The Heart Flashcards
Conduction System consists of what 4 things in what order/
Sinoatrial node Atrioventricular node Bundle of His Purkinje Fibers
Phase ___
• Rapid depolarization
• Na+ channels open
0
Phase ___
• Partial repolarization
• Na+ channels close
1
Phase __
• Plateau
• Ca2+ channels open
2
Phase ___
• Repolarization
• Ca2+ channels close
• K+ channels open
3
Phase \_\_ • Pacemaker/resting • Degradation of membrane potential slowly- Ca2+ channels
4
What ions act in phase 0?
Na open
What ions act in phase 1?
Na channels close
What ions act in phase 2?
Ca open
What ions act in phase 3?
Ca channels close
K channels open
What ions act in phase 4?
None active
_______ period
• Cannot be stimulated
Absolute refractory
_______ period
• Below the threshold
• Respond to greater-than-normal stimulus
Relative refractory
QT is rate dependent and
must be adjusted at a HR > ___ bpm
60 (QTc)
Do women or men generally have longer QT?
Women
____ arrhythmia:
Occurs in there is an additional ca influx in phase 4 that can result in ectopic beats
Delayed after-depolarization
Vaughn-Williams Classification
– Na+ Channel blockers
• Subgroups: Ia, Ib, and Ic
Phase 0
Class I
Vaughn-Williams Classification
- β-adrenoceptor blockers
Phase 2 and 4
Class II
Vaughn-Williams Classification
- K+ Channel blockers
Phase 3
Class III
Vaughn-Williams Classification
- Ca2+ Channel blockers
Phase 2
Class IV
Vaughn-Williams Classification
- Miscellaneous
•Class V
Class ____ Na+ Channel blockers
• Moderate Na+ Channel blockade
• Eg. quinidine, procainamide, disopyramide
Class Ia
Class ____ Na+ Channel blockers
• Weak Na+ Channel blockade
• Eg. Lidocaine, Tocainide, Mexilitine, Phenytoin
Class Ib
Class ____ Na+ Channel blockers
- Strong Na+ Channel blockade
- Eg. Moricizine, Flecainide, Propafenone
Class Ic
______
- MOA: Na+ channel blockade (moderate)
- Use: Treatment of PVC and VT
- ADRs: • Anticholinergic-Dry mouth (32%), constipation, urinary hesitancy
- Cardiac- QT prolongation
- Drug-Drug interactions:• Other anticholinergic medications (i.e. glycopyrrolate or atropine)
- Increased risk of QT prolongation with macrolide antibiotics (i.e. erythromycin or clarithromycin)
Disopyramide
• Brand name: Norpace, Norpace CR
Is what type of drug?
Disopyramide
• Brand name: Norpace, Norpace CR
Class 1a antiarrhythmic meds
- MOA: Na+ channel blockade (weak)
- Use: Treatment of documented life-threatening ventricular dysrhythmias
- ADRs: • GI- nausea, vomiting, heartburn
- Neuro- dizziness, light-headedness, tremors, convulsion (toxic)
- Drug-Drug interactions:• Use the lowest effective dose of local vasoconstrictor
Mexiletine
• Brand name: Mexitil
• MOA: Na+ channel blockade (strong)
• Use: Treatment of documented life-threatening dysrhythmias
• ADRs:
• GI: nausea, vomiting, altered taste, constipation
• Neuro- dizziness
• Drug-Drug interactions:
• Use the lowest effective dose of local vasoconstrictor
MOA= mechanism of action; GI= gastrointestinal; ADR= adverse drug reaction L
Propafenone
• Brand name: Rythmol/Rythmol SR
Is what type of drug?
Mexiletine
• Brand name: Mexitil
Class 1b antiarrhythmic meds
Is what type of drug?
