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Pathoma Chapter 8: Cardiology
Terms in this set (129)
What is the leading cause of death in the United States?
Ischemic Heart Disease, group of syndromes related to myocardial ischemia
Ischemic heart disease is usually due to what? What are risk factors?
Atherosclerosis of coronary arteries which decreases blood flow to the myocardium.
Risk factors for IHD are similar to those for atherosclerosis, incidence increases with age
What is stable angina? What is it due to? What type of injury to myocytes?
Chest pain that arises with exertion or emotional stress
1. Atherosclerosis of coronary arteries with >70% stenosis
2. Decreased blood flow is unable to meet metabolic demands of the myocardium during exertion
Reversible injury to myocytes--no necrosis!
Stable angina presents as what? How is it relieved?
1. chest pain (lasting <20min) that radiates to the left arm or jaw
3. shortness of breath
Tx: rest or nitroglycerin
What does the EKG show in stable angina? Why?
ST segment depression due to subendocardial ischemia
What is unstable angina? Caused by what? What type of injury?
chest pain that occurs at rest
Caused by rupture of an arthrosclerotic plaque with thrombosis and incomplete occlusion of a coronary artery
reversible injury to myocytes--no necrosis
What does the EKG show in unstable angina? Why? Risk of progression to what?
ST segment depression due to subendocardial ischemia
Risk progression to MI
Unstable angina is relieved by what?
What is Prinzmetal angina? Due to what? What type of myocyte injury?
episodic chest pain unrelated to exertion
Due to coronary artery vasospasm
Reversible injury to myocytes--no necrosis
EKG shows what in prinzmetal angina? Why?
ST segment elevation due to transmural ischemia
Prinzmetal angina is relieved how
2. Ca channel blockers
Define Myocardial Infarction. Due to what?
Necrosis of cardiac myocytes
Due to rupture of an atherosclerotic plaque with thrombus and complete occlusion of the coronary artery
What are other causes that are associated with myocardial infarction that do not include rupture of an atherosclerotic plaque?
1. coronary artery vasospasm (prinzmetal angina or cocaine use)
3. vasculitis (Kawasaki disease)
What are the clinical features of myocardial infarction?
1. severe crushing chest pain lasting > 20 minutes that radiates to the let arm or jaw
*NOT relieved by nitroglycerine
Infarctions usually involve what part of the heart
*right ventricle and both atria are usually spared
Occlusion of the left anterior descending artery leads to infarction of what?
1. anterior wall
2. anterior septum of the left ventricle
*most common artery in MI (45% of cases)
Occlusion of the right coronary artery leads to infarction of what?
1. posterior wall of LV
2. Posterior septum of LV
3. papillary muscles of LV
*second most commonly involved artery in MI
Occlusion of the left circumflex artery leads to infarction of what?
lateral wall of the left ventricle
Initial phase of infarction leads to what? What does EKG show?
1. subendocardial necrosis involving <50% of the myocardial thickness
ST segment depression
Continued or severe ischemia in a myocardial infarction leads to what? What does EKG show?
1. transmural necrosis involving most of the myocardial wall (transmural infarction)
ST segment elevation
Lab tests detect elevated cardiac enzymes. What are the 2 tests used to detect enzymes related to myocardial infarction
1. Troponin I - most sensitive and specific marker for MI
2. CK-MB - useful for detecting reinfarction that occurs days after an initial MI
Describe the levels of troponin I during and following MI
1. Levels rise 2-4 hours after infarction
2. Peak at 24 hours
3. return to normal after 7-10 days
Describe the levels of CK-MB following an MI
1. rise 4-6 hours after infarction
2. Peak at 24 hours
3. return to normal at 72 hours
What are the 6 treatments for an MI?
