ARRHYTHMIAS Flashcards
refers to any disturbance in the rate, regularity, site of origin, or conduction of the cardiac electrical impulse; can be a single aberrant beat or a sustained rhythm disturbance
arrythmia
awareness of one’s own heartbeat
palpitations
a sudden fainting spell - can indicate a decrease in cardiac output/function
syncope
caused by rapid arrhythmias that increase the oxygen demands of the myocardium
angina
why arrhythmias happen
(HISDEBS) Hypoxia Ischemia and Irritability Sympathetic stimulation Drugs Electrolyte disturbances Bradycardia Stretch
ambulatory, portable EKG machine with memory; patient wears for 24-48hrs; 1 or more often 2 leads (1 limb, 1 precordial lead)
holter monitor
better for rhythm disturbances that happen so infrequently that a holter monitor is likely to miss it; records 3-5min of data, but is initiated by the patient when he/she experiences symptoms (palpitations)
event monitor
5 steps of rhythm analysis
- calculate rate
- determine regularity
- assess P waves
- determine PR interval
- determine QRS duration
sequence for calculating heart rate
300 - 150 - 100 - 75 - 60 - 50
calculating rate in 6 second strip
count # of waves, multiply by 10
if there are p waves in an arrhythmia strip, where is the origin of the arrhythmia?
in the atria
if there are inverted p waves, what is likely happening?
current flowing backwards from AV node - atria
if p waves and qrs complexes are independent of each other, what is the cause of the arrhythmia?
AV dissociation
how long is a normal PR interval?
0.12-2.0sec (3-5 small boxes)
how long is a normal QRS interval?
0.04-0.12sec (1-3 small boxes)
name the 5 types of arrhythmias
- arrhythmias of sinus origin
- ectopic rhythms
- reentrant arrhythmias
- conduction blocks
- pre-excitation syndromes
when electrical activity follows the usual conduction pathways, but are either too fast, too slow, or irregular
arrhythmias of sinus origin
when the electrical activity originates elsewhere than the sinus node
ectopic rhythms
when the electrical activity is trapped within an electrical racetrack whose shape and boundaries are determined by various anatomic or electrical myocardial features
reentrant arrhythmias
when the electrical activity originates in the sinus node and follows the usual pathways, but encounters unexpected blocks and delays
conduction blocks
when the electrical activity follow accessory conduction pathways that bypass the normal ones, providing an electrical shortcut, or short circuit
pre-excitation syndromes
sinus tachycardia
rate > 100bpm; seen in CHF, severe lung disease, hyperthyroidism
sinus bradycardia
rate
how does inspiration/expiration affect HR?
inspiration: accelerates HR
expiration: decelerates HR
sinus arrest
occurs when sinus node stops firing
other myocardial cells spring into action when sinus node stops firing and take over pacing of the heart
escape beats
prolonged electrical inactivity; no cardiac output/no blood flow
asystole
treatment for asystole
CPR and epinephrine IV
most common escape rhythm; depolarization originates near the AV node and usual pattern of atrial depolarization does not occur, thus NO P WAVES
junctional escape
single ectopic supraventricular beats can originate in the atria (atrial premature beats/premature atrial contractions) or near the AV node (junctional premature beats)
atrial & junctional premature beats
ex: paroxysmal supraventricular tachycardia (PSVT), atrial flutter, atrial fibrillation, multifocal atrial tachycardia (MAT), paroxysmal atrial tachycardia (PAT)
sustained supraventricular arrhythmias
regular narrow QRS complex tachycardia; usually sudden and initiated by a premature supra ventricular beat (atrial/junctional) and termination is abrupt; P waves are retrograde if visible; rate of 150-250bpm
paroxysmal supraventricular tachycardia
can help diagnose and terminate an episode of PSVT; baroreceptors sense changes in pressure which cause reflex response from brain to heart via vagus n. to slow HR
carotid massage
the most common regular supraventricular tachycardia; occurs when a reentry circuit forms within or just next to the AV node. the circuit usually involves two anatomical pathways: the fast pathway and the low pathway, which are both in the right atrium
AV nodal reentrant tachycardia
regular, saw-toothed waves; 2:1, 3:1, 4:1 flutter waves to QRS segment; atrial rate of 250-350bpm
atrial flutter
treatment for atrial flutter
cardioversion/drugs
irregularly irregular without discernible p waves; undulating baseline with an atrial rate of 350-500bpm and variable ventricular rate
atrial fibrillation
treatment that may slow ventricular rate
carotid massage
irregular with a rate of 100-200bpm; at least 3 different P wave morphologies from different atrial foci (P waves of variable shapes), aka wandering atrial pacemaker when rate
multifocal atrial tachycardia
regular with a rate of 100-200bpm, results from enhanced automaticity of an ectopic atrial focus or reentrant circle within the atria; characteristic warm-up period in the automatic form
paroxysmal atrial tachycardia
most common of the ventricular arrhythmias; QRS complex is wide and bizarre b/c ventricular depolarization does not follow normal conduction
premature ventricular contractions
a run of 3 or more consecutive PVCs, with a rate of 120-200bpm; can be uniform or polymorphic (tornadoes de pointes)
ventricular tachycardia
means twisting of the points; form of VT usually seen in pots with prolonged QT intervals
torsades de pointes
what sustained ventricular arrhythmia is an emergency preceding cardiac arrest?
sustained VT
congenital or result from electrolyte disturbance (hypocalcemia, hypomagnesemia or hypokalemia), during MI, some drugs
prolonged QT
pre-terminal event, seen almost solely in dying hearts; most frequently encountered arrhythmia in adults who experience sudden death; no true QRS complexes; no cardiac output
ventricular fibrillation
treatment for Vfib
CPR/ defibrillation immediately
benign rhythm seen during an acute myocardial infarction (or during the early hours following reperfusion); regular rhythm occurring at 50-100bpm; represents a ventricular escape focus that has accelerated sufficiently to drive the heart; rarely sustained, does not progress to VF, and rarely requires treatment
accelerated idioventricular rhythm
treatment of arrhythmias: arrhythmia is induced in lab, source of arrhythmia is mapped to determine appropriate therapy
programmed electrical stimulation
treatment of arrhythmias: implantable cardioverter-defibrillators are the standard form of protection for patients with life threatening arrhythmias; surgically implanted under the skin below the shoulder, deliver a shock when a dangerous arrhythmia is detected
defibrillators
