Custodial HTK Cardioplegia

Question 1

HTK

Answer 1

Custodial HTK Solution
single dose cardioplegia

solution for cardioplegia and multiple organ protection - FDA approved

Question 2

Principle

Answer 2

withdrawal off etraceullular sodium and calcium

buffering extra cellular space
- histidine long buffer
- histidine HCI

Question 3

physical properties

Answer 3

acidic –> pH 7.02 - 7.2 at 25 degrees celsius

osmaolality is 310 mosmol/kg

good for up to a year

low potassium concentrationto minimize risks and low sodium concentration for safe organ inactivation

histidine is used as a buffer

Question 4

mannitol

Answer 4

Mannitol maintains physiological or slightly increased osmolality and thereby counteracts the colloidal osmotic pressure of intracellular protein to reduce cellular edema. Mannitol may also act as a free-radical scavenger

Question 5

tryptophan

Answer 5

protects and stabilizes cell membranes

substrate for anaerobic metabolism

intermediary in the Krebs cycle

precursor of nicotinamide adenine dinucleotide, improved production of ATP during reperfusion and inhibiting the production of lactate through glycolysis

Question 6

histidine/histidine hydrochloride

Answer 6

“Game changer”

The histindine/histidine hydrochloride buffering system provides normal osmolarity and enhances the solution’s buffering capacity during the ischemic-induced acididosis.

Question 7

administration

Answer 7

Best route is Antegrade with no AI or mild AI

pts with sever AI, use antegrade through coronary ostial perfusion (handheld cannula)

combination of antegrade and retrograde

Question 8

initial loading dose

Answer 8

25 cc/kg –> smaller patients
- minimum adult dose 2000 cc

Question 9

cross clamp removal

Answer 9

give 200 mg of lidocaine –> HELPS WITH ARRYTHMIAS

and 2 grams of magnesium

Question 10

time factor

Answer 10

important bc you want to give solution time to get to the heart muscle

Question 11

endoplege sinus catheter

Answer 11

goes to IJ –> SVC –> RA –> Coronary sinus Ostium –> middle cardiac vein –> coronary sinus

• inflates ballon to measure pressures in coronary sinus

Question 12

when heart is arrested what is the membrane potential

Answer 12

it is negative because you have increased Potassium in the cell and increased sodium outside of the cell

Question 13

pacemaker potential

Answer 13

heart has a special condition that makes it “autonomous”.
This organ can develop, itself, the action potencial trough Sinoatrial node. This event is know as PACEMAKER POTENTIAL.

Question 14

Phases of action potential

Answer 14

0 – 1 = rising phase
Na⁺ channels Voltage Dependents (Depolarization)

1 = peak phase
Na⁺ channels are closing and K ⁺ channels are openning

2 = plateau
Ca⁺⁺ channels are openning

3 = falling phase
Most of Na⁺ channels are closed, and the majority of K⁺ are open. (Repolarization)

4 = undershoot phase/refractory period.
Both channels are closed and the cell´s interior is negative again.

Question 14

alpha ketoglutarate acid

Answer 14

provides good nutrition to the myocardium

Question 15

Triptofan

Answer 15

protects the membrane

decreases the O2 consumption and increases the chance of spontaneous return to the normal heart rhythm

Question 16

histidine

Answer 16

is a great buffer