Nagelhout CV Pharmacology - Final Flashcards
Cardiac pharm can be summarized by the treatment of which 4 conditions?
-arrhythmias
-HTN
-Angina
-HF
Clinical predictors of increased periop CV risk:
-major risk factors
-Unstable coronary syndrome (recent MI or unstable or sever angina)
-Decomp HF (Class IV)
-Significant arrhythmias (symptomatic)
-severe valve disease
Clinical predictors of increased periop CV risk:
-intermediate risk factors
-mild angina (class I-II)
-previous MI (Q waves)
-comp HF
-IDDM
-Renal insufficiency (Crt > 2)
Clinical predictors of increased periop CV risk:
-minor risk factors
-old age
-abnormal EKG (LVH, LBBB)
-rhythm other than NSR (Afib)
-low functional capacity (<4 METS)
-hx CVA
-uncontrolled systemic HTN
Surgical case risk factors for periop cardiac events
-High Risk (>5%)
-major vasc surgery
-emergent major operations
-prolonged cases with large fluid shift or blood loss
Surgical case risk factors for periop cardiac events
-Intermediate Risk (1-5%)
-carotid endarterectomy
-endovasc aortic aneurism
-H+N surgery
-intraperitoneal or intrathoracic
-ortho
-prostate surgery
Surgical case risk factors for periop cardiac events
-Minor risk (<1%)
-superficial cases
-cataract surgery
-breast surgery
-ambulatory surgery
Periop cardiac risk reduction
-pharmacologic interventions
-beta blockers (continue thru DOS, don’t start DOS)
-statins (start asap after surgery, ok to take thru DOS)
-alpha-2 blockers
-NTG NOT EFFECTIVE
Periop cardiac risk reduction
-non-pharm interventions
-PCI/CABG mixed results on efficacy for periop risk
-monitoring (PAC, CVC, 12 lead EKG, TEE) not shown to effectively prevent
Typically, drugs that depress the heart are _, whereas drugs that stimulate the heart are _
anti-arrhythmic (propofol, anesthetics)
arrhythmogenic (pressors)
Path of electricity thru heart:
_ -> _ -> _ _
SA -> AV -> Purkinje Fibers
Antiarrhythmics
-Class I
Na channel blockers
-“LA effect on heart”
- depression of depolarization
ex)
IA: Quinidine(IA), Procainamide (IA),
IB: Lidocaine, Phenytoin, Tocainide
IC: Flecainide, Propafenone
Antiarrhythmics
-Class II
Beta Blockers
ex) Esmolol, Propranolol, Metoprolol, Timolol, Carvedilol, Nadolol, Acebutolol
Antiarrhythmics
-Class III
K Channel Blockers
-prolongs AP and delays repolarization
ex) Amiodarone, Bretylium, Ibutilide, Sotalol, Dofetilide (Tikosyn)
Antiarrhythmics
-Class IV
Calcium Channel Blockers
-dominant in AV node
ex) Verapamil, Diltiazem
Antiarrhythmics
-Misc/Class V
ex) Adenosine, ATP, Digoxin, Atropine
Increased _ permeability causes depolarization above the atria.
calcium
-causes SA and AV node depolarization
If pt is having an atrial arrhythmia, treat it with a class _ antiarrhythmic.
Class IV (CCB)
Increased _ permeability causes depolarization below the atria.
sodium
-causes purkinje depolarization
If pt is having a ventricular arrhythmia, treat it with a class _ or class _ antiarrhythmic.
Class I or Class III (Na or K Channel blocker)
How do antiarrhythmics that prolong the refractory time help prevent arrhythmias?
-bc an arrhythmia can’t fire increased APs when the cell is already in the repolarization phase
-concept of absolute vs. relative refractory period
-Nag used an example of jumping up in the air and coming back down. You can’t jump again while you’re coming back down. It is akin to extending the “coming down from the air” phase.
Causes of rhythm disturbances
-General causes
-age
-LA dilation
-adrenergic stim
-drug tox
-hypoxia
-hypovolemia
-hemodynamic instability
-reperfusion after CPB
-HTN
-hypo or hyper glycemia
-pulm disease
-beta blocker withdrawal(upregulation of receptors!)
-too light anesthesia
Causes of arrhythmias
-Structural heart disease causes
-CAD
-MI
-CHD
-Cardiomyopathy(CM)
-SSS
-Long QT
-WPWS
-SB
-AVB
Causes of arrhythmias
-Transient Disturbances
-stress(metabolic or not), laryngoscopy, hypoxia, hypercarbia, device malfunctions, surgical stim, CVC
The most common arrhythmia is _
A fib
-clotting is a big risk
1st line goal of treating Afib:
rate control THEN rhythm control
-GOAL HR is < 110
For chronic rate control for Afib, consider _ first, then _
CCB
Beta blocker
T/F Avoid CCB in COPD/DMII pts.
false, avoid BETA BLOCKERS
-beta blockers stimulate the B2 receptor, can cause bronchoconstriction, vasoconstriction, and drops BG
Which is the preferred rate control medication class for Afib for a pt with systolic dysfunction or CAD?
