ECG Flashcards
what are the limb leads
1,2,3, aVR, aVL, aVF
what are the chest leads
V1, V2, V3, V4, V5, V6
what leads are for the lateral wall of the left ventricle (limb leads)
lead 1 and aVL
what leads are for the inferior wall of the heart
lead 2,3, aVF
what leads are for the anterior and septal walls of the left ventricle
leads V1-V4
what leads are for the lateral wall of the left ventricle (chest leads)
leads V5 and V6
what artery supplies anterior wall, septal wall, part of lateral wall of left ventricle
left anterior descending (LAD) artery
what artery correlates with lead V1-V4
left anterior descending (LAD) artery
what artery correlates with anterior wall infarction
left anterior descending (LAD) artery
what artery supplies inferior wall and part of posterior wall of left ventricle
right coronary artery (RCA)
what artery correlates with leads 2, 3, aVF
right coronary artery (RCA)
what artery correlates with inferior wall infarction
right coronary artery (RCA)
what artery supplies lateral wall of left ventricle
left circumflex (Lcx) artery
what artery correlates with leads 1, aVL, V5, V6
left circumflex (Lcx) artery
what artery causes lateral wall infarction
left circumflex (Lcx) artery
what could cause ST elevation in leads V1-V4
anterior wall MI (LAD artery)
what could cause ST elevation in leads 2,3, aVF
inferior wall MI (RCA)
what could cause ST elevation in leads 1, aVL, V5, V6
lateral wall MI (Lcx)
what could cause ST depression. in leads 1, aVL
ischemia in inferior wall
what could cause deep Q waves
necrosis
initiates the electrical impulse in the right atrium
SA node
the impulse spreads through this, causing atrial contraction
atria
impulse delayed here briefly to allow ventricles to fill with blood
AV node
impulse moves down through inter ventricular septum
bundle of his
impulse transmitted to right and left ventricles via the right and left ____________
bundle branches
impulse rapidly distributed to ventricular myocardium causing ventricular contraction
purkinje fibers
normal path of conduction
- SA node
- AV node
- Bundle of his
- bundle branches
- purkinje fibers
atrial depolarization
P wave
conduction delay at AV node
PR interval
ventricular depolarization
QRS complex
period between ventricular depolarization and repolarization
ST segment
ventricular repolarization
T wave
time from beginning of ventricular depolarization to the end of repolarization
QT interval
what are the formulas to calculate HR
of QRS complexes x 6
300 / (# of large squares between R-R waves) –> best seen in lead II
or
number of QRS complexes x 6
what is the electrical axis if:
lead 1: positive
lead aVF: positive
normal axis (0 to 90)
what is the electrical axis if:
lead 1: negative
lead aVF: positive
Right axis deviation (90 to 180)
what is the electrical axis if:
lead 1: positive
lead aVF: negative
Left axis deviation (-30 to -90)
what is the electrical axis if:
lead 1: negative
lead aVF: negative
extreme axis (180 to -90)
how many seconds is a small box
0.04 s
how many seconds is a large box
0.2 s
what is normal axis
down and left
movement of positive charge
depolarization
- left ventricle hypertrophies
- right ventricle damaged
left axis deviation
- QRS positive in I and aVF
normal axis
- right ventricle hypertrophies
- left ventricle damaged
right axis deviation
- ectopic focus (depolarization in reverse)
extreme deviation
what chest leads are mostly positive
V5 and V6
what chest leads are isoelectric (transition zone)
V3 and V4
what chest leads are mostly negative
V1 and V2
what does right atrial enlargement show
big P wave in lead II and V1
what does left atrial enlargement show
biphasic P wave (up and down) in lead V1
and
double humped P wave in lead II
what does right ventricular hypertrophy show
Big R in V1
Big S in in V5
what does left ventricular hypertrophy show
huge S in V1
huge R in V5 and V6
