Week 6 Vasoactive drugs Flashcards
Autonomic nervous system is made of:
Sympathetic and Parasympathetic
Sympathetic preganglionic fibers are _____ and postganglionic fibers are _____
Short, Long
Inervated organs/target tissue are far away whereas ganglion are located directly beside the spinal cord
What is the goal of the autonomic nervous system?
Maintain homeostasis
Parasympathetic preganglionic fibers are _____ and postganglionic fibers are _____
Long, Short
What is the origin of SNS preganglionic neurons?
Thoracic & Lumbar; T1-L2
What is the origin of PNS preganglionic neurons?
Cervical & Scaral
What is the presynaptic neurotransmitter for SNS?
Acetylcholine
What do preganglionic fibers interact with in the Adrenal glands?
Chromaffin cells
What is the neurotransmitter for postganglionic synapses in the SNS?
Norepinephrine
What is the one exception to the postganglionic neurotransmitter in the SNS?
Sweat glands; Acetycholine
Chromaffin cells release:
80% Epinephrine, 20% Norepinephrine (reversed w/ pheochromocytoma)
When Epinephrine and Norepinephrine are secreted from the Adrenal Medulla, they are then considered
Hormones
What three substances are synthesized in nerve terminals or adrenal medulla?
Epinephrine, norepinephrine, and dopamine
What are the effects of cortisol being secreted from the adrenal cortex?
enhances norepinephrine conversion to epinephrine
What nerve is the major regulator of the parasympathetic nervous system?
Vagus (CNX)
What neurotransmitter is secreted at the postganglionic synapse of the PNS?
Acetylcholine
What are the 5 functions of the vagus nerve?
- Slow HR (negative chronotropic)
- Slow Conduction (negative dromotropic)
- Salivate
- Miosis
- Empties (bladder/rectum)
What 2 Na channel blockers lengthens AP?
procanimide
flecinide
What NA. channel blocker shortens AP?
Lidocaine
T/F Lidocaine is used for long term treatment of arrythmias
FALSE- poor oral bioavalibility
How do Class 1 antiarrythmic medications work? (lidocaine, procanimide, flecainide)
lengthens AP and Phase 0 depolarization to decrease conduction speed
What antiarrythmic increases pacemaker capture threshold?
Flecainide
What is the beta blocker of choice to treat tachycardia perioperatively?
esmolol OR labetalol for tachycardia & HYPERTENSION
What antiarrythmic class is Amiodarone in?
Class III
What neurotransmitter is released from ALL preganglionic auntonomic fibers?
Acetylcholine
What neurotransmitters are released in the ANS and PNS postganglionic fibers?
ANS: Norepinephrine OR Dopamine
PNS: Acetylcholine
_____ activates alpha1 which results in an ______ in blood pressure which causes ______ due to barorecptor response
Phenylephrine, increase, reflex bradycardia
What receptors does epinephrine work on?
Small alpha
Some beta 1 and 2
What receptors does norepinephrine work on?
Large alpha
some beta 1
What receptors does dopamine work on?
Some alpha1 and beta1, small beta2, large dopamine receptor
What receptors does isoproterenol work on?
Large beta1 and beta2
What receptors does dobutamine work on?
Large beta1 small beta2
What are the NATURAL catecholamines?
Epinephrine
Norepinephrine
Dopamine
What are the synthetic catecholamines?
Isoproterenol
Dobutamine
What are the synthetic noncatecholamines?
Ephedrine
Phenylephrine
What receptor does ephedrine act on?
some alpha1, small beta1 and 2
What receptor does phenylephrine work on?
Large alpha1
What sympathomimetic has both direct AND indirect effects?
Ephedrine
What are the effects of alpha 1 receptor stimulation?
vascular smooth muscle constriction (increased SVR), pupil dilation
What are the effects of alpha 2 receptor stimulation?
sedation, bradycardia, vasodialation
What are the effects of beta 1 receptor stimulation?
Positive chronotropic and inotropic effects
increased renin and angiotensin and cAMP
What are the effects of beta 2 receptor stimulation?
bronchodialation, vasodialation, tocolytic
What are the effects of dopamine receptor stimulation?
Increase CO and renal/mesenteric blood flow
D2: inhibits norepi release
What are the three mechanisms that remove neurotransmitters from the synaptic cleft?
- Uptake into presynaptic terminals
- Extraneural uptake
- Diffusion
What is a sympathomimetic?
Drug that produces same effects as catecholamines
What two enzymes metabolize norepinephrine?
