Angina and ischemia Flashcards
Coronary perfusion gradient
aortic root pressure - LV pressure
perfused during diastole
Laplace’s equation
wall stress = r x p / (2h)
Left main CA
originate from left coronary sinus
travels between LA and pulmonary trunk to reach the AV groove, divides into
- LAD
- circumflex
LAD artery
anterior interventricular groove
diagonal branches: anterior surface of LV
septal branches: anterior 2/3 of the interventricular septum and the apical portion of the anterior papillary muscle
Circumflex CA
left AV groove and passes around the left border of the heart to reach the posterior surface
obtuse marginal branches: supplies lateral & posterior wall of the LV
Right main CA
originate from right coronary sinus
right AV groove, passing posterior to btw RA and RV
Marginal branches: RV, including SA and AV nodes
Right posterior descending: distal part of the right main CA, travels from the inferoposterior aspect of the heart to the apex, inferior & posterior walls of both ventricles and posterior 1/3 of interventricular septum
Conductance vessels
epicardial &myocardial penetrating
large in diameter
compressed by contracting cardiac muscle during diastole
Resistance vessels
Arterioles and capillaries
smaller in diameter
surrounded by smooth muscle, can change diameter in response to stimuli (NO, adenosine)
precapillary sphincters can vary flow through coronary capillaries
Coronary sinus
coronary veins accompany the coronary arteries and converge into here
posterior surface of the heart in the AV groove
empties into RA
Stable angina
usually due to atherosclerosis of CA chest pain on exertion arteries must be >75% occluded adenosine released locally in response to ischemia (dilates BV, chest pain) relieved by rest ST depression
Unstable angina
at rest or minimal exertion
artery may be >90% occluded
loss of predictability of anginal attacks
does not respond to NO
ST depression, T wave inversion/depression
Atypical angina
do not have chest pain
instead have other symptoms - weakness, faintness, sweating, nausea
more commonly seen in diabetic patients
same pathophysiology as stable angina
MI
death of myocardial tissue secondary to ischemia
begin after 15-20 minutes of severe ischemia
First 12 hours of MI - histo & gross
Micro
• EM changes in myocytes and their membranes within the first 15-20 min
• Wavy fibers – intracellular edema
• Coagulation necrosis – hypereosinophilic myocytes
• Contraction band necrosis – compaction of Z-lines of sarcomeres
Macro
• If no reperfusion of infracted area then pallor due to extrusion of erythrocytes from capillary bead
• If reperfused then hemorrhagic from blood vessel bursting
Vulnerable plaque
thin fibrous cap + large soft lipid cholesterol pool underneath
- prone to rupture
usual cause for sudden-onset MI