Myocardial Protection and Cardioplegia 11B Flashcards
Four Main Objectives of Cardioplegia
•Immediate/sustained electromechanical arrest
•Rapid/sustained homogenous myocardial
cooling
•Maintenance of therapeutic additives in effective concentrations
•Periodic washout of metabolic inhibitors
Two Main Goals of Cardioplegia
I. Prevent myocardial ischemic damage (induction/maintenance)
II. Prevent/minimize injury (reperfusion)
3 Phases of Cardioplegia
I.Induction of arrest
II.Maintenance of arrest
III.Reperfusion
Pure Crystalloid Cardioplegia Induction Advantages (4)
- History of use
- Ease
- Cheap
- Low viscosity
Pure Crystalloid Cardioplegia Induction Disadvantage (6)
-Cellular edema •Low O2 capacity •Left shift oxy-Hgb curve •Activates platelets, leukocytes, and complement •Impaired membrane stabilization •Hemodilution
Cellular edema is a disadvantage of what cpg solution?
Pure crystalloid cpg
Low O2 capacityis a disadvantage of what cpg solution?
Pure crystalloid cpg
With a Lactated Ringer’s 1000mL cpg what do you add prior to use?
Add prior to use
Procaine 10% 2.7 mL
With a Normosol 1000 mL cpg what do you add prior to use? (3)
Add prior to use
Lidocaine 75mg
Ntg 500 mcg
Albumin 25% 12.5 g
Normosol 1000 mL is made of what? (3)
NaHCO2 35mEq
KCL 35mEq
Mannitol 25% 12.5 g
Lactated Ringer’s 1000mL is made of what? (4)
KCL20mEq
MgCl 32mEq
Mannitol 12.5 g
NaHCO2 6.5mEq
Cold Blood CPG Induction Advantages (4)
- O2 carrying capacity
- Reduced hemodilution
- Buffering/oncotic effects
- O2 radical scavengers present
Cold Blood CPG Induction Pitfalls if HCT high enough? (3)
- Sludging
- Oxy-Hgb curve disruption
- Possible red cell damage
Warm Blood CPG Induction Advantages (3)
- Improved aerobic metabolism
- Improved LV function
- Improves compromised hearts
Warm Blood CPG Induction Disadvantages
Expensive due to additives
Low Potassium Maintenance - how often ?
-Usually every 15 to 20 minutes
•Restores arrest post wash-out
Low Potassium Maintenance - what kinds?
- Cold blood cardioplegia or crystalloid
* Restores arrest post wash-out
Hot Shot solutions?
- Aspartate Glutamate
- Tham
- Dextrose
- CPD
During “hot shots” warm blood may be substituted why?
cost
HTK stands for?
Histidine-Tryptophan-Ketoglutarate
HTK is what type of solution?
Intracellular cardioplegia solution
HTK solution
Low sodium concentration
Histidine
Tryptophan
Mannitol
HTK cardiac surgery Benefits?
Longer safe time of ischemia
During valve surgery
Minimally invasive procedures
HTK initial use ?
organ preservation
Del Nido Solution (4:1) Additives ? (5) **
Mannitol 20% 16.3 mL MgSO4 50% 4 mL NaHCO2 8.4% 13 mL KCL 2mEq/L 13 mL Lidocaine 1 % 13 mL
Warm retrograde cardioplegia flow must be
what to minimize myocardial lactate
production?
> 100 mL/min **
When do you use the single clamp technique ?
Used with calcified stiff aortas **
Side biting technique benefits? ischemic time?
Ischemic time is only with fully clamped aorta
Shorter clamp times **
Intermittent Crossclamp - clamp time sum of?
Clamp time is the sum of all fully ischemic times **
Intermittent Crossclamp negatives?
- Increased risk of stroke
* Not commonly used
Fibrillatory Arrest
Creates a nearly motionless heart by placing an alternating current generator in contact with the left ventricle.
Fibrillatory Arrest - what side of heart can be opened?
Left side of heart can be opened without the fear of ejecting air into the aorta
Fibrillatory Arrest should be used in conjunction with what?
hypothermia
What do you keep elevated during Fib Arrest?
KEEP MAP ELEVATED *
Fibrillatory Arrest Advantages? (2)
- Avoid cross clamp
* Quiescent heart with coronary perfusion
Fibrillatory Arrest Disadvantages? (2)
- Higher energy requirement than arrested heart
* Spontaneous ejection will result in air emboli
Anesthetic agents do what for preconditioning?
↑ preconditioning
Erythropoietin do what for myocardial injury?
↓myocardial injury
Statins increase what?
↑NO release
Neutrophil depletion decrease what?
↓V fib
Goal of Perfusionist during CPG delivery?
especially?
GOAL: optimize uniformity and effectiveness of delivery (especially retrograde) ***
What do you monitor during CPG delivery?
Temperature
pH
Electrical Activity
Decrease TEMP what happens to ?
HOH >< H + OH = pH
^ HOH >< Decrease H + Decrease OH = ^ pH
Increase TEMP what happens to ?
HOH >< H + OH = pH
Decrease HOH >< ^ H + ^ OH = decrease pH
Failure to arrest look at what? (6)
- Aortic insufficiency
- Cross-clamp or cardioplegia needle malpositioned
- Inadequate solution (low potassium)
- Low flow?
- Low pressure?
- Temperature?
Use of suction-based stabilizers is use when?
Reduces what?
-Used during OFF Pump surgery
-Has reduced the problem of working on a moving target
•Provide good exposure without excess compression of ventricle
Ischemic Preconditioning ?
Brief period of vessel occlusion before occluding for construction of the anastomosis
Used during off pump procedures
Off Pump Procedures keep systemic bld pressure at what ?
Keep normal to high systemic blood pressure
May increase flow through collaterals
vessels
K+ does what for CPG?
electromechanical arrest
Na+ does what for CPG?
↓ edema/intracelluar Ca++ buildup
Ca++ does what for CPG?
Membrane stabilization
NaHCO3 does what for CPG?
↑pH
THAM does what for CPG?
↑pH
Glucose does what for CPG?
Substrate, ↑Osmolarity, ↓ edema
Mannitol does what for CPG?
↑ Osmolarity
KCl high and low K doses concentrations?
100mmol/L
40 mmol/L
THAM high and low K doses concentrations?
12mmol/L
12mmol/L
MgSO4 high and low K doses concentrations?
9 mmol/L
9 mmol/L
CPD high and low K doses concentrations?
20 mL
20 mL