Exam 2 - Arrhythmias Tisdale Flashcards
PR interval range
0.12-0.20 seconds
QRS duration
0.08-0.12 seconds
QT and QTc interval range
QT: 0.38-0.46 seconds
QTc: 0.36-0.45 seconds for men;
0.36-0.46 seconds for women
does the QT interval get shorter or longer as heart rate increases?
QT interval gets shorter
Torsade de pointes occurs when QTc interval is _____ ms or more
500 ms or more
5 types of supraventricular arrhythmias
-sinus bradycardia
-AV block
-sinus tachycardia
-A fib
-supraventricular tachycardia
3 types of ventricular arrhythmias
-premature ventricular complexes (PVCs)
-ventricular tachycardia
-ventricular fibrillation
sinus bradycardia is HR < ___ beats per minute
< 60
mechanism of sinus bradycardia
decreased automaticity of the SA node
main treatment for sinus bradycardia
atropine 0.5-1 mg IV, repeat every 5 min
what are the 3 alternative drugs to atropine for sinus bradycardia?
-dopamine
-epinephrine
-isoproterenol
2 drugs for treatment of sinus bradycardia after heart transplant or spinal cord injury
-aminophylline 6 mg/kg IV over 20-30 min
-theophylline
long term tx for pts unwilling to get a permanent pacemaker
theophylline oral 5-10 mg/kg/day titrated to effect
which of the following is false about A fib?
a. no atrial depolarizations
b. 120-180 bpm
c. irregularly regular rhythm
d. absent P waves
c. irregularly regular rhythm (it is irregularly irregular)
what is paroxysmal A Fib?
AF that is intermittent and terminates within 7 days of onset
what is persistent A Fib?
AF that is continuous and sustains for > 7 days and requires intervention
what is long-standing persistent A Fib?
AF that is continuous for > 12 months in duration
what is successful AF ablation?
freedom from AF after percutaneous or surgical intervention to eliminate AF
2 mechanisms of A Fib
-abnormal atrial/pulmonary vein automaticity
-atrial reentry
hyperthyroidism and thoracic surgery are etiologies of _____ _____ _____
reversible atrial fibrillation
4 goals of therapy for treating A fib
-prevent stroke/systemic embolism
-slow ventricular response by inhibiting conduction of impulses to ventricles
-convert A fib to normal sinus rhythm
-maintain sinus rhythm (reduce freq of episodes)
what CHADsVASc score for men and women are oral anticoagulants REASONABLE in A Fib?
men - 1 or more
women - 2 or more
warfarin is preferred over DOACs in which two pts with A Fib?
-pts with mechanical heart valves (INR 2.5-3.5)
-pts with moderate-to-severe mitral valve stenosis (INR 2.0-3.0)
warfarin or apixaban are preferred in which 2 pts with A Fib?
-pts with CrCl < 15 mL/min (End-stage CKD)
-pts on hemodialysis
true or false: DOACs are preferred over warfarin for MOST pts with A Fib
true
reversal agent for rivaroxaban, apixaban, and edoxaban
andexanet alfa
reversal agent for dabigatran
idarucizumab
which DOAC is not recommended in CrCl > 95 mL/min?
a. dabigatran
b. rivaroxaban
c. apixaban
d. edoxaban
d. edoxaban
what drugs/drug classes can be used for ventricular rate control?
non-DHP CCBs, beta blockers, digoxin, amiodarone
how often should INR be measured for pt on warfarin with A Fib?
measure weekly at initiation, the monthly after INR is stable
what are the four conditions for hemodynamic unstability?
-systolic BP less than 90
-HR > 150 bpm
-pt has lost consciousness
-pt experiencing chest pain
which two drugs should not be given to pts with decompensated HF?
diltiazem, verapamil
goal for ventricular rate control
100-110 bpm and asymptomatic
if pt is hemodynamically unstable with A fib, what is the treatment?
DCC (direct current cardioversion)
if A Fib has been present for 48 hours or less, can we convert to sinus rhythm?
yes
if A fib has been present for more than 48 hours, can we convert to sinus rhythm?
no (until pt has been anticoagulated for 3 weeks or a TEE has been performed to rule out a clot in the atrium)
what drugs are used for conversion to sinus rhythm for A Fib? (5 of them; slide 62)
-amiodarone
-ibutilide
-procainamide
-flecainide
-propafenone
what are the two “pill in the pocket” drugs we talked about?
flecainide and propafenone
what drugs are used for maintenance of sinus rhythm for pts with A Fib? (6 of them; slide 67)
-amiodarone
-dofetilide
-dronedarone
-sotalol
-propafenone
-flecainide
dofetilide is CI in CrCl < ____
< 20
for inpatient initiation of dofetilide, we only proceed if QTc is less than _____ ms
440 ms
doses for dofetilide if Cr > 60, 40-60, and 20-39
> 60 -> 500 mcg twice daily
40-60 -> 250 mcg twice daily
20-39 -> 125 mcg twice daily
after 1st dose of dofetilide in the hospital, when would we decrease the dose?
if QTc increases > 15% or > 500 ms after 2-3 hours
when would we discontinue dofetilide if we have given at least 2 doses already?
if QTc > 500 ms anytime after the 2nd dose
for inpatient initiation of sotalol, we only proceed if QTc is ____ or less
450 ms
what is the dose for inpatient initiation of sotalol if CrCl is > 60, and between 40-60?
> 60 -> 80 mg twice daily
40-60 -> 80 mg once daily
verapamil inhibits p-glycoprotein, so there is an interaction with what two drugs? (2 of them; slide 54)
digoxin, dofetilide (dec doses of these)
what are the 3 IV BB’s we use for ventricular rate control for A Fib?
esmolol
propranolol
metoprolol
what drug should be used in conversion of hemodynamically stable A Fib HFrEF pt (LVEF of 40% or less) to sinus rhythm?
a. IV amiodarone
b. IV ibutilide
c. IV amiodarone
d. flecainide
e. propafenone
c. IV amiodarone
which works faster for conversion of hemodynamically stable AF to sinus rhythm if pt has normal LV function?
a. IV amiodarone
b. IV ibutilide
b. IV ibutilide
for conversion of hemodynamically stable AF to sinus rhythm, why do we not administer procainamide if pt has already received amiodarone or ibutilide?
risk of excessive QT prolongation and torsades de pointes
how often after each dose of sotalol do we check QTc interval? What are we looking for?
-check every 2-4 hours
-if QTc < 500 ms after 3 days (or after 5th or 6th dose if once daily), pt can be discharged OR can be inc to 120 mg BID and pt can be followed for 3 days on this dose
-if QTc is 500 ms or greater, d/c sotalol
what is the HR range for supraventricular tachycardia?
110-250 bpm
4 mechanisms for reentry for supraventricular tachycardia
-AV node (60%)
-accessory pathway (WPW syndrome; 30%)
-atria (4-8%)
-SA node (4%)
what is important about dronedarone that causes less side effects than amiodarone?
dronedarone does NOT contain iodine while amiodarone does, so no side effects related to that for dronedarone
what is the stepwise therapy for termination of hemodynamically stable SVT (IV drugs)?
- vagal maneuvers and/or IV adenoside
- if not effective, use IV BBs, diltiazem, or verapamil
- if not effective, synchronized DCC
