Term
| 3 variables that determine myocardial O2 demand |
|
Definition
1. heart rate
2. contractility
3. left ventricular wall stress or tension (radius and systolic pressure) |
|
|
Term
|
Definition
| adequacy of coronary arterial blood flow |
|
|
Term
O2 saturation of
coronary arterial blood:
coronary venous blood:
vs
renal arterial:
renal venous: |
|
Definition
artery - 98%
vein - 25-40%
artery - 98%
vein - 80% |
|
|
Term
consequences of ischemia:
clinical
hemodynamic
EKG
biochemical |
|
Definition
angina
increased diastolic stiffness, asynergy
ST depression/elevation, arrhythmias
lactate production |
|
|
Term
| if myocardial O2 demand increases, how do you increase supply? |
|
Definition
| increase in coronary arterial blood flow (vs renal system in which kidney cell could extract more O2) |
|
|
Term
| most common cause of myocardial ischemia |
|
Definition
| increase in O2 demand that can't be met by increase in supply (due to atherosclerotic CAD) |
|
|
Term
symptoms of stable angina pectoris
where?
when?
radiates to?
relieved by? |
|
Definition
squeezing, pressure like retrosternal chest pain that is reproducibly induced by activities that increase myocardial O2 demands (exercise, excitement, eating a large meal, smoking); pressure like discomfort radiates to axilla, left shoulder, jaw, left arm
+/- diaphoresis, dyspnea, nausea
lasts several minutes
relieved by rest, relaxation, sublingual nitroclycerine |
|
|
Term
| testing for myocardial ischemia |
|
Definition
exercise tolerance testing
look for ST depression
echocardiography - identify LV segments that contract abnormally during exercise
radionuclide myocardial perfustion
if pt can't exercise, infuse dobutamine - increases myocardial O2 demands by increasing HR and LV contractility; or adenosine (vasodilator) |
|
|
Term
| treatment for angina pectoris |
|
Definition
1. Medical - blunt increase in O2 demand
- B blockers reduce HR, LV wall tension and contractility; no influence on O2 supply
- Verapamil and diltiazem - Ca channel blockers - reduce O2 demand, induce relaxation of coronary artery smooth muscle -> increase O2 supply
- dihydropyridines - Ca channel blockers - reduce O2 demand by reduce LV wall tension; no effect on HR or contractility; relax smooth muscle -> increase O2 supply
- nitroglycerin - like dihydropyridines
2. Non-medical - improve coronary arterial blood flow
- Percutaneous coronary intervention (PCI) - baloon +/- stent
- Coronary artery bypass grafting (CABG) |
|
|
Term
| why would you use nonmedical (PCI or CABG) instead of medical (beta blockers, Ca channel blockers, nitroglycerine) to treat angina? |
|
Definition
If pt is refractory to medical therapy
Improves survival in pts w/ severe multivessel CAD or significant narrowing of left main coronary artery |
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