AntiDysrhythmics

Question 1

What are the 4 classes of Antidysrhythmics?

Answer 1

1. Sodium Channel Blockers
2. Beta Blockers
3. Potassium Channel Blockers
4. Calcium Channel Blockers

Question 2

What are the subclasses and medications within the Class I - Sodium Channel Blockers?

Answer 2

1A: Quinidine, Procainamide, Disopyramide
1B: Lidocaine, Phenytoin, Mexiletine
1C: Flecainide, Propafenone

Question 3

What are some drugs in the class three – potassium channel blockers?

Answer 3

Amiodarone
Sotalol
Dofetilide

Question 4

What are two Class 4 - CCB used for arrhythmias

Answer 4

Verapamil and Diltiazem

Question 5

Should drugs administered for the chronic suppression of cardiac arrhythmias be continued up to the time of induction of anesthesia?

Answer 5

Yes, these drugs pose little threat to the uneventful course of anesthesia and should be continued up to time of induction

Question 6

Catheter ablation techniques are preferred treatments for?

Answer 6

Many supraventricular, arrhythmias, including atrial and certain types of atrial fibrillation

Question 7

Magnesium is involved in many enzymatic reactions and produces:

Answer 7

systemic and coronary vasodilation,
inhibits platelet aggregation, and
decreases myocardial reperfusion injury.

Question 8

Atrial fibrillation after heart surgery is a c ommon
complication that has been associated with prolonged hospitalization and cardiovascular morbidity. Prophylactic therapy with _______, _______, _______, and ______ has been effective in reducing the occurrence of atrial fibrillation, length of hospital stay, and cost of hospital treatment and may be effective in reducing the risk of stroke.

Answer 8

amiodarone, b blockers, sotalol, and magnesium

Question 9

The two major physiological mechanisms that cause ectopic cardiac arrhythmias are:

Answer 9

Reentry and enhanced automaticity

Question 10

factors encountered in the perioperative period that facilitate cardiac arrhythmias due to both mechanisms (reentry and enhanced automaticity) include:

Answer 10

Hypoxemia
Electrolyte and acid base abnormalities
Myocardial ischemia
Altered sympathetic, nervous system activity
Bradycardia
Administration of certain drugs

Question 11

antiarrhythmic drugs produce pharmacological effects by blocking passage of ions across which ion channels present in the heart?

Answer 11

Sodium ion, potassium ion and calcium ion channels

Question 12

what determines the clinical effect of anti-arrhythmic drugs

Answer 12

The effect these drugs have on the action potential and refractory of the cardiac action potential.

Question 13

Cardiac arrhythmic drugs are most commonly classified into four groups based primarily on the ability of the drug to:

Answer 13

1. Control arrhythmias by blocking specific ion channels.
2. Disrupt currents during the cardiac action potential.

Question 14

Class 1 antiarrhythmics are sodium channel blockers, they inhibit what kind of sodium am ion channels?

Answer 14

Inhibit, fast sodium ion channels

Question 15

Class 2 - Antiarrythmics (Beta Blockers) have what MOA

Answer 15

Decrease rate of depolarization

Question 16

Class 4 - antiarrhythmics (CCBs) inhibit what kind of calcium channels?

Answer 16

inhibit SLOW calcium channels

Question 17

Which antiarrhythmics have no effect on ventricular tachycardia?

Answer 17

-Calcium Channel Blockers (Verapamil & Dilt)
-Digitalis
-Adenosine

Question 18

Which class of antiarrhythmics have no effect on paroxysmal super ventricular tachycardia?

Answer 18

Class 1B: Lidocaine, Mexiletine, Tocainide

Moricizine (a 1A drug)

Question 19

Although used in the past, __________ is no longer recommended as prophylactic treatment for patients in the early stages of acute MI and without malignant ventricular ectopy

Answer 19

Lidocaine

Question 20

Supraventricular Tachyarrhythmias associated with Wolff-Parkinson-White syndrome are effectively suppressed by which antidysrhythmic

Answer 20

Quinidine - Class 1A
(fast sodium channel blocker)

Question 21

Quinidine is a class 1A drug that is effective in the treatment of acute and chronic super ventricular arrhythmias however it is rarely used because?

Answer 21

Of its side effects. Low therapeutic ratio with SEs including
-Heart Block
-Hypotension
-Proarrythmia effects

Question 22

MOA of Class 1A AntiArrythmics

Answer 22

Fast Sodium Channel Blockers in the Ventricular Myocyte. (but some potassium too lol)

Increased AP duration and prolongation of repolarization phase.

Slows/decreases the slope of the phase 4 upstroke of the action potential, slowing conduction.

Prolongs the Effect/Absolute Refractory Period, which prolongs the QRS and QT with some potassium channel blockade.

Question 23

Despite being in the same class and sub class, how do Procainamide and Quinidine differ in their treatments of arrhythmias?

Answer 23

They are equally effective for ventricular tacky arrhythmias, but procainamide is less effective at terminating atrial tacky arrhythmias.

IV admin of procainamide is usually better tolerated than IV Quinidine, but still may cause hypotension.

