Cardiac Pathology

Question 1

What are the properties of stable angina?

Answer 1

Stable angina is chest pain that arises with exertion or emotional stress.

1. Due to atherosclerosis of coronary arteries with > 70% stenosis; decreased blood flow is not able to meet the metabolic demands of the myocardium during exertion.
2. Represents reversible injury to myocytes (no necrosis)
3. Presents as chest pain (lasting < 20 minutes) that radiates to the left arm or jaw, diaphoresis, and shortness of breath
4. EKG shows ST-segment depression due to subendocardial ischemia.
5. Relieved by rest or nitroglycerin

Question 2

What is the significance of ST segment depression on EKG

Answer 2

It signifies subendocardial damage due to ischemia.

Question 3

What is the significance of ST segment elevation

Answer 3

Signifies transmural ischemic necrosis - there is damage to endocardium, pericardium and epicardium due to complete occulsion of the blood vessel

Question 4

What are the properties of unstable angina?

Answer 4

Unstable angina is chest pain that occurs at rest.

1. Usually due to rupture of an atherosclerotic plaque with thrombosis and incomplete occlusion of a coronary artery
2. Represents reversible injury to myocytes (no necrosis)
3. EKG shows ST-segment depression due to subendocardial ischemia.
4. Relieved by nitroglycerin
5. High risk of progression to myocardial infarction

Question 5

Prinzmetal angina.

Answer 5

Prinzmetal angina is episodic chest pain unrelated to exertion.

1. Due to coronary artery vasospasm
2. Represents reversible injury to myocytes (no necrosis)
3. EKG shows ST-segment elevation due to transmural ischemia.
4. Relieved by nitroglycerin or calcium channel blockers

Question 6

What are the properties of MI

Answer 6

Necrosis of cardiac myocytes

1. Usually due to rupture of an atherosclerotic plaque with thrombosis and complete occlusion of a coronary artery
2. Other causes include coronary artery vasospasm (due to Prinzmetal angina or cocaine use), emboli, and vasculitis (e.g., Kawasaki disease).
3. Clinical features include severe, crushing chest pain (lasting > 20 minutes) that radiates to the left arm or jaw, diaphoresis, and dyspnea; symptoms are not relieved by nitroglycerin.
4. Infarction usually involves the left ventricle (LV); right ventricle (RV) and both atria are generally spared

Question 7

What blood vessels cause posterior, anterior and lateral wall damage?

Answer 7

Anterior is LAD, posterior is right coronary artery and lateral is left circcumflex artery

Question 8

What happens in the initial phase of infarction and what tests can be done to check for acute MI

Answer 8

1. Initial phase of infarction leads to subendocardial necrosis involving < 50% of the myocardial thickness, EKG shows ST-segment depression
2. Continued or severe ischemia leads to transmural necrosis involving most of the myocardial wall (transmural infarction); EKG shows ST-segment elevation.

Laboratory tests delect elevated cardiac enzymes:

1. Troponin I is the most sensitive and specific marker (gold standard) for Ml, Levels rise 2-4 hours after infarction, peak at 24 hours, and return to normal by 7-10 days.
2. CK-MB is useful for detecting reinfarction that occurs days after an initial Ml; creatine kinase MB (CK-MB) levels rise 4 - 6 hours after infarction, peak al 24 hours, and return to normal by 72 hours - these can be monitored to see if there is a 2nd acute MI in a short duration

Question 9

What are complications of PCI or fibrinolysis after acute MI?

Answer 9

Complications involved with returning oxygen to dead tissue so:

1. Contraction band necrosis
2. Reperfusion injury

Question 10

What is an easier way to remember Robbins table 12 - 5.

Answer 10

Question 11

Robbins table 12 - 5.

