The Heart Flashcards by Michael McMahan

Conduction System consists of what 4 things in what order/

Sinoatrial node

Atrioventricular node

Bundle of His

Purkinje Fibers

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Phase ___
• Rapid depolarization
• Na+ channels open

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Phase ___
• Partial repolarization
• Na+ channels close

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Phase __
• Plateau
• Ca2+ channels open

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Phase ___
• Repolarization
• Ca2+ channels close
• K+ channels open

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Phase \_\_
• Pacemaker/resting
• Degradation of 
membrane potential 
slowly- Ca2+ channels

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What ions act in phase 0?

Na open

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What ions act in phase 1?

Na channels close

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What ions act in phase 2?

Ca open

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What ions act in phase 3?

Ca channels close

K channels open

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What ions act in phase 4?

None active

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_______ period

• Cannot be stimulated

Absolute refractory

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_______ period
• Below the threshold
• Respond to greater-than-normal stimulus

Relative refractory

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QT is rate dependent and

must be adjusted at a HR > ___ bpm

60 (QTc)

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Do women or men generally have longer QT?

Women

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____ arrhythmia:

Occurs in there is an additional ca influx in phase 4 that can result in ectopic beats

Delayed after-depolarization

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Vaughn-Williams Classification
– Na+ Channel blockers
• Subgroups: Ia, Ib, and Ic

Phase 0

Class I

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Vaughn-Williams Classification
- β-adrenoceptor blockers

Phase 2 and 4

Class II

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Vaughn-Williams Classification

K+ Channel blockers

Phase 3

Class III

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Vaughn-Williams Classification

Ca2+ Channel blockers

Phase 2

Class IV

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Vaughn-Williams Classification

Miscellaneous

•Class V

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Class ____ Na+ Channel blockers
• Moderate Na+ Channel blockade
• Eg. quinidine, procainamide, disopyramide

Class Ia

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Class ____ Na+ Channel blockers
• Weak Na+ Channel blockade
• Eg. Lidocaine, Tocainide, Mexilitine, Phenytoin

Class Ib

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Class ____ Na+ Channel blockers

Strong Na+ Channel blockade
Eg. Moricizine, Flecainide, Propafenone

Class Ic

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______ * 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?

- 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

The Heart Flashcards

(79 cards)