1. Aspirin or Heparin - limits thrombosis
2. Supplemental O2 - minimizes ischemia
3. Nitrites - vasodilate veins and coronary arteries
4. Beta Blocker - slows heart rate, decreasing O2 demand and risk for arrhythmia
5. ACE inhibitor - decreases LV dilation
6. Fibrinolysis or angioplasty - opens blocked vessel
gross and microscopic changes
Reperfusion of irreversibly damaged cells results in what post MI
Calcium influx, leading to hyperconstricton of myofibrils (contraction band necrosis)
Return of oxygen and inflammatory cells leads to what Post MI
free radical injury, further damaging myocytes (reperfusion injury)
What are the gross/microscopic changes post MI < 4 hours
Complications: cardiogenic shock (massive infarction), CHF, arrhythmia
What are the gross/microscopic changes post MI 4-14 hours
gross: dark discoloration
microscopic: coagulative necrosis
What are the gross/microscopic changes post MI 1-3 days
gross: yellow pallor
Complications: fibrinous pericarditis, presents as chest pain with friction rub
What are the gross/microscopic changes post MI 4-7 days
gross: yellow pallor
Complications: rupture of ventricular free wall (leading to cardiac tamponade), interventricular septum (leads to shunt), or papillary muscle (leads to mitral insufficiency)
What are the gross/microscopic changes post MI 1-3 weeks
gross: Red border emerges as granulation tissue enters from edge of infarct
microscopic: granulation tissue with plump fibroblasts, collagen, and blood vessels
What are the gross/microscopic changes post MI months
gross: white scar
Complications: aneurysm, mural thrombus, or Dressler syndrome
What is sudden cardiac death? When does it occur? Why?
Unexpected death due to cardiac disease.
1. without symptoms
2. <1 hour after symptoms arise
Usually due to fatal ventricular arrhythmia
What is the most common etiology of sudden cardiac death? 90% of patients who have sudden cardiac death have preexisting what
Patients have severe arteriosclerosis
What are the less common causes of sudden cardiac death?
1. mitral valve prolapse
3. cocaine abuse
What is chronic ischemic heart disease? Leads to what?
poor myocardial function due to chronic ischemia damage with or without infarction
Leads to CHF
Broadly define congestive heart failure
Pump failure divided into left and right sided failure
What are the 5 causes of left sided heart failure? Due to what?
3. dilated cardiomyopathy
4. myocardial infarction
5. restrictive cardiomyopathy
Due to decreased forward perfusion and pulmonary congestion
Pulmonary congestion leads to pulmonary edema. Which leads to what symptoms?
2. paroxysmal nocturnal dyspnea (due to increased venous return when lying flat)
Small congested capillaries in the lung may burst, leading to intraalveolar hemorrhage, marked by hemosiderin-laden macrophages (heart failure cells)
In left sided heart failure decreased flow to the kidneys leads to activation of what?
activation of the renin-angiotensin system
Which pulls fluid in, exacerbating CHF
What is the mainstay of treatment for left sided heart failure?
Right sided heart failure is most commonly due to left sided heart failure. What are the other causes of right sided heart failure?
1. left to right shunt
2. chronic lung disease (cor pulmonale)
Clinical features of right sided heart failure are due to congestion. What are they?
1. Jugular venous distention
2. Painful hepatosplenomegaly with characteristic nutmeg liver -- may lead to cardiac cirrhosis
3. Dependent pitting edema -- due to increased hydrostatic pressure
When do congenital defects arise? What percent of live births?
during embryogenesis weeks 3-8 -- most defects are sporadic
1% of live births
Congenital defects often result in what
shunting between left (systemic) and right (pulmonary) circulations
Defects with left to right shunting are generally asymptomatic at birth but can eventually reverse. Describe the pathophys.
Increased flow through the pulmonary circulation results in hypertrophy of pulmonary vessels and pulmonary hypertension
Increased pulmonary resistance eventually results in reversal of shunt, leading to late cyanosis (Eisenmenger syndrome) with right ventricular hypertrophy, polycythemia, and clubbing
Defects with right to left shunt present as what shortly after birth?
Define ventricular septal defect. Associated with what?
Defect in septum that divides right and left ventricles
Associated with fetal alcohol syndrome
*most common congenital heart defect
Ventricular Septal defect results in what? Tx?
left to right shunt
Tx: surgical closure (small ones may close spontaneously)
Size of defect in ventral septal defect determines extent of shunting and age at presentation. Describe small vs large defects.
Large: Eisenmenger syndrome
Define atrial septal defect. Most common type?
Defect in the septum that divides the right and left atria
Most common type is ostium secundum (90%)
Ostium primium atrial septal defect is associated with what?
Atrial Septal Defects result in what? what is an important complication?
1. left to right shunt
2. split S2 on auscultation - increased blood in right heart delays closure of the pulmonary valve
What is patent ductus arteriosus? Associated with what?
failure of the ductus arteriosus to close
associated with congenital rubella
Patent ductus arteriosus results in what?
left to right shunt between the aorta and pulmonary artery
What is the function of the ductus arteriosus during development?
shunt blood from the pulmonary artery to the aorta bypassing the lung
Describe PDA presentation.