Question 24

True or False: Procainamide undergoes hepatic metabolism and its half-life is dependent on if a patient is a rapid or slow acetylator.

Answer 24

True.

Patients who are rapid acetylators, the
elimination half-time of procainamide is 2.5 hours compared with 5 hours in slow acetylators

Question 25

Chronic administration of procainamide may be associated with a syndrome that resembles?

Answer 25

Systemic lupus erythmatosus (same with Hydalazine)

Question 26

Hypotension from procainamide is more likely caused by _________ than peripheral vasodilation

Answer 26

Direct myocardial depression

Question 27

What is lidocaine principle used for when relating to anti-arrhythmias?

Answer 27

Suppression of ventricular arrhythmia is having minimal if any effect on supraventricular tachyarrhythmias

Question 28

Advantages of lidocaine over quinidine or procainamide:

Answer 28

- rapid onset in prompt disappearance of effects when continuous infusion is stopped - greater therapeutic index - reduced side effect profile

Question 29

MOA of Lidocaine (and Class 1B)

Answer 29

Shorten the action potential duration via decreasing rate of spontaneous phase 4 depolarization and shortening the refractory period in cardiac ventricular muscle cells.

Question 30

When does the "Effective" or "Absolute" Refractory period in the ventricular myocyte occur?

Answer 30

From Phase 0 to the middle of Phase 3.

Question 31

Does lidocaine have active hepatic metabolites?

Answer 31

Metabolites may possess cardiac antiarrhythmic activity

Question 32

Phenytoin (Class 1B) is particularly effective in the suppression of ventricular arrhythmia's associated with?

Answer 32

Digitals toxicity in may be useful in the treatment of paradoxical ventricular tachycardia or torsades de pointes

Question 33

IV dose of Phenytoin when using for cardiac arrythmias

Answer 33

100mg (1.5mg/kg) every 5min until rate is controlled

Question 34

Phenytoin exerts a greater effect on the EKG ______interval than does lidocaine and shortens the _____ interval more than any of the other antiarrhythmic drugs.

Answer 34

QTc

Question 35

Phenytoin toxicity most commonly manifests as:

Answer 35

CNS disturbances, especially cerebellar disturbances. Symptoms include ataxia, nystagmus, vertigo, slurred speech, sedation, and mental confusion

Question 36

What are Phenytoins effects on blood sugar?

Answer 36

Phenytoin partially inhibits insulin secretion and may lead to increased blood glucose levels in patients who are hyperglycemic.

Question 37

Warfarin, phenylbutazone, and isoniazid may inhibit metabolism and increase _______ blood levels

Answer 37

phenytoin

Question 38

Wide complex Ventricular rhythm is usually associated with what class of antiarrythmics?

Answer 38

Class 1C (Flecainide, Propenone)

Question 39

The ability of some volatile anesthetics to depress the sinoatrial node is a consideration to acknowledge during the administration of phenytoin. Why?

Answer 39

With Phenytoin, conduction of cardiac impulses through the atrioventricular node is improved, but activity of the sinus node may be depressed. So volatiles can double the SA depression.

Question 40

Leukopenia, granulocytopenia, and thrombocytopenia may occur as a manifestation of drug-induced bone marrow depression by which drug?

Answer 40

Phenytoin

Question 41

Which Beta-Blockers are approved for prevention of sudden death following myocardial infarction?

Answer 41

Acebutolol, propranolol, and metoprolol

Question 42

Multifocal atrial tachycardia may respond to esmolol or metoprolol but is best treated with:

Answer 42

Amiodarone

Question 43

Dose of Amiodarone in ACLS

Answer 43

150mg and if not effective 300mg IV for VT or VF resistant to defib

Question 44

What drug can enhance conduction of cardiac impulses through accessory bypass tracts and can dangerously increase the ventricular response rate in patients with Wolff-Parkinson-White syndrome?

Answer 44

Digitalis

Question 45

If you have Wolff-Parkinson-White syndrome, what antiarrythmics would and wouldnt you want to use ?

Answer 45

Do not want to use any drug that depresses the AV node, this would encourage alternate conduction pathways. Avoid CCB, BetaBlockers, Digoxin. Sodium Channel Blockers Potassium Channel Blockers good

Question 46

Digitalis toxicity is a risk and may manifest as virtually any cardiac arrhythmia, Most commonly?

Answer 46

atrial tachycardia with block

Question 47

Can you use Adenosine in WPW?

Answer 47

Apparently, yes according to Stoelting. Ninja says NO lol

Question 48

MOA of Adenosine

Answer 48

Adenosine stimulates cardiac adenosine1 receptors to increase potassium ion currents, shorten the action potential duration, and hyperpolarize cardiac cell membranes.

Question 49

Why is Adenosine so short lived?

Answer 49

elimination half-time 10 seconds) are due to carrier-mediated cellular uptake and metabolism to inosine by adenosine deaminase

Question 50

Side Effects of Adenosine

Answer 50

may produce transient atrioventricular heart block – Bronchospasm has been observed after the IV administration of adenosine