Class 5 Deck 2 Flashcards
What are the hemodynamic effects of negative inotrope / chronotrope
- Decrease contractility
- Decrease HR
- Decrease CO
- Decrease BP
- Increase L/R atria pressures
What are the indications for negative inotrope / chronotrope use?
- Decrease myocardial O2 consumption
- Treat sinus tach / SVT
- Myocardial preservation
negative inotrope / chronotrope are contraindicated in what?
- Low CO
- Bronchospastic pulmonary disease
- 2nd degree block
Resting fractional O2 extraction from myocardial capillary blood is?
65-75%
What is the essence of myocardial profusion?
-Coronary profusion pressure (CPP) = driving pressure - intramyocardial pressure
Myocardial blood flow can increase _______ by local metabolic vasodilitation
5 fold
Duration of _______ regulates the time available for coronary perfusion to the LV endocardium
Diastole (lower HR = more time for blood to flow to coronaries)
What are the 3 etiologies for myocardial ischemia?
- Demand ischemia (↑ demand w/ fixed perfusion)
- Supply ischemia (↓ perfusion from ↓ driving pressure)
- Plaque instability
Pressure work requires ______ energy than volume work
More (heart working against ↑ pressure requires more O2 than heart working against ↑ volume)
What is preload?
force or load acting to stretch ventricular fibers at end-diastole
What is afterload?
-force that myocardial fibers sense that opposes fiber shortening during contraction
______ is an index of afterload?
-SVR
A normal heart is preload _______ and afterload _______.
- Sensitive
- Insensitive
Inotropes only help what types of hearts?
-Dilated (Reducing ESV and EDV = ↓ wall stress and MVO2)
What are the goals in myocardial ischemia?
-Maintain CPP w/ smallest heart size possible
