Chapter 10 Gravelee - Myocardial Protection , CH 15 324-35 WBCs

Question 1

Anesthetic Agents - do what?

Answer 1

provide some degree of cardioprotection.
Ameliorate deleterious effects of reactive oxygen species on myocardium during ischemia reperfusion
EX Isoflurane

Question 2

Anesthetic Agents do what for preconditioning ?

Answer 2

↑ preconditioning

Question 3

Acute normovolemic hemodilution how does it enhance myocardial protection?

Answer 3

• avoids blood transfusion to patient
• **-↓A fib and conduction block ***
• Less myocardial injury, CK-MB release and decreased inotrope requirement.

Question 4

CK-MB

Answer 4

shows levels of of CK released from damaged myocardial muscle

Question 5

Acute normovolemic hemodilution cons?

Answer 5

Some patients are too anemic from this

Efficacy not always proven

Question 6

Neutrophil depletion, how does it enhance myocardial protection?

Answer 6

↓ V fib – post bypass

Lower inotrope use and lower postop cardiac enzyme release

Question 7

How does Neutrophil deletion work?

Answer 7

Neutrophils are released during CPB, and then cause tissue injury by the release of enzymes, reactive oxygen species and other toxic substances
Use Neutrophil filtration

Question 8

Erythropoietin how does it enhance myocardial protection?

Answer 8

↓ myocardial injury

Question 9

How does Erythropoietin work?

Answer 9

• its a noncardioplegia medication
• it is the primary growth factor that controls the precursor to RBC production. Commonly used in pts with depressed bone marrow or depressed erythropoietin production
• ALSO has antiapoptic effects
• it protects myocytes from hypoxia and oxidative stress

Question 10

Myocytes

Answer 10

are long, tubular cells that develop from myoblasts to form muscles in a process known as myogenesis. There are various specialized forms of myocytes: cardiac, skeletal, and smooth muscle cells, with various properties.

Question 11

N-acetylcysteine how does it enhance myocardial protection?

Answer 11

**↓ oxidative stress **

Question 12

How does N-acetylcysteine work?

Answer 12

• Noncardioplegia medication

- A reactive oxygen species scavenger

Question 13

Reactive Oxygen Species

Answer 13

chemically reactive molecules containing oxygen. Examples include oxygen ions and peroxides. ROS are formed as a natural byproduct of the normal metabolism of oxygen and have important roles in cell signaling and homeostasis.[1] However, during times of environmental stress (e.g., UV or heat exposure), ROS levels can increase dramatically.[1] This may result in significant damage to cell structures. Cumulatively, this is known as oxidative stress

Question 14

Deferoxamine how does it enhance myocardial protection?

Answer 14

↓lipid peroxidation *******
Increase LVEF
Decreased postop wall motion abnormalities

Question 15

Statins how does it enhance myocardial protection?

Answer 15

**↑NO release **
Anti-inflammatory properties
Antioxidative properties
Decreased monocytes adhesion

Question 16

How does Deferoxamine work?

Answer 16

• Noncardioplegia medication
• it is an iron chelator that reduces myocardial injury by reducing the amount of hydroxyl radical formation by iron catalyzed Fenton reactions (aka reduces amount of iron)

Question 17

What are statins?

Answer 17

Statins are a class of drugs used to lower cholesterol levels by inhibiting the enzyme HMG-CoA reductase, which plays a central role in the production of cholesterol in the liver, which produces about 70 percent of total cholesterol in the body. Also increase NO release

Question 18

Ischemic preconditioning

Answer 18

an initial sublethal ischemic injury conveys protection against subsequent ischemic insults
Having to do with adenosine receptor , multiple kinase and alterations in the Katp channels
(bc ATP repletion following brief episodes of ischemia occurs slowly)

Question 19

Fibrillatory Arrest

Answer 19

relies in principle of ischemic preconditioning bc the protective events of short intervals of ischemia have been related to adenosine receptor, multi kinase and alterations in Katp channel.

Question 20

Fib Arrest Cons

Answer 20

Repeated aortic clamping

Anastomotic time limited

Question 21

Perfusion-assisted direct coronary artery bypass (PADCAB)

This is used during OFF PUMP cases.

Answer 21

directly perfuses myocardium supplied by a bypassed coronary artery by providing a controlled flow down the conduit.
Inflow to the circuit and pump is provided by a catheter placed in the ascending aorta or femoral artery. Use of MPS - a computer controlled blood delivery system, allows for exact control of coronary perfusion pressure.
This pressure is independent of systemic pressure bc body is taking care of that

Question 22

Selectin Family

Answer 22

transmembrane molecules expressed on the surface of leukocytes and activated endothelial cells.
The initial attachment of leukocytes from the blood stream during inflammation is afforded by the selectin family and causes slowing of downstream move until a complete stop of leukocytes along endothelium.

Question 23

Members in Selectin Family -

Answer 23

P, E and L-selectin

Question 24

P-selectin does what?

Answer 24

released by exocytosis within minutes of activation of agents such as histamine/thrombin ect.
Largely responsible for the rolling phase of leukocyte adhesion cascade.

Question 25

Neutrophil activation during CPB how?

Answer 25

through interaction with activated vascular endothelium, shown through loss of L-selectin