Topic 11B Flashcards
1
Q
Two Main Goals of Cardioplegia
A
- Prevent myocardial ischemic damage (induction/maintenance)
- Prevent/minimize injury (reperfusion)
2
Q
limit detrimental changes such as (7)
A
- rapid cellular conversion from aerobic (O2) to anaerobic metabolism (no O2)
- high-energy phosphate (e.g. ATP) depletion
- intracellular acidosis
- calcium influx
- cell membrane disruption
- Intracellular Ca++ accumulation
- Cellular edema (inability to consume oxygen)
3
Q
Cardioplegia Setups include:
A
crystalloid
blood
MPS
4
Q
Crystalloid=
A
Single pass system
5
Q
Blood cardioplegia setup=
A
- Fixed ratio (Bridged or Non-bridged)
2. Variable/controlled ratio
6
Q
MPS=
A
microcardioplegia
7
Q
3 Phases of Cardioplegia include
A
Induction of arrest
Maintenance of arrest
Reperfusion
8
Q
Cold Induction Solutions (Crystalloid and Blood)= (4)
A
- ECF cardioplegia solution
- Potassium depolarization arrest
- Depolarizes the cardiac myocyte with hyperkalemia
- Ca++ ATPase and Na+/K+ATPase still operative and need energy
9
Q
Pure Crystalloid Cardioplegia Induction:
Advantages (4)
A
History of use
Ease
Cheap
Low viscosity
10
Q
Pure Crystalloid Cardioplegia Induction:
Disadvantages (6)
A
Cellular edema Low O2 capacity Left shift oxy-Hgb curve Activates platelets, leukocytes, and complement Impaired membrane stabilization Hemodilution
11
Q
Generic Crystalloid Solutions: Lactated Ringer’s 1000 mL KCL= MgCl= Mannitol= NaHCO2=
A
KCL 20 mEq
MgCl 32 mEq
Mannitol 12.5 g
NaHCO2 6.5 mEq
12
Q
Lactated Ringer’s 1000 mL: What do you add prior to use?
A
Procaine 10% 2.7 mL
13
Q
Generic Crystalloid Solutions: Normosol 1000 mL NaHCO2= KCL= Mannitol=
A
NaHCO2 35 mEq
KCL 35 mEq
Mannitol 25% 12.5 g
14
Q
Normosol 1000 mL: What do you give prior to use? (3)
A
Lidocaine 75 mg
Ntg 500 mcg
Albumin 25% 12.5 g
15
Q
Cold Blood Cardioplegia Induction
Advantages (4)
A
O2 carrying capacity
Reduced hemodilution
Buffering/oncotic effects
O2 radical scavengers present
16
Q
Cold Blood Cardioplegia Induction
Disadvantages (3)
A
Sludging
Oxy-Hgb curve disruption
Possible red cell damage
17
Q
Warm Blood Cardioplegia Induction
Advantages (3)
A
Improved aerobic metabolism
Improved LV function
Improves compromised hearts
18
Q
Warm Blood Cardioplegia Induction
Disadvantages
A
Expensive due to additives
19
Q
Low Potassium Maintenance= (3)
A
- Usually every 15 to 20 minutes
- Cold blood cardioplegia or crystalloid
- Restores arrest post wash-out
20
Q
Preparation for Reperfusion= (6)
A
Substrate-enhanced warm cardioplegia Limit calcium Limit PO2 Controlled reperfusion De-air adequately Avoid ventricular distension
21
Q
Know the SV per tubing size
A
look at lab notes from last quarter
22
Q
Controlled reperfusion=
A
The endothelium is damaged during ischemia–damage can increase through unregulated reperfusion
•Upon XC Removal: MAP → 40 mmHg for 1-2 minutes then MAP→ 70 mmHg after 2 minutes
23
Q
Hot Shot=
A
- Just prior to removal of the aortic cross clamp
- In addition to cross clamp drugs
24
Q
Cross clamp drugs (4)
A
Aspartate Glutamate Tham Dextrose CPD --Due to cost: warm blood may be substituted
25
Custodial Cardioplegia =(HTK)
Histidine Tryptophan Ketoglutarate
26
Custodial Cardioplegia (HTK): Intracellular cardioplegia solution (4)
Low sodium concentration
Histidine
Tryptophan
Mannitol
27
Benefits of HTK Cardioplegia: Initial use
organ protection
28
Benefits of HTK Cardioplegia: Now used in cardiac surgery because (3)
Longer safe time of ischemia
During valve surgery
Minimally invasive procedures
29
Del Nido Solution (4:1)=
Plasmalyte base which is similar to ECF
30
Warm Continuous Retrograde Blood Cardioplegia:
Lichtenstein (1991) suggested that the heart
could be maintained at
37ºC throughout the cross clamp period to enhance perioperative myocardial function
31
Warm Continuous Retrograde Blood Cardioplegia:
“Warm Heart Trial” (1994): Studied nearly 2000 patients randomized to normothermic or hypothermic cardioplegia-- they found that...
