Myocardial Blood Supply

Question 1

Left coronary artery
-originates
-supplies
(think what does it become)

Answer 1

Originates @ left aortic sinus

Supplies: left atrium, most of left ventricle, AV bundle and AV node (only 20% of the time), anterior 2/3 of the IV septum, SA node (40% of the time)

Left coronary –> becomes LAD, left marginal, and left circumflex (which supplies left artery to SA node)

Question 2

Right coronary artery
-originates
-supplies
(think what does it become)

Answer 2

Originates @ right aortic sinus

Supplies: right atrium, SA and AV nodes, posterior 1/3 of IV septum, diaphragmatic surface of left ventricle

Right coronary –> becomes posterior descending, right artery to SA node, right marginal, and AV node branch

Question 3

Artery to the SA node

Answer 3

60% of the time it originates from RIGHT coronary and supplies the SA node and pulmonary trunk

40% of the time it originates from the LEFT CIRCUMFLEX and supplies the SA node and left atrium

Question 4

Left marginal artery

if present

Answer 4

Originates @ left circumflex

Supplies: left border of the LV

Question 5

Right marginal artery

Answer 5

Originates @ right coronary

Supplies: right ventricle and apex

Question 6

Anterior IV (anterior descending, LAD)

Answer 6

Originates @ left coronary artery

Supplies: right & left ventricle, IV septum (ant 2/3)

Question 7

Posterior IV (post descending)

Answer 7

Originates @ right coronary artery

Supplies: right & left ventricle, IV septum (post 1/3)

Question 8

AV node branch

Answer 8

Originates @ right coronary artery (80% of the time), may originate off the left coronary (20% of the time)

Supplies AV node

Question 9

(left) Circumflex artery

Answer 9

Originates @ left coronary artery

Supplies: left atrium and ventricle (40% of the time it will supply the SA node)

Question 10

Top 6 occlusion sites

- leads associated

Answer 10

1. LAD - 3 possible occlusions
   - Anteroseptal: V1-V3
   - Anterior: V4-V6
   - Lateral: I, aVL, V5-6
2. Right coronary
   - Inferior: II, III, aVF
3. Circumflex branch
   - Lateral: I, aVL, V5-6
4. Left coronary (before splitting into LAD & circumflex)
5. Posterior IV
   - Posterior: V1-2

Question 11

Inferior Infarct

Answer 11

Right Coronary artery

Leads II, III, aVF

Question 12

Posterior Infarct

Answer 12

Posterior descending

Leads V1-2

Question 13

Lateral Infarct

Answer 13

LAD or Left circumflex

Leads: I, aVL, V5-6)

Question 14

Anteroseptal Infarct

Answer 14

LAD

Leads V1-3

Question 15

Anterior Infarct

Answer 15

LAD

Leads V4-6

Question 16

Determinants of Myocardial Blood flow (4)

Answer 16

1. Diastolic BP - driving force - if it is too high it will impede blood flow back to the heart
2. Resistance - increased resistance will decrease signal to vasodilate (nitric oxide blocked by plaque)
3. Vasomotor tone - aka flexibility - increased SNS output will cause an increase in tone which is a normal response to high BP and other cardiac issues
4. LV end-diastolic pressure - a low pressure will decrease the stretch, therefore decreasing squeeze and decreasing amount of blood ejected for myocardial blood flow

Question 17

Venous Drainage

- main site

Answer 17

Main site = coronary sinus
- Great cardiac vein continues to become the sinus, the middle & small cardiac vein dump into the sinus

The only veins that do NOT dump into the sinus are the

• anterior cardiac veins which dump directly into RA
• smallest cardiac veins

Question 18

Great Cardiac vein

Answer 18

runs along the ant IV septum w/ the LAD

continues to become the coronary sinus

Question 19

Middle Cardiac vein

Answer 19

runs along the posterior descending; dumps into coronary sinus

Question 20

Small cardiac vein

Answer 20

rulls along the acute margin of the RV, paralleling the right marginal artery

dumps into the coronary sinus

Question 21

Anterior cardiac vein

Answer 21

2 or 3 small arteries that drain the sternocostal surface of the right ventricle

dump DIRECTLY into the right atrium