Introduction to Cardiac Electrophysiology

Question 1

Ventricular myocyte

Answer 1

Na rushes in a depolarization…then K out while Ca in…then just K out in order to maintain

Question 2

Ik1

Answer 2

Inward rectifier that allows K flow out of the cell to keep potential negative during diastole

Question 3

Pacemaker cell

Answer 3

Current through F-type Na channels and T-type Ca channels allow it to reach the threshold of the L-type Calcium channels

Question 4

Sequence of activation

Answer 4

SA - atria - AV node - septum - purkinje - ventricular myocytes

Question 5

P
PR
QRS
T

Answer 5

Atrial depolarizaiton
Delay at AV
Ventricular depolarization
Ventricular repolarization

Question 6

aVR
aVF
aVL

Answer 6

Right arm + (-150)
Left leg + (90)
Left arm + (-30)

Question 7

I
II
III

Answer 7

• RA to + LA (0)
• RA to + LL (60)
• LA to +LL (120)

Question 8

Leads measure

Answer 8

AP propogation

Will peak when half of cell is positive and half negative

Propogation from neg to positive…if flipped then peak will be negative

Question 9

Signal magnitude

Answer 9

Shows propogation direction

Big signals if AP propogate parallell or anti-paralell to their direction

Question 10

Mean QRS axis

Answer 10

Normal if complex mainly pos in leads 1 and 2

If QRS up in 1 and 2 stop

Otherwise find most isoelectric…look at lead perpindicular

If QRS up, then positive pole, if down then negative