Answer 11

1. We can also get paricarditis during day 1 to day 3 period which will present as friction rub, this will only happen during transmural MI
2. When macrophages come in during day 4 to day 7 then a key complication is rupture of the wall leading to cardiac tamponade
3. Interventircular septum can also rupture leading to a shock
4. Papillary muscle can also rupture leading to mitral valve insufficiency
5. Hallmark of granulation tissue is darker red tissue
6. Mural thrombosis happens after a few weeks

Question 12

What is an autoimmune complication associated with MI after several weeks to months of recovery

Answer 12

Dresseler syndrome: Tranmural infarction and inflammation at the pericardium exposes pericardial antigens to the immune system which leads to development of antibodies against pericardial tissue several weeks after infarction. This leads to autoimmune induced pericarditis

Question 13

Sudden cardiac death.

Answer 13

1. Unexpected death due to cardiac disease; occurs without symptoms or < 1 hour after
2. Symptoms arise usually due to fatal ventricular arrhythmia
3. Most common etiology is acute ischemia; 90% of patients have preexisting severe atherosclerosis.
4. Less common causes include mitral valve prolapse, cardiomyopathy, and cocaine abuse.

Question 14

Define cor pulmonale

Answer 14

Right sided heart failure, usually can be due to lack of O2 saturation, or shunting of blood vessels in the alveoli

Question 15

What are some of the common features of congenital heart defects?

Answer 15

1. Arise during embryogenesis (usually weeks 3 through 8); seen in 1% of live births
2. Most defects are sporadic.
3. Often result in shunting between left (systemic) and right (pulmonary) circulations.
4. Detects with left-to-right shunting may be relatively asymptomatic at birth, but the shunt can eventually reverse.
5. Increased flow through the pulmonary circulation results in hypertrophy of pulmonary vessels and pulmonary hypertension.
6. Increased pulmonary resistance eventually results in reversal of shunt, leading to late cyanosis (Eisenmenger syndrome) with right ventricular hypertrophy, polycythemia, and clubbing.
7. Defects with right-to-left shunting usually present as cyanosis shortly after birth.

Question 16

What are ASD associated with?

Answer 16

There are different types of it:

1. Ostium secondum, most common.
2. Ostium primum is associated with Down’s syndrome

Question 17

What is VSD associated with?

Answer 17

It is the most common congenital heart defect, associated with fetal alcohol syndrome

Question 18

What is PDA associated with?

Answer 18

Congenital rubella

Question 19

What is Tetralogy of Fallot associated with?

Answer 19

N/A

Question 20

Whats transposition of the great vessels associated with?

Answer 20

Maternal diabetes

Question 21

What is tricuspid atresia associated with?

Answer 21

Often associated with ASD

Question 22

What is coarctation of the aorta associated with?

Answer 22

Turner syndrome

Question 23

Explain VSD.

Answer 23

1. Defect in the septum that divides the right and left ventricles
2. Most common congenital heart defect
3. Associated with fetal alcohol syndrome
4. Results in left-to-right shunt; size of defect determines extent of shunting and age at presentation.
5. Small defects are often asymptomatic; large defects can lead to Eisenmenger syndrome.
6. Treatment involves surgical closure; small defects may close spontaneously

Question 24

Explain ASD.

Answer 24

1. Defect in the septum that divides right and left atria; most common type is ostium secundum (90% of cases).
2. Ostium primum type is associated with Down syndrome.
3. Results in left-to-right shunt and split S, on auscultation (increased blood in right heart delays closure of pulmonary valve)
4. Paradoxical emboli are an important complication, this originate on the right side and can make it to the left into systemic circulation like for example can go to the brain.

We see split S2 on auscultation.

Question 25

Explain PDA.

Answer 25

1. Failure of ductus arteriosus to close; associated with congenital rubella
2. Results in left-to-right shunt between the aorta and the pulmonary artery
3. During development, the ductus arteriosus normally shunts blood from the pulmonary artery to the aorta, bypassing the lungs.
4. Asymptomatic at birth with holosystolic ‘machine-like’ murmur; may lead to Eisenmenger syndrome, resulting in lower extremity cyanosis
5. Treatment involves indomethacin, which decreases PGE, resulting in PDA closure (Prostaglandin E maintains patency of the ductus arteriosus).

Question 26

Explain Tetralogy of Fallot.

