Ishemic Heart Disease 2/Valves Flashcards
What is a stunned myocyte?
myocytes injured by acute ischemia, which look normal microscopically, but need time (several days) to repair before they work normally again
What is reperfusion injury?
hemorrhage and other injurious phenomena associated with bringing oxygen and calcium to injured tissue, attributed to reactive oxygen species and metabolic effects of calcium
Why is there an oxidative burst after reperfusion of ischemic cardiomyocytes?
In ischemic cardiomyocytes, lack of oxygen causes the electron transport in mitochondria to back up, thereby priming various components of the electron transport chain to generate oxygen free radicals when oxygen returns
What occurs at the same time as the oxidative burst during reperfusion?
large influx of calcium
What is the prime target of the excess oxygen radicals and calcium in reperfusion injury?
mitochondrial permeability transition pore (mPTP)
What happens when oxygen radicals and calcium bind to mPTP in reperfusion?
results in opening of the mPTP and collapsing of mitochondrial function (messes up membrane potential needed for mitochondria to make ATP)
What is the mitochondrial permeability transition pore (mPTP)?
is a voltage-dependent channel that is regulated by calcium and oxidative stress
What 3 proteins influence the function of the mPTP? Where are they?
1) voltage-dependent anion channel (VDAC): outer membrane
2) adenine nucleotide translocator (ANT): inner membrane
3) cyclophilin D (CypD): matrix side of inner membrane
The mPTP connects what parts of the mitochondria?
mitochondrial matrix and cytoplasm
What is the “no reflow phenomenon”?
failure of relieving obstruction at the arterial level to restore blood flow, attributed to microvascular obstruction or edema
What is “ischemic preconditioning”?
resistance to mild-moderate ischemia due to induction of protective proteins by brief episodes of ischemia
How does ischemic preconditioning begin?
the activation of various G-protein coupled receptors by various autocoids
What are autocoids? When are they released?
adenosine, bradykinin, and opioids, which are released during the brief periods of ischemia and reperfusion
In ischemic conditioning, activation of GPCR initiates a complex signaling cascade, including multiple kinases, that leads to what?
opening of potassium channels in the mitochondrial membrane and maintenance of the mPTP and the electrical potential of the inner mitochondrial membrane
What is the primary mechanism for the protective effect of conditioning?
preservation of mitochondrial function and ATP production
One of the protective mechanisms of conditioning involves turning on what pathway in the mitochondria?
reperfusion injury salvage kinase (RISK) pathway
What are the 2 arms of the RISK pathway?
1) Action of phosphatidylinositol-3 kinase (PI-3K) on Akt (protein kinase B) and on the mTOR
2) mitogen-associated protein kinase (MAPK) and p42/p44 ERK
The 2 arms of the RISK pathway converge on what?
p70s6 kinase to activate glycogen synthase kinase beta, which acts to prevent opening of the mPTP
What are hibernating myocytes?
chronically ischemic myocytes, which have cleared cytoplasm due to catabolism of their contractile proteins and need time to regenerate their contractile proteins before they work normally again
What is the word for light microscopic appearance of hibernating myocytes?
myocytolysis
What is acute rheumatic fever?
Acute, immunologically mediated, multisystem inflammatory disease that occurs after group A, beta-hemolytic streptococcal infections
What is rheumatic heart disease?
cardiac manifestation of rheumatic fever associated with inflammation of all parts of the heart, with valvular inflammation and scarring the most prominent clinical features
What is Jones criteria?
Diagnostic criteria for acute rheumatic fever (must have 2 or more):
1) carditis
2) migratory polyarthritis of large joints
3) Subcutaneous nodules
4) Erythema marginatum skin rashes
5) Sydenham chorea (neurological disorder)
MINOR: fever, migratory arthralgias, prolonged PR interval, High ESR or WBC count
Describe the gross pathology of acute rheumatic heart disease?
tiny (1-2 mm) verrucous (wartlike) vegetations lined up on line of valve closure. Fibrinous pericarditis.
Describe the microscopic pathology of acute rheumatic heart disease?
fibrin + platelet thrombi on valves and Aschoff bodies with Anitschkow cells (caterpillar cells)
What is an Aschoff body? Where are they found?
collecitons of lymphocytes (T cells), scattered plasma cells, and Anitschkow cells occasionally punctuating zones of fibrinoid necrosis– can be found in any of hte 3 layers of the heart
What are Anitschkow cells?
plump activated macrophages with abundant cytoplasm and central nuclei with chromatin in slender, wavy ribbon shape
Acute rheumatic fever typically occurs in who? What is the major symptom?
children, carditis
In adults, what is the major symptom of rheumatic fever?
arthritis
How long does it take for symptoms of rheumatic fever to start?
2-3 weeks after infection
True or false: actue rheumatic heart disease is more common than chronic.
FALSE: chronic is more common
What are the symptoms of chronic rheumatic heart disease?
recurrent carditis, severe carditis and carditis at an early age
When do you first see symptoms of chronic rheumatic heart disease?
average 20 years after carditis
What is the ONLY cause of acquired mitral stenosis?
rheumatic heart disease