Asymptomatic at birth with a continuous "machine like" murmur; may lead to Eisenmenger syndrome, resulting in lower extremity cyanosis
What is treatment for patent ductus arteriosus
1. Indomethacin, which decreased PGE, resulting in PDA closure
*PGE maintains patency of the ductus arteriosus
Tetralogy of fallot is characterized by what?
1. stenosis of the right ventricular outflow tract
2. right ventricular hypertrophy
4. aorta that overrides the VSD
Right to left shunt in tetralogy of fallot leads to what?
Degree of stenosis in tetralogy of fallot determines extent of shunting and cyanosis
Tet patient will squat in response to cyanotic spells. Why?
squatting increase arterial resistance which decreases shunting and allows more blood to reach the lungs
Describe the heart on chest x-ray in tetralogy of fallot
Transposition of the great vessels is characterized by what? Associated with what?
pulmonary artery arising from the left ventricle and aorta arising from the right ventricle
*associated with maternal diabetes
transposition of the great vessels presents with what? Why?
early cyanosis - pulmonary and systemic circuits do not mix
What is required for survival after birth in someone with transposition of the great vessels? What can be administered to maintain patent ductus arteriosus until surgical repair is performed?
Creation of shunt allowing blood to mix
Transposition of the great vessels results in what morphologic changes of the heart?
1. hypertrophy of the right ventricle
2. Atrophy of the left ventricle
Truncus arteriosus is characterized by what? Why?
1. single vessel arising from both ventricles
*Truncus fails to divide
Truncus arteriosus presents with what? Why?
early cyanosis - because deoxygenated blood from the right ventricle mixes with oxygenated blood from the left ventricle before pulmonary and aortic circulations separate
Define tricuspid atresia. Associated with what? Presents with?
1. tricuspid valve orifice fails to develop, right ventricle is hypoplastic
Associated with ASD, resulting in right to left shunt
Presents with early cyanosis
Define coarctation of the aorta. Divided into what two types?
narrowing of the aorta
Describe infantile coarctation of the aorta. Location? Presentation? Associated with?
Associated with PDA.
Coarctation lies after (distal to) the aortic arch, but before (proximal to) the PDA
Presents as lower extremity cyanosis in infants, often at birth
Associated with Turners
Describe adult coarctation of the aorta. Location? Presentation? Associated with?
Coarctation lies after (distal to) the aortic arch.
Presents as hypertension in the upper extremities and hypotension with weak pulses in the lower extremities, classically discovered in adulthood
Associated with bicuspid aortic valve
Collateral circulation develops across intercostal arteries in adult coarctation of the aorta. What does this show on CXR?
engorged artiers cause "notching" of ribs on xray
Heart as four valves that prevent backflow. What are the valves? Valvular lesions generally result in what?
Tricuspid, pulmonary, mitral, aortic
Stenosis (decreased caliber of the valve orifice) or regurgitation (backflow)
Define acute rheumatic fever. When does it occur? What is it caused by?
Systemic response of pharyngitis due to group A strep
Affects children 2-3 weeks after an episode of strep throat
Caused by molecular mimicry, where bacterial M protein resembles proteins in human tissue
Diagnosis of Acute rheumatic fever is based on what?
Evidence of prior strep infection (e.g. elevated ASO or anti-DNase B titers) with the presence of major (JONES criteria) and minor criteria (fever, elevated ESR)
What is JONES criteria?
1. Migratory Arthritis - swelling and pain in a large joint that resolves within days and migrates to involve another large joint
2. Pancarditis - endocarditis, myocarditis, pericarditis
3. Subcuteneous Nodules
4. Erythema marginatum - annular, nonpruritic rash with erythematous borders, commonly involving trunk and limbs
5. Sydenham Chorea - rapid, involuntary muscle movements
Describe the pancarditis seen in acute rheumatic fever
1. Endocarditis - mitral valvue is involved more commonly than the aortic valve; characterized by small vegetations along lines of closure that lead to regurgitation
2. Myocarditis with Aschoff bodies - characterized by foci of chronic inflammation, reactive histiocytes with slender, wavy nuclei (Anitschkow cells), giant cells, and fibrinoid material
3. Pericarditis - leads to friction rub and chest pain
* myocarditis is the most common cause of death during acute phase
Describe the progression of acute rheumatic fever.
