32. Arrhythmias Flashcards
S/sx arrhythmias
Feels like “fluttering” in their chest or “skipping a beat”
Dizziness, SOB, fatigue, lightheadedness, chest pain
___ is used to diagnose arrhythmias
Electrocardiogram (ECG)
A ___ is an ambulatory ECG device that records electrical activity of the heart for 24-48hrs. Used to detect arrhythmias that are intermittent.
Holter monitor
Normal sinus rhythm originates in the ___
sinoatrial (SA) node
____ is the heart’s natural pacemaker
SA node
Normal HR range is ___
60-100BPM
Describe the conduction pathway
SA node
AV node
Bundle of His, splits to right and left branch
Purkinje fibers
3 reasons why arrhythmias may be occuring
- SA node can be firing at an abnormal rate or rhythm
- Scar tissue from prior heart attack can block and divert signal transmission
- another part of the heart may be acting as the pacemaker
The SA cells have automaticity. What does this mean?
Unlike other myocytes, the pacemaker cells initiate their own action potential (does not require external stimulation)
Describe phase 0 of the cardiac action potential
Heartbeat is initiated when rapid ventricular depolarization occurs in response to influx of Na
Causes ventricular contraction (represented by QTS complex on ECG)
Describe phase 1 of the cardiac action potential
early rapid repolarization (Na channels close)
Describe phase 2 of the cardiac action potential
Plateau in response to influx of Ca and efflux of K
Describe phase 3 of the cardiac action potential
Rapid ventricular repolarization in response to an efflux of K, causes ventricular relaxation (represented by T wave on ECG)
The most common cause of arrhythmias is __ or __
Myocardial ischemia or infarction
Non-cardiac conditions that can trigger or predispose of a pt to an arrhythmia include ____
electrolyte imbalances (es. potassium, magnesium, sodium, and calcium)
Elevated sympathetic states (E.g. hyperthyroidism, infection)
Drugs (illicit drugs, antiarrhythmics, and QT prolonging meds)
Arrhythmias are generally classified into 2 broad categories based on point of origin: _____ and ___
supraventricular (originating above AV node)
Ventricular (originating below AV node)
___ is the most common type of arrhythmia
Afib
____ are referred to as a skipped heartbeat
Premature ventricular contractions (PVCs)
A series of premature ventricular contractions (PVCs) in a row resulting in a HR of > ___BPM, is known as ___ (medical emergency)
> 100 BMP
Ventricular tachycardia (VTach, VT)
Untreated VTach can degenerate into _____ which is also a medical emergency
Ventricular fibrilation (VFib)
QTc is considered prolonged when it is > ____ milliseconds (msec) but more worrisome when it is > ____msec
> 440 msec
500 msec
Prolonged QT interval is a risk factor for ____, a particularly lethal ventricular tachyarrhythmia that can cause ____
TdP
sudden cardiac death
Drug-induced QT prolongation increases with ____
Higher doses
Multiple QT-prolonging drugs taken at the same time
Reduced drug clearance d/t renal/liver disease or drug interaction
Electrolyte abnormalities (hypokalemia, hypomagnesemia, hypocalcemia)
Other cardiac conditions (cardiac damage is a risk for arrhythmias, including TdP
Female gender
Drugs that increase or prolong QT interval
Antiarrhythmics - Class Ia, Ic, and III
Anti-infectives - antimalarials (e.g. hydroxychloroquine), azole antifungals (all except isavocunazonium), macrolides, quinolones, lefamulin
Antidepressants - SSRIs (highest risk with citalopram and escitalopram), TCA, mirtazapine, trazodone, venlafaxine
Antiemetics - 5-HT3 receptor antagonists, droperidol, metoclopramide, promethazine
Antipsychotics - first gen (e.g. haloperidol, chlorpromazine, thioridazine), second gen (highest risk of ziprasidone)
Onc meds - androgen deprivation therapy (e.g. leuprolide), TKIs (e.g. nilotinib), oxaliplatin
Others - cilostazol, donepezil, fingolimod, hydroxyzine, loperamide, methadone, ranolazine, solifenacin, tacrolimus