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Flashcards in Path - Heart Deck (49):
1

What cells are almost exclusively on oxidative phosphorylation?

cardiac myocytes

2

Why is the myocardium vulnerable to ischemia?

It has a limited amt of blood supply to the heart (only 4 vessels).
1. left mainstem coronary artery
2. left circumflex
3. left anterior descending branch (LAD)
4. right coronary artery

3

3 Major Pathologic changes of valves?

1. dmg to collagen that weakens leaflets --> mitral valve prolapse
2. nodular calcification beginning in interstitial cells --> calcific aortic stenosis
3. fibrotic thickening --> rheumatic heart disease

4

What happens in Congestive Heart Failure? How does the body try to resolve this?

- In CHF, heart is unable to pump blood at rate sufficient to metabolic demands of the tissues.
- Several physiologic mechanisms maintain arterial pressure and organ perfusion such as myocardial hypertrophy

5

What is the pathophysiology & progression to heart failure?

Pressure (systemic hypertension) or volume overload (aortic stenosis) → increase in mechanical work → myocyte adaptation → increase in size (hypertrophy) of myocyte → increase in size and weight of the heart

*aortic stenosis = opening of the aortic valve is narrowed

6

Myocyte hypertrophy not accompanied by a proportional increase in capillary numbers → weak blood supply for hypertrophied heart while oxygen consumption is elevated. What does this eventually lead to?

- More vulnerability of hypertrophied heart to ischemia-related decompensation, which leads to cardiac failure

7

What are 3 causes of cardiac hypertrophy?

1. hypertension - pressure overload
2. valvular disease - pressure &/or volume overload
3. myocardial infarction - regional dysfunction w/ volume overload

8

What are the causes and consequences of LEFT-SIDED HEART FAILURE?

- Causes:
1. Ischemic heart disease
2. Hypertension
3. Aortic and mitral valvular diseases
4. Primary myocardial diseases

- Consequences:
1. Passive congestion (blood back up in the pulmonary circulation)
2. Stasis of blood in the left-sided chambers
3. Inadequate perfusion of downstream tissues

9

What is the morphology of LEFT-SIDED HEART FAILURE in the HEART and LUNG?

10

What is special about cardiac muscle cells & neural cells?

They are permanent cells, so they never divide. However, it is possible to stimulate cardiac stem cells to undergo regen.

11

What are heart failure cells?

mac's w/ injected RBCs (hemociderin laden)

12

What is cor pulmonale?

isolated right-sided heart failure--infrequent occurrence; blood will pool in systemic system

13

What is the morphology of right-sided heart failure in the liver?

1. congestion of hepatic & portal vessels
2. congestive hepatomegaly

14

What is one of the most prevalent birth defects (incidence of up to 5%)? And what is a major cause of this disease

congenital cardiovascular malformations

Causes:
1. GENETIC - sporadic genetic abnormalities (major cause); down syndrome (mut in TFs: NKX2.5, GATA4)
2. ENVIRONMENTAL- alone or w/ genetic factors (congenital rubella infection, gestational diabetes, teratogen exposure, nutritional factors--folate supplements reduce risk)
3. IDIOPATHIC - aka we don't know--unknown cause(s)!!

15

What are the 3 groups Congenital Heart Disease (CHD) can be classified as?

1. malformations causing left-to-right shunt (*most common CHD)
2. malformations causing right-to-left shunt
3. malformation causing an obstruction

16

Describe the fetal circulation.

- Lungs are not in use, so the fetal heart gets O2 from placenta.
- Foramen Ovale gets blood from placenta and is a valve betw the R&L side of the heart--communication.
- Ductus arteriosis - blood from pulm. a. to the aorta (deoxy blood bc not as much blood needed in fetus), but some of the blood still goes to lung to give the tissue some O2.

17

What is Eisenmenger syndrome?

when a left-to-right shunt CHD becomes a right-to-left shunt (this is an inevitable event unless treated)

18

What is arterial septal defect?

- type of left-to-right shunt
- abnormal, fixed openings in atrial septum
- tx: ASD closure

19

What is patent foramen ovale (PFO)?

- type of left-to-right shunt
- failure to close foramen ovale (usu closes at age 2)
- do NOT confuse w/ ASD

20

What is a ventricular septal defect (VSD)?

- type of left-to-right shunt (*most common)
- incomplete closure of ventricular septum

21

What is a patent ductus arteriosus (PDA)?

- connects aorta & pulm. a.
- essential in fetal circ.; can be induced to remain open (PG E1 analogs)
- tx: NSAIDS, indomethacin

22

Describe right-to-left shunt in general. What is an example of this type of shunt?

- R-to-L = cyanotic CHD
- hypoxemia/cyanosis --> clubbing of fingers (hypertrophic osteoarthritis), polycythemia
- paradoxical embolism (prone to embolism bc blood is thicker)
- Ex: Tetralogy of Fallot (TOF) - enlarged boot-shaped heart, blue tongue, 4 defects

23

What are the 4 defects seen in Tetralogy of Fallot (TOF)?

1. overriding aorta (abnormal position)
2. subpulmonary stenosis (narrowing of artery)
3. ventricular septal defect (deoxy mixes w/ oxy blood)
4. right ventricular hypertrophy (R-to-L shunt)

24

What is obstructive congenital disease?

- abnormal narrowing of chambers, valves, or BVs
- atresia = complete obstruction
- ex. coarctation of aorta, aortic valvular stenosis, pulmonary valvar stenosis
- 2 types: w/ PDA, w/o PDA

25

What is ischemic heart disease (IHD)?

