Atrial fibrillation Flashcards
What is a significance of the P wave?
Atrial contraction
what is the significance of the QRS complex?
Ventricular contraction
what is the significance of the T wave?
Ventricular repolarizations
what is the significance of the PR interval?
it is the impulse through the atria and AV node
what is the significance of the QTc interval? What is the equation?
it is the time between the ventricle polarization and depolarization
prolonged QT interval precedes torsades de pointes
QTc= QT interval/sqrt(RR interval)
RR interval is the duration of one cardia cycle
which drugs can cause proarrhythmias
Class 1A /III antiarrhytmics Macrolides Quinolones Famotidine TCAs, ziprasidone, haloperidol etc
which factors may contirbute to arrhythmias
MI
HF
Medications
what are the class 1 A antiarrhytmics
disopyramide (double)
quinidine (quarter)
Procainamide (pounder)
what are the class 1B antiarrhythmics
lidocaine (lettuce)
tocainide (tomato)
mexiletine (mayo)
Phenytoin (pickles)
what are the 1C antiarrhytmics
moricizine (more)
flecainide (fries)
propafenone (please)
what are the class 2 antiarrhythmics
beta blockers (propronolol, esmolol)
what are the class 3 antiarrhytmics
amiodarone dronaderone sotalol ibutilide dofetilide
what are the class IV antiarrhytmics?
Verapamil and diltiazem
quinidine
class 1A Qunidex, quinaglute MOA=stabilize the membrae channel by interfering with sodium channel influx I=Supraventricular Tachy, Ventricular tachycardia EKG= prolong QT, prolong QRS because block potassium channels also in phase 3 PK= strong cyp3a4 inhibitor/substrate CI= patients taking quinolines that prolong QT Se= Diarrhea* hypotension, syncope, QT prolongation, cinchonism (HA, diz, tinitus) Other: different salt forms gluconate and sulfate not interchangeable, take with food or milk, keep constant Na intake cuz dec Na inc qunidine levels DDI=digoxin(inc d) warfarin (inc INR), grapefruit juice, verapamil, diltiazem, amiodarone, erythromycin
procainamide
class 1A Pronestyl (SR)
MOA=stabilize the membrae channel by interfering with sodium channel influx
I= Supraventricular Tachy, Ventricular tachycardia
EKG= prolong QT, prolong QRS because block potassium channels also in phase 3
has metabolite NAPA that is renally cleared
SE=hypotension, bradycardia, can cause blood dyscrasias , can become ANA+
Other: take on an empty stomach, monitor x 3months for blood dyscrasia
disopyramide
class 1A Norpace MOA=interfering with sodium channel influx, negative inotrope I= Supraventricular Tachy, Ventricular tachycardia EKG=prolong QT, prolong QRS because block potassium channels also in phase 3 PK=major cyp3a4 substrate SE= strong anticholinergic CI=do not use in BPH, urinary retention, glaucoma, myasthenia gravis Other: take on an empty stomach
lidocaine
class 1B - xylocaine MOA=block sodium ion channels I=ventricular tachy, especially faolowing an MI (ischemic tissue) EKG= decrease the QT PK=hepatically eliminated SE=hypotension, hallucinations, diorientation, Other:can give in endotrachial tube but need higher dose
mexiletine
class 1B- Mexitil MOA=block sodium ion channels I= ventricular tachy EKG= shorten QT PK= SE=GI Side effects*, hypotension, hallucinations, diorientation, Other:can give in endotrachial tube but need higher dose
flecainide
class 1 c - Tambocor MOA=block sodium channels, negative inotrope I=SVT, (VT) EKG=really increase QRS PK=kidney and liver clearance CI=do not use if Structural changes to the heart like LVH, HF, CAD SE=dizziness, visual disturbance Other: not commonly used cuz pro arrhythmia, amiodarone DDI dec dose F 50%
beta blockers
esmolol, propranolol, metoprolol, atenolol
MOA= esmolol is b1 selective, propranolol is not
I=SVT, VT
EKG=increase PR segment, can cause AV block
PK=decrease the heart rate
SE=do not use propranolol with patients who hae problem breathing copd asthma
metoprolol/timolon in long-term prophylaxis in pat with an MI, esmolol short acting IV used for acute surgical arrhythmias
amiodarone
class III -Cordarone
MOA=increase refractory period, block potassium channels, Na channels, beta blocker
I=SVT, VT, most arrhythmias
