coronary anatomy and normal cardiac cycle/heart sounds

Question 1

What usually supplies the SA and AV nodes?

Answer 1

RCA. infarcts may casue nodal dysfunction

Question 2

right vs. left dominant ciculation

Answer 2

right dominant circulation- about 85% of people. posterior descending artery arises from the RCA
left dominant- 8%: posterior descending artery arises from the LCX (left circumflex)
codominant circulation- 7%: PDA arises from both RCA and LCX

Question 3

How is the heart arranged in the chest? complications related to this anatomy?

Answer 3

most posterior part of the heart is the left atrium. enlargement can cause dysphagia d/t compression of the esophagus or hoarseness due to compression of the left recurrent laryngeal nerve.

Question 4

What supplies the right ventricle?

Answer 4

the acute marginal artery, which arises from the RCA

Question 5

What is supplied by the LAD?

Answer 5

anterior 2/3 of the interventricular septum, anterior papillary muscle, and anterior surface of left ventricle.

Question 6

What is supplied by the posterior descending?

Answer 6

posterior 1/3 of the interventricular septum and posterior walls of the ventricles.

Question 7

What is supplied by the LCX?

Answer 7

lateral and posterior walls of the left ventricle

Question 8

Why does physiologic S2 splitting exist?

Answer 8

S2- closure of aortic and pulmonic valves. you hear S2 splitting during inspiration- takes longer for the pulm valve to close.

Question 9

S3 vs. S4: which is which?

Answer 9

S3: Ken- tucky (or the non-PC: FUCK, YOU’RE screwed). implies fluid overload/high filling pressures, as with CHF or mitral regurg. may be normal in kids and pregnant women. it is an extra sound at the BEGINING of diastole.
S4: Tennessee (well FUCK, YOU) always abnormal. atrial “kick” at the very end of diastole. seen with left ventricular hypertropy and high atrial pressures. Left atrium must push against a stiff LV wall

Question 10

JVP waves/draw the JVP:

Answer 10

a wave: atrial contraction
c wave: RV contraction (closed tricuspid valve bulges into the RA)
v wave: increase RA pressure due to filling against a closed tricuspid valve
x descent: atrial relaxation and downward displacement of closed tricuspid during ventricular contraction. this is ABSENT in tricuspid regurg
y descent: blood flow from RA to RV