COMT and MAO
What are the effects of beta 3?
lipolysis, thermogenesis in brown fat, bladder relaxation
What are the steps to catecholamine synthesis?
Tyrosine-> Dopa -> Dopamine -> Norepinephrine -> Epinephrine
Synthetic non-catecholamines are metabolized by
MAO
What cardiac phase does epinephrine effect?
Increases spontaneous phase 4 depolarization
What is the dose of Epinephrine push to support blood pressure?
2-8mcg
What are the lab changes caused by epinephrine?
Hypokalemia and hyperglycemia
Can epinephrine cross the BBB into the brain/CNS?
No, it is poorly lipid soluble
Why is epinephrine added to local anesthetics?
- decreased bleeding
- vasoconstriction to decrease absorption- thus longer effects
- less absorption leading to cardiotoxicity
What is the effect of epinephrine on diastolic blood pressure?
decreases it, widening the pulse pressure
What is the issue with giving too high of a dose of epinephrine? (10-20mcg)
the alpha stimulation causes an increase in afterload that may impede increases in CO
What is racemic epinephrine for?
stabilizes mast cells for severe croup (subglottic edema) and postextubation. diluted and nebulized must be observed for 2H rebound swelling
what is the dose for anaphylaxis Epi?
0.5-1.5mg
What should be done with 1:1,000 epi?
Dilute or IM for anaphylaxis
How much epi should be given at a time during a code?
1mg of 1:10,000
What is the concentration of “baby epi”?
1:100,000
What two drugs interact with epinephrine?
Halothane: arrythmias
Cocaine: block reuptake
nonselective beta blockers: alpha 1 exaggerated response
What are the effects of norepinephrine?
increased HR, conduction, contractility, SVR
What are 2 cautions in using norepinephrine?
increases O2 consumption and causes metabolic acidosis
What neurotransmitter is secreted from postganglionic sympathetic nerve endings?
norepinephrine
Why does norepinephrine effect drug metabolism?
by decreasing hepatic blood flow
Norepinephine should be used with caution in what patient population?
right sided heart failure due to increased preload
How do you treat pressor extravasation?
phentolamine 5-10mg in 10mL NS
What occurs with administration of dopamine at 0.5-3mcg/kg/min?
d1 and d2 vasodialation
What occurs with administration of dopamine at 3-10mcg/kg/min?
Beta1 and Alpha1 increases
What is the half life of Dopamine?
1-2 minutes
What individuals should use caution with dopamine?
individuals with increased intraocular pressure (increases it even more)
T/F the precursor to dopamine, L-dopa can cross the BBB but dopamine cannot.
TRUE
Dopamine has direct and indirect effects that:
Direct: vasoconstriction, inotropey
Indirect: inotrope that depends on norepinephrine for actions
How is dopamine metabalized?
MAO and COMT
What is the concern with high dose (10-20mcg/kg/min) dopamine?
vasoconstriction combats the renal perfusion effects
What are Dopamines effects on glucose?
can inhibit insulin which can cause hyperglycemia
Why is dopamine good for post cardiopulmonary bypass patients?
increases CO, dialates vascular beds, decreases SVR -> mimics balloon pump
What is the most potent beta sympathomimetic?
isoproterenol
how is isoproterenol metabolized?
COMT
What is the dose of isoproterenol and what is it best at treating?
1-5mcg/min Heart block
What is dobutamine good for?
Heart failure, weaning from bypass
Why do we no longer use isoproterenol for inotropic effects?
dobutamine and milranone are better
When using isoproterenol, the net increase in cardiac output is due to:
Increased systolic blood pressure
Why does isoproterenol cause a DECREASED map?
high risk for arrythmias
decreased coronary blood flow
increase myocardial O2 requirements
Is dobutamine selective or nonselective?
Selective Beta1
What is the dosage for dobutamine?
2-10mcg/kg/min
What medications must be dissolved in D5W and why?
Dopamine and Dobutamine- to avoid inactivation of the catecholamine in an alkaline solution
dobutamine infusion greater than 3 days can cause:
Down regulation which can cause the need to increase dosage
What effects does dobutamine have on the coronary arteries?
vasodialates
What are the effects of ephedrine?
direct: binds to alpha and beta receptors
indirect: inhibits neuronal norepinephrine reuptake and displaces more norepinephrine from storage vesicles
DOSE: 5-15mg
What is the dose for ephedrine?
