The Heart Flashcards
1
Q
conduction system
A
SA node
AV node
bundle of his
purkinje fibers
2
Q
phase 0
(2)
A
rapid depolarization
Na channel sopen
3
Q
phase 1
(2)
A
partial repolarization
Na channels close
4
Q
phase 2
(2)
A
plateau
Ca channels open
5
Q
phase 3 (3)
A
repolarization
Ca channels close
K channels open
6
Q
phase 4
(2)
A
pacemaker/resting
degradation of membrane potential slowly- Ca channels
7
Q
- Absolute refractory period
A
- Cannot be stimulated
8
Q
- Relative refractory period
A
- Below the threshold
9
Q
- Respond to greater-than-normal stimulus
A
- Supernormal excitatory period
10
Q
QT vs. QTc
QT is rate dependent and
must be adjusted at a HR — bpm
A
> 60
11
Q
Prolonged QT
≥ – msec in women
≥ – msec in men
A
460
450
12
Q
Cardiac Arrhythmias
Site
(3)
A
- Atrial
- Junctional
- Ventricular
13
Q
Cardiac Arrhythmias
Rate
(2)
A
- Tachycardia (HR > 100 bpm)
- Ex. Atrial Fibrillation,
SVT, Ventricular
tachycardia, and
ventricular fibrillation - Bradycardia (HR < 60 bpm)
- Ex. Heart block and
asystole
14
Q
Cardiac Arrhythmias
Mechanism
(4)
A
- Delayed after-
depolarization - Re-entry
- Ectopic pacemaker
activity - Heart block
15
Q
Antiarrhythmic Medications
Vaughn-Williams Classification
* Class I –
* Class II-
* Class III-
* Class IV-
* Class V-
A
Na+ Channel blockers
* Subgroups: Ia, Ib, and Ic
β-adrenoceptor blockers
K+ Channel blockers
Ca2+ Channel blockers
Miscellaneous
16
Q
Class I Antiarrhythmic Medications
USE-
A
DEPENDENT CHANNEL BLOCKADE
17
Q
Na+ Channel blockers
* Class Ia
(2)
A
- Moderate Na+ Channel blockade
- Eg. quinidine, procainamide, disopyramide
18
Q
Na+ Channel blockers
* Class Ib
(2)
A
- Weak Na+ Channel blockade
- Eg. Lidocaine, Tocainide, Mexilitine, Phenytoin
19
Q
Na+ Channel blockers
* Class Ic
(2)
A
- Strong Na+ Channel blockade
- Eg. Moricizine, Flecainide, Propafenone
20
Q
Mnemonic
* Class IA- “Double Quarter Pounder”
* Class IB- “Lettuce, Tomato, Mayo, Pickles”
* Class IC- “More Fries Please”
A
- Disopyramide, Quinidine, Procainamide
- Lidocaine, Tocainide, Mexiletine, Phenytoin
- Moricizine, Flecainide, Propafenone
21
Q
Class Ia Antiarrhythmic medications
Disopyramide, Quinidine, Procainamide
Disopyramide
* Brand name:
* MOA:
* Use:
A
Norpace, Norpace CR
Na+ channel blockade (moderate)
Treatment of PVC and VT
22
Q
Class Ia Antiarrhythmic medications
Disopyramide, Quinidine, Procainamide
Disopyramide
ADRs:
(2)
A
- Anticholinergic-Dry mouth (32%), constipation, urinary hesitancy
- Cardiac- QT prolongation
23
Q
Class Ia Antiarrhythmic medications
Disopyramide, Quinidine, Procainamide
Disopyramide
Drug-Drug interactions:
(2)
A
- Other anticholinergic medications (i.e. glycopyrrolate or atropine)
- Increased risk of QT prolongation with macrolide antibiotics
(i.e. erythromycin or clarithromycin)
24
Q
Class Ib Antiarrhythmic medications
Lidocaine, Tocainide, Mexiletine, Phenytoin
Mexiletine
* Brand name:
* MOA:
* Use:
A
Mexitil
Na+ channel blockade (weak)
Treatment of documented life-threatening ventricular
dysrhythmias
25
Class Ib Antiarrhythmic medications
Lidocaine, Tocainide, Mexiletine, Phenytoin
Mexiletine
* ADRs:
(2)
* GI- nausea, vomiting, heartburn
* Neuro- dizziness, light-headedness, tremors, convulsion (toxic)
26
Class Ib Antiarrhythmic medications
Lidocaine, Tocainide, Mexiletine, Phenytoin
Mexiletine
* Drug-Drug interactions:
(1)
* Use the lowest effective dose of local vasoconstrictor
27
Class Ic Antiarrhythmic medications
Moricizine, Flecainide, Propafenone
Propafenone
* Brand name:
* MOA:
* Use:
Rythmol/Rythmol SR
Na+ channel blockade (strong)
Treatment of documented life-threatening dysrhythmias
28
Class Ic Antiarrhythmic medications
Moricizine, Flecainide, Propafenone
Propafenone
* ADRs:
(2)
* GI: nausea, vomiting, altered taste, constipation
* Neuro- dizziness
29
Class Ic Antiarrhythmic medications
Moricizine, Flecainide, Propafenone
Propafenone
* Drug-Drug interactions:
(1)
* Use the lowest effective dose of local vasoconstrictor
30
Class I Antiarrhythmic medications
Na+ Channel blockers-Dental Implications
* Monitor ...