Acute attack usually resolves but may progress to chronic rheumatic disease
*repeat exposure to group A strep may cause a relapse of acute rheumatic fever and increase the risk for chronic rheumatic disease
What is chronic rheumatic heart disease? Results in what?
Valve scarring that arises as a consequence of rheumatic fever
Results in stenosis with classic fish mouth appearance
*almost always involves the mitral valve, leads to thickening of chordae tendineae and cusps
(occasionally involves the aortic valve, leading to fusion of the commissures)
What are the complications of chronic rheumatic heart disease?
What is aortic stenosis? Due to what?
Narrowing of the aortic valve oriface, due to fibrosis and calcification from wear and tear
When does Aortic stenosis present? What increases risk?
Presents in late adulthood (>60yo)
Bicuspid aortic valve increases risk and hastens disease onset -- fewer cusps resutls in increased "wear and tear" on each cusp
Aortic stenosis may also arise as a consequence of chronic rheumatic valve disease. What distinguishes it?
coexisting mitral stenosis and fusion of the aortic valve commissures
Cardiac compensation in aortic stenosis leads to what sounds?
prolonged asymptomatic stage during which systolic ejection click followed by a crescendo-decrescendo murmur is heard
What are the complications of aortic stenosis?
1. concentric left ventricular hypertrophy - may progress to cardiac failure
2. angina and syncope with exercise - limited ability to increase blood flow across the stenotic valve leads to decreased perfusion of the myocardium and brain
3. microangiopathic hemolytic anemia - RBCs are damaged (producing schistocytes) when crossing calcified valve
What is treatment for aortic stenosis?
valve replacement after onset of complication
What is aortic regurgitation? Arises due to what?
Back flow of blood from the aorta into the left ventricle during diastole
Arises due to aortic root dilation (eg. syphilitic aneurysm and aortic dissection) or valve damage (infectious endocarditis)
*most common cause is isolated root dilation
What are the clinical features of aortic regurgitation? Define and describe pathophys.
Hyperdynamic circulation due to increased pulse pressure -- presents with bounding pulse (water-hammer pulse), pulsating nail bed (Quincke pulse) and head bobbing
Pulse pressure = systolic pressure - diastolic pressure
Diastolic pressure decreases due to regurgitation, while systolic pressure increases due to increased stroke volume
What sound does aortic regurgitation make?
Early blowing diastolic murmur
Aortic regurgitation results in what? Treatment?
LV dilation and eccentric hypertrophy (volume overload)
Tx: valve replacement once LV dysfunction develops
Define mitral valve prolapse. Why?
Ballooning of mitral valve into left atrium during systole, due to myxoid degeneration (accumulation of ground substance) of the valve making it floppy
Seen in 2-3% of US adults
Mitral valve prolapse may be seen in what syndromes
2. Ehlers-Danlos syndrome
Mitral valve prolapse has what sound?
incidental mid systolic click followed by a regurgitation murmur, usually asymptomatic
Click and murmur become softer with squatting (increased systemic resistance decreased left ventricular emptying)
What are complications of mitral valve prolapse? Tx?
severe mitral regurgitation
Tx: valve replacement
Define mitral regurgitation. What does it usually arise from?
Reflux of blood from left ventricle into the left atrium during systole
Usually arises as a complication of MVP. Other causes:
1. LV dilation (left sided cardiac failure)
2. infective endocarditis
3. acute rheumatic heart disease
4. papillary muscle rupture after myocardial infarction
What are the sounds of mitral regurgitation?
Holosystolic blowing murmur, louder with squatting (increased systemic resistance decreased left ventricular emptying) and expiration (increased return to left atrium)
Mitral regurgitation results in what clinically?
1. volume overload
2. left sided heart failure
Define mitral stenosis. Due to?
Narrowing of the mitral valve orifice due to chronic rheumatic valve disease
What are the sounds of mitral stenosis?
Opening snap followed by diastolic rumble
Volume overload in mitral stenosis leads to dilation of the left atrium, leading to what three problems?
1. pulmonary congestion with edema and alveolar hemorrhage
2. Pulmonary hypertension and eventual right sided heart failure
3. Atrial fibrillation with associated risk for mural thrombi
inflammation of the endocardium that lines the surface of cardiac valves due to bacterial infection
What is the most common overall cause of endocarditis? What decreases the risk of endocarditis?
strep viridans - low virulence organism that infects previously damaged valves (chronic rheumatic heart disease and MVP)
Strep viridans endocarditis results in what? Describe how strep viridian's created the vegetations on the valve
Small vegetation that do not destroy the valve (subacute endocarditis)
1. Damaged endocardial surface develops thrombi vegetations (platelets and fibrin)
2. Transient bacteremia leads to trapping of bacteria in the vegetations
Staph aureus is the most common cause of endocarditis in what population? What valve?