5-15mg
How does phenylephrine work and what is the dosage?
alpha1 receptors, primarily venoconstriction 50-200mcg bolus
What is a common concern with phenylephrine?
reflex bradycardia due to baroreceptor response to increase in SVR
What is a less common effect of ephedrine?
anti-emetic, 0.5mg/kg IM
Why is the second dose of ephedrine less responsive than the first?
tachyphylaxis
What causes ephedrine tachyphylaxis?
- depletion of norepinephrine stores
- persistent block of receptors
- occupied receptor sites
What is the most common ephedrine supplied dose? dilution?
50mg/mL
dilute into 5mL NS to achieve 10mg/mL concentration
give 0.5mL at a time to give 5mg
What is the most common phenylephrine supplied dose? dilution?
10mg/mL
1. 0.1mL drug in 9.9mL NS = neo stick 100mcg/mL
2. 10mg in 100mL bag = 100mcg/mL
3. 20mg in 250mL bag = 80mcg/mL
4. 10mg in 250ml bag = 40mcg/mL
Does phenylephrine cause arterial or venous constriction?
Venous
How many mcg at a time should be given to support blood pressure?
50-200mcg
What is the dosage for a continuous infusion of phenylephrine?
20-50mcg/min
What receptor does dexmedetomidine work on?
Alpha2
While an alpha agonist causes reflex bradycardia, an alpha antagonist causes
reflex tachycardia
What is the dosage of a vasopressin infusion?
0.04-0.1unit/min
What is the infusion rates for norepinephrine, epinephrine, and dobutamine? (Hint: they’re all the same)
1-20mcg/min
What is the milrinone infusion dosage?
0.375-0.75mcg/min
with or without bolus of 37.5-75mcg/kg
What class of antiarrythmics greatly decreases Phase 0 depolarization?
Class IC
Slightly in Class IA
(blocks NA channels)
What occurs in phase 0 of the cardiac cycle?
NA channels lead to depolarization of the cell
How do class III antiarrythmics effect refractory period?
greatly increased
How do class III antiarrythmics effect action potential?
greatly increased
What is an example of a cardiac glycoside?
digoxin
What are indications for digoxin?
SVT, PAT, Afib, Aflutter, CHF
How does digoxin work?
slows conduction of impulses through AV node
positive inotrope
Why is digoxin not a first choice drug?
increases risks of sudden cardiac death from cardiac dysrhythmias
What is a major concern with digoxin?
Narrow theraputic range; Toxicity
What are the direct and indirect effects of digoxin?
direct: modify electrical and mechanical activity
indirect: evoked by reflex alteration in ANS activity
What ratio of individuals experiencing toxic levels of digoxin show symptoms?
1:5
What is the therapeutic digoxin level?
0.5-2.5ng/mL
What are early signs of digoxin toxicity?
anorexia, n/v
What ekg changes are associated with digoxin toxicity?
atrial or ventricular dysrhythmias, incomplete to complete heart block
How do we treat digoxin toxicity?
correct cause
treat dysrhythmia
pacer if needed
potassium replacement if needed
what drugs can cause digoxin toxicity and why?
diuretics from hypokalemia
What anesthetic drug effects cardiac glycoside levels?
succinylcholine
What sympathomimetics could cause an increased risk of dysrythmias in individuals taking cardiac glycosides?
Beta agonists
what can occur when giving IV calcium to an individual on cardiac glycosides?
dysrythmias
What is the interaction between antacids and digoxin?
decreased GI absorption = subtheraputic levels
What is the MOA of Phosphodiasterase inhibitors?
decreases hydrolysis of cAMP and cGMP to increase intracellular concentrations of CA in myocardium and vascular smooth muscle-> increasing intracellular calcium levels and contractility -> uptake of calcium causes smooth muscle relaxation/ decreased SVR
Amrinone is also know as:
Inamrinone
Why is amrinone no longer used?
milrinone is more potent with less side effects
What is a useful purpose of milrinone in arteriografts?
reverse vasospasm
What causes milrinones long half life?
highly protein bound
Which drug decreases cardiac filling pressures more: dobutamine or milrinone?
milrinone
what are side effects of milrinone?
decreased SVR and venous return could cause hypotension
potentially proarrythmic in CHF
Where in the body is calcium used?
- neuromuscular junction
- skeletal muscle contraction
- cardiac muscle contraction
- blood coagulation
- exocytosis of neurotransmitters
- bone component
What is the effect of calcium on the heart?
positive inotrope
What is the calcium dosage of inotropic purposes?
