心血管治疗药物DrugsthatAffecttheCardiovascularSystem.pptVIP

Pharmacology Drugs that Affect the Cardiovascular System Topics Electrophysiology Vaughn-Williams classification Antihypertensives Hemostatic agents Cardiac Function Dependent upon Adequate amounts of ATP Adequate amounts of Ca++ Coordinated electrical stimulus Adequate Amounts of ATP Needed to: Maintain electrochemical gradients Propagate action potentials Power muscle contraction Adequate Amounts of Calcium Calcium is ‘glue’ that links electrical and mechanical events. Coordinated Electrical Stimulation Heart capable of automaticity Two types of myocardial tissue Contractile Conductive Impulses travel through ‘action potential superhighway’. A.P. SuperHighway Sinoatrial node Atrioventricular node Bundle of His Bundle Branches Fascicles Purkinje Network Electrophysiology Two types of action potentials Fast potentials Found in contractile tissue Slow potentials Found in SA, AV node tissues Fast Potential Fast Potential Phase 0: Na+ influx “fast sodium channels” Phase 1: K + efflux Phase 2: (Plateau) K + efflux AND Ca + + influx Phase 3: K+ efflux Phase 4: Resting Membrane Potential Cardiac Conduction Cycle Slow Potential Slow Potential Cardiac Pacemaker Dominance Intrinsic firing rates: SA = 60 – 100 AV = 45 – 60 Purkinje = 15 - 45 Cardiac Pacemakers SA is primary Faster depolarization rate Faster Ca++ ‘leak’ Others are ‘backups’ Graduated depolarization rate Graduated Ca++ leak rate Potential Terms Dysrhythmia Generation Abnormal genesis Imbalance of ANS stimuli Pathologic phase 4 depolarization Ectopic foci Dysrhythmia Generation Abnormal conduction Analogies: One way valve Buggies stuck in muddy roads Reentrant Circuits Warning! AHA Recommendation Classifications Describes weight of supporting evidence NOT mechanism Class I Class IIa Class IIb Indeterminant Class III View AHA definitions Vaughn-Williams Classification Class 1 Ia Ib Ic Class II Class III Class IV Misc Description of mechanism NOT evidence Class I: Sodium Channel Blockers Decrease Na+ movement i