EKG=prolong QT
PK=VERY LONG half-life and Vd
CI=
SE=HYPOTHYROID*/hyperthyroid, hypotension, inc LFTs, photosensitivity/blue skin discoloration if extended sun, <3% Pulmonary fibrosis (5-15%)
BBW: lung damage, liver toxicity, exacerbate arrythmias, corneal micro deposits
Other: most popular, preg cat D, dec IV50% of PO,
dronaderone
MOA=increase refractory period, block potassium channels I=SVT, VT EKG=prolong QT PK=cyp3a4 substrate, CI=class 4 HF, recent decompensated HF, QTc > 500msec, bradycardia < 50, strong cyp inhibitor, severe heaptic impairment, 400mg po SE=GI side effects Other:pregnancy category X
sotalol
class III MOA=increase refractory period, block potassium channels, non selective beta blocke I=SVT, VT Dose 80-160mg BID, adjust by CrCL EKG=prolong QT CI= If baseline QTc > 450 , betapace AF in CrCl =160mg/day, Magnesium can be given to reverse torsades de pointes w/ these agents
ibutilide
Class 3-Corvert
MOA=increase refractory period, block potassium channels
I=SVT, VT
EKG=prolong QT
PK=
SE=
Other: class 1A or 3 should be avoided withing 4 hours after infusion
dofetilide
class 3 Tikosyn MOA=increase refractory period, block potassium channels I=SVT, VT EKG=prolong QT PK=metabolized by CYP3A4 CI=baseling QTc > 440 msec, CrCl <20, cimetidine, TMP, prochlorparezine, megestrol, ketoconazole, verapamil SE= Other:mandatory 3 day hospitalization for initiation, MD must be certified to prescribe, Pharmacy msut be enrolled in TIPS to dispense
verapamil
class IV MOA=calcium channel blocker I=supraventricular arrhytmias invovling AV nodal reentry EKG= PK= CI= SE=can worsen AV block and ventricular failure Other:
diltiazem
MOA= I= EKG= PK= CI= SE= Other:
propafenone
MOA= I= EKG= PK= CI= SE= Other:
digoxin
MOA=enhances vagal tone I= EKG=increase PR PK= CI= SE= Other:
adenosine
MOA=activates adenosine receptor, activating the potassium Kach receptor, hyper polarization, decrease HR I= EKG=increases PR PK= CI= SE= Other:
atropine
MOA= I= EKG= PK= CI= SE= Other:
what are the pathophysiologic consequnces of atrial fibrillation/atrial flutter?
- hemodyanmic symptoms: palpiations, can induce tachyardia-mediated cardiomyopathy, angina, fatigue, syncope
- Thromboembolic complications like stroke
3
compare rate and rhythm control strattegies in atrial fibrillation/flutter
Rate
attempts to control only the ventricular response rate (heart rate=pulse)
can releive hemodynamic symptoms
prevents tachycardia mediated Cardiomyopathy
no use of antiarrhythmics
requires long term anticoagulation
Rhythm control
attempts otresotre and maintain normal sinus rhythm
prevents hemodynamic symtpos and prevents tachycardiamediated CMP
reduces thromboembolic risk
what is the stroke provention theraphy for a patient with atrila fibrillation/flutter
warfarin
dabigatran
rivaroxaban
ASA+/- clopidogrel
which drugs can cause bradycardia?
beta blockers
calcium channel blockers non dihydropyridines
what are the primary and secondary preventions of sudden cardiac death?
1
how do you identify a patient that requires and implantable cardioverter defibrillator?
1
develop an appropriate treatment and monitoring plan for a patient with a fib/atrial flutter
Mx: electrolytes
develop an appropriate treatment and monitoring plan for a patient with a bradyarrhytmia
Mx: electrolytes
develop an appropriate treatment and monitoring plan for a patient with a ventricular tachycardia/fibrillation
Mx: electrolytes
calculate the dose for an antiarrhytmic agent using appropriate pahrmacokinetic parameters
1
which medications lead to QT prolongation
Class I, Class III : amiodarone, disopyramide, dronaderone, procainamide, sotalol
quinolone antibiotics
macrolide antibiotics
azole antifungals
TCAs
antipsychotics:chlorpromazine, thioridazine, pimozide, ziprasidone, haloperidol
droperidol, apomorphine, foscarnet, methadone, pentamidine
what is the black box for all antiarrhythmics
antiarrhythmic drugs have not been shown to enhance survival in non-life threatening ventricular arrhythmias and may increase mortality, greatest risk in pts with structural heart disease.
which electrolytes can affect arrhythmias?
