HIGH ACUITY – FINAL EXAM – HTD
DYSRHYTHMIA INTERPRETATION / NURSING MANAGEMENT
conduction system steps to follow when interpreting an ECG (8)
•
... [Show More] repolarization = relax
• depolarization = squeeze
• HR = 75 (300/4) = 300 for big, 1500 for small
• R-R interval is 0.80 sec
• P wave is a smooth rounded upward deflection
• PR interval is 0.16 sec
• each P wave is followed by a QRS complex
• QRS complex is 0.06 sec
• QT interval 0.36 sec
• normal sinus rhythm
normal values
• SA node (goes to AV nodes + across the heart)
= pacesetter = 60-100 beats
• AV node = normal rates at 40-60 bpm
• purkinje fibers = normal rates at 20-40 bpm
normal EKG configuration
P wave • reflects atrial depolarization (little/round = normal, depressed/flat = problem)
PR interval
(atrial)
• depicts conduction of impulse from SA node through AV node & downward to ventricles
o PR interval = 0.12-0.2 sec
o > 0.2 = conduction delay (you’re look @ a heart block)
QRS complex
• reflects ventricular depolarization (squeezing); atrial repolarization (relaxing)
o QRS complex = < 0.12 sec
o > 0.12 = bundle branch block or conduction delay
o the interval between QRS is known at the R-R interval
ST segment • completion of ventricular depolarization + beginning of ventricular repolarization
• when ventricles completed squeezing and starting to relax = important for STEMI
T wave • represents repolarization of ventricles
• ventricles starting to relax, completion of the heart
QT interval
(ventricles)
• represents ventricular depolarization and repolarization = ventricles from start to finish
o QT interval = less than half of the R-R interval
o > 0.50 = considered dangerously prolonged
risk factors for development of dysrhythmias
electrolyte abnormalities
potassium
low high
• EKG changes = prolonged PR & QT
intervals, ST segment depression
(ischemia), T wave flattening/inversion
• dysrhythmias = PVCs, AV blocks
• EKG changes = tall peaked T waves,
QRS complex widens
• dysrhythmias = cardiac arrest, asystole
magnesium
low high
• EKG changes = prominent U waves *
and flattening of T wave, prolonged
PR and QT intervals and widening of
QRS complex
• dysrhythmias = torsade des pointes *
• EKG changes = bradycardia,
prolonged PR, QRS and QT intervals,
widened QRS complexes
• dysrhythmias = complete heart blocks,
cardiac arrest
calcium
low high
• EKG changes = prolonged ST segment
• dysrhythmias = PVCs
• EKG changes = shortened ventricular
repolarization and QT interval
• dysrhythmias = first degree AV block
hypoxemia • no oxygen to heart in form of ischemia or infarction = due to CAD, MI
fluid
abnormalities
fluid volume excess fluid volume deficit
• ventricular enlargement, decreased
contractility, premature beats; AV
blocks
• tachycardias
altered body
temperature
hyperthermia hypothermia
• increases body’s oxygen demand
• HR increases by 10 bpm for every 1o F
• may increase myocardial excitability
• decreases body’s oxygen demand
• EKG changes = bradycardia < 60 bpm,
prolonged PR and QT intervals and
wide QRS complexes
cardiac dysrhythmias: sinus dysrhythmias
types of rhythms
• normal sinus
• sinus bradycardia = rate <60
• sinus tachycardia = rate 100-150
common features
• normal P waves, P wave for every QRS
• normal PR interval + QRS complex
• heart rate will just be off
cardiac dysrhythmias: atrial dysrhythmias
atrial fibrillation
characteristics major characteristics (3)
• multiple foci firing = firing from everywhere
• decreased stroke volume = not enough fill
• prone to forming clots increasing risk of PE or
thrombotic stroke; “atrial kick” = one good
squeeze that sends clot into circulation
• atrial rate > 350 bpm = irregular regular rhythm
• anti-coagulation medications for chronic A-fib =
on warfarin = (cardioversion, do TEE first)
• absence of P waves = fibrillatory wave
• a normal QRS with highly irregular
QRS intervals = inconsistent
• fibrillatory waves (waves are
dissimilar, some pointy, inverted,
biphasic, etc.)
• ~have to listen to heart for full
minutes~
atrial flutter
characteristics treatment
• atrial rate = 250-350 bpm
• no P waves present = atrial oscillations
• sawtooth waves or flutter waves = consistent
• AV node unable to respond to every impulse
• ventricular rhythm = regular or irregular
• synchronized cardioversion preferred
• ABCD drugs = adenosine, betablockers, calcium channel blockers,
digitalis = all decrease HR [Show Less]