Chapter 32: Arrhythmias Flashcards
What are the 3 ways an arrhythmia can be caused
- The SA node can be firing at an abnormal rate or rhythm
- Scar tissue from a prior heart attack can block and divert signal transmission
- Another part of the heart may be acting as the pacemaker
What is used to diagnose arrhythmias
ECG
A ____ monitor is an ambulatory ECG device that records the heart’s electrical activity for 24-48 hours to detect intermittent arrhythmias
Holter
A normal sinus rhythm (NSR) beings in the ____ node
SA (the heart’s natural pacemaker)
Which pacemaker cells have automaticity, meaning they initiate their own action potential
SA (pacemaker) cells
In phase 0 of the action potential, rapid, ventricular depolarization initiates a heartbeat in response to influx of __, causing ventricular contraction
Na
In phase 2 of the action potential, there is a plateu in response to an influx of __ and efflux of ___
Ca
K
In phase 3 of the action potential, there is rapid ventricular repolarization in response to an efflux of __
K
The most common cause of arrhythmias
Myocardial ischemia or infarction
Which non-cardiac conditions can trigger or predispose a patient to arrhythmias
- electrolyte imbalances (esp K, Mg, Na and Ca)
- elevated sympathetic states (e.g., hyperthyroidism, infection)
- drugs (including illicit drugs and antiarrhythmics)
What is the most common type of arrhythmia
AFib
In AFib, the atria are not able to adequately contract, leading to
blood stagnation in the atria, which increases the risk of clot formation. The clot can embolize to the brain and cause a stroke
Patients with AFib may require what medication class
Anticoagulants to reduce the risk of blood clots
Common ventricular arrhythmias include
Premature ventricular contractions (PVCs)
PVCs are referred to as
a skipped heart beat
In some people, PVCs can be related to
too much stress or caffeine, nicotine or exercise
A series of PVCs in a row, resulting in HR of > __ BPM, is known as ____
> 100 BPM
Ventricular tachycardia
Untreated ventricular tachy can degenerate into ____
Vfib (a medical emergency)
Which drug is used frequently for the treatment of Ventricular arrhythmias
IV lidocaine
Which key drugs can increase or prolong the QT interval
- Antiarrhythmics: Class I (especially Class Ia) and Class III
- Antibiotics: Quinolones and macrolides
- Azole Antifungals: All except isavuconazonium
- Antidepressants: TCAs (e.g., amitriptyline, clomipramine, doxepin); SSRIs (e.g., citalopram, escitalopram) – sertraline is preferred in cardiac patients; SNRIs, mirtazapine and trazadone
- Antiemetic drugs: 5-HT3 RA, droperidol, and phenothiazines
- Antipsychotics (most): chlorpromazine, clozapine, haloperidol, olanzapine, paliperidone, quetiapine, risperidone, thioridazine, ziprasidone
- Other drugs: Donepezil, fingolimod, methadone, tacrolimus
Prolongation of the QT interval is a risk factor for ___, a particularly lethal ventricular tachyarrhythmia which can cause ____
TdP
sudden cardiac death
The risk of drug-induced QT prolongation increases with:
- Higher doses
- multiple QT-prolonging drugs
- reduced drug clearance with renal or liver disease
- drug interactions that decrease clearance (with enzyme inhibitors)
- with hypokalemia and/or hypomagnesemia
- other cardiac conditions
Which drugs are used in arrhythmias per Vaughan Williams Classification
- Remember Double Quarter Pounder, Lettuce, Mayo, Fries Please! Because Dieting During Stress Is Always Very Difficult*
- Class I
- Ia: Disopyramide, Quinidine, Procainamide
- Ib: Lidocaine, Mexiletine
- Ic: Flecainide, Propafenone
-Class II: Beta-blockers
- Class III
- Dronedarone, Dofetalide, Sotalol, Ibutilide, Amiodarone (SAD KID)
-Class IV: Verapamil, Diltiazem
What is rate control and which drugs are used for it
Patient remains in AFib and takes meds to control the ventricular rate (HR)
• BB or non-DHP CCBs (sometimes digoxin)
What is the goal for rhythm control and which drugs are used
Goal is to restore and maintain NSR
• Class Ia, Ic, or III antiarrhythmic or electrical cardioversion
If AFib is permanent, avoid ___-control antiarrhythmic drugs
rhythm
Which anticoags are preferred for non-valvular Afib
DOACs (e.g, apixaban, rivaroxaban)
The goal resting HR is < __ BPM in patients with symptomatic AFib, however, a more lenient rate-control strategy of < __ BPM may be reasonable in patients who are asymptomatic and have preserved LV function
80
110
Patients with HFrEF should NOT receive which drug class
non-DHP CCB
AFib has a high rate of thromboembolism. If the pt is not already using therapeutic anticoagulation, it should be started at least __ weeks before cardioversion & continued for at least __ weeks after successful cardioversion to NSR
3
4
Class I antiarrhythmics are ____ blockers
Na-channel
Class II antiarrhythmics are ____ blockers
Beta-blockers (remember: 2 Bs)
Class III antiarrhythmics are ____ blockers
K-channel
Class IV antiarrhythmics are ____ blockers
Calcium-channel (non-HDP)
Digoxin is a ____ blocker
Na-K-ATPase
Na-channel blockers have _____ inotrope potential, which ↓ the force of the heart’s contraction
Negative
Which 2 potassium-channel blockers are preferentially used in AF for patients with HF
Amiodarone and dofetalide
Which medication is a beta-blocker but blocks K channels
Sotalol
MOA of digoxin
Decreases HR by enhancing vagal tone and increases force of contraction (positive inotrope)