Coronary Artery Disease (CAD)

Question 1

What does it mean to be Right Dominant?

Answer 1

PDA supplied by RCA (85% of population)

Question 2

What does it mean to be Left Dominant?

Answer 2

PDA supplied by LCx (15% of population)

Question 3

What are the effects of a Left main occlusion in a Left dominant heart?

Answer 3

Loss of anterior, lateral, and posterior walls

Question 4

The more ____ the occlusion, the more damage occurs.

Answer 4

Proximal (closer to the aorta)

Question 5

Describe the Right Coronary Artery?

Answer 5

-Originates at the right aortic sinus
-Supplies 25-35% of LV
-Supplies SA node (60% of ppl)

Question 6

RCA Occlusion causes what symptoms?

Answer 6

Bradycardia or arrhythmias

Question 7

What are the two branches of the RCA?

Answer 7

-PDA (85% of people)
-Right Ventricular

Question 8

What is the PDA?

Answer 8

-Supplies inferior wall, septum and posteromedial papillary muscle
-Gives rise to septals

Question 9

What is the Right Ventricular branch of the RCA?

Answer 9

-Supplies anterior RV, SA Node
-Has Acute Marginal Branches

Question 10

Describe the Left Coronary Artery.

Answer 10

“widow-maker”
-Originates as Left Main (0-10mm length)
-Left Main splits into LAD and Left Circumflex

Question 11

Describe the LAD.

Answer 11

-Travels down interventricular groove to apex
-Gives off Septals and Diagonals
-37% of people have ramus (looks like a 1st diag)
-Supplies 45-55% of LV
-Supplies septum, bundle branches, and Purkinje system

Question 12

Describe the Left Circumflex.

Answer 12

-In 15% of people, PDA is off L Cfx
-Travels down left AV groove
-Gives off Obtuse Marginal (OM) Branches
-Supplies Posterolateral- LV, Lateral Wall of LV, SA node- 38%, and 15-25% of LV (unless left dominant- then 50%).

Question 13

What EKG changes are seen with Left Main occlusion?

Answer 13

V1-V6
-Affects entire LV

Question 14

What EKG changes are seen with LAD Occlusion?

Answer 14

V1-V4
-Affects Anterior LV

Question 15

What EKG changes are seen with Left Circumflex Occlusion?

Answer 15

I, aVL, V5, V6
-Affects Lateral LV

Question 16

What EKG changes are seen with RCA Occlusion?

Answer 16

II, III, aVF
-Affects RV & posterior LV

Question 17

How do you calculate Coronary Perfusion Pressure (CPP)?

Answer 17

CPP = AoDP – LVEDP
-normal 60-80, autoregulated between 50-150mmhg
-Coronary blood flow mainly occurs during diastole
-Increased HR decreases time for diastolic filling

Question 18

What are the 3 ways to optimize CPP?

Answer 18

1) Can increase DBP
2) Can lower LVEDP
3) Lower HR (Heart at rest should have a low LVEDP, increases width of CPP gradient).

Question 19

How does coronary sinus SvO2 compare to systemic SvO2?

Answer 19

Systemic SVO2 = 70% vs. coronary sinus SVO2 = 35-50%
-Cardiac muscle extensively extracts O2.
-Ischemia develops when O2 demand > supply.

Question 20

How do you calculate Coronary Blood Flow (CBF)?

Answer 20

Coronary Blood Flow (CBF) = Coronary Perfusion Pressure (CPP) / Coronary Vascular Resistance (CVR)
-Normal value = 225 – 250 mL / min
-Autoregulated between 50-150 mmHg

Question 21

What factors INCREASE Coronary Vascular Resistance (CVR)?

Answer 21

-Inc O2, Dec CO2, Dec H+
-Inc Alpha-Adrenergic tone (constriction of epicardial arteries)
-Inc Cholinergic tone
-Inc Vasopressin (ADH), Angiotensin, and Thromboxane

Question 22

What factors DECREASE Coronary Vascular Resistance (CVR)?

Answer 22

-Dec O2, Inc CO2, Inc H+ (Decreased O2 causes the release of vasodilator substances)
-Inc Beta-Adrenergic tone
-Inc Prostacyclin
-Inc Nitric Oxide, Inc Endothelium-derived factor, Inc Prostaglandin (I2)

Question 23

What is a Left Main Equivalency?

Answer 23

If you have 2 proximal and a distal in the LAD, that is a “L Main Equivalent”.
-50% in one area + 50% in another is the same as Left Main.
-Sequential lesions are additive.

Question 24

Why do older patients with CAD tend to do better than younger?

Answer 24

Older patients develop collaterals over time

Question 25

What are the 3 main determinants of Myocardial O2 Consumption (Demand)?

Answer 25

-HR
-Contractility
-Wall Stress

Question 26

How does HR affect Myocardial O2 Consumption?

Answer 26

The most important factor.
-Doubling of HR more than doubles the O2 demand.

Question 27

How does Contractility affect Myocardial O2 Consumption?

Answer 27

-More contraction = more energy required = more O2 required
-Approximated by the ESPVR curve on PV Loop
-Echocardiogram gives most accurate determination

Question 28

How does Wall Stress affect Myocardial O2 Consumption?

Answer 28

-Law of LaPlace: Tension (wall stress) = (Pressure x radius) / (2 x wall thickness)
-Doubling MAP more than doubles MVO2 (Decreases SVR to decrease O2 demand)
-Inc PL increases demand
-Inc wall thickness decreases wall tension (Hypertrophy results in response to increased AL)

Question 29

MI in the Posterior Wall of the heart will cause what ECG Changes?

Answer 29

Tall R Waves, ST segment depression, and upright T waves in V1-V4 (reciprocal changes)

Question 30

Which is the preferred Induction Agent for Cardiac Tamponade?

Answer 30

Ketamine