The Heart Flashcards
what is the order of the conduction system
- SA node -> AV node -> bundle of his -> Purkinje fibers
what happens in phase 0 of cardiac AP
- rapid depolarization
- Na+ channels open
what happens in phase 1 of cardiac AP
- partial repolarization
- Na+ channels close
what happens in phase 2 of cardiac AP
- plateau
- Ca2+ channels open
what happens during phasse 3 of cardiac AP
- repolarization
- Ca2+ channels close
- K+ channels open
what happens in phase 4 of cardiac AP
- pacemaker/resting
- degradation of membrane potential slowly- Ca2+ channels
whatis the absoluate refractory period
cannot be stimulated
what is the relative refractory period
- below the threshold
- respond to greater than normal stimulus
what are the 3 types of refractory period
- absolute refractory period
- relative refractory period
- supernormal excitatory period
what happens during the P wave
atrial depolarization
what happens during the PR interval
time to start of atrial depolarization to start of ventricular depolarization
what happens during th QRS complex
ventricular depolarization also includes atrial repolarizationwh
what happens during the T wave
ventricular repolarization
what happens during the QT interval
time between start of ventricular depolarization and end of repolarization
QT is ______ and must be adjusted at a HR of ______ bpm
rate dependent; greater than 60 bpm
what is prolonged QT in men and women
- women: greater than 460msec
- men: greater than 450 msec
what are the sites of arrhythmias
- atrial
- junctional
- ventricular
what are examples of tachycardia
- a fib
- SVT
- ventricular tachycardia
- ventricular fibrillation
what are examples of bradycardia
heart block and asystole
what are the mechanissm of cardiac arryhthmias
- delayed after depolarization
- re-entry
- ectopic pacemaker activity
- heart block
what are class I antiarrhythmic medications
- Na+ channel blockers
- subgroups: Ia, Ib, and Ic
what are class II antiarrhythmic medications
beta adrenoreceptor blockers
what are class III antiarrhythmic medications
K+ channel blockers
what are class IV antiarrhythmic medications
Ca2+ channel blockers
what are class V antiarrhythmic medications
miscellaneous
what phase do B agonists work on
stimulate phase 4
where do class I antiarrhythmic medications work
inhibit phase 0
where do class II antiarrhythmic medications work
stimulate phase 2
where do class IV antiarrhythmic medications work
inhibit phase 2
where do class III antiarrhythmic medications work
inhibit phase 3
what do class Ia antiarrhythmic meds do and give examples
- moderate Na+ channel blockade
- quinidine, procainamide, disopyramide
- increase ERP
what do class Ib antiarrhythmic meds do
- weak Na+ channel blockade
- Lidocaine, tocainide, mexilitine, phenytoin
- decrease ERP
what do class Ic antiarrhythmic meds do and what are exmaples
- strong Na+ channel blockade
- moricizine, flecainide, porpafenone
- increased ERP = increased QT duration
what is the brand name, MOA, use, ADRs, and drud-drug interactions of disopyramide
- brand name: norpace, norpace CR
- MOA: Na+ channel blockade (moderate)
- use: tx of PVC and VT
- ADRs: anticholinergic- dry mouth, constipation, urinary hesitancy, cardiac QT prolongation
- drug: drug interactions: other anticholinergic meds, increased risk of QT prolongation with macrolide antibiotics
what is the brand name, MOA, use, ADRs, and drud-drug interactions of mexiletine
brand name: mexitil
- MOA: Na+ channel blockade- weark
- use: treatment of documented life threatening ventricular dysrhythmias
- ADRs: nausea, vomiting, heartburn, dizziness, light headedness, tremors, convulsion
- Drug: drgu interactions: use the lowest effective dose of vasoconstrictor
what is the brand name, MOA, use, ADRs, and drud-drug interactions of propafenone
brand name: rythmol/rythmol SR
- MOA: Na+ channel blockade- strong
- use: treatment of documented life threatening ventricular dysrhythmias