1000-3000mg
The active form of calcium is:
ionized
acidosis ______ calcium levels, whereas alkalosis ______ calcium levels
increases, decreases
What is the most common type of hypertension?
primary/essential
When should antihypertensive medications be stopped before surgery? why?
continue until surgery
rebound hypertension can occur with abrupt cessation
Metoprolol MOA, dose, onset, and half-life:
selective Beta1 blocker/antagonist
1-5mg IVP
1-5mins
3-7hrs
Labetalol l MOA, dose, onset, and half-life:
nonselective alpha1, beta1and2 antagonist
5-20mg IVP
1-5min
6hrs
Esmolol MOA, dose, onset, and half-life:
selective beta1 blocker/antagonist
500-1000mcg/kg
1-2min
9mins (metab plasma esterases)
Nicardipine MOA, dose, onset, and half-life:
Dihydropyridine CCB
100-400mcg
2-10mins
2-4hrs
Hydralazine MOA, dose, onset, and half-life:
arteriolar dialator
5-20mg
5-20min
2-8hr
Nitroprusside MOA, dose, onset, and half-life:
NO donor
infusion only 0.25-4mcg/kg
1-2min
<10mins
Nitroglycerin MOA, dose, onset, and half-life:
NO donor
20-400mcg
1-2min
1-3min
When administering a beta2 agonist, an ETT decreases MDI dose by what percentage?
50-70%
What is the purpose for selective beta blockers and some examples?
low-mod doses are unlikely to cause bronchospasm and mask hypoglycemia
acebutolol, atenolol, metoprolol, bisoprolol
What is a major concern of using beta blockers?
mask signs of hypoglycemia -> increases risks of coma
What are some examples of nonselective beta blockers?
propranolol, carvedilol, labetalol
What are some side effects of beta blocker use?
bradycardia
heart block
CHF, claudication
bronchospasm
sedation, impotence
angina/MI
What population should nonselective beta blockers be avoided in?
lung patients (asthma, COPD)
selective beta blockers are safe for them
What is an example of a Alpha1 blocker? What are the effects and side effects?
Prazosin
decreases SVR via vasodialation, decreases preload and CO
SE: vertigo, fluid retention, orthostatic hypotension
What are the two most common Alpha2 blockers?
dexmedetomidine
clonidine
Why does dexmedetomidine cause CNS effects while clonidine acts primarily on blood pressure management?
the subtype receptors dex acts on are primarily found in the CNS whereas the ones clonidine work on are in vascular smooth muscle
What are some side effects of Alpha2 agonists?
bradycardia, sedation, decreased pain perception, rash, impotence, ortho hypotension
What is the most common side effect of an ACE inhibitor?
Cough
minor: URI symptoms
What is the most DANGEROUS side effect of an ACE inhibitor?
Angioedema- upper airway blockage = emergency
What is the MOA of an ACE inhibitor?
ACE is the enzyme that converts ang I to ang II, this reaction occurs in the lungs. ACE inhibitors prevent ang I from becoming the more potent ang II
What is the MOA of ARBS?
blocks the vasoconstricting effects of angiotension II without affecting ACE activity
When should ACEs and ARBs be d/c’ed prior to surgery?
12-24 hours prior
What drug might be useful intraoperatively for a patient who routinely takes ACE/ARBs?
vasopressin (assist in the alpha reaction to sympathomimetics)
How do dihyrdopyridine CCBs work?
bind to calcium channels on vascular smooth muscle, promoting vasodilation NICARDIPINE
How do NON dihydropyridine CCBs work?
block calcium channels in heart muscle, reduce Ca in cardiac cells, leading to a decrease in the heart rate and contractions DILTIAZEM
What type of calcium channel blockers have more effect on blood vessles?
dihydropyridines
What type of calcium channel blockers have more effect on the heart?
non-dihydropyridines
what are the two non dihydropyridines?
Verapamil
diltiazem
what are some examples of dihydropyridines?
nifedipine, amlodipine, nicardipine, clevidipine
What are the three conditions dihydropyridines treat?
- hypertension
- prinzmetal angina
- raynaud’s syndrome
What are side effects associated with dihydropyridine use?
reflex tachycardia, negative inotropy, hypoxemia d/t worsening VQ mismatch (shunting)
do nondihydropyridine CCBs also have vasodilatory effects?
yes
What does inhibition of PDE3 cause?
positive inotropy
what does inhibition of PDE cause?
vascular smooth muscle relaxation
What do PDE5 inhibitors treat?
