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Unformatted text preview: CV Pharmacology More Vasodilators Dr. Brunton 08/12/2010 17:36:00 Vasodilators: Effects on Preload & Afterload Focus on Ca channel blockers and Direct-acting Beta antagonists The goals of vasodilator therapy: 1) bring myocardial O2 demand and myocardial O2 supply into balance o If heart operating with too little oxygen, the physiological effects have done all they can i.e adenosine generation Pt must have damaged endothelial and vessels are plugged up Need to target bigger vessels Allow heart to fill less to improve overlap of thick/thin filamentshelps with failing heart b/c heart is pumping more easily can actually increase Cardiac output If overdue it (i.e too much vasodilation) can cause too much blood to periphery Must closely monitor pt for breathing rate, etc 2) Lower BP o Good as long as its consistent with maintaining perfusion Increases with age b/c vessels harden (deposits accumulate inside them), less elasticity Myocardial O2 supply and demand Increase perfusion of the heart to increase myocardial O2 supply o Left circumflex coronary aa, Right coronary aa, Left-anderior descending coronary aa Increase ventricular wall stress increases myocardial O2 demand o MVO2 is proportional to wall stress can be altered by preload (how much filling) and afterload (pressure against which heart has to expel blood) o Alter preload by altering venous tone, alter afterload by altering arteriole tone o Ohms law (V=IR) Relationship b/w vascular tone and parameters of Cardiovascular physiology Vessel Type...
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This note was uploaded on 09/14/2011 for the course PHARM pp taught by Professor Staff during the Spring '11 term at UCSD.
- Spring '11