this stimulates muscular contraction (Lub-dub/pulse) - answerelectrical conductivity
(conduction from SA node causes contraction)
disorder of impulse formation, conduction of impulses, or both
SA node normal pacemaker of heart (60-100 bpm)
secondary pacemakers:
AV node (40-60 bpm)
His-purkinje fibers (20-40 bpm)
normal sinus rhythm starts w normal sinus node - answerdysrhythmias
graphic tracing of electrical impulses produced by heart
waveforms represent activity of charged ions across membranes of myocardial cells -
answerECG monitoring
represents passage of electrical impulse through atrium causing atrial depolarization
(contraction)
in response to SA node
beginning of atrial systole - answerp wave
measured from beginning of p wave to beginning of QRS complex represents time
taken for impulse to spread through atria, AV node, and bundle of His, branches, and
purkinje fibers to point immediately preceding ventricular contraction atrial systole &
ventricular electricity
delay of AV node to allow filling of ventricles
BBs can stretch this out (make longer) - answerPR interval (0.12-0.20 sec)
consists of 3 distinct waves
represents time taken for depolarization (contraction) of both ventricles (systole)
depolarization/stroke volume/ventricular contraction/ventricular systoles/75 ml -
answerQRS (0.08-0.12)
measured from S wave of QRS complex to beginning of T wave
represents time between ventricular depolarization & repolarization (diastole)
has to be isoelectric (flat) - answerST
represents time for ventricular repolarization
should be upright - answert wave
measured from beginning of QRS complex to end of T wave
, represents time taken for entire electrical depolarization & repolarization of ventricles
has to be between 0.3-0.4 sec - answerQT
is 0.2 sec (whole box=1 sec)
is 0.04 sec - answerbig box
little box
count:
# of QRS complexes in 1 min
R-R intervals in 6 sec, and multiply by 10 - answercalculating HR
clip excessive hair on chest wall
rub skin w dry gauze
may need to use alcohol for oily skin
apply electrode pad - answerpatient prep for ECG
an abnormal signal that does not reflect electrical activity of the heart during the cardiac
cycle (leads fall off) - answerartifact
observation of HR & rhythm at distant site
2 types:
centralized monitoring system
advanced alarm system alerts when it detects dysrhythmias, ischemia, or infarction -
answertelemetry monitoring
interpret rhythm & assess clinical status of pt (LOC)
is pt hemodynamically stable?
determine cause of dysrhythmia
assess & treat pt, not the monitor - answerassessment of pt
rate
rhythm
PR interval-0.12-0.20 sec
QRS complex-0.08-0.12 sec
ST segment-isoelectric
QT interval-<0.40 sec
T wave upright - answerassessment of heart rhythm
normal rhythm in aerobically trained athletes & during sleep
can occur in response to parasympathetic nerve stimulation (carotid sinus massage,
valsalva maneuver, hypothermia, vagal stimulation) & certain drugs (BBs, CCBs)
also associated w some disease states (hypothyroidism, hypoglycemia, MI) -
answersinus brady
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