Conduct System

Question 1

Where is the SA node located and what artery supplies it?

Answer 1

Located in the RA sulcus terminalis; SA node artery (branch of the RCA in 60% or LCX in 40%)

Question 2

Where is the AV node located and what artery supplies it?

Answer 2

Located in the Triangle of Koch; AV node artery (branch of the RCA in 85% or LCX in 15%)

Question 3

What makes up the Triangle of Koch?

Answer 3

Tendon of Todaro + TV annulus + ostium of the coronary sinus

Question 4

How does the left bundle branch traverse and what artery supplies it?

Answer 4

From intraventricular septum to behind the non-coronary cusp of the AV and separates into anterior and posterior fascicles; Anterior fascicle = branches of LAD; Posterior fascicle = branches of PDA

Question 5

How does the right bundle branch traverse and what artery supplies it?

Answer 5

Travels down the right side of the intraventricular septum towards the apex of the RV; Septal branches of the LAD

Question 6

What are the phases of a pacemaker action potential?

Answer 6

Phase 4, Phase 0, and Phase 3

Question 7

What is Phase 4 of a pacemaker action potential?

Answer 7

Funny currents (mixed Na/K channel) which allows Na+ to slowly enter and spontaneously depolarize + around -50mV, T-Type Ca channels (transient) open and further depolarize the cell + around -40mV, L-Type Ca channels open as well resulting in an action potential

Question 8

What is Phase 0 of a pacemaker action potential?

Answer 8

Depolarization primary by the Ca influx through the L-type Ca channels that opened at the end of Phase 4

Question 9

What is Phase 3 of a pacemaker action potential?

Answer 9

K channels open, causing K+ to leave the cells and hyperpolarizes the cell + L-type Ca channels close to decrease Ca influx + at the end of Phase 3, funny currents begin starting Phase 4

Question 10

Where is there automaticity in the heart?

Answer 10

SA node+ subsidiary atrial foci + AV node + His-Purkinje system

Question 11

What are two basic mechanisms of focal arrhythmias?

Answer 11

1. Abnormal automaticity:cells that normally exhibit automaticity are altered.
2. Triggered: cells with repetitive afterdepolarizations - changes in potential before or after repolarization (early vs. late)

Question 12

Whatis the mechanism of reentry arrhythmias?

Answer 12

Impulses that re-excite myocardial cells that are not in a refractory state; predicated on some form of unidirectional conduction block –> conduction thus propogates along an alternative route that has a faster speed of conduction than the refractory period of the cells causing the unidirectional block

Question 13

What is a key difference between a Holter monitor vs loop recorder?

Answer 13

Holter = Typically continuous monitoring for 24 hours; Loop = longer term evaluation of rhythm assessment

Question 14

What are the 5 ways to diagnosis arrythmias?

Answer 14

1. EKG 2. Holter Monitoring 3. Echocardiography 4. Loop recorder 5. EP study

Question 15

Pacemaker Action Potential image

Answer 15

See Excel