Ischemic Heart Disease Flashcards
(49 cards)
Three ways a heart might have inadequate O2 delivery (broad)
Decreased Perfusion
Other oxygenation causes
Inadequate O2 secondary to increased demand
Causes of decreased perfusion of the heart (5)
Progressive stenosis Thromboembolus Vasospasm Vasculitis Hypovolemia
Non-perfusion oxygenation issues (5)
Anemia CO Congenital Heart Disease Asphyxia Lung Disease
Once stenosis reaches _____%, there is a decreased ability to meet the demand
75%
severe/fatal usually requires a 70% reduction in diameter
Where is the most severe narrowing typically?
The proximal 2cm
Thrombus formation usually results from
rupture or fissure of plaque with platelet aggregation, release of thromboxane
Vasospasm is associated with…
Adrenergic stimulation, local factors (NO, endothelin, platelet factors), HTN/Platelet Activity
Two types of coronary vessels
Epicardial (Conductance Vessels – get athero)
Intramyocardial (Resistance Vessels - autoregulation and flow)
How does hypoxia kill muscle cells
Switch to anerobic glycolysis, lactate buildup, lowered pH, impaired membrane fxn lets K leak and Na in
Injury becomes permanent after…
20-40 minutes
Irreversible Injury to the heart…whats that like
Necrosis and permanent loss of functional myocardium
What is acute ischemic heart disease
blockage of flow in a coronary vessel leads an entire region of myocardium to become necrotic (MI)
What is chronic ischemic heart disease
Ischemia leading to loss f individual myocytes and diffuse fibrosis, resulting in myocarfial dysfunction and eventually heart failure
Morphology of reversible injury
Stunned Myocytes
Mitochondrial swelling, Relaxation of myofibrils, distortion of cristae
Morphology of irreversible injury (in chronic)
Chronic loss of myocytes, esp. in subendocardial
Coagulative necrosis + Apoptosis
Area becomes fibrotic
Subendocardial band of infarcted myo at watershed
Morphology of acute ischemia (MI) - Gross
Early – Pallor with hyperemic border
3-7 days: hyperemic border with central, yellow-brown softening. Possibly hemorrhage.
Eventual replacement w/ red-brown, depressed, scarred area.
Eventually gray and fiber like
Phases of color of a post-MI heart
White–> Yellow Brown –> Red-Brown –> Gray
Morphology of acute ischemia (MI) – Microscopic
Necrosis of Myocytes
Inflammation, Infiltration w/ Inflamm cells
Clean up of necrotic debris
Replacement of myocardium w/ scar tissue
Morphology of reperfusion injury?
Presence of contraction bands in damaged myocytes.
Two main symptoms of cardiac ischemia?
Chest Pain + Diaphoresis
Describe the chest pain of an MI
Crushing Pain over sternum
Radiates to left arm/back
NOT sharp or fluctuating
Describe MI diaphoresis
Shortness of Breath, Sweating, Nausea
Three serum enzymes associated with ischemic heart
Troponin I/T
Creatinine kinase (MB isoenzyme)
Lactic dehydrogenase
Whats the deal with troponin?
Cardio specific/Sensitive
Increase w/ CMB, elevated up to 7 days
Most sensitive/specific
