cardiology 3: valvular heart disease and arrhythmias Flashcards
what are the 3 usual mechanisms of abnormal rhythms?
reentry, triggered activity and automaticity
what is sick sinus syndrome?
anything that causes sinoatrial syndrome
what are the 2 indications for treatment for sick sinus syndrome?
- a symptomatic patient
- tachy-brady syndrome where tx of tachyarrhythmias might precipitate or worsen bradycardia.
what is a first-degree heart block and general causes/tx?
- PR interval >200 ms
- can be caused by medications
- no tx
describe 2nd degree wenckebach?
- gradual prolongation of PR interval until QRS drops.
- Occurs during periods of high vagal tone during sleep (OSA) or in endurance athletes
what is a mobitz 2?
abrupt loss of p wave conduction to ventricle with no evidence of gradual prolongation.
what is a 3rd degree heart block?
p waves not conducted to the ventricle
how can you tell a counterclockwise rotation atrial flutter?
this is a counterclockwise rotation around the right atrium.
see negative sawtooth flutter waves in 2,3,AvF (with positive deflection in V1)
how can you tell a clockwise rotation atrial flutter?
positive flutter waves in 2,3,Avf with a negative deflection in V1
what are the types of categories of afib?
- first detected (only 1 diagnosed episode)
- paroxysmal (more than 2 episodes, self terminating <7 days, most <24 hours)
- persistent (more than 2 episodes, each last > 7 days)
- permanent (>6-12 months)
in what circumstance is immediate DC cardioversion indicated for afib?
- hemodynamic instability
- onigoing MI
- symptomatic hypotension
- angina
- heart failure
- WPW with rapid ventricular rate
in patients that you want to DC cardioversion with slow afib, considerations?
consider inserting a temporary pacemaker before DC cardioversion because the patient could have sinus nodal disease and may have asystole after cardioversion
what would you use for pharmacologic cardioversion for Afib >7 days?
- 1st line: dofetilide
- 2nd line: amiodarone or ibutilide
what would you use for pharmacologic conversion for Afib <7 days?
- 1st line: flecainide, ibutilide, dofetilide, propafenone
- 2nd line: amiodarone
- Exception: if <48 hours and poor cardiac function, amiodarone is 1st line.
in what scenarios would you not shock a hemodynamically stable patient with abnormal tachycardiac atrial rhythm?
- dig intoxication
- hypokalemia
what is a acceptible resting heart rate for Afib patients?
- <110 if LVEF>40% and no symptoms related to arrhythmias.
- The strict control of heart rate is considered 80bpm at rest or 110 bpm during a 6-minute walk.
what medications can you use for Afib rate control w/o HF?
- beta blockers (atenolol or metoprolol)
- CCB (verapamil diltiazem)
- Digoxin can be synergistic
in the acute setting, what cna you use for tx of Afib with HF and no preexcitation?
- IV beta blockers (esmolol, metoprolol, or propanolol) to slow ventricular rate
- Amniodraone to slow ventricular rate and possibly restore sinus rhythm
- CCB with caution (verapamil/diltiazem) to slow ventricular response cautiously with hypotension or heart failure because of negative inotropic effects
- Digoxin/amiodarone provided no accessory pathway
what afib rhythm control medications require hospital monitoring to initiate therapy?
dofetilide and sotalol
what do you need to keep in mind if you’re going to use a class Ic agent for Afib?
with propafeone and flecainide, unopposed use can organize Afib into Aflutter which can degenerate into VF/VT. You need to use an AV nodal blocking agent like CCB, BB, or digoxin.
what is used for medication refractory Afib?
- RF ablation of the pulmonary veins.
- provides definitive rate control but does not cure the underlying cause.
- You still need to be on anticoagulation.
when can you cardiovert a stable patient?
If<48 hours, cardiovert.
If>48 hours, anticoagulate for 3 weeks or do TEE cardioversion.
for patients undergoing cardiac surgery, what medication should be used to prevent post-operative Afib?
give oral beta blocker unless contraindicated.
which patient group does not need antithrombotic therapy for Afib?
Lone afib (age<60 w/o heart disease and w/o risk factors)