cardioplegia

Question 1

What is myocardial protection?

Answer 1

protecting the heart muscle from damage during open heart surgery with the help of cardioplegia and cool down

Question 2

What is cardioplegia?

Answer 2

a pharmacologically induced, reversible cardiac arrest.

hyperkalemia

Question 3

When is ante/retrograde cardioplegia used?

Answer 3

Antegrade cardioplegia is done through the right and left coronary arteries (using one or two cannulas) and it is the general solution to perfuse heart muscle during ECC

Retrograde cardioplegia is done through coronary sinus as an alternative solution if the antegrade cardioplegia is not possible, due to an aortic insufficiency

Question 4

What different cannulas are used for cardioplegia?

Answer 4

ante:
1C:
\+ only one incision
- no control over l/r pressure/flow
2C:
\+ controlled perfusion of l/r
- opening of aorta required
- needs 2 pumps

retro:
incision in rA -> sinus coronaris
- subendocardial area of thebesian veins not perfused

Question 5

Explain crystalline cardioplegia.

Answer 5

crystalline cardioplegia solution is applied at low temperature of 4°C, resulting in a rapid cooling of the heart -> electrophysiological cardiac arrest

+ simple application
- no oxygen supply

Question 6

Explain blood cardioplegia.

Answer 6

the cardioplegia is a mixture of 4 parts blood from the oxygenator and one part 4°C solution. cooling process slower than crystalline cardioplegia

+ oxygen supply

• more complicated
• needs two pumps

Question 7

What is the meaning of hypothermia?

Answer 7

• oxygen demand reduced
• ischemia tolerance increased
• metabolic activity reduced

Question 8

What kinds of hypothermia exist?

Answer 8

gentle: 37-32°C, 4-10min
mean: 32-28°C, 10-16min
deep: 28-18°C, 16-60min
severe: 18-4°C, 60-90min

Question 9

What are the dangers of hypothermia?

Answer 9

• infection
• altered drug behavior
• narcotics harder to control
• blood more viscous
• more dissolved gases in blood

Question 10

What is to keep in mind after hypothermia?

Answer 10

ACT is reduced by up to 13-30%

Question 11

Explain the relation of oxygen and low temperature.

Answer 11

30°C -> 50% oxygen usage
25°C -> 25% oxygen usage
15°C -> 10% oxygen usage