Propafenone
• Brand name: Rythmol/Rythmol SR
Class 1c antiarrhythmic meds
Class _____ Antiarrhythmic medications Dental Implications
• Monitor vital signs (pulse to irregularity)
• Consider stress reduction protocol
• Xerostomia- assess salivary flow as a factor in caries,
periodontal disease, and candidiasis
(most significant with Ia medications)
• After supine positioning, have patient sit upright
for at least 2 minutes before standing to avoid
orthostatic hypotension
• Avoid or limit dose of vasoconstrictor
I Antiarrhythmic medications Na+ Channel blockers-
Class\_\_\_\_ Antiarrhythmic medications • Block sympathetic stimulation to the heart • Decrease heart rate • Decrease automaticity • block NE’s effects on Ca2+ channels • Slow conduction through AV node (increase refractory period) • Prevent ischemia AV nodal blocking agent
Class II β-adrenoceptor blockers
____ drug:
• MOA: selective β1-adrenoceptor blocker
• Use: hypertension, CAD, angina, HF, supra-ventricular arrhythmias
• ADRs:
• Common: hypotension, bradycardia, fatigue, sexual dysfunction, drowsiness
• Drug-Drug interactions:
• Increased hypotension with fentanyl and inhaled anesthetics
• Decreased effect of vasoconstrictors (i.e. epinephrine)
• NSAIDS may reduce the efficacy (> 3 weeks of treatment)
Metoprolol
• Brand name: Lopressor (tartrate) Toprol XL (succinate)
Metoprolol
• Brand name: Lopressor (tartrate) Toprol XL (succinate)
is a Class __ Antiarrhythmic medications
II; β-adrenoceptor blockers
Class __ Antiarrhythmic medications dental implications
• Monitor vital signs
• Consider stress reduction protocol
• Shorter appointments
• After supine positioning, have patient sit upright
for at least 2 minutes before standing to avoid
orthostatic hypotension
• Use vasoconstrictors and inhaled anesthetics with caution
Class 2
Class __ Antiarrhythmic medication
• K+ channel blockers
• Delay repolarization (prolong action potential)
• QT prolongation→→→ risk of TdP
• Agents
• 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)
Class 3
____ drugs
• MOA: K+ channel blocker, also blocks Na+ and Ca2+ channels, b
receptors
• Use: supraventricular and ventricular arrhythmias
• ADRs:
• Effects seven organ systems: eyes, lungs, heart, thyroid, liver, GI, skin
• Drug-Drug interactions:
• Bradycardia and hypotension with vasoconstrictors and inhaled anesthetics
• Increased photosensitivity with tetracycline
• Many interactions secondary to CYP3A4 inhibition
Amiodarone (most effective and most toxic)
• Brand name: Cordarone or Pacerone
Amiodarone (most effective and most toxic)
• Brand name: Cordarone or Pacerone
Is what type of drug?
Class III Antiarrhythmic medications K+ channel blockers
Class ____ Antiarrhythmic medications
MOA: Block calcium from entering cell through voltage
sensitive “slow” L-type channels
• Slow conduction in SA and AV node (non-dihydropyridine)
• heart rate
• AV block
• Shorten plateau (phase 2) of action potential
• Deceased delayed after-depolarization (DAD)
• ectopic beats
IV Calcium Channel Blockers
What are the 2 types of Class IV Antiarrhythmic meds?
Dihydropyridine
Non-Dihydropyridine
Class IV Antiarrhythmic
- Selective for smooth muscle
- End in “dipine”
- Nifedipine
- Amlodipine
- etc….
- Common side effects:
- Reflex tachycardia
- Hypotension
- Peripheral edema
- Gingival Hyperplasia
INcrease HR
Dihydropyridine
Class IV Antiarrhythmic
- Selective for myocardium
- Two agents
- Diltiazem
- Verapamil
- Common side effects:
- Bradycardia/AV block
- Hypotension
- Edema
- Gingival Hyperplasia
Decrease HR
Non-Dihydropyridine
What drug?
• MOA: Non-dihydropyridine calcium channel blocker
• Use: Angina, atrial fibrillation, hypertension
• ADRs:
• Constipation, dizziness, lightheadedness, hypotension, bradycardia,
gingival enlargement
• Drug-Drug interactions:
• Bradycardia and hypotension with general and inhaled anesthetics
• Many interactions secondary to CYP3A4 inhibition
Verapamil
• Brand name: Calan, Isoptin, or Verlan
What class of drug is verapamil • Brand name: Calan, Isoptin, or Verlan
Class IV Antiarrhythmic Ca channel blocker
- 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
Adenosine
Adenosine is what type of drug?
Class V antiarrhythmic
What ion is needed for actin and myosin contraction?
Ca
- amount of blood in left ventricle at the end of diastole
= Preload
LV End Diastolic Volume (EDV)
- pressure heart has to overcome to eject blood
about equal to Systemic blood pressure
Afterload
- amount of blood in left ventricle at the end of systole
LV End Systolic Volume (ESV)
= EDV – ESV (mL)
Stroke Volume (SV): SV
= SV/EDV X 100% (%)
Ejection Fraction (EF): EF
= HR X SV (mL/min)
Cardiac Output (CO): CO
ability of
the heart to contract
Inotropy-
If SV is low, how is EDV affected?
Low too
What is the point where SV and EDV are working as efficiently as possible? Can you go past this point and cause better or worse SV?