Answer 26

1. Characterized by (I) stenosis of the right ventricular outflow tract, (2) right ventricular hypertrophy, (3) VSD, and (4) an aorta that overrides the VSD
2. Right-to-left shunt leads to early cyanosis; degree of stenosis determines the extent of shunting and cyanosis - this determines survival.
3. Patients learn to squat in response to a cyanotic spell; increased arterial resistance decreases shunting and allows more blood to reach the lungs.
4. ‘Boot-shaped’ heart on x-ray

Question 27

Transposition of Great vessels.

Answer 27

1. Characterized by pulmonary artery arising from the left ventricle and aorta arising from the right ventricle
2. Associated with maternal diabetes
3. Presents with early cyanosis; pulmonary and systemic circuits do not mix.
4. Creation of shunt (allowing blood to mix) alter birth is required for survival.
5. PGE can be administered to maintain a PDA until definitive surgical repair is performed.
6. Results in hypertrophy of the right ventricle and atrophy of the left ventricle

Question 28

Explain Truncus Arteriosus.

Answer 28

1. Characterized by a single large vessel arising from both ventricles
2. Truncus fails to divide.
3. Presents with early cyanosis; deoxygenated blood from right ventricle mixes with oxygenated blood from left ventricle before pulmonary and aortic circulations separate.

Question 29

Explain tricuspid atresia.

Answer 29

Tricuspid valve orifice fails to develop; right ventricle is hypoplastic.

Often associated with ASD, resulting in a right-to-left shunt; presents with early cyanosis

Question 30

Explain coarctation of the aorta.

Answer 30

1. Narrowing of the aorta; classically divided into infantile and adult forms
2. Infantile form is associated with a PDA; coarctation lies after (distal to) the aortic arch, but before (proximal to) the PDA.
3. Presents as lower extremity cyanosis in infants, often at birth
4. Associated with Turner syndrome

Adult form is not associated with a PDA; coactation lies after (distal to) the aortic arch.

1. Presents as hypertension in the upper extremities and hypotension with weak pulses in the lower extremities; classically discovered in adulthood
2. Collateral circulation develops across the intercostal arteries; engorged arteries cause ‘notching’ of ribs on x-ray
3. Associated with bicuspid aortic valve

Question 31

What is Eisenmenger syndrome?

Answer 31

When there is a large atrio septal defect then there is blood shunting from left to right side of the heart, this causes increased blood flow through the pulmonary circulation leading to pulmonary hypertension. Right sided cardiomegaly would take place over time and pulmonary hypertension would go to a point when there will be reverse of shunting of blood leading to right to left shunting, increased amount of deoxygenated blood would flow in the systemic circulation leading to cyanosis and clubbing of the fingers

Question 32

Explain acute RF.

How do patient develop chronic RF?

Answer 32

• Systemic complication of pharyngitis due to group A [5-hemolytic streptococci; affects children 2-3 weeks after an episode of streptococcal pharyngitis (“strep throat”)
• Caused by molecular mimicry; bacterial M protein resembles proteins in human tissue.

Diagnosis is based on Jones criteria.

Evidence of prior group A |5-hemolytic streptococcal infection (e.g., elevated ASO or anti-DNase B titers) with the presence of major and minor criteria.

Minor criteria are nonspecific and include fever and elevated ESR.

Major criteria:

1. Migratory polyarthritis—swelling and pain in a large joint (e.g., wrist, knees, ankles) that resolves within days and “migrates” to involve another large joint
2. Pancarditis
   
   1. Endocarditis—Mitral valve is involved more commonly than the aortic valve. Characterized by small vegetations along lines of closure that lead to regurgitation
   2. Myocarditis with Aschof bodies that are characterized by foci of chronic inflammation, reactive histiocytes with slender, wavy nuclei (Anitschkow cells), giant cells, and fibrinoid material; myocarditis is the most common cause of death during the acute phase.
   3. Pericarditis—leads to friction rub and chest pain
3. Subcutaneous nodules
4. Erythema marginatum—annular, nonpruritic rash with erythematous borders, commonly involving trunk and limbs
5. Sydenham chorea (rapid, involuntary muscle movements)

Acute attack usually resolves, but may progress to chronic rheumatic heart disease; repeat exposure to group A-hemolytic streptococci results in relapse of the acute phase and increases risk for chronic disease.

