Therapeutics - Arrhythmias Part 1 Flashcards
a normal sinus rhythm (NSR) originates where? where transmitted?
what is a normal rate?
originates at SA node (pacemaker)
transmitted through the AV node to the His-Purkinje system
normal is 60-100 beats/minute
define arrhythmia
anything other than NSR
if SA node fails, what takes over next?
AV node/his purkinje system
but much slower
3 categories to classify arrhythmias
above the bundle of His = supraventricular arrhythmia
below the bundle of His = ventricular arrhythmias (prolly emergency)
conduction blocks
true or false
supraventricular arrhythmias have NORMAL QRS complexes
true
what are the different types of conduction blocks
1st, 2nd, 3rd degree
left or right bundle branch block
essentially a diconnect between the atria and the ventricles
what is the heart rate in sinus bradycardia
less than 60bpm
true or false
sinus bradycardia is a supraventricular arrhythmia
true
true or false
decreased vagal tone causes sinus bradycardia
FALSE - increased vagal tone (parasympathetic)
2 meds that can cause sinus bradycardia
beta blockers
verapamil
give 2 scenarios in which a patient presenting with sinus bradycardia is not a concern
when asleep
athletes - have such strong contractions that their heart doesnt need to beat as fast
5 signs of hypoperfusion
altered mental status
hypotension
shock
angina
acute heart failure
can sinus bradycardia cause hypoperfusion?
YES
treatment regimen for sinus bradycardia
FIND THE CAUSE - could be from a med, MI, or just that the patient is very athletic and fit. may not need treatment
if treatment is needed - 1mg of IV atropine every 3-5 mins for a max of 3mg
if atropine fails, can use transcutaneous pacing (electrodes to set pace), dopamine, epinephrine
dose of atropine for sinus bradycardia
1mg IV repeated every 3-5 mins for a max of 3mg
Sinus tachycardia is what heart rate
over 100bpm
true or false
sinus tachycardia is a ventricular arrhythmia
false - supraventricular
2 potential causes of sinus tachycardia
-the body’s reflex to maintain blood pressure and cardiac output
medications
can be a normal response! - ie: when exercising
can sinus tachycardia cause signs of organ hypoperfusion
yes
what meds can cause sinus tachycardia
anything that is sympathetic
ie - epinephrine, caffeine, nicotine, cocaine
OR anything that BLOCKS the parasympathetic – atropine
true or false
atropine makes the heart rate decrease
false - INCREASE
treatment algorithm for sinus tachycardia (no doses yet)
like bradycardia - find the cause and correct.
can do vagal maneuver to decrease vagal tone (decrease sympathetic tone) – increasing intrabdominal pressure does this
1ST LINE - adenosine
for chronic treatment if needed - beta blocker or non DHP CCB
as mentioned, adenosine is 1st line to treat sinus tachycardia
what is the dose
6mg IV bolus
repeat with 12mg bolus every 2 mins to max of 30mg
after the bolus - flush the line so it all gets in the body
does atropine work right away to treat sinus tachycardia?
YES
patient counseling points when they’re given adenosine (for sinus tachycardia)
what can they expect?
chest heaviness, flushing, wheeze/SOB in asthma
also, may feel their heart stop at first - this is normal
patient’s HR is 38bpm
They are a swimmer
what is course of action
NOTHING - no concern. patient is physically fit and their heart is likely very strong and doesnt have to pump very often
patient’s HR is 129bpm after exercising. they are very out of breath
what is course of action
NOTHING - this is a physiologic response
should resolve in 1-2 mins. if it’s still happening after like hours later, then we may start something
in which arrhtyhmia may a patient’s EKG appear “irregularly regular” ventricular rate with no readable p waves
atrial fibrillation
the ventricular rate in an afib patient can range from ___ to ___
normal to RVR (160 - rapid ventricular rate)
“3 pillars” of atrial fibrillation
paroxysmal (7 days or less)
persistent (over 7 days)
permanent
true or false
we do not treat paroxysmal a fib patients
FALSE - there is a high probability that the arrhythmia will come back once it is gone. we treat chronically
a big part of a fib management is reducing stroke risk.
patients are ____ as indicated after bleed risk has been calculated
anticoagulated
as far as symptom management of a fib, it is really ___ vs ___
rate control vs rhythm control
overweight patient has afib
what is recommendation
over 10% weight loss
true or false
caffeine must be avoided in all afib patients
false - only if it triggers the afib
true or false
inactivity is a risk factor for arrhythmia
true
what is the site of clot formation in afib patients
the left atrial appendage
the AFFIRM, RACE, PIAF trials all compared rate vs rhythm control in afib patients
what was the ultimate conclusion
all the patients received oral anticoagulants - just differed in rate vs rhythm control
really no difference - except 1-2 trials concluded that patients on antiarrhythmics had better exercise tolerance – but that’s about it
while previous trials showed that there is essentially no benefit of antiarrhythmics over rate control drugs for afib, what did a newer study conclude?