- resulting from myocardial ischemia, an imbalance betw myocardial perfusion & cardiac demand for oxy blood
- result = cardiac hypoxia
- 90% of cases: atherosclerotic lesions in coronary aa. --> IHD
- varying degrees of acute plaque change, thrombosis, & vasospasm
- consequences: angina pectoris (chest pain due to ischemia), myocardial infarction, sudden cardiac death

26

What are the 3 types of angina pectoris?

1. stable angina (most common)
2. unstable angina
3. prinzmetal angina

27

Stable angina?

- produced by physical activity, emotional stress, or heavy meal
- relieved by rest or vasodilators (nitroglycerine, Ca chnl blockers [inc perfusion])

28

Unstable angina?

prolonged/severe angina; unpredictable even at rest; mostly caused by disruption of atherosclerotic plaque

29

Prinzmetal angina?

uncommon form of episodic myocardial ischemia caused by coronary artery spasm, unrelated to physical activity; responds to vasodilators

30

What is the #1 cause of death in US?

myocardial infarction (MI)

31

What are the early changes after onset of severe myocardial ischemia?

Loss of ATP & accumulation of lactate; first 30 min = reversible changes (swelling of cell = reversible)

- will eventually lead to irreversible injury when cytoplasmic memb is not intact

32

KNOW the sequence of events in the progression of myocardial ischemic injury.

1. ATP depletion
2. Loss of contractility in cardiomyocytes
3. ATP reduction (due to anaerobic production)
4. Reversible cell injury (if within 30 mins)
5. Irreversible cell injury
6. Microvascular injury

33

What are the patterns of infarction & what are the differences between the two?

Transmural infarct - involving the entire thickness of the left ventricular wall from endocardium to epicardium

Subendocardial infarct - multifocal areas of necrosis confined to the inner 1/3-1/2 of the left ventricular wall.

34

What is used to detect & diagnose someone w/ myocardial infarction?

cardiac-specific troponins T & I (cTnT & cTnl) & CK-MB

35

What is Rheumatic fever (RF) & what is its progression?

RF = acute inflamm disease following group A streptococcal pharyngitis
- becomes acute rhematic carditis (ARC)
- if chronic = rheumatic heart disease (RHD) w/ valvular abnormalities --> mitral valve (stenosis)

36

What are Aschoff bodies?

focal inflammatory lesions consisting of foci of T lymphocytes, , occasional plasma cells, & plump activated mac's called Anitschkow cells

37

what is infective endocarditis (IE)?

a microbial infection of heart valves or mural endocardium leading to formation of vegetations; acute & subacute forms

38

Describe acute infective endocarditis (IE).

infection of a previously normal valve by highly virulent organism; rapidly necrotizing & destructive lesions; difficult ot cure; death w/i days to weeks

39

Describe subacute infective endocarditis (IE).

organisms w/ lower virulence; infections of deformed valves; less destructive; cure can be achieved w/ ABs

40

What are the clinical features of Infective Endocarditis?

- fever/chills, new or changing murmur, vascular lesions, including petechiae, "splinter" hemorrhages under nails & *Janeway lesions (small erythematous, non-tender or nodular lesion on soles or palms--caused by septic emboli)
- modified "Duke criteria" for diagnosis

41

What is the morphology of Infective Endocarditis (IE)?

- vegetations = classic
- friable, bulky, potentionaly destructive
- aortic & mitral valves, most common sites
- prone to embolization

42

So what are the 4 major forms of vegetative endocarditis?

1. rheumatic heart disease (RHD): small, warty vegetations along the lines of closure of valve leaflets
2. infective endocarditis (IF): large, irregular mass on valve
3. nonbacterial thrombotic endocarditis (NBTE): small, bland vegetations at line of closure
4. Libman-Sacks endocarditis (LSE): small/medium-sized vegetations on either or both sides of the valve leaflets

43

Who needs AB prophylaxis one hour before dental procedures or operations on the mouth?

Only recommended for pts w/ high risk of infective endocarditis:
1. Artificial heart valve
2. Heart valve repaired w/ artificial material
3. History of endocarditis
4. Heart transplant w/ abnormal heart valve function
5. Certain types of congenital heart defects

44

What congenital heart defects that require antibiotic prophylaxis?

1. cyanotic congenital heart disease that has not been fully repaired
2. congenital heart defect repaired w/ artificial material or a device for first six months after repair procedure
3. repaired congenital heart disease w/ residual defects

45

What are the most common causes of myocarditis in the US?

viral infections

46

What is a cardiomyopathy?

any dysfunction of myocardium; associated w/ mechanical or electrical dysfunction

47

What are the 3 morphologic patterns of cardiomyopathies?

1. dilated (systolic dysfunction)
2. hypertrophic
3. restrictive
*last 2 are diastolic dysfunction

48

What causes dilated cardiomyopathy?

- supraphysiologic stress & excess catecholamine (cardiotoxicity--Ca overload in myocyte or focal vasoconstriction)
- cocaine, dopamine
- DEFECT IN: force generation, force transmission, &/or myocyte signaling

49

what is hypertrophic cardiomyopathy?

"hunned per cent" genetic disorder--autosomal dominant; mutations in proteins of sarcomere; abnormal diastolic filling
- DEFECT IN: energy transfer from mito to sarcomere &/or direct sarcomeric dysfunction