Exam 2 - Arrhythmias Tisdale Flashcards by Rehman Hameed

PR interval range

0.12-0.20 seconds

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QRS duration

0.08-0.12 seconds

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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

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does the QT interval get shorter or longer as heart rate increases?

QT interval gets shorter

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Torsade de pointes occurs when QTc interval is _____ ms or more

500 ms or more

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5 types of supraventricular arrhythmias

-sinus bradycardia
-AV block
-sinus tachycardia
-A fib
-supraventricular tachycardia

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3 types of ventricular arrhythmias

-premature ventricular complexes (PVCs)
-ventricular tachycardia
-ventricular fibrillation

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sinus bradycardia is HR < ___ beats per minute

< 60

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mechanism of sinus bradycardia

decreased automaticity of the SA node

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main treatment for sinus bradycardia

atropine 0.5-1 mg IV, repeat every 5 min

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what are the 3 alternative drugs to atropine for sinus bradycardia?

-dopamine
-epinephrine
-isoproterenol

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2 drugs for treatment of sinus bradycardia after heart transplant or spinal cord injury

-aminophylline 6 mg/kg IV over 20-30 min
-theophylline

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long term tx for pts unwilling to get a permanent pacemaker

theophylline oral 5-10 mg/kg/day titrated to effect

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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)

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what is paroxysmal A Fib?

AF that is intermittent and terminates within 7 days of onset

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what is persistent A Fib?

AF that is continuous and sustains for > 7 days and requires intervention

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what is long-standing persistent A Fib?

AF that is continuous for > 12 months in duration

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what is successful AF ablation?

freedom from AF after percutaneous or surgical intervention to eliminate AF

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2 mechanisms of A Fib

-abnormal atrial/pulmonary vein automaticity
-atrial reentry

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hyperthyroidism and thoracic surgery are etiologies of _____ _____ _____

reversible atrial fibrillation

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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)

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what CHADsVASc score for men and women are oral anticoagulants REASONABLE in A Fib?

men - 1 or more
women - 2 or more

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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)?

1. vagal maneuvers and/or IV adenoside 2. if not effective, use IV BBs, diltiazem, or verapamil 3. if not effective, synchronized DCC