- ADRs: nausea, vomiting, altered taste, constipation, dizziness
- Drug: drgu interactions: use the lowest effective dose of vasoconstrictor
what are the dental implications with Na+ channel blockers
- monitor vital signs - pulse to irregularity
- considers tress reduction protocol
- xerostomia- assss salivary flow as a factor of caries, perioodntal 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
what do beta adrenoreceptor blockers/class II meds do
- block sympathetic stimulation to the heart
- decrease HR
- decrease automaticity
- block NEs effects on Ca2+ channels
- slow conduction through AV nodes ( increase refractory period)
- prevent iscemia
- AV nodal blocking agent
what is the receptor affinity for metoprolol, betaxolol, acebutol, esmolol, atenolol, nebivolol
B1»_space;» B2
what is the receptor affinity for propranolol, careolol, penbutolol, pindolol, timolol
B1= B2
what is the receptor affinity for butoxamine
B2»_space;> B1w
what is the receptor affinity for labetalol and carvedilol
B1 = B2 > A1 > a2
what is the mnemonic for B1 selective antagonist
- “Beta blockers Acting Exclusively At Myocardium”
- Betaxolol
- Acebutol
- Esmolol
- Atenolol
- Metoprolol
what is the brand name, MOA, use, ADRs, and drud-drug interactions of metoprolol
- brand name: lopressor (tartrate), Toprol XL (succinate)
- MOA: selective B1 adrenoreceptor blocker
- use: hypertension, CAD, angina, HF, supraventricular arrhythmias
- ADRs: hypotension, bradycardia, fatigue, sexual dysfunction, drowsiness
- drug: drug interactison: icnreased hypotension with fentanyl and inhaled anesthetics. decreased effect of vasoconstrictors
- NSAIDS may reduce the efficacy greater than 3 weeks of tx
what are the dental implications for B adrenoreceptor blockers
- monitor vital signs
- consider stress reduction protocol
-shorter apppointments - after supine positioning ahve patient sit upright for at least 2 monutes before standing to avoid orthostatic hypotension
- use vasoconstrictors and inhaled anesthetics with caution
what do class III antiarrhythmic medication
- K+ channel blockers
- delay repolarization ( prolong AP)
- QT prolongation -» risk of Tdp
- agents: amiodarone (all classes activity)
- dofetilide ( pure class III)
- dronedarone (amiodarone analog- less toxic)
- sotalol ( exhibits class III and II activity)
- ibutilide ( pure class III activity)
what is the mnemonic for class III drugs
- A Big Dog Is Darn Scary
- amiodarone
- bretylium
- dofetilide
- Ibutilide
- Dronedarone
- Sotalol
what is the brand name, MOA, use, ADRs, and drud-drug interactions of amiodarone
- brand name: cordarone or pacerone
- MOA: K+ channel blocker, also blocks Na+ and Ca2+ channels, beta receptors
- use: supraventricular and ventricular arrhythmias
- ADRs: seven organ systems: eyes, lungs, heart, thyroid, liver, GI, skin
- drug to drug itneractions: bradycardia and hypotension with vasoconstrictors and inhaled anesthetics. increased photosensitivity with tetracycline. many interactions secondary to CYP3A4 inhibition
what are the most effective and most toxic class III drugs
amiodarone
what are the dental implications with class III drugs
- monitor vital signs
- consider stress reduction protocol- short appointments, delay appointment if pt is in distress
- after supine positioning, have pt sit upright for at least 2 minutes before standing to avoid orthostatic hypotension
- use vasoconstrictors and inhaled anesthetics with caution
- avoid dental light in patients eyes/offer dark glasses with amiodarone
what is the MOA with class IV drugs
- calcium channel blockers
- block calcium from entering the cell through voltage sensitive slow L type channels
- slow conduction in SA and AV node (non-dihydropyridine)
- decreased HR
- AV block
- shorten plateau ( phase 2) of AP
- deceased delayed after depolarizaation (DAD)
- decreased ectopic beats
describe dihydropyridine class IV drugs
- selective for smooth muscle
- end in “dipine”
- common side effects: reflex tachycardia, hypotension, peripheral edema, gingival hyperplasia