Beta blocker-class II
Which type of medication is used as a last resort in treating Afib if other rate control drugs fail or if you want to try to convert quickly to SR?
Antiarrhythmics (Amio)
T/F We should try to convert chronic Afib pts to SR with meds intraop.
false
-don’t do this; leave them unless they’re symptomatic or acutely develop Afib in your care.
T/F A patient has an arrhythmia that originates in the purkinje system, so giving a CCB or beta blocker would work well.
false!
-only give CCB or BB if arrhythmia originates from AV node, won’t work for ventricular arrhythmias
Best way to urgently convert Afib-RVR:
DC cardioversion
Adenosine is an agonist on which receptors?
Purinergic receptors
How are Labetalol and Esmolol the same? How are they different?
Same:
Both are beta blockers
Differences:
Labetalol is an alpha blocker causing vasocontraction. Longer DOA 3-6 hrs.
Esmolol has a short duration of action of 5-10 min as a result of rapid hydrolysis in the plasma by non-specific esterase enzymes (RBC esterase). Can cause bronchoconstriction (potentially bronchospasm, care w/ asthmatics)
How early should a pt be started on a beta blocker before surgery?
7 days at least
T/F heart failure is #1 cause/risk of morbidity in anesthesia
TRUE
Why do people experience chest pain
-blockage of coronary arteries causes ischemia
-ischemia promotes release bradykinin, and other byproducts that stimulate pain receptors in heart
4 cardinal clinical features of angina
- character = pressure/heavy/squeezing pain (burning or vague pain in atypical)
- site and distribution
- provocation
- duration = builds rapidly w/in 30 seconds and lasts 5-15 minutes
T/F if chest pain lasts only 10 minutes, it’s classified as angina and if it is more than 15 mins, it is an MI
TRUE
Most heart tissue is salvageable if reperfusion occurs within ____ mins
100% within 15 mins
60% within 40 mins
first hour is key
Most angina drugs work by ________. Why?
decreasing cardiac demand because increasing supply is much harder
3 categories of angina
- stable = lesion (predictable, progressive, exertional angina, 80%); <15 mins, s/s subside
- unstable = combination of 1 & 3, angina from lesion and spasm (15% people) >15 mins, s/s persist despite rest/NTG -> MI
- variant = spasm (prinzmetal angina, 5% of people, no lesion)
Exercise induced: stable, unstable, variant
stable = yes
unstable = yes
variant = no/rarely
Occurs at rest: stable, unstable, variant
stable = no
unstable = yes
variant = yes
Night pain: stable, unstable, variant
stable = occasionally
unstable = yes
variant = early morning
T/F many sx of angina are masked by anesthesia
TRUE
ST segment: stable, unstable, variant
stable = depressed
unstable = elevated OR depressed
variant = usually elevated
List some conditions that are detrimental to myocardial oxygen balance
-decrease supply
-increase demand
decreased supply = tachycardia, hypotension, coronary artery spasm, hypocapnia, anemia, hypoxic, low 2,3 DPG
increased demand = tachycardia, increased preload, increased afterload (HTN), increased contractility
What is a strong predictor of perioperative ischemia under anesthesia
tachycardia (higher than 100 usually)
Keep patient’s heart rate less than ____ in OR for greatest benefit (and during ischemia!)
70
Why are beta blockers prescribed for ischemia when they constrict vessels?
They decrease the cardiac demand so much that the constriction is a non issue
Why does nitroglycerin make your chest pain go away
dilates veins in legs, blood pools in legs, decrease preload, demand decreases, pain goes away
First line therapy for ACUTE angina attack
Nitrates! = nitroglycerin
Cornerstone for chronic prophylaxis in angina:
beta blockers
Most effective drug class for variant angina (prinzmetal):
calcium channel blockers
Useful drugs for patients with CAD/angina AND diabetes or vascular disease
ACE inhibitors
Canadian classification of angina
I = does not occur w/normal activity but long or strenuous activity
II = slight limitation of ordinary activity, may occur w/walking or climbing stairs, in the cold, etc
III = marked limitation of ordinal physical activity, walking one block or one flight of stairs at normal pace
IV = inability to carry on ANY physical activity without discomfort, **present at rest*
Contraindications for nitrates
significant or symptomatic hypotension
Side effects of nitrates
-reduction of blood pressure
-headache
-dizziness
-palpitations