Anti-Arrhythmic Flashcards
1
Q
Cardiac Action Potential Phase 0
A
- Rapid depolarization
- Rapid Na entry; increases membrane potential
- Negative to positive state
2
Q
Cardiac Action Potential Phase 1
A
- Inactivation/closing of Na channels
- K+, Cl- out
3
Q
Cardiac Action Potential Phase 2
A
- “Plateau” phase
- Balance of Ca2+ in, K+ out– causes positive charge
- Contraction of the heart
4
Q
Cardiac Action Potential Phase 3
A
- Rapid repolarization
- Ca2+ channels close, K+ channels stay open until membrane potential reaches -85 to-95 mV in cell
5
Q
Cardiac Action Potential Phase 4
A
- Resting membrane potential
- Heart is relaxed
6
Q
Anti-Arrhythmic drugs: general
A
- Alter membrane ion conduction
- Increase or decrease conduction velocity
- Change the duration of the refractory period
- Suppress abnormal automaticity
7
Q
Vaughn-Williams Classification
A
- Class 1: Na channel blockers (1A, 1B, 1C)
- Class 2: beta blockers
- Class 3: K channel blockers
- Class 4: Ca channel blockers
- Misc. agents (digoxin, adenosine, magnesium, etc.)
8
Q
Class 1: Na channel blockers
A
- Reduce rate and rise of phase 0 and of the AP (slows conduction)
- Oldest anti arrhythmic drug on market
- Groups are broken down by their potency
9
Q
1A
A
- quinidine, procainamide, disopyramide
- Moderately potent (also blocks K+)
- Moderate time to take effect and stay bound to receptor for moderate amount of time
- Increases AP duration and duration of refractory period
- Treats both atrial and ventricular arrhythmias
- Can precipitate new arrhythmias
10
Q
1B
A
- Lidocaine, mexilitene
- Weak potency
- Works very fast and offsets very fast
- Doesn’t reduce AP duration but shortens refractory period
11
Q
1C
A
- Flecainide, propafenone
- Strong potency
- Strongest because they have the slowest time to take effect but stay bound the longest
- Slows conduction velocity but little impact on AP duration and refractory period
- Should NOT be used in those with structural heart disease (need a “normal” heart)
12
Q
Procainamide
A
- Class 1: 1A Na channel blocker
- Moderately potent (also blocks K+)
- Moderate time to take effect and stay bound to receptor for moderate amount of time
- Increases AP duration and duration of refractory period
- Treats both atrial and ventricular arrhythmias
- Active metabolite that is cleared via kidney– would need to monitor renal function
- ADR’s: hypotension (parenteral), lupus-like syndrome (30% get this, usually reversible unless have baseline autoimmune disorder), agranulocytosis, nausea, diarrhea
- Can precipitate new arrhythmias
13
Q
Quinidine
A
- Class 1: 1A Na channel blocker
- Moderately potent (also blocks K+)
- Moderate time to take effect and stay bound to receptor for moderate amount of time
- Increases AP duration and duration of refractory period
- Treats both atrial and ventricular arrhythmias
- Most toxic
- ADR’s: HA vertigo, tinnitus, GI disturbances (significant- N/diarrhea), thrombocytopenia, hemolytic anemia, hepatitis
- Can precipitate new arrhythmias
14
Q
Disopyramide
A
- Class 1: 1A Na channel blocker
- Moderately potent (also blocks K+)
- Moderate time to take effect and stay bound to receptor for moderate amount of time
- Increases AP duration and duration of refractory period
- Treats both atrial and ventricular arrhythmias
- Negative inotrope
- ADR’s: anticholinergic effects (tachy, etc.), exacerbates HF (don’t use in pt’s with HF), increases dig toxicity
- Approved for ventricular arrhythmias
- Can precipitate new arrhythmias
15
Q
Lidocaine
A
- Class 1: 1B Na channel blocker
- Weak potency
- Works very fast and offsets very fast
- Doesn’t reduce AP duration but shortens refractory period
- Therapeutic uses: treats ventricular arrhythmias only
- Used IV or IM; never orally (high 1st pass effect)
- Used for acute ventricular arrhythmias
- ADR’s: CNS toxicity (paresthesia- numbness/tingling, confusion, seizure, tremor)
16
Q
Mexiletine
A
- Class 1: 1B Na channel blocker
- Weak potency
- Works very fast and offsets very fast
- Doesn’t reduce AP duration but shortens refractory period
- Therapeutic uses: treats ventricular arrhythmias only
- Used PO never IV
- Longer duration of activity (t1/2= 8-20 hours)
