Flashcards in B2.002 Big Case MI Deck (43):
What is the principle of Bayesian logic?
The likelihood of a diagnosis depends on the prior probability.
Characterize the chest pain relating to angina pectoris/ myocardial infarction
radiating to left arm/ neck
sever pressure or heaviness
List 3 differences between angina and MI.
Angina: precipitated by stress, duration in minutes, relieved by rest
MI: acute onset, unremitting, associated with nausea/vomiting/diaphoresis
List groups in order of lowest incidence of MI to highest: white men, black men, white women, black women
white women< black women = white men< black men
What is the primary reason for the decrease in CVD over the last 20 years?
Societal changes and resulting increases in prevention
When does the heart receive most of its blood supply?
How does the left ventricular myocardium receive blood?
Coronary arteries during diastole
How does the right ventricular/atrial myocardium receive blood?
From the chamber (reptilian)
Which part of heart is most susceptible to MI due to occlusion?
Left ventricular myocardium
List the heart conduction pathway.
SA node > atrial muscle > AV node > bundle of His > left/right bundle branches > Purkinje fibers > ventricular muscle
corresponds to phase 2 of ventricular action potential
What are the calcium dependent action potentials/ pacemakers?
SA node, AV node
What does it mean to be a pacemaker?
No resting membrane potential
What are the sodium dependent action potentials/ nonpacemakers?
atrial myocytes, bundle of His, Purkinje fibers, ventricular myocytes
Which part of an ECG is associated with MI?
Draw the ventricular action potential and label phases 0-4.
4 flat, 0 sharp rise, 1 sharp downtick, 2 slight linear decrease, 3 quick decrease curve
Describe the phases of the ventricular action potential.
Phase 4: stable resting potential
Phase 0: depolarization due to Na current
Phase 1: transient repolarization due to K current
Phase 2: plateau due to balance between Ca and K ions
Phase 3: repolarization phase due to K current
Describe phases of SA node action potential.
Phase 4: pacemaker potential where funny sodium current > K current
Phase 0: upstroke of action potential due to Ca current
Phase 3: repolarizing phase where K current > depolarizing currents
What is the MDP?
maximum diastolic potential, most negative potential in the SA node, 50 mV
How does the slope of phase 4 in the AV node compare to the SA node?
less steep in AV node
How does the action potential in the AV node relate to the SA node?
similar shape, same ionic currents, lower intrinsic firing rate
How does the atrial action potential compare to the ventricular action potential?
similar shape, same ionic currents
What is hypoxia?
Insufficient O2 levels
Which step of the action potential is ATP dependent?
L-type calcium channel phosphorylation
Which action potential is reduced due to impaired calcium current?
How does hypoxia affect ventricular action potential?
insufficient O2 > decreased ATP > impairment of Ca current > decreased duration of action potential
How does hypoxia change the action potential graph?
Shorter phase 2/3, appears skinnier
What is ischemia?
Insufficient blood flow
Ischemia contributes to hypoxia. How else does it affect the action potential?
decreased blood flow > extracellular K accumulation > depolarization of resting membrane potential> resting potential more positive than normal
How do hypoxia/ischemia affect ATP production?
How do hypoxia/ischemia affect the inner Na conc?
How do hypoxia/ischemia affect the inner K conc?
How do hypoxia/ischemia affect the K-ATP current?
How do hypoxia/ischemia affect Ca-L current?
How do hypoxia/ischemia affect outer K conc?
ischemia increases it
How do you detect MI vs. angina?
Presence of biomarkers due to necrosis in MI.
What are three results of plaque rupture?
healing, embolism, thrombosis
What are the major coronary arteries?
R. Coronary artery and L. Coronary artery
What are the branches of the L. Coronary artery?
Circumflex and anterior interventricular (anterior descending)