EAST-AFNET trial in 2020 showed that EARLY rhythm control showed better outcomes
this conclusion is not very clinically relevant rn - but things could change
RATE CONTROL:
what is the goal resting heart rate for afib patients
100-110 bpm
dont NEED to get below 100
3 general rate control options for afib patients
beta blockers
non DHP calcium channel bloc.
digoxin
true or false
theoretically, ANY beta blocker can be used for rate control in afib patients
TRUE - just need to select for comorbidities
ie - pick selective if pt has asthma, 1 of the 3 options for heart failure if the pt has heart failure
for acute rate control for afib, what is the loading dose of metoprolol tartrate?
maintenance?
5mg IV over 5 mins
maintenance is 25mg-100mg PO BID
3 metoprolol tartrate contraindications
2nd or 3rd degree heart block
sick sinus syndrome
severe bradycardia (WILL SLOW HEART MORE)
2 patients in which metoprolol tartrate should be avoided (not necessarily contraindicated
hyperreactive airway (asthma)
diabetics - may make it hard to see if hypoglycemic
true or false
both non DHP and DHP can be used as rate control in afib patients
FALSE - only non DHP
loading dose verapamil for acute rate control for afib
maintenance?
loading - 5-10mg IV over 2 mins. can repeat in 15-30 mins 10mg. then 5-10mg/hr infusion
maintenance - 40-120mg PO TID (or long acting)
true or false
non DHP’s (verapamil and diltiazem) MUST BE AVOIDED IN HFREF
TRUE - CAN EXACERBATE HEART FAILURE
consideration when prescribing verapamil
watch for 3A4 DDI
verapamil brand names
calan, verelan
true or false
digoxin is used for rhythm control in afib patients
FALSE - rate control
true or false
beta blockers and non DHP calcium channel blockers are generally preferred rate control agents over digoxin, because they are better than digoxin at maintaining normal sinus rhythm
TRUE
important note about digoxin when looking for rhythm control results
the max response may take hours bc of long distribution phase
explain the dosing of digoxin and why this is the case
loading dose IV is 1-1.5mg – split up q 6 hours. bc every patient’s heart responds differently to cardiac glycosides - have to see how patient tolerates
true or false
digoxin dose needs to be adjusted for renal dysfunction
true
the serum concentrations of digoxin should be kept below….
1.2mcg/L
true or false
digoxin is CI in HFREF
false - it’s okay if necessary
any DDI concern with dogoxin?
watch for p-glycoprotein interactions!
inhibitors - vreapamil, quinidine, flecainide, amiodarone, propafenone
maintenance dose digoxin
start at 0.125mg eveyr other day
eventually to 0.5mg QD
true or false
digoxin is given as a single IV push for acute rate control
FALSE - given in divided doses. unpredictable response from pt to pt
1 good thing about digoxin over b blockers and non DHP CCB
no effect on blood pressure! good if the patient has low BP and we dont want to lower anymore
digoxin afib controversey
possibly increased mortality in afib patients
in general, afib patients should be STARTED on..
beta blocker
if not enough and at max dose - add non DHP
or can start with non DHP
if an afib patient is hemodynamically unstable, what is done right away
a cardioversion (restore regular rhythm)
elderly pt has long standing afib. heart rate is 126bpm. she is asymptomatic
what to recommend
give diltiazem 20mg IV once OR verapamil loading dose of 5-10mg
or can do STARTING DOSE of a beta blocker – 100mg metoprolol tartrate is NOT appropriate
will a valsalva maneuver work in an afib patient
NO
important note about doing a cardioversion on an afib patient
the patient MUST be anticoagulated for at least 3 weeks. this is bc when we cardiovert, a potential clot can go straight to the brain
diltiazem loading and maintenance dose for afib
loading - 0.25mg/kg IV over 2 mins can increase to 0.35mg/kg in 15 mins
then 15mg/hr IV infusion
60-90mg TID or QID PO (or long acting)
safer options for an afib patient who is hemodynamically stable and has decompensated heart failure (sudden worsening of heart failure)
IV amiodarone
____ can be added to an AV nodal blockade
magnesium