Question 33

Answer 33

Vegetations at the edge of the valve signifies Strep A infection, this leads to mitral valve regurgitation, always happens at the mitral valve

Question 34

What kind of cardiac defects result from acute and chronic RF.

Answer 34

Acute causes mitral valve regurgitation, chronic causes mitral valve stenosis.

Question 35

Answer 35

This is an Ashoff body, characteristic of RF, consists of area of inflammation with giant cells with with fibrinoid material

Question 36

Answer 36

These are Anitschkow cells, these basically are histiocytes with a slender wavy nuclei running down the middle, sometimes its called the caterpillar nucleus, this is a hallmark cell of acute or chronic RF. Myocarditis is the most common cause of death during the acute phase of RF

Question 37

Explain chronic RF.

Answer 37

Question 38

Explain aortic stenosis.

Answer 38

1. Narrowing of the aortic valve orifice
2. Usually due to fibrosis and calcification from “wear and tear”
   
   1. Presents in late adulthood (> 60 years)
   2. Bicuspid aortic valve increases risk and hastens disease onset. A normal aortic valve has three cusps; fewer cusps results in increased “wear and tear” on each cusp.
3. May also arise as a consequence of chronic rheumatic valve disease; coexisting mitral stenosis and fusion of the aortic valve commissures distinguish rheumatic disease from “wear and tear” - this is important to know
4. Cardiac compensation leads to a prolonged asymptomatic stage during which a systolic ejection click followed by a crescendo-decrescendo murmur is heard.

Complications include

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) while crossing the calcified valve.

Treatment is valve replacement after onset of complications.

Question 39

Explain aortic regurgitation.

Answer 39

Question 40

Explain mitral valve prolapse.

Answer 40

1. Ballooning of the mitral valve during systole, seen in 2% - 3% of the US population.
2. Due to myxoid degeneration (accumulation of ground substance) of the valve, making it floppy
   
   1. Etiology is unknown; may be seen in Marfan syndrome or Ehlers-Danlos syndrome
3. Presents with an incidental mid-systolic click followed by a regurgitation murmur; usually asymptomatic
   
   1. Click and murmur become louder with squatting (increased systemic resistance decreases left ventricular emptying).
4. Complications are rare, but include infectious endocarditis, arrhythmia, and severe mitral regurgitation.
5. Treatment is valve replacement.

Question 41

Explain mitral valve regurgitation.

Answer 41

MITRAL REGURGITATION

1. Reflux of blood from the left ventricle into the left atrium during systole
2. Usually arises as a complication of mitral valve prolapse; other causes include l.V dilatation (e.g., left-sided cardiac failure), infective endocarditis, acute rheumatic heart disease, and papillary muscle rupture after a myocardial infarction.

Clinical features

1. Holosystolic “blowing” murmur; louder with squatting (increased systemic resistance decreases left ventricular emptying) and expiration (increased return to left atrium)
2. Results in volume overload and left-sided heart failure

Question 42

Explain mitral valve stenosis.

Answer 42

Question 43

Explain endocarditis and its most common causes.

Answer 43

Endocarditis is the inflammation of the endocardium, most importantly at the valves of the heart.

1. S. Viridans is the most common overall cause. It is a low-virulence organism that only infects previously damaged valves, this is called subacute endocarditis. However a complication of this is that bacteria that is temperorily in the blood can get stuck in these valves and can cause further damage.
2. S. Aureus is the most common cause in (V drug abusers.
   
   1. High-virulence organism that infects normal valves, most commonly the tricuspid.
   2. Results in large vegetations that destroy the valve
3. S. Epidermidis is associated with endocarditis of prosthetic valves.
4. S. Bovis is associated with endocarditis in patients with underlying colorectal carcinoma.
5. HACEK organisms (Haemophilus, Actinobacilus, Cardiobacterium, Eikenella, Kingella) are associated with endocarditis with negative blood cultures.

