Cardiolegia Prep for Bruce's Final Exam

Question 1

Potassium in the cardioplegia does what to the heart?

Answer 1

Changes the resting membrane potential of the myocardium rendering it unexcitable

Question 2

2 transport mechanisms?

Answer 2

Active

Passive

Question 3

Active transport mechanism

Answer 3

• Requires energy

- Moves solutes against concentration gradient

Question 4

Define Pumps ?

Answer 4

carrier proteins that mediate primary active transport.

Question 5

Describe the Sodium-Potassium pump?

Answer 5

Na+ / K+ pump is energized by the hydrolysis of ATP into ADP & a phosphate group.

• 3 Na+ are expelled against their concentration gradient.
• 2 K+ are pulled into the cell against their concentration gradient.

Question 6

Intracellular values of:

Na+
K+
Cl -

Answer 6

Na+ = 12 NM (microns)
K+ = 139 NM (microns)
Cl - = 10 NM (microns)

Question 7

Extracellular values of:

Na+
K+
Cl -

Answer 7

Na+ = 145 NM (microns)
K+ = 4 NM (microns)
Cl - = 150 NM (microns)

Question 8

Cardiac threshold ?

Answer 8

fires at 70

Question 9

Greater than ___mEq/L cardioplegia may lead to cell membrane damage.

Answer 9

40 mEq/L

Question 10

2 advantage of chemical arresting agent ?

Answer 10

• Preservation of
  energy stores.
• Recovery of function

Question 11

How does K+ arrest the heart ?

Answer 11

Administration of K+ changes the K+ outside of the cell. K+ therefore raises the RMP of the cardiac cell to a voltage that is greater than threshold (-70). Its then unexcitable because it is stuck in a refractory state.

Question 12

4 mmol of CLP = __ mv

Answer 12

-84 mv

Question 13

10 mmol of CLP = __ mv

Answer 13

-70 mv

Question 14

20 mmol of CLP = __mv

Answer 14

-52 mv

Question 15

5 Constituents of Cardioplegia?

Answer 15

• Buffer
• Arresting Agent
• Calcium
• Hypertonic
• Oxygen Delivery

Question 16

High dose K+ =

Answer 16

20 mEq/L

Question 17

Low dose K+ =

Answer 17

8 - 10 mEq/L

Question 18

3 disadvantages of Cardioplegia.

Answer 18

• Ischemic Injury do to non-continuous blood flow.
• Calcium Paradox
• Stone Heart

Question 19

Ischemic injury happens during ___ ?

Answer 19

Re-perfusion

Question 20

Cellular responds to ischemia by.

Answer 20

• Humeral signaling events
• Cell membrane receptors
• Self destruct messages
• Immune reaction
• Apoptosis

Question 21

Multidose cardioplegia results in what ?

Answer 21

Calcium Paradox

Question 22

Prevent Calcium Paradox with what ?

Answer 22

• diltiazem (Ca+ channel blocker)

- Trace Ca+ levels

Question 23

It is believed that low levels of ATP cause what ?

Answer 23

Leakage of Ca+ from the sarcoplasmic reticulum.

Question 24

ATP is required to maintain what ?

Answer 24

sarcoplasmic reticulum stores of Calcium

Question 25

Reperfusion with Ca produces massive Ca release but the absence of ATP results in

Answer 25

Tetanic Contracture (Stone Heart)

Question 26

Q10

Answer 26

reaction rate changes for every 10°C change in temperature

Question 27

22°C =

Answer 27

MVO2 reduction by 97%

Question 28

Na+ K+ pumps are located in the cell surface and the ____ ____ _____.

Answer 28

T-tubule membranes

Question 29

Intermittent CLP delivery has long controlled periods of:

Answer 29

ischemia

Question 30

Continuous CLP delivery strives for:

Answer 30

no ischemia

Question 31

“Continuous cardioplegia delivery” really means this. .

Answer 31

– Continuously intermittent?
– Generally has shorter ischemic periods
– Often used with warm cardioplegia
– (Warm + Ischemic = Bad)