Optimal sarcomere length
_____ is a :
Positive Inotropic medications
•Cardiac glycosides
•Digoxin- inhibits Na-K ATPase
Digotoxin
_____ drug:
• MOA: inhibition of Na+-K+ ATPase/ vagal tone to heart
• Use: heart failure, atrial fibrillation (rate-control)
• ADRs (narrow therapeutic index medication):
• Nausea, vomiting, diarrhea
• Bradycardia/ heart block
• Visual disturbances (green-yellow halo)
• Drug-Drug interactions:
• Other drugs that cause bradycardia or hypokalemia
• Increased levels with macrolide antibiotic
• Increase risk of arrhythmia with adrenergic agonists or succinylcholine
Digoxin
• Brand name: Digitek, Lanoxicaps, Lanoxin (available IV/PO)
______ Dental Implications
• Monitor vital signs
• Increased gag reflex may make dental procedures,
such as taking radiographs or impressions difficult
• After supine positioning, have patient sit upright
for at least 2 minutes before standing to avoid
orthostatic hypotension (bradycardia)
• Use vasoconstrictors with caution (adrenergic stimulation)
• Avoid dental light in patient’s eye/offer dark glasses
• Stress reduction protocol
Digoxin-
- MOA: b1- adrenergic receptor agonist
- Use: acute decompensated heart failure, cardiogenic shock
- ADRs:
- Increased heart rate and blood pressure
- Arrhythmias
- Chest pain
- Drug-Drug interactions: none of significance
- Dental Implications: none
DOBUTamine
• Brand name: Dobutrex (only available IV)
- MOA: Phosphodiesterase-3 enzyme inhibitor
- Use: acute decompensated heart failure, cardiogenic shock
- ADRs:
- Arrhythmias (ectopic beats, NSVT, VT)
- Hypotension
- Chest pain
- Drug-Drug interactions: none of significance
- Dental Implications: none
Milrinone
• Brand name: Primacor (only available IV)
• MOA: Sensitize troponin to Ca2+ (inotropy) and KATP channel activation
in smooth muscle (vasodilation)
• Use: acute decompensated heart failure
• ADRs:
• Arrhythmias (ectopic beats, NSVT, VT)- supposedly less than DOBUTamine
• Hypotension
• Headache
• Drug-Drug interactions: none of significance
• Dental Implications: none
Levosimendan
• Brand name: Simdax (not available in the U.S.)
Cardiac myocytes supplied with blood during ______
diastole
Increase in Heart rate leads to less time in diastole leading to _____ blood flow
Decreased blood flow to heart muscle
______ Nervous System
b1 adrenoceptors
• force of contraction (positive inotropic effect)
• heart rate (positive chronotropic effect)
• automaticity
• Repolarization
• Reduced cardiac efficiency
SYMPATHETIC
\_\_\_\_\_\_ Nervous System Muscarinic (M2) receptors • Cardiac slowing • automaticity • Inhibition of AV node conduction
PARASYMPATHETIC
Increase myocardial O2 supply
Organic nitrates
Increase myocardial O2 supply and Decrease O2 demand
Calcium channel blockers-
Decrease myocardial O2 demand
b-adrenocepter antagonists-
improves angina w/o changing BP or HR
Ranolazine-
What class of antianginal drug is the best agent to use for angina?
B blockers
Major side effects • Contraindicated with PDE-5 Inhibitors • Headache • Syncope/hypotension • Tachycardia • Tolerance • Methemoglobinemia
- Nitroglycerin
- Isosorbide dinitrate/mononitrate
- Sodium Nitroprusside
• Contraindicated with PDE-5 Inhibitors
• Organic nitrates
- MOA: Stimulate production of intracellular cGMP
- Use: Angina and heart failure
- ADRs:
- Headache (common), flushing, dizziness, postural hypotension
- Drug-Drug interactions:
- Increased effects with other vasodilator type medications
Isosorbide Mononitrate
• Brand name: Imdur, Ismo
Antianginal Medications _______-:
MOA: Block calcium from entering cell through voltage
sensitive “slow” L-type channels
• Slow conduction in SA and AV node (non-dihydropyridine)
• heart rate
• AV block
• Vasodilatation of arterioles
• Decrease arterial pressure and wall tension
• Decrease myocardial contractility
• Increase flow through areas of fixed coronary obstruction
Calcium Channel Blockers
• MOA: Dihydropyridine calcium channel blocker
• Use: Angina, hypertension, also vasospastic angina
• ADRs:
• Edema (common), dizziness, lightheadedness, hypotension, flushing,
gingival enlargement (rare- but more common than non-DHP)
• Drug-Drug interactions:
• Hypotension with sedatives, opioids, general and inhaled anesthetics
• NSAIDS reduce blood pressure lowering effect
Amlodpine
• Brand name: Norvasc
Antianginal medications \_\_\_\_\_\_\_: • Block sympathetic stimulation to the heart • Decrease heart rate • Decrease automaticity • block NE’s effects on Ca2+ channels • Slow conduction through AV node (increase refractory period) • Prevent ischemia • Decrease myocardial oxygen demand • HR, contractility, SBP
β-adrenoceptor blockers
What are the following drugs used for?
Metoprolol
Atenolol
Carvedilol
B Blockers for antiangina
• MOA:
• inhibits late inward sodium current (Ina) in ischemic myocardium reduced
myocardial wall tension and O2 consumption
• At higher concentrations inhibits rapid delayed rectifier potassium current (Ikr)
prolonged action potential and QT interval
Ranolazine
• MOA: Inhibition of late inward sodium current (Ina)
• Use: Angina
• ADRs:
• Bradycardia, hypotension, dizziness, QT prolongation, TdP, xerostomia
• Drug-Drug interactions:
• Many due to CYP 450 3A4 metabolism
Dental implications:
• Assess salivary flow as a factor in caries, periodontal disease, and candidiasis
• Use vasoconstrictors and inhaled anesthetics with caution
Ranolazine
• Brand name: Ranexa