describe non- dihydropyridine class IV drugs
- selective for myocardium
- diltiazem and verapamil
- common SE: bradycardia/AV block, hypotension, edema, gingival hyperplasia
what is the brand name, MOA, use, ADRs, and drud-drug interactions of verapamil
- brand name: calan, isoptin, or verlan
- MOA: non dihydropyridine calcium channel blocker
- use: angina, a fib, 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
what are the dental implications with Class IV drugs
- monitro vital signs
- consider stress reduction protocol
- shorter appointments
- after supine positioning have pt sit upright for at least 2 minutes before standing to avoid orthostatic hypotension
- use vasoconstrictros and inhaled anesthetics with caution
- place on frequent recall to monitor for gingival hyperplasia
describe adenosine
- class V antiarrhythmic meds
- 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 RBCs and vascular endothelium
- ADRs = flushing, chest pain, SOB
- no dental implications
what is EDV
amount of blood in LV after diastole
LV EDV =
preload
what is afterload
pressure heart must overcome to eject blood
afterload =
systemic BP
what is ESV
amount of blood in LV at the end of systole
what is the formula for SV
SV = EDV - ESV
what is the formula for ejection fraction
EF = SV/EDV x100%
what is the formula for CO
CO= HR x SV
what is inotropy
ability of the heart to contract
what are the positive inotropic medications
- cardiac glycosides
- digoxin- inhibits Na-K ATPase
- DOBUTamine -B1 adrenoreceptor agonist
- milrinone- phosphodiesterase inhibitor
-levosimendan- calcium sensitizer
what is the brand name, MOA, use, ADRs, and drud-drug interactions of digoxin
- brand name: Digitek, lanoxicaps, Lanoxin
- MOA: inhibition of Na-K+ ATPase/ increases vagal tone to heart
- use: HF, A fib (rate-control)
- ADRs: narrow therapeutic index. 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
what are the dental implications with positive inotropic medications
- monitor vital signs
- increased gag reflex may make dental procedures such as taking radiographs or impressions difficult
- after supine positioning have pt sit upright for at least 2 minutes before standing to avoid orthostatic hypotension
- use vasoconstrictors with caution - adrenergic stimulation
- avoid dental light in pt eyes
- stress reduction protocol
what is the brand name, MOA, use, ADRs, and drud-drug interactions of DOBUTamine
- brand name: Dobutrex
- MOA: beta1 adrenergic receptor agonist
- use: acute depressed HF, cardiogenic shock
- ADRs: increased HR and BP, arrythmias, chest pain
- drug: drug interactions: none of significance
what are the dental implications with DOBUTamine
none
what is the brand name, MOA, use, ADRs, and drud-drug interactions, and dental implications of milrinone
brand name: primacor
- MOA: phosphodiesterase 3 enzyme inhibitor
- use: acute decompensated HF, cardiogenic shock
- ADRs: arrhythmias, hypotension, chest pain
- drug: drug interations: none
- dental implications: none
what is the brand name, MOA, use, ADRs, and drud-drug interactions, and dental implications of levosimendan
- brand name: simdax ( not available in US)
- MOA: sensitize to troponin to Ca2+ and KAtp channel activation in smooth muscle
- use: acute decompensated HF
- ADRs: Arrhythmias, hypotension, headache
- drug: drug interactions: none
- dental implications: none
what is the function of myocardial O2 supply
- arterial O2 content: decreased anemia and hypoxia
- coronary blood flow: decreased atherosclerosis and vasospasm
myocardial oxygen supply is a function of:
HR
cardiac myocytes supplied with blood during:
diastole
increased HR = _____ time in diastole
decreased
what are the MVO2 determinants
- HR
- myocardial contractility
- myocardial wall stress: preload and afterload
what do B1 adrenoreceptors do
- sympathetic NS
- increased force of contraction (positive inotropic effect_
- increased HR (positive chronotropic effect)