Normothermic patients experienced a lower incidence
| of post-operative low output syndrome with no differences in mortality or myocardial infarction
32
Warm retrograde cardioplegia flow must be
>100 mL/min to minimize myocardial lactate production
33
Cross clamp drugs right after cross clamp removal
lidocaine
| mannitol
34
Single Clamp Technique=
One clamp episode
One unclamp episode
Distals and proximals done during one ischemic time
35
Single Clamp Technique is used with
Used with calcified stiff aortas
36
Side Biting Clamp Technique=
Two clamp episodes
Two unclamping episodes
Distals done during first ischemic time
Proximals done during second ischemic time
37
Side Biting Clamp Technique has shorter
cross clamp times
38
Side Biting Clamp Technique= Ischemic time is
only with fully clamped aorta
39
Intermittent Crossclamp=
Increased risk of stroke
| Not commonly used
40
Intermittent Crossclamp: clamp time is
the sum of all fully ischemic times
41
Fibrillatory Arrest=
Creates a nearly motionless heart by placing an
alternating current generator in contact with the left
ventricle
42
Fibrillatory Arrest: Left side of heart can be
opened without the fear of ejecting air into the aorta.
43
Fibrillatory Arrest: Should be used in conjunction with
hypothermia
44
Fibrillatory Arrest: Advantages
Avoid cross clamp
| Quiescent heart with coronary perfusion
45
Fibrillatory Arrest: Disadvantages
Higher energy requirement than arrested heart
| Spontaneous ejection will result in air emboli
46
Fibrillatory Arrest: Keep ____ elevated
MAP
47
Additional Strategies to Enhance Protection (7)
```
Anesthetic agents (↑ preconditioning)
Acute normovolemic hemodilution (↓ A fib)
Neutrophil depletion (↓ V fib)
Erythropoietin (↓ myocardial injury)
N-acetylcysteine (↓ oxidative stress)
Deferoxamine (↓lipid peroxidation)
Statins (↑NO release)
```
48
Anesthetic agents does what?
(↑ preconditioning)
49
Acute normovolemic hemodilution does what?
(↓ A fib)
50
Neutrophil depletion does what?
(↓ V fib)
51
Erythropoietin does what?
(↓ myocardial injury)
52
N-acetylcysteine does what?
(↓ oxidative stress)
53
Deferoxamine does what?
(↓lipid peroxidation)
54
Statins does what?
(↑NO release)
55
Monitoring Effectiveness for the Perfusionist
| •GOAL:
```
optimize uniformity and effectiveness of delivery
(especially retrograde)
•Temperature
•pH
•Electrical Activity
```
56
Monitoring-Temperature: Thermo coupled needle usually inserted
septal muscle
| myocardial temp probe
57
Monitoring-Temperature: Ensure delivery of
```
adequate dose
(is it going where it belongs?)
```
58
Monitoring-Temperature: See efficacy of delivery
•Antegrade-
•Retrograde-
* Antegrade-cases of aortic insufficiency
| * Retrograde-cannula position ( in RA?)
59
Monitoring-Temperature: Determine when
next dose needed
| timers
60
What can the perfusionist do if arrest is not occurring as
| expected?
is aortic valve competent/insufficient
did it go the the LV
change from antegrade to retrograde
is the aortic clamp not on all the way (dilutes cardioplegia)
low K instead of high K?
bridge open or closed?
hypertrophied LV walls require a higher pressure
61
Temperatures effect on pH and partial pressure assuming O2 content is constant: Increase temp=
```
Shift curve to the right
Decrease HOH
Increase H+
Increase OH-
Decrease pH
```
62
Temperatures effect on pH and partial pressure assuming O2 content is constant: Decrease temp=
```
Shift curve to the left
Increase HOH
Decrease H+
Decrease OH-
Increase pH
```
63
Failure to arrest can be due to
```
Aortic insufficiency
Cross-clamp or cardioplegia needle malpositioned
Inadequate solution (low potassium)
Low flow?
Low pressure?
Temperature?
```
64
Myocardial Protection for Off-Pump Procedures:
| Regional ischemia unavoidable- May become...
global problem when multiple vessels grafted
65
Myocardial Protection for Off-Pump Procedures:
| Use of suction-based stabilizers has reduced the problem of
working on a moving target
•Provide good exposure without excess compression of
ventricle
66
Myocardial Protection for Off-Pump Procedures:
| Ischemic preconditioning=
Brief period of vessel occlusion before occluding for
| construction of the anastomosis
67
Myocardial Protection for Off-Pump Procedures:
| Keep normal to high...
systemic blood pressure
•May increase flow through collaterals
vessels
68
Myocardial Protection for Off-Pump Procedures:
| Attach proximal end of graft before
attaching distal
| •Immediate re-establishment of flow to ischemic area
69
Myocardial Protection for Off-Pump Procedures:
| Use of _______ shunt
intracoronary
70
Myocardial Protection for Off-Pump Procedures:
| Perfusion-assisted...
direct coronary artery bypass (PADCAB)
| •Perfuse completed grafts
71
Ingredients to know (7)
```
K+
Na+
Ca++
NaHCO3
THAM
Glucose
Mannitol
```
72
Actions of K+
electromechanical arrest
73
Actions of Na+
↓ edema/intracelluar Ca++ buildup
74
Actions of Ca++
Membrane stabilization
75
Actions of NaHCO3
↑ pH
76
Actions of THAM
↑ pH
77
Actions of Glucose
Substrate, ↑ Osmolarity, ↓ edema
78
Actions of Mannitol
↑ Osmolarity
79
Solution Concentrations: KCl
High K
Low K
High K= 100 mmol/L
| Low K= 40 mmol/L
80
Solution Concentrations: THAM
High K
Low K
High K= 12 mmol/L
| Low K= 12 mmol/L
81
Solution Concentrations: MgSO4
High K
Low K
High K= 9 mmol/L
| Low K= 9 mmol/L
82
Solution Concentrations: Dextrose
High K
Low K
High K= 250 mmol/L
| Low K= 250 mmol/L
83
Solution Concentrations: CPD
High K
Low