Path - Heart Flashcards
What cells are almost exclusively on oxidative phosphorylation?
cardiac myocytes
Why is the myocardium vulnerable to ischemia?
It has a limited amt of blood supply to the heart (only 4 vessels).
- left mainstem coronary artery
- left circumflex
- left anterior descending branch (LAD)
- right coronary artery
3 Major Pathologic changes of valves?
- dmg to collagen that weakens leaflets –> mitral valve prolapse
- nodular calcification beginning in interstitial cells –> calcific aortic stenosis
- fibrotic thickening –> rheumatic heart disease
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
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
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
What are 3 causes of cardiac hypertrophy?
- hypertension - pressure overload
- valvular disease - pressure &/or volume overload
- myocardial infarction - regional dysfunction w/ volume overload
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
What is the morphology of LEFT-SIDED HEART FAILURE in the HEART and LUNG?
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.
What are heart failure cells?
mac’s w/ injected RBCs (hemociderin laden)
What is cor pulmonale?
isolated right-sided heart failure–infrequent occurrence; blood will pool in systemic system
What is the morphology of right-sided heart failure in the liver?
- congestion of hepatic & portal vessels
2. congestive hepatomegaly
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:
- GENETIC - sporadic genetic abnormalities (major cause); down syndrome (mut in TFs: NKX2.5, GATA4)
- ENVIRONMENTAL- alone or w/ genetic factors (congenital rubella infection, gestational diabetes, teratogen exposure, nutritional factors–folate supplements reduce risk)
- IDIOPATHIC - aka we don’t know–unknown cause(s)!!
What are the 3 groups Congenital Heart Disease (CHD) can be classified as?
- malformations causing left-to-right shunt (*most common CHD)
- malformations causing right-to-left shunt
- malformation causing an obstruction
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.
What is Eisenmenger syndrome?
when a left-to-right shunt CHD becomes a right-to-left shunt (this is an inevitable event unless treated)
What is arterial septal defect?
- type of left-to-right shunt
- abnormal, fixed openings in atrial septum
- tx: ASD closure
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