What is the half-life of Adenosine?
Half-time is 0.6-1.5 seconds
Should follow administration with a flush syringe to get it in fast
______ is one of the few vasodilators that also lowers heart rate.
AV node depression bradycardiaCoronary and peripheral artery vasodilation (Tx for angina pectoris and HTN)
Which of the following are myocardial effects of Ca channel blockers?
A. Decreased myocardial contractility B. Decreased heart rate C. Decreased SA node activity and/or AV node conduction D. Vascular smooth muscle relaxation E. All of the above
E. All of the above
The following are the 4 classes of anti-arrhythmic drugs. Indicate which class each describes (Class I, II, III, or IV)
Ca channel blockers
K channel blockers
Na channel blockers
Class I - Na channel blockers
Class II - Beta blockers
Class III - K channel blockers
Class IV - Ca channel blockers
Which drug is used to identify / treat AV nodal supraventricular tachycardias (re-entrant tachycardias, atrial tachycardia) and how?
Stimulates supraventricular potassium channels hyperpolarization, decreased depolarization
(These channels are not present in ventricular myocytes)
Which of the following drugs is a positive inotrope but negative chronotrope?
Negative Chronotropin AgentSlows conduction through AV node -> reduce ventricular rateIncreases parasympathetic nervous system activity -> decreases SA node activity
Positive inotropic agentInhibits Na-K-ATP transport system: Increased intracellular Na -> increased intracellular Ca > increased contractility
What effect do Ca channel blockers have on the heart?
Decrease myocardial depolarization rate and conduction velocity
Which drug has anti-arrhythmic properties of all 4 classes? (Class I, II, III, and IV)
What effect do K channel blockers have on the heart?
Prolong cardiac depolarization and action potential duration.
They also decrease proportion of the cardiac cycle when myocardium is excitable
sotalo and bretylium belong to what drug class?
Class III - K channel blocker
What is the initial IV dose for Amiodarone?
300 mg IV or 5mg/kg
What is the initial dose of Adenosine? What about subsequent doses?
Starting dose = 6 mg IV, then 12 mg IV, then 12 mg
What is the drug of choice for supraventricular tachydysrhythmias and how does it work?
Diltiazem (Cardizem) - Blocks Ca channels of AV node
Which drug causes transient heart block (AV Node) leading to a brief ventricular asystole?
Which Ca Channel blocker crosses blood-brain barrier and is used for prevention of cerebral vasospasm?