* Consider ...
* Xerostomia-
* After supine positioning, have patient
* Avoid or limit dose of ---
vital signs (pulse to irregularity)
stress reduction protocol
assess salivary flow as a factor in caries,
periodontal disease, and candidiasis
(most significant with Ia medications)
sit upright
for at least 2 minutes before standing to avoid
orthostatic hypotension
vasoconstrictor
31
Class II Antiarrhythmic medications
β-adrenoceptor blockers
* Block sympathetic stimulation to the heart
(3)
* Decrease heart rate
* Decrease automaticity
- block NE’s effects on Ca2+ channels
* Slow conduction through AV node (increase
refractory period)
32
Class II Antiarrhythmic medications
β-adrenoceptor blockers
* Prevent ---
--- blocking agent
ischemia
AV nodal
33
Medication: Metoprolol, Betaxolol, Acebutolol*,
Esmolol, Atenolol, Nebivolol
Receptor Affinity:
β1 >>> β2
34
Medication: Propranolol, Carteolol, Penbutolol*,
Pindolol*, Timolol
Receptor Affinity:
β1 = β2
35
Medication: Butoxamine
Receptor Affinity:
β2 >>> β1
36
Medication: Labetalol & Carvedilol
Receptor Affinity:
β1 = β2 ≥ α1 > α2
37
β1-Selective Antagonist Mnemonic
* “Beta blockers Acting Exclusively At Myocardium”
* Betaxolol
* Acebutelol
* Esmolol
* Atenolol
* Metoprolol
38
Class II Antiarrhythmic medications
β-adrenoceptor blockers
Metoprolol
* Brand name:
* MOA:
* Use:
Lopressor (tartrate) Toprol XL (succinate)
selective β1-adrenoceptor blocker
hypertension, CAD, angina, HF, supra-ventricular arrhythmias
39
Class II Antiarrhythmic medications
β-adrenoceptor blockers
Metoprolol
ADRs:
* Common: (5)
hypotension, bradycardia, fatigue, sexual dysfunction, drowsiness
40
Class II Antiarrhythmic medications
β-adrenoceptor blockers
Metoprolol
Drug-Drug interactions:
(3)
* Increased hypotension with fentanyl and inhaled anesthetics
* Decreased effect of vasoconstrictors (i.e. epinephrine)
* NSAIDS may reduce the efficacy (> 3 weeks of treatment)
41
Class II Antiarrhythmic medications
β-adrenoceptor blockers- Dental Implications
* Monitor ...
* Consider ...
* -- appointments
* After supine positioning, ...
