APA wk4 EKG lead selection, placement, & ST seg monitor Flashcards
What is an ECG technically speaking?
Technically, it is the net dipole moment of the heart displayed on the vertical axis in millivolts versus the time on the horizontal axis.” (Pardo & Miller, 2018, p. 345)
-As heart depolarizes and repolarizes, electrical currents are dispersed. The current spreads and electrodes detect the activity. (Klabunde, 2012, p. 38)
What is a three lead ECG?
Right arm, left arm, and left leg. Potential difference between 2 electrodes is recorded, other lead serves as ground (commonly seen in pediactrics)
Between what leads are the majority of dysrhythmias and ischemia detected?
Communication between V5 and lead II
what pump does not work properly from ischemia d/t hypoxia
Na+, K+ ATPase Pump (decreased membrane potential)
Lateral wall 12-lead
I, aVL, V5, V6
Inferior wall 12-lead
II, III, aVF
Septal wall 12-lead
V1, V2
Anterior wall 12-lead
V3, V4
How would you place ECG leads on somebody with situs invertus?
opposite, heart anatomy on opposite side
Name waves of ecg and what each one is
P wave: atrial depolarization
ORS complex: ventricular depolarization
T wave: ventricular repolarization
PR interval is
time needed for activity to travel from atria to AV
QT
time needed for ventricular depolarization and repolarization
ST segment
isoelectric period, entire ventricle is depolarized
Second degree Mobitz II
“If some P’s don’t get through, then you have a Mobitz II”
Second degree Mobitz I (wekenbach)
“Longer, longer, longer, drop… then you have a wekenbach”
Third degree AV Block
“Ps and Qs don’t agree, then you have a 3rd degree”
what is a common cause of ecg artifact in or?
cautery
ST segment represents beginning
of ventricular repolarization
What leads must be accounted for in applying diagnostic criteria for myocardial injury?
V2 and V3, otherwise false positives would increase.
Changes in ST segment is the result of
myocardial oxygen insufficiency representing injury or infarction (unless false positive)
What makes up Lead ll
Right arm(-)to left leg/foot(+)
What makes up lead 1
Right arm(-)to left arm(+)
Lead III
Left arm(-) to left leg/foot(+)
AvF points towards where in einthovens triangle?
Positive Left leg/foot
avR points towards?
Positive lead in Right arm
avL
Points toward positive lead in left arm
Limb leads
II, II, III
Augmented leads?
AvF, aVL, aVR
Precordial leads?
V1-v6 project out perpendicular to other lead
Where is 0 degrees?
Where lead one points to the right
Degrees avL?
-30
Degrees lead 2?
60
Degrees lead 3?
120
Degrees avf?
90
Mean vector depoliraztion of heart points towards which lead?
Lead 2
Precordial leads S wave what inflection and R wave?
Downward, upward
Period of ecg that depolarization begins?
ST segment
Leads show greatest shift of the ST junction and must be accounted for in applying diagnostic for mi?
V2 v3