Erectile dysfunction and pulmonary hypertension
What do PDE3 treat?
myocardial infarction, intermittent claudication, heart failure
What are side effects of PDE5s?
headache, flushing, dyspnea
What are side effects of PDE3s?
Ventricular dysrhythmias, headache, hypotension
What does inhaled nitric oxide do?
relaxes pulmonary arterial vasculature & improves ventilation-perfusion matching
Is inhaled nitric approved for the adult population?
NO
What is the “Off label” use of nitric oxide in adults to treat?
severe pHTN in the setting of right heart dysfunction/failure in heart/lung transplants
What would occur if inhaled nitric oxide was stopped abruptly?
rebound pulmonary hypertension
What is the indication for nitrates?
suspected MI, volume overload w/ HF, hypertension
Do nitrates primarily dilate veins or arteries?
veins AND coronary arteries
Whats the MOA of nitrates and SNP?
generates NO stimulates production of cGMP to cause peripheral vasodialation
What’s the rate of a nitroglycerin gtt?
5-600mcg/min
How does SNP work?
interacts with oxyhemoglobin leading to an increase of cGMP to inhibit Ca entry into cell and thus vascular smooth muscle relaxation
What is a major concern associated with a nitroprusside drip and when does it become a valid concern?
Cyanide toxicity
+3 days of administration
>2mcg/kg/min
Nitroprusside side effects:
inhibits platelet aggregation
VQ mismatch/shunting/decreased PaO2
increases ICP
tachy/decreased BP/+inotropy
Coronary steal
decreased renal function
Nitroprusside should be used with caution in what patient population?
neuro peeps/ increases ICP
What is coronary steal and what medication causes it?
vasodilation of a myocardial segment’s vasculature is associated with “steal” of blood from another myocardial segment
nitroprusside
How is cyanide toxicity treated?
d/c SNP
100%O2
sodium bicarb
sodium thiosulfate (150mg/kg)+/ hydroxycobalamin (5mg/kg)
What are the three things caused by cyanide toxicity?
- Anoxic tissue ischemia
- anaerobic metabolism
- Lactic acidosis
What is methemoglobinemia?
an adverse effect of SNP, uncommon
dose to cause exceeds 10mg/kg
What vessels does hydralazine work on?
arteries
What are two major concerns when administering hydralazine?
reflex bradycardia
coronary steal
What patient population should not receive hydralazine?
patients experiencing MI or CAD
What is the sympatholytic of choice for pregnant women?
hydralazine
How does hydralazine affect SVR?
Decreases it
What can occur with long term use of hydralazine?
systemic autoimmune syndrome
What is the dose for hydralazine?
2.5-5mg/5min 20mg max
What is a common nitrate used to prevent angina and to decrease SVR in HF?
Isosorbide dinitrate
How does isosorbide dinitrate work?
similarly to Nitro
What is a side effect of isosorbide?
orthostatic hypotension
Isosorbide dosage:
60-120mg
Why would an MAOI create issues with blood pressure management?
MAOIs alter the break down of catacholimines
What amino acid is the”building block” of catacolimines?
tyrosine
What are the two ways neurotransmitters can be metabolized?
- reuptake
- metabolized by MAO into homovinellic acid
When in the operative period is hypotension most common?
during induction
What is the blood pressure goal during surgery?
Maintain within 20% of baseline with a map of >65
What occurs if we do not maintain our blood pressure goals perioperatively?
MI
AKI
Stroke
Delirium
When should a beta blocker be D/C’ed prior to surgery?
maintained until day of surgery
When should a CCB be D/C’ed prior to surgery?
maintained until day of surgery
What blood pressure necessitates postponing procedure?
SBP >180 or DBP >110
What is the onset time for ephedrine?
2-5min
Why isnt ephedrine used as a drip?
Tachyphylaxis
What is the push dose of ephedrine?
5-15mg/ 1-2 doses over 5-10minutes
What non-catacholamine sympathomimetic is resistant to COMP and MAO?
Ephedrine
What happens if patients taking MAOIs receive ephedrine?
exaggerated hypertensive effect
What is the push dose for phenylephrine?
80-100mcg
What is the onset for phenylephrine?
less than a minute
If a patient is bradycardic and hypotensive, what is the first line medication?
ephedrine
If a patient is nsr-tachy and hypotensive what is the first line medication?
phenylephrine
What is the ratio of baby epi?
1:100,000
What is the normal push dose of baby epi?
2-8mcg every 1-5mins
What is the normal push dose of norepinephrine?