* Use (2) with caution
vital signs
stress reduction protocol
Shorter
have patient sit upright
for at least 2 minutes before standing to avoid
orthostatic hypotension
vasoconstrictors and inhaled anesthetics
42
Class III Antiarrhythmic medication
(3)
* K+ channel blockers
* Delay repolarization (prolong action potential)
* QT prolongation→→→ risk of TdP
43
Class III Antiarrhythmic medication
Agents
(6)
* Amiodarone (exhibits all antiarrhythmic classes activity)
* Dofetilide (pure class III activity)
* Dronedarone (amiodarone analog- less toxic)
* Sotalol (exhibits class III and class II activity)
* Ibutilide (pure class III activity- only available IV)
* Bretylium (no longer available)
44
Mnemonic
Class III- “A Big Dog Is Darn Scary”
* Amiodarone, Bretylium, Dofetilide, Ibutilide,
Dronedarone, Sotalol
45
Class III Antiarrhythmic medications
K+ channel blockers
Amiodarone (most effective and most toxic)
* Brand name:
* MOA:
* Use:
Cordarone or Pacerone
K+ channel blocker, also blocks Na+ and Ca2+ channels, b receptors
supraventricular and ventricular arrhythmias
46
Class III Antiarrhythmic medications
K+ channel blockers
Amiodarone (most effective and most toxic)
ADRs:
* Effects seven organ systems:
eyes, lungs, heart, thyroid, liver, GI, skin
47
Class III Antiarrhythmic medications
K+ channel blockers
Amiodarone (most effective and most toxic)
Drug-Drug interactions:
(3)
* Bradycardia and hypotension with vasoconstrictors and inhaled anesthetics
* Increased photosensitivity with tetracycline
* Many interactions secondary to CYP3A4 inhibition
48
Class III Antiarrhythmic medications
K+ channel blockers- Dental Implications
* Monitor ...
* Consider ...
* --- appointments
* Delay appointment if patient in ---
* After supine positioning,
* Use (2) with caution
* Avoid ...
vital signs
stress reduction protocol
Shorter
distress
have patient sit upright
for at least 2 minutes before standing to avoid
orthostatic hypotension
vasoconstrictors and inhaled anesthetics
dental light in patient’s eye/offer dark glasses (Amiodarone)
49
Class IV Antiarrhythmic medications
Calcium Channel Blockers
MOA:
Block calcium from entering cell through voltage
sensitive “slow” L-type channels
* Slow conduction in SA and AV node (non-dihydropyridine)
* decrease heart rate
* AV block
* Shorten plateau (phase 2) of action potential
* Deceased delayed after-depolarization (DAD)
* decrease ectopic beats
50
Dihydropyridine
Selective for ---
* End in ---
* Common side effects:
(4)
smooth muscle
“dipine”
* Nifedipine
* Amlodipine
* etc....
* Reflex tachycardia
* Hypotension
* Peripheral edema
* Gingival Hyperplasia
51
Non-Dihydropyridine
Selective for ---
* Two agents
(2)
* Common side effects:
(4)
myocardium
* Diltiazem
* Verapamil
* Bradycardia/AV block
* Hypotension
* Edema
* Gingival Hyperplasia
52
Class IV Antiarrhythmic medications
Calcium channel blockers
Verapamil
* Brand name: (3)
* MOA:
* Use: (3)
Calan, Isoptin, or Verlan
Non-dihydropyridine calcium channel blocker
Angina, atrial fibrillation, hypertension
53
Class IV Antiarrhythmic medications
Calcium channel blockers
Verapamil
ADRs:
(6)
* Constipation, dizziness, lightheadedness, hypotension, bradycardia,
gingival enlargement
54
Class IV Antiarrhythmic medications
Calcium channel blockers
Verapamil
Drug-Drug interactions:
(2)
* Bradycardia and hypotension with general and inhaled anesthetics
* Many interactions secondary to CYP3A4 inhibition
55
Class IV Antiarrhythmic medications
Dental Implications
* Monitor ...
* Consider...
* --- appointments
* After supine positioning,
* Use (2) with caution
* Place on frequent recall to monitor for ---
vital signs
stress reduction protocol
Shorter
have patient sit upright
for at least 2 minutes before standing to avoid
orthostatic hypotension
vasoconstrictors and inhaled anesthetics
gingival hyperplasia
56
Class V Antiarrhythmic medications
Unclassified agent
Adenosine
* Produced endogenously
* Binds to the A1 receptor in the AV node causing AV node block
* Used to terminate SVT
* Half-life is 20-30 seconds
* Metabolized by red blood cells and vascular endothelium
* ADRs= flushing, chest pain, shortness of breath
* No dental implications
