Diseases of the Myocardium and Pericardium Flashcards
What causes restrictive cardiomyopathy?
How is it different from constrictive pericarditis?
Restrictive cardiomyopathy involves a problem with the ventricles and is usually due to amyloidosis, sarcoidosis, hemochromatosis, or myocardial fibroelastosis.
A ventricular biopsy is abnormal in all of these conditions.
Constrictive pericarditis can be fixed simply by removing an abnormal pericardium;
look for a pericardial knock on examination, calcification of the pericardium, and a normal ventricular biopsy.
Watch for an S4 sound (which indicates stiff ventricles) and signs of right-sided heart failure (jugular venous distention and peripheral edema) in both conditions.
These two disorders are mentioned together because both can cause a restrictive-type cardiac physiology, but the treatments are quite different.
What is the most common kind of cardiomyopathy? What causes it?
Dilated cardiomyopathy,
which is most commonly caused by chronic coronary artery disease or ischemia, although by strict definition this is not a true cardiomyopathy.
For the USMLE, watch for alcohol, myocarditis, or doxorubicin as the cause of dilated cardiomyopathy.
Which cardiomyopathy is likely in a young person who passes out or dies while exercising or playing sports and has a family history of sudden death?
Hypertrophic cardiomyopathy, which may be autosomal dominant.
This idiopathic condition causes asymmetric ventricular hypertrophy that reduces cardiac output (an example of diastolic dysfunction).
Look for a systolic ejection murmur along the left sternal border (similar to aortic stenosis) that increases with standing or with a Valsalva maneuver (these maneuvers decrease the volume of blood in the left ventricle).
Treat with beta-blockers or disopyramide (to allow the ventricle more time to fill).
Competitive sports should be avoided.
Positive inotropes (e.g., digoxin), diuretics, and vasodilators are contraindicated because they worsen the condition.
Describe the usual symptoms of cardiac tamponade. How is it diagnosed and treated?
Cardiac tamponade is classically associated with penetrating trauma to the left chest.
Patients classically have the Beck triad: hypotension (caused by impaired cardiac filling), distended neck veins, and muffled heart sounds.
Patients will have normal breath sounds, which can distinguish tamponade from tension pneumothorax.
Pulsus paradoxus is an exaggerated fall in blood pressure on inspiration that occurs in tamponade.
Treated with pericardiocentesis. If stable do an echo first to confirm the diagnosis.
How do you treat Cardiac Tamponade?
If the patient is unstable, treat with pericardiocentesis;
put a catheter through the skin and into the pericardial sac and aspirate blood and fluid.
If the patient is stable, you can first perform echocardiography to confirm the diagnosis.
How is cardiac tamponade diagnosed?
Patients classically have the Beck triad: hypotension (caused by impaired cardiac filling), distended neck veins, and muffled heart sounds.
Patients will have normal breath sounds, which can distinguish tamponade from tension pneumothorax.
Pulsus paradoxus is an exaggerated fall in blood pressure on inspiration that occurs in tamponade.
What is Beck’s Triad?
hypotension
(caused by impaired cardiac filling),
distended neck veins, and
muffled heart sounds.