3-12mcg/1-2mins
Why are we less likely to give a push dose of norepinephrine?
higher risk of a lethal dose
What is the push dose for vasopressin?
0.5-1unit
What is the indication to give a push of vasopression?
hypotension in pt’s taking ACE
sepsis
shock
bypass
catecholamine resistance
What medication can be given if vasopressin does not help hypotension?
methylene blue 1-3mg/kg
What is the MOA of methylene blue?
interferes with NO/inhibits vasorelaxants
Pronation and hypotension can cause what adverse event?
blindness
What is our first line treatment for hypertension perioperatively?
increase volatile gas- probably due to ANS/gases cause vasodialation
What physiological process causes thereputic hypertension to occur?
stroke
In what setting could hydralazine cause significant hypotension?
in the presence of nitrates or acute ETOH intoxication
What is the preferred antihypertensive agent for ischemia?
nitroglycerine
What are the two choice drugs for severe acute hypertension?
nitroglycerine and sodium nitroprusside
What are the the two choice drugs for hypertension in the setting of tachycardia?
Esmolol and labetolol
What is the first choice drug for primary/essential hypertension?
thiazide diuretic
What two drug classes are used to manage bradycardia?
anticholinergics: atropine/glyco
catecholamines: epi/ephedrine/isoproterenol
While undergoing cardiopulmonary bypass the ______ artery is a more accurate measurement than the radial.
Brachial
What is Pulsus Paradoxus?
decreases in systolic blood pressure during inspiration
What has higher levels of proteins, plasma or interstitial fluid?
plasma
What is Cushing’s triad?
hypertension
bradycardia
irregular respirations
Cardiac output =
Stroke volume x Heart rate
What is the determining factor of stroke volume?
venous return/preload
What are anesthetic agents effects on cardiac output?
decreased
Why should norepinephrine be used with caution in patients with right sided heart failure?
increase in preload can more advanced failure
High dose dopamine can cause:
reflex bradycardia
T/F dobutamine is a racemic mixture
True
What plant are cardiac glycosides derived from?
foxglove
What could occur with digoxin toxicity and direct current cardioversion?
Ventricular fibrillation
A Frank-Sterling Curve shift to the left indicates:
increased inotropy/CO
What are the effects of digoxin on EKG?
prolonged PR
shortened QTc
ST depression
small T wave
T/F ekg changes related to digoxin go away once drug is cleared
False, EKG changes remain weeks after drug discontinuation
What is a lusitropic state?
relaxation (difficult in diastolic heart failure)
What causes milrinone to have such a long half life?
highly protein bound
What does clonidine treat?
HTN, tremors from CNS stimulants, opioid withdrawls
What is the dosage for dexmetatomidine?
0.1-1.5mcg/kg/min
T/F dexmedetomidine can be stopped abruptly with no issues regardless of dose.
False, withdraw symptoms occur when at high dose for multiple days
What is the push dose for dexmedetomidine?
0.25-1mcg/kg
T/F If a patient is taking propranolol, this affects the metabolism of other drugs such as local anesthetics and fentanyl
True
Whats the difference between metoprolol tartrate and succinate?
tartrate 1/2 life: 2-3hrs
succinate 1/2 life: 5-7hrs
How is esmolol metabolized?
plasma esterases
What is the push dose of esmolol?
0.5mg/kg
What are indications for esmolol?
electroconvulsion therapy, phenochromocytoma excision, thyrotoxicsis, pregnancy, epi/cocaine cardio toxicity
What would occur with absorption of cocaine or epinephrine to an individual taking a beta1 antagonist?
pulmonary edema, cardiovascular collapse
Why is esmolol a painful injection?
It’s acidic
What are contraindications for an esmolol push?
AV block, acute cardiac failure
What is the heart rate goal when giving a beta blocker?
65-80
What part of the cardiac cycle do Beta blockers work in?
decrease rate of phase 4 spontaneous depolarization
How should excessive beta blockade be treated?
7mcg/kg atropine, 2-25mg isoproterenol
glucagon, ca cl, pacer
What two medications should NEVER be given to a patient with excessive Beta blockade?
Epinephrine and dopamine
What cardiac arrythmia does propranolol treat?
torsades
What are the two mixed alpha and beta blockers?
Labatolol and caredilol
What is the ratio of alpha to beta selectivity for labatolol?
1:7
What are the two subtypes of CCBs?
