ECG Flashcards
Paper speed
25mm/sec
Light lines
(1mm) 0.04 sec
Heavy lines
(5mm) 0.2 sec
HR =
= 300 ÷ # heavy lines between 2 QRS’s
HR= 1500 ÷ # mm between 2 QRS’s
Leads are
electrodes which measure the difference in electrical potential
- bipolar
- unipolar
bipolar leads measure
the difference in electrical potential between two different points on the body (bipolar leads)
unipolar leads meaure
the difference in electrical potential between one point on the body and a virtual reference point with zero electrical potential, located in the center of the heart (unipolar leads)
polarity is
depolarization moving toward a positive electrode produces a positive deflection
QRS is ____ in left and lateral lead
upright +
QRS is ____ in right sided lead
downward -
_____ monitor the RV
Right chest leads (V1 &V2)
____ monitor the LV
Left chest leads (V5 & V6)
ventricular hypertrophy
More muscle = more volts = greater amplitude
Left Ventricular hypertrophy
Big R waves in Left-sided Leads
I, aVL, V5, V6
Right Ventricular hypertrophy
Big R waves in Right-sided Leads
V1,V2
EKG and coronary artery disease
- ischemia
- injury
- infarct
Ischemia occurs when
blood supply is insufficient to meet oxygen demand in the ventricles
Ischemic changes in the EKG alter
ventricular repolarization and affect the ST segment and the T wave
Ischemia due to sudden high oxygen demand in the presence of fixed coronary obstruction will result in:
depression of the ST segment
Ischemia due to acute coronary artery obstruction during low oxygen demand will result in:
T wave inversion
stress induced myocardial ischemia
increased oxygen consumption with inability to increase coronary flow appropriately
ischemia during acute coronary syndrome
ischemia due to decreased coronary flow without increased oxygen consumption
transmural infarcts produce
Q waves
absence of noraml transmural vector produces a
negative deflection in leads over infarcted myocardium
a significant Q wave is
- is ≥ one fourth the amplitude of the R wave.
- is ≥ one small box (0.04 seconds) wide.
- is usually in at least 2 leads reflecting the same region of the left ventricle.
Transmural
ST elevation with Q waves
Subendocardial
ST depression no Q wave
location of V1-V2
anteroseptal wall
location of V3-V4
anterior wall
