
left and/or right ventricular systolic pump function is impaired, leading to progressive cardiac enlargement, a process callled remodeling, and often, but not invariably, producing symptoms of congestive heart failure...
there is, however, no close correlation between the degree of contractile dysfunction and the severity of symptoms...
mural thrombi may be present, particulary in the left ventricular apex....
histologic examination reveals extensive areas of interstitial and perivascular fibrosis...
myocyte necrosis and cellular infiltration may be present but are not prominent...
although no cause is apparent in many cases, dilated cardiomyopathy is probably the end result of myocardial damage produced by a variety of toxic, metabolic, or infectious agents...
dialated cardiomyopathy may be the late sequel of acute viral myocarditis, possibly mediated through an immunologic mechanism...
right ventricular dysplasia is a unique cardiomyopathy marked by progressive replacement of the right ventricular wall with adipose tissue...often associated with ventricular arrhythmias...
Hypertrophic Cardiomyopathy
hypertrophic
cardiomyopathy (HCM) is characterized by left
ventricular hypertrophy, typically of a nondilated chamber, without obvious
cause such as hypertension of aortic stenosis...
it is found in about 1 in 500 of the general population...
two features of HCM have attracted the greatest attention...(1) heterogeneous left ventricular hypertrophy, often with preferential hypertrophy of the interventricular septum resulting in asymmetric septal hypertrophy; and (2) a dynamic left ventricular outflow tract pressure gradient, related to a narrowing of the subaoritc area as a consequence of the midsystolic apposition of the anterior mitral valve leaflet against the hypertrophied septum, systolic anterior motion (SAM) of the mitral valve...
myofiber disarray is the key feature of Hypertrophic Cardiomyopathy...
Restrictive Cardiomyopathy
the hallmark of the restrictive cardiomyopathies is abnormal diastolic function; the ventricular walls are excessively rigid and impede ventricular filling...
myocardial fibrosis, hypertrophy, or infiltration due to a variety of causes is usually responsible...
the infiltrative diseases, which represent important causes for secondary restrictive cardiomyopathy, may also show some impairement of systolic function...
myocardial involvement with amyloid is a common cause of secondary restricitve cardiomyopathy, although restriction is also seen in hemochromatosis, glycogen deposition, endomyocardial fibrosis, sarcoidosis, Fabry's disease, the eosinophilias, and scleroderma; in the transplanted heart and following medistinal radiation...
Eosinophilic Endomyocardial Disease
also called Loeffler's endocarditis and fibroplastic endocarditis, this disease appears to be a subcategory for the hypereosinophilic syndrome in which the heart is predominantly involved, with cardiac damage the apparent result of the toxic effects of eosinophilic proteins...
typically, the endocardium of either or both ventricles, thereby compromising the size of the ventricular cavity and serving as a source of pulmonary and systemic emboli...
hepatosplenomegaly and localized eosinophilic infiltration of other organs are usually present....
management includes diuretics, afterload reducing agents, and anticoagulation...
the use of glucocorticoids and cytotoxic drugs (hydroxyurea in particular) appears to have improved survival substantially...surgical treatment, as for endomyocardial fibrosis, may be helpful in selected patients...
Myocarditides
myocarditis, cardiac inflammation, is most commonly the result of an infectious process...myocarditis may also result from a hypersensitivity to drugs or may be caused by radiation, chemicals, or physical agents...
in an unknown number of cases, acute myocarditis progresses to chronic dilated cardiomyopathy...while almost every infectious agent is capable of producing myocarditis, clinically significant acute myocarditis in the US is caused most commonly by viruses, especially coxsackievirus B...
the clinical manifestations range from an asymptomatic state, with the presence of myocarditis inferred only by the finding of transient electrocardiographic ST-T wave abnormalities, to a fulminant condition with arrhythmias, heart failure, and death...
Chagas'
Disease
chagas' disease, caused by the protozoan Trypanosoma cruzi and transmitted by an insect vector, produces an extensive myocarditis that typically becomes evident years after the initial infection...
it is one of the most common causes of heart disease encountered in central and south america; in rural endemic areas 20-75% of the population may be affected...
the chronic form is characterized by dilatation of several cardiac chambers, fibrosis and thinning of the ventricular wall, aneurysm formation (especially at the left ventricular apex), and mural thrombi...
Giant Cell Myocarditis
characterized
by the presence of multinucleated giant cells
in the myocardium...
it usually causes rapidly fatal congestive heart failure and arrhythmia in young adults to middle-aged adults...
at necropsy, the distinctive features include cardiac enlargement, ventricular thrombi, grossly visible serpiginous areas of myocardial necrosis in both ventricles, and microscopic evidence of giant cell myocarditis remains obscure, although it occurs in association with thymoma, SLE, and thyrotoxicosis....
Pericarditis
pericardial inflammation is usually secondary to a variety of cardiac diseases, thoracic or systemic disorders, or metastases from neoplasms arising in remote sites...
primary pericarditis is unusual and almost always of viral origin...
most evoke an acute pericarditis, but a few, such as tuberculosis and fungi, produce chronic reactions...
since it is often impossible from pathologic examination to determine the etiologic basis for the reaction, a morphologic classification follows...
Serous Pericarditis
serous inflammatory exudates are characteristically produced by noninfectious inflammations, such as rheumatic fever, systemic lupus erythematosus, scleroderma, tumors, and uremia...
an infection in the tissues continguous to the pericardium, for example, a bacterial pleuritis, may cause sufficient irritation of the parietal pericardial serosa to cause a sterile serous effusion that may progress to serofibrinous pericarditis and ultimately to a frank suppurative reaction...
in some instances, a well defined viral infection elsewhere -- upper respiratory tract, pneumonia, parotitis, antedates the pericarditis and serves as the primary focus of infection...
infrequently, viral pericarditis occurs as an apparent primary involvement, usually in young adults, that may accompany myocarditis (myopericarditis)...
Fibrinous and Serofibrinous Pericarditis
in fibrinous pericarditis, the surface is dry, with a fine granular roughening...
in serofibrinous pericarditis, an increased inflammatory process induces more and thicker fluid, which is yellow and cloudy owing to contained leukocytes and erythrocytes (which may be sufficient to give a visibly bloody appearance) and often fibrin...
as with all inflammatory exudates, fibrin may be digested with resolution of the exudate, or it may become organized...
the development of a loud pericardial friction rub is the most striking characteristic of fibrinous pericarditis...
a collection of serous fluid may obliterate the rub by separateing the two layers of the pericardium...
pain, systemic febrile reactions, and signs suggestive of cardaic failure may accompany the pathognomonic friction rub...