Dihydropyridines and
nondihydropyridines:
phenylalkylamines (verap) and benzothiazapines (Dilt)
How do nondihydropyridines work?
bind to calcium channel to maintain inactive state
What is one thing all CCB’s treat?
coronary artery vasospasm
which nondihydropyridine is a racemic mixture?
verapamil
Verapamil MOA:
racemic mixture: dextro: slows NA channels, levo: slows calcium channels- decreasing AV conduction
Why cant verapamil be given to a patient with WPWS?
could cause ventricular arrythmias
What are the three indications for verapamil?
- SVT
- Angina
- Hypertension
What CCB works best on cerebral vessels?
nimodipine
What can occur with abrupt cessation of CCBs?
coronary vasospasm
What CCB has the most profound vasodilatory effects?
nicardapine
Which CCB comes in a lipid solution?
clevidipine
Which CCB should not be given to patients with hyperlipidemia or pancrentitis?
clevidipine
How do we treat a diltiazem overdose?
dopamine and calcium
What can occur when administering volatile gases to patients on CCB’s?
prolonged PR interval
What are some nonpharmalogical methods to decrease blood pressure?
low sodium diet, weight loss, exercise, fluid restriction
Why arent beta blockers first line for essential hypertension management?
adherance/compliance isssues
What can occur with abrupt cessation of a beta blocker?
angina, MI
What is a serious side effect of beta blocker usage in diabetic individuals?
blunts sympathetic nervous system response to hypoglycemia
What is an indication to give an oral alpha 1 blocker such as prazosin preoperatively?
resection of phenochromatoma
What drug class does clonidine belong to?
alpha2 agonist
How do treat ACE inhibitor inducted angioedema?
0.3-0.5mg of 1:1,000 epinephrine Subq
What type of cardiac issue contraindicates the use of clevidpine?
Aortic stenosis= decreased coronary artery perfussion
What is an example of a PDE5?
Sidenafil, tadalafil, vardenafil
What is the first line medication for SVTs?
Diltiazem; predominantly blocks cl channels in the AV node, slowing conduction
What calcium channel blocker should be avoided in patients with muscular dystrophy?
verapamil- skeletal muscle weakness
How does CRRT affect the half-life of milrinone?
increases; up to 20 hours
What is the drug of choice for fascicular VT?
Verapamil
What causes nitric oxide to become toxic?
When it is oxidized into nitric Dioxide
What can cause the development of cyanide toxicity to be more likely and why?
hypothermia/decreases enzymatic activity and greater accumulation of cyanide
What is an administration consideration for nitroprusside?
must be shielded from light
What happens with coronary steal?
increases ischemic area of MI
What is an administration consideration for amiodarone?
needs a micron filter
What is an administration consideration for nitroglycerine?
needs special non PVC plastic tubing
Nitroglycerine infusions shouldnt be given to patients with what cardiac disease?
hypertrophic obstructive cardiomyopathy & AS
What is the bolus dosage of amiodarone for VT/VF resistant to defibrillation?
300mg bolus
What compound do nitrites need to be active?
thio-compound
How should nitro tolerance be managed?
12-24 hour drug free period, rebound MI from drug free period can occur
what two electrolyte alterations cause an increase in the occurrence of ventricular fibrillation
hypokalemia
hypomagnesmia
What three things cause arrhythmias to occur?
- reentry
- enhanced automaticity
- triggered
what rate increases risks of ventricular arrhythmias; brady or tachy?
brady
how do sodium channel blockers work?
decrease na influx, decrease conduction and velocity of the action potential
how to potassium channel blockers work?
prolong repolarization and duration of the AP/refractory period
class IA prodrug:
procanimide
class IB prodrug:
lidocaine
class IC prodrug:
Flecanide
class II prodrug:
beta blockers: metoprolol, labetolol, and esmolol
class III prodrug:
Amiodarone
What are the two prodrugs in class IV antiarrythmics?
verapamil and diltizam
What cardiac phase do class I antiarrythmics work on?
phase 0 depolarization
+ lidocaine phase 4
what are the effects of class I antiarrythmics on action potential?
classes IA and IC lengthen while class IB shortens
What causes torsades to occur during the cardiac phase?
early depolarization during delayed repolarization
what does bradycardia in the presences of a prolonged QT interval increase the risk of?
torsades event
what class of antiarrythmics treat incessant ventricular tachycardia?
Class IA and IC slow conduction enough
what classes of antiarrythmics treat wide complex tachycardias?
IC and III
in the setting of CHF, being on amiodarone long term can cause high risks of:
Vfib
what is the dosage for procanimide?
