Pharmacology Chapter 19 Antiarrhythmic Drugs

An increase in the rate of phase _____ depolarization in the SA node increases heart rate, whereas a change in the threshold voltage to a more positive value decreases the heart rate.

4

Where is K high and Na high

Where is Ca high

Na is high outside

K is high inside

Ca is hight outside

What is ca induced ca release

Ca flows into the sarcoplasmic reticulum causing more Ca to be released

What is the funny current

K flowing out

Na flowing in

Gated by HCN channel

HCN channel are activated by ________

hyperpolarization

Ryanodine receptor is on ______ ______

______ type channel allows Ca from outside to inside

sarcoplasmic reticulum

L

The period after the initiation of an action potential during which another action potential cannot be initiated and propagated regardless of stimulus is known as the _______ refractory period

effective

The rate of phase ____ depolarization strongly influences the conduction velocity and depends on the membrane potential during phase _____

0, 4

The more _______ the membrane potential at the beginning of phase 0 depolarization, the greater is the maximal dV/dt for phase 0.

negative

SA node and AV node depends on ______ in phase 0

Purkinje fibers and Ventricular myocytes depend on _______ in phase 0

Ca (slower)

Na (faster)

Conduction is faster in Purkinje/myocytes or SA/AV

Purkinje and Myocyte (Use Na)

Class 1 Antiarrhythmic work on _______ response fibers

Fast (Na channel blockers)

Class 1A , 1B, 1C Sodium channel blockers

1A bind open Na channels (Quinidine, Procainadmide, Disopyramide)

1B Bind inactivated Na channels (lidocaine, Mexiletine)

1C Strongest Na block (Flecainide, Propafenone)

Which phase do each Antiarrhythmic work on

Class 1: Phase 0 (slower conduction Na)

Class 2: Phase 4 (B1)

Class 3: Phase 3 (K)

Class 4: Phase 0 (Ca)

Which Class 1 Antiarrhythmic to use

Ischemic Ventricular Arrhythmia

No structural heart disease

Lidocaine (1B)

Fecainide or Propafenone (1C)

Propanolol

Metoprolol

Esmolol

Sotalol

Non selective (B1 and B2)

B1 selective

B1 selective ultra short acting

Non selective B and Class 3 (K blockers)

Amiodarone vs Dronedarone

Amiodarone is multichannel blocker

Dronedarone is amiodarone without iodine

Verapamil

Diltiazem

Amlodipine

Cardiac selective

Intermediate effect

Minor antiarrhythmic use

Amiodarone, Quinidine, Propafenone Inhibit CYP2D6 may reduce effectiveness of oral _______

opioids

What type of antiarrhythmics to use

Supraventricular

Ventricular

B blockers, Class IV, 1C, amiodarone

1B, 1C (Class 3)

Contraindication of 1C antiarrhythmics

Ischemic or post MI hearts