- ADR’s: CNS toxicity (paresthesia- numbness/tingling, confusion, seizure, tremor), GI upset
17
Q
Flecainide
A
- Class 1: 1C Na channel blocker
- Strong potency
- Strongest because they have the slowest time to take effect but stay bound the longest
- Slows conduction velocity but little impact on AP duration and refractory period
- Generally more well tolerated
- Elimination via liver and kidney
- ADR’s: can cause ophthalmic problems– need routine monitoring of eyes
- Should NOT be used in those with structural heart disease (need a “normal” heart)
18
Q
Propafenone
A
- Class 1: 1C Na channel blocker
- Strong potency
- Strongest because they have the slowest time to take effect but stay bound the longest
- Slows conduction velocity but little impact on AP duration and refractory period
- Generally more well tolerated
- Mild beta-blocking properties (have similar structures to beta blockers)
- ADR’s: proarrythmias/ conduction abnormalities, HF exacerbation, metallic taste/ constipation
- Should NOT be used in those with structural heart disease (need a “normal” heart)
19
Q
Class 2: Beta blockers
A
- Suppression of abnormal pacemaker activity by blocking sympathetic (beta1 receptor) activity in SA/AV node (used for rate control)
- Used s/p MI as prophylaxis against sudden death and vfib (will treat both conditions with one drug)
- Propranolol, metoprolol, esmolol
- ADR’s: bronchospasm, cardiac depression, AV block, hypotension, exercise intolerance, sexual dysfunction
20
Q
Propranolol
A
- Class 2: beta blockers
- Suppression of abnormal pacemaker activity by blocking sympathetic (beta1 receptor) activity in SA/AV node (used for rate control)
- Used s/p MI as prophylaxis against sudden death and vfib (will treat both conditions with one drug)
- ADR’s: bronchospasm, cardiac depression, AV block, hypotension, exercise intolerance, sexual dysfunction
21
Q
Metroprolol
A
- Class 2: beta blockers
- Suppression of abnormal pacemaker activity by blocking sympathetic (beta1 receptor) activity in SA/AV node (used for rate control)
- Used s/p MI as prophylaxis against sudden death and vfib (will treat both conditions with one drug)
- ADR’s: bronchospasm, cardiac depression, AV block, hypotension, exercise intolerance, sexual dysfunction
22
Q
Esmolol
A
- Class 2: beta blockers
- Suppression of abnormal pacemaker activity by blocking sympathetic (beta1 receptor) activity in SA/AV node (used for rate control)
- Used s/p MI as prophylaxis against sudden death and vfib (will treat both conditions with one drug)
- ADR’s: bronchospasm, cardiac depression, AV block, hypotension, exercise intolerance, sexual dysfunction
- Short acting for acute arrhythmias (often used in inpatient setting to get rid of arrhythmias in a short time frame)
23
Q
Class 3: K channel blockers
A
- Mechanism of action: Block K channels to delay repolarization (phase 3)– increases AP and eRP
- Treats both atrial and ventricular arrhythmias
- Increase risk of subsequent arrhythmias (TdP)
- Ibutilide, sotalol
24
Q
Ibutilide
A
- Class 3: K channel blockers
- Mechanism of action: Block K channels to delay repolarization (phase 3)– increases AP and eRP
- Treats both atrial and ventricular arrhythmias
- Increase risk of subsequent arrhythmias (TdP)
- Blocks K, Na, and beta receptors, a good treatment for acute afib w/in 7 days
25
Q
Sotalol
A
- Class 3: K channel blockers
- Mechanism of action: Block K channels to delay repolarization (phase 3)– increases AP and eRP
- Treats both atrial and ventricular arrhythmias
- Increase risk of subsequent arrhythmias (TdP)
- Blocks K and beta receptors, treatment for ventricular arrhythmias and afib
- ADR’s: can cause brady and bronchospasm, cardiac depression, TdP
- No significant DDI’s– good to use if pt is on a lot of meds
- Do not use if LVEF <25%
- Renally cleared
26
Q
Amiodarone
A
- Class 3: K channel blockers
- Mechanism of action: Block K channels to delay repolarization (phase 3)– increases AP and eRP
- Treats both atrial and ventricular arrhythmias
- Increase risk of subsequent arrhythmias (TdP)
- Has class 1, 2, &4 electrophysiological properties– broad spectrum of therapeutic action (widely used)
- t1/2= 1-10 weeks, takes long time to reach steady state
- DDI’s: digoxin and warfarin + more!