Question 44

What are the clinical features and lab findings of endocarditis?

Answer 44

Clinical features of bacterial endocarditis include

1. Fever—due to bacteremia
2. Murmur—due to vegetations on heart valve
3. Janeway lesions (erythematous nontender lesions on palms and soles).
4. Osler nodes (tender lesions on fingers or toes, O for ouch!), and splinter hemorrhages in nail bed - due to embolization of septic vegetations
5. Anemia of chronic disease—due to chronic inflammation

Laboratory findings

1. Positive blood cultures
2. Anemia of chronic disease
3. Transesophageal echocardiogram (TEE) is useful for detecting lesions on valves.

Question 45

What is the etiology of sterile endocarditis?

Answer 45

Question 46

Libman Sacks Endocarditis.

Answer 46

Libman-Sacks endocarditis is due to sterile vegetations that arise in association with SLE.

Vegetations are present on the surface and undersurface of the mitral valve and result in mitral regurgitation.

Question 47

Explain dilated cardiomyopathy.

Answer 47

1. Dilation of all four chambers of the heart; most common form of cardiomyopathy
2. Results in systolic dysfunction (ventricles cannot pump), leading to biventricular CHF; complications include mitral and tricuspid valve regurgitation and arrhythmia.
3. Most commonly idiopathic; other causes include
   
   1. Genetic mutation (usually autosomal dominant)
   2. Myocarditis (usually due to coxsackie A or B)—characterized by a lymphocytic infiltrate in the myocardium (Fig. 8.19); results in chest pain, arrhythmia with sudden death, or heart failure. Dilated cardiomyopathy is a late complication.
   3. Alcohol abuse
   4. Drugs (e.g., doxorubicin)
   5. Pregnancy—seen during late pregnancy or soon (weeks to months) after childbirth
4. Treatment is heart transplant.

Question 48

Explain hypertrophic and restrictive cardiomyopathy.

Answer 48

Hypertrophic cardiomyopathy:

1. Massive hypertrophy of the left ventricle
2. Usually due to genetic mutations in sarcomere proteins; most common form is autosomal dominant
3. Clinical features include
4. Decreased cardiac output—Left ventricular hypertrophy leads to diastolic dysfunction (ventricle cannot fill).
5. Sudden death due to ventricular arrhythmias; hypertrophic cardiomyopathy is a common cause of sudden death in young athletes.
6. Syncope with exercise—Subaortic hypertrophy of the ventricular septum results in functional aortic stenosis.
7. Biopsy shows myofiber hypertrophy with disarray (Fig. 8.20).

Restrictive cardiomyopathy

1. Decreased compliance of the ventricular endocardium that restricts filling during diastole
2. Causes include
   
   1. amyloidosis,
   2. sarcoidosis,
   3. hemochromatosis,
   4. endocardial fibroelastosis,
   5. and Loefller syndrome (endomyocardial fibrosis with an eosinophilic infiltrate and eosinophilia).
3. Presents as congestive heart failure; classic finding is low-voltage EKG w:ith diminished QRS amplitude.

Question 49

Explain metastatic tumors to the heart.

Answer 49

1. Metastatic tumors are more common in the heart than primary tumors.
2. Common metastases to the heart include breast and lung carcinoma, melanoma, and lymphoma.
3. Most commonly involve the pericardium, resulting in a pericardial effusion

Question 50

Explain primary heart tumors.

Answer 50

MYXOMA

1. Benign mesenchymal tumor with a gelatinous appearance and abundant ground substance on histology
2. Most common primary cardiac tumor in adults
3. Usually forms a pedunculated mass in the left atrium that causes syncope due to obstruction of the mitral valve

RHABDOMYOMA

1. Benign hamartoma of cardiac muscle
2. Most common primary cardiac tumor in children; associated with tuberous sclerosis
3. Usually arises in the ventricle

Question 51

What is a high yield fact to know about Rhabdomyoma associated with heart?

Answer 51

Often happens in children and is associated with tuberous sclerosis