100mg IVP and 2-6mg/min
what are the toxic levels of procanimide and lidocaine?
p: >8mcg/ml
l: >5mg/ml
what does phenytoin treat cardiac wise?
decreases ventricular arrhythmias and torsades with dig toxicity
what is the dosage for phenytoin?
100mg/iv
how does phenytoin treat arrhythmia?
decrease automaticity and conduction
what are side effects of phenytoin?
CNS disturbances
What does flecainide treat?
ventricular and atrial/reenty arrythmias such as WPWS
What antiarrythmic class prevents the risk of sudden cardiac dealth?
Beta blockers
T/F the plasma level of amiodarone is higher than the level in the myocardium.
False, myocardial level is 10-50 times higher
What are the major side effects of chronic amiodarone use?
pulmonary toxicity/pheumonitis
What arrythmias can amiodarone cause?
torsades and other ventricular arrythmias
Can amiodarine induced bradycardia be treated with atropine?
No, it is resistant
Grayish blue slate skin discoloration occurs with chronic use of what drug?
amiodarone
What arrythmia can solotol cause?
torsades
What arrythmias do class IV treat?
Afib,flutter, WPWS
What cardiac phase do class IV antiarrythmias work in?
Phase 2 contraction
Verapamil dosage?
5-10mg
Diltiazem dosage?
20mg
What drug should never be given to a patient with WPWS and why?
Diltiazem, enhances conduction of accessory pathways
What is the dosage for Digoxin?
0.5-1mg in two doses in 24hr
Adenosine is an alternate to what medication for SVT?
CCBs
T/F Atrial fibbrilation is an indication for adenosine.
False
What is the dosage for adenosine?
6mg, 12mg, 12mg
What is the MOA of adenosine?
stimulates Adenosine receptors in cardiac muscle that increase intracellular potassium which causes a decrease in AP duration
What two things increase the effects of adenosine?
- dipyridamole
- transplanted heart
Is adenosine safe to use in a patient with WPWS?
yes
What is a frightening thing that occurs when administering adenosine?
transient heart block
How long is the half life of adenosine?
10 seconds, necessitating RAPID IV push
What antiarrythmic can alter thyroid function and why?
amiodarone, high percentage of iodine in the molecule
What can phenytoin NOT be mixed with?
D5W
What is the dose for IVP metoprolol
1-5mg
What drug should not be given to an individual taking PDE5s?
Nitroglycerin
What is the symatholytic of choice to use in an individual who takes PDE5s?
CCBs
What is the most common dysrhythmia that occurs in surgery and what is the frequency?
sinus arrythmia, 70%
What surgeries most commonly yield arrythmias?
cardiac and abdominal
Which volatile gas causes less QT prolongation/less risk of arrythmias?
Sevoflurene
Which inotrope is less effective in a transplanted heart?
dopamine
What drug should be used in a bradycardic emergency in a transplanted heart?
epinephrine and isoprenaline
What is the pneumotic that helps us remember antiarrythmic classes?
Some (sodium blockers)
Block (beta blockers)
Potassium (potassium blockers)
Channels (calcium blockers)
Calcium channel blockers are a ________ inotrope and should not be used in patients with ______ heart failure
negative, systolic
This indicates that it prolongs repolatization
what is the cardiac moa of epi?
increases stimulation of the AV node and decreases the refractory period
why does ephedrine have such a long duration or action?
it is resistant to MOA and COMT
what is the ivp dose of vasopressin?
1-2 unit
What is the preferred treatment for WPWS?
procainamide
Adenosine can be given while lidocaine cannot
What phases of the cardiac cycle are effected by class III antiarrythmics?
Phase 1 and 3
Where do class IV antiarrythmics work in the cardiac cycle?
mostly phase 2
phase 4 in pacemaker cells
Why do we want to shorten the AP (contraction/depolarization) and lengthen repolarizaion period with antiarrhythmics?
less time for ectopic beats to occur
where do class II antiarrythmics work in the cardiac cell?
Phase 4, pacemaker
phase 2, myocyte
What phase of the cardiac cycle do class 1 antiarrythmics work on?
Phase 0 in nonpacemaker
How does lidocaine work since it shortens AP while other sodium channel blockers lengthen the AP?
works on the conduction by decreasing conduction in the SA node to allow AV node to become the primary pacemaker at a lower rate
What is the ACLS dosage of vasopressin?
20 units
What is a contraindication for flecainide?
heart block