IV drug users
High virulence organism that infects normal vauves, most commonly the tricuspid
Results in large vegetations that destroy the valve (acute endocarditis)
Strep epidermis is associated with endocarditis of what? Strep bovis is associated with endocarditis in what patients
Strep epi: prosthetic valves
Step bovis: those with underlying colorectal cancer
What are the HACEK organisms in endocarditis with negative blood cultures
What are the clinical features of bacterial endocarditis
1. Fever - due to bacteremia
2. Murmur - due to vegetations of the heart valve
3. Janeway lesions (erythematous nontender lesions on palms and soles), Osier nodes (tender lesions on fingers and toes) and splinter hemorrhages in nail beds and Roth spots (due to embolization of septic vegetation
4. anemia of chronic disease - due to chronic inflammation
What are the laboratory findings in bacterial endocarditis?
1. positive blood cultures
2. anemia of chronic disease (low Hb, low MCV, high ferritin, low TIBC, low serum iron, and low % saturation)
3. transesophageal echocardiogram for lesions on valves
Non-bacterial thrombic endocarditis is due to what
sterile vegetations that arise in association with hypercoaguable state or underlying adenocarcinoma
Vegetations arise on the mitral valve along line sof clsure and result in mitral regurg
Lebman-Sacks endocarditis is due to what?
Sterile vegetations that arise with SLE.
Vegetations are present on the surface and undersurface of the mitral valve and result in mitral regurg
Group of myocardial diseases that result in cardiac dysfunction
dilation of all three chambers of the heart
*most common form of cardiomyopathy
What are complications of dilated cardiomyopathy? Tx?
1. mitral and tricuspid regurgitation
Tx: heart transplant
Dilated cardiomyopathy results in what
Systolic dysfunction (ventricles cannot pump), leading to biventricular congestive heart failure
What is the most common cause of dilated cardiomyopathy? What are the other causes?
Most common: Idiopathic
1. genetic mutation (autosomal dominant)
2. Myocarditis - characterized by a lymphocytic infiltrate in the myocardium due to coxsackie A/B, results in chest pain, arrhythmia with sudden death or heart failure.
3. Alcohol abuse
4. Drugs (doxorubicin)
5. Pregnancy - seen during late pregnancy or soon (weeks to months) after childbirth
Define hypertrophic cardiomyopathy
Hypertrophy of the left ventricle due to genetic mutations in sarcomere proteins (autosomal dominant)
What are the clinical features of hypertrophic cardiomyopathy?
1. decreased cardiac output - left ventricular hypertrophy leads to diastolic dysfunction (ventricle cannot fill)
2. Sudden death due to ventricular arrhythmias; HOCM is a common cause of sudden death in young athlets
3. Syncope with exercise - subaortic hypertrophy of the ventricular septum results in functional aortic stenosis
Biopsy of hypertrophic cardiomyopathy shows what?
myofibril hypertrophy with disarray
Define restrictive cardiomyopathy.
Decreased compliance of the ventricular endocardium that restricts filling during diastole
Restrictive cardiomyopathy is caused by what
3. endocardial fibroelastosis (children
4. Loeffler syndrome (endomyocardial fibrosis with an eosinophilic infiltrate and eosinophila)
Restrictive cardiomyopathy presents as what? Finding on EKG?
Congestive heart failure
low voltage EKG with diminished QRS amplitude
Define myxoma. Seen in who?
Benign mesenchymal tumor with a gelatinous appearance and abundant ground substance on histology
*most common primary cardiac tumor in adults
Myxoma usually forms what in the left atrium? What symptoms arise?
Pedunculated mass in left atrium that causes syncope due to obstruction of mitral valve
Define rhabdomyoma. Seen in who?
Benign hamartoma of cardiac muscle (most often in ventricle)
Most common primary cardiac tumor in children, assocated with tuberous sclerosis
What is more common in the heart: metastasis or primary tumor?
Metastatic tumors are more common the heart than primary tumors. What are the common metastasis of the heart?
1. breast and lung carcinoma
Metastasis most commonly involve what part of the heart?
*often resulting in pericardial effusion
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