- increased automaticity
- repolarization
- reduced cardiac efficiency
what do muscarinic receptors do
- parasympathetic NS
- cardiac slowing
- decreased automaticity
- inhibition of AV node conduction
coronary artery disease can lead to:
- stable ischemic disease
- acute coronary syndromes: UA, NSTEMI, STEMI
what ACS syndroms have No ST elevation to the most ST elevation
- UA -> NSTEMI -> STEMI
what is the pathophysiology of IHD and ACS
mismatch of myocardial O2 supply and demand
what are the antianginal meds and what do they do
- organic nitrates: increased myocardial O2 supply
- calcium channel blockers - increased myocardial O2 supply and decreased O2 demand
- Beta- adrenoreceptor antagonists: decreased myocardial O2 demand
- ranolazine: improves angina without changing BP or HR
- Ivabradine- not approved for use in US
double product =
HR x SBP
what are the forms of antianginal meds
- organic nitrates: nitroglycerin and isosorbide dinitrate/mononitrate
- sodium nitroprusside
what are the major SE of antianginal meds
- headache
- tachycardia
- methemoglobinemia
- syncope/hypotension
- tolerance
antianginal meds are contraindcated with:
PDE-5 inhibitors
what are the available products for organic nitrates
- SL tablets
- spray
- intravenous
- ointment
- patch
- capsules
- LA tablets (ISMN and ISDN)
which organic nitrate forms are immediate relief
SL tablets, spray, IV, ointment
what is the brand name, MOA, use, ADRs, and drug to drug interactions for isosorbide mononitrate
- brand name: Imdur, Ismo
- MOA: stimulate production of intracellular cGMP
- use: angina and HF
- ADRs: headache, flushing, dizziness, postural hypotension
- drug: drug interactions: increased effects with other vasodilator type meds
what are the dental implications with organic nitrates
- monitor vital signs
- stress reduction protocol
- after supine positioning, have pt sit upright for at least 2 mins before standing to avoid orthostatic hypotension
- use vasoconstrictors with caution
- sublingual nitroglycerin available for acute angina attack
what is the MOA for calcium channel blockers for anitanginal meds
- block calcium from entering cell through voltage sensitive slow L-type channels
- slow conduction in SA and AV node: decreased HR, AV block
- vasodilation of arterioles
- decrease arterial pressure and wall tension
- decrease myocardial contractility
- increase flow through areas of fixed coronary obstruction
what are the two types of antianginal medications that are calcium channel blockers
- dihydropyridine
- non- dihydropyridine
what is the brand name, MOA, use, ADRs, and drud-drug interactions of amlodipine
- brand name: norvasc
- MOA: dihydropyridine calcium channel blocker
- use: angina, HTN, vasospastic angina
- ADRs: edema, dizziness, lightheadedness, hypotension, flushing, gingival enlargement
- drug: drug interactions: hypotension with sedative, opioids, general and inhaled anesthetics. NSAIDs reduce bloos pressure lowering effect
what do beta adrenoreceptor blockers do as antianginal meds
- block sympathetic stimulation to the heart
- decrease HR
- decrease Automaticity
- block NEs affects on Ca2+ channels
- slow conduction through AV node (increase refractory period)
- prevent ischemia
- decrease myocardial oxygen demand
- decrease HR, contractility and SBP
prefer _________ B1 selective agents for angina
non-selective
what are the most common meds used to treat angina
beta blockers
what is the MOA of ranolazine
- inhibits late inward sodium curren in ischemic myocardium - reduced myocardial wall tension and O2 consumption
- at higher concentrations inhibits rapid delayed rectifier potassium current - prolonged action potenial and QT interval
what is the brand name, MOA, use, ADRs, and drud-drug interactions, and dental implications of Ranolazine-
- brand name: ranexa
- MOA: inhibition of late inward sodium current
- 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 of vasoconstrictors and inhaled anesthetics with caution