- ADR’s: pulmonary fibrosis, hepatic dysfunction, grey-blue skin, corneal deposits, hypo/hyperthryoidism (mainly composed of iodine)
- Important to be diligent with monitoring (need to check thyroid/liver function tests and get CXR as baseline and check repeatedly), no skin or eye tests but looking for them and referring if comes up
27
Q
Dofetilide (Tikosyn)
A
- Class 3: K channel blockers
- Mechanism of action: Block K channels to delay repolarization (phase 3)– increases AP and eRP
- Treats both atrial and ventricular arrhythmias
- Increase risk of subsequent arrhythmias (TdP)
- Blocks only K
- Treatment and prophylaxis of afib
- ADR’s: proarrhythmic: must be started inpatient; provider must be registered to prescribe and pharmacy to dispense (72 hr monitoring)
- DDI: with HCTZ and verapamil
28
Q
Dronedarone
A
- Class 3: K channel blockers
- Mechanism of action: Block K channels to delay repolarization (phase 3)– increases AP and eRP
- Treats both atrial and ventricular arrhythmias
- Increase risk of subsequent arrhythmias (TdP)
- May also block Ca, Na currents
- Strong CYP 3A4 interactions
- Lacks iodine atoms
- ADR’s: GI intolerance, lacks pulmonary/thyroid/hepatic effects vs amiodarone
- May be a little safer but can’t use in pt’s with decompensated HF
29
Q
Class 4: Ca Channel blockers
A
- Mechanism of action: slows conduction in AV node by blocking Ca channels, used for rate control
- Non-DHP’s only: benzothiazepine- diltiazem, and phenylalkylamine- verapamil
- Good alternative to beta blockers in those with asthma/COPD
- ADR’s: constipation, hypotension, heart block, exacerbation of HF
30
Q
Verapamil
A
- Class 4: Ca channel blockers
- Mechanism of action: slows conduction in AV node by blocking Ca channels, used for rate control
- Good alternative to beta blockers in those with asthma/COPD
- ADR’s: constipation, hypotension, heart block, exacerbation of HF
- DDI’s: with digoxin, dofetilide, simvastatin, lovastatin
31
Q
Diltiazem
A
- Class 4: Ca channel blockers
- Mechanism of action: slows conduction in AV node by blocking Ca channels, used for rate control
- Good alternative to beta blockers in those with asthma/COPD
- ADR’s: constipation, hypotension, heart block, exacerbation of HF
32
Q
Digoxin
A
- Misc. Group
- Inhibits Na/K/ATPase transport system: increases intracellular Na/Ca (increases contractility)
- Increase vagal efferent activity: reduces SA firing rate (decreased HR) and reduces conduction velocity
- Requires therapeutic drug monitoring
- DDI’s: multiple, watch for K and Mg levels