Na K
Ca Mg
how does potassium affect digoxin?
hypokalemia can increase risk of digoxin toxicity
what risk factors contribute to torsades de pointes
bradycardia cardiac hypertrophy baseline long qt hypokalemia, hypomagnesemia renal failure
which medications prolong the qt
K channel blockers like class 1A/3 antiarrhythmics, macrolides, quinolines, famotiidine, TCAs
what should you monitor for amiodarone?
Chest X ray and pulmonary function test baseline
Thyroid & liver function test & ECG baseline and every 3-6 months
Eye exam baseline and every year
what are the difference between dronaderone and amiodarone
lower efficacy better side effect profile more GI side effects shorter half life = 30hr no interaction with warfarin
what defines atrial fibrillaiton
supraventricular tachycardia with rapid atrial rate of 400-600bpm and disorganized. Ventricualr rate can be normal to rapid 100-160bpm and irreguarly irregular
what define atrial flutter
rapid but organized atrial activation 270-330bpm with regular to irrgular ventriacular response
in evaluating patients with possible atrial fibrialltion, what should you evaluate?
ECG
Thyroid, renal, hepatic function
history and physical
triggers: alcohol, caffeine, exercise, sleep depvation, emothinal stress
what are the three categories of atrial fibriallation
Paroxysmal 7 days
Permanent > 1 year or cardioversion failed
what three stages of acuity for atrial fibrillation
acute: new episode < 48 hours
recurrent >= 2 episodes
lone afib : > 60yo without cardiopulmonary dz inc hypertension
what is the goal for HR for Rate control?
60-80bpm at rest and 90-115 for exercise
what agents do you use for rate control?
beta blockers
non-dyhydropyridine CCB
digoxin
amiodarone
what is the CHADS2 score
prior stroke or TIA 2 Age >75 1 hypertension 1 diabetes Mellitus 1 HF 1
what is recommended if they have a chads 0
ASA 81-325 daily + clopidogrel 75mg daily
what is recommended for stroke prevention if they have a CHADS1
ASA 81-325mg daily + clopidogrel 75mg daily OR Warfarin INR 2-3 OR Dabigatran
what is reccommended for stroke prevention in CHADS 2 or more
warfarin INR 2-3
OR
Dabigatran
dabigatran
pradaxa
MOA= direct thrombin inhibitor (factor II)
PK= rapid onset and short half life (12-17 hours) twice daily dosing
Dosing: ClCr: > 30 150mg BID, 15-30 75mg bid, < 15 not recommended
what are the differences between Electrical shock vs pharmacological cardioversion
EC
more effective but causes myocardial injury and requires sedation
PC
convenient and may facilitate EC but less effective and varries with the agents. Can put patients at risk for proarrhytmias and durg interactions.
what should you check before performing a cardioversion
electrolytes K, MG and digoxin levels
who should get cardioversion
if hemodyanmically unstable based on low CO, hypotension, acute MI, shock, angina, pulmonary edema= USE EC
If hemodyanmically stable, you can used EC, EC + PC , or PC
Should you use anticoagulation if a patient is undergoing cardioversion?
yes need it before and after cardioversion if patient has had Afib > 48 hours because at risk for developing atrial thrombi
what is the anticoagulation therapy for elective cardioversion?
before cardioversion warfarin for 3 weeks or more INR 2-3, TEE w/o anticoagulation
After cardioversion warfarin for >= 4 weeks INR 2-3
what is the anticoagulation therapy for immediate cardioversion?
Before cardioversion: heparin bolus and infusion
After cardiversion Warfarin 4 weeks or more INR 2-3
What are the non-pharm treatments for atrial fibrillation
- radioffrequency catheter ablation: ablate ectopic foci
- pulmonary vein isolation ablation : ablation of av node
- surgical maze procetur
what is AV block
partial or ocmplete of interpution of impulse transmission of the atrial to theventricles
how do you treate AV block?
atropine dopamine, epinephrine, isoproterenol transcutaneous pacing (external pacing)
If it’s chronic : permanent pacemaker
what is a PVC
premature ventricular contraction
ventricles contract without the presence of a P wave
define ventricular tachycardia
series of PVCs at > 100bpm
non-sustained is <30 seconds, after 30 seconds is sustained
how to treat VT
If hemodynamically unstable: electric shock
long term suppression dependend on SCD sudden cardiac death risk
ventricular fibrrilaltion tx
electric shock
IV epinephrine
amiodarone
