Different Ventricular Arryhthmias Flashcards
Dr. Stewart EXAM V
Which drugs are used for rhythm control?
Class I: Disopyramide, Qunidine, Procainamide
Class III: Amidarone (Pacerone), Dronedarone (Multaq), Dofetilide (Tikosyn), Sotalol (Betapace)
Which drugs are used for rate control?
Class II: Beta-blockers
Class 4: non-DHP-CCBs
Main Atrial Arrhythmias
-Afib: irregularly irregular rhythm
-Aflutter: can be regularly irregular rhythm (AV nodal conduction in consistent ratio)
-> Treatment is the same as is in Afib: Rate control versus rhythm control
Supraventricular tachycardia (SVT)
-Atrioventricular reentrant tachycardia above the bundle of His
-typically initial depolarization from the SA node, then reentry from the ventricle
-reentry circuit from the ventricle back to the atrium
-patient presents with extreme tachycardia
-narrow complex
Which arrhythmias are considered narrow VS wide?
-narrow (QRS) complex -> atrial arrhythmias
-wide (QRS) complex -> ventricular arrhythmias
Which drug is used to treat SVT?
Adenosine
-blocks conduction through the AV node -> resulting in a reset of the reentry pathway
How is Adenosine administered?
-6 mg over 1-2 sec -> immediately rapid flush of 20 ml NS
-if ineffective: increase to 12 mg -> NS flush
-if ineffective: DC -> cardioversion (shock back to a normal rhythm)
-after that, a rate-controlling agent is needed: Class II or IV (Metoprolol succinate or CCB)
Ventricular Arrhythmias
-Premature ventricular complexes (PVCs)
-Ventricular tachycardia (Vtach)
-Ventricular fibrillation (Vfib)
-Torsades de pointes (TdP) - polymorph Vtach
-Sinus bradycardia
-Atrioventricular node block (AVB
How are PVC patients managed?
-benign: young healthy asymptomatic
-when benign -> symptoms treatment with BB
-concerning if: with structural heart disease or ischemic event -> may lead to ventricular tachycardia
-> treat with AAD
In the CAST trial, which drugs were associated with post-MI and HF - increased mortality?
-Class Ic: Encainide, Flecainide, Morizicine
-worked well: Amiodarone (pacerone), Dronedarone (Multaq)
-> Dronedarone is NOT safe for patients with HF and Afib
Which arrhythmic disease is referred to as polymorphic Vtach (ventricular tachycardia)?
Torsades de Pointes (Tdp)
What are potential causes of Torsades de Pointes?
-Hypokalemia (may caused by diuretic) -> replenish K+
-Hypomagnesia -> replenish
-Hypoxia
-Digoxin toxicity
-Acute MI
-CCB (prolong the QT interval -> higher risk for Tdp)
Other drugs causing Tdp
QT-prolonging drugs
Class Ia: Qunidine
Class III
When might a Bradyarrhtmia be concerning?
-in elderly patients:
SA node dysfunction
tachy-brady syndrome: run high and low
-pacemaker therapy: patients may be treated with a BB/CCB and a pacemaker at the same time
AV node block
-interruption of impulse transmission from the atria to the ventricles
-may need atropine
Where to avoid Class Ic drugs?
in patients with a history of MI (post-MI) and LV dysfunction (CAST trial)
Encainide
Flecainide
Morizicine
In which patient population should Dronedarone (Multaq) be avoided?
patients with HF and Afib
Which drug should be initiated inpatient?
Dofetilide (Tikosyn)
Class I/III are safer when initiated inpatient
Complexitiy of Amiodarone
-blocks K+ channel (primarily) -> QTc prolonging!
-blocks Na+ channel
-Beta-blocker activity: slows HR
ADR of Amiodarone (pacerone)
-Hepatoxicity
-Pulmonary fibrosis
-Hyperthoiridsm/Hypothyroidism
-Eye and skin toxicity
-somewhat QTc
What class does Sotalol belong to?
-Class III -> prolongs QT
-L-isomer with Class II beta-blocking activity
-renal elimination
What to monitor when using Dofetilide
-given PO inpatient
-monitor QT interval
-monitor electrolytes and ECG
-monitor renal function
Common QT-prolonging drugs
-Class III: amiodarone, dofetilide, sotalol
-FQ
-azoles
-antipsychotics (quetiapine)
-macrolides: azithromycin, clarithromycin
-ondansetron
-methadone
levels of 450-500 are high and should be monitored closely
Which drug classes can cause AV nodal blockade?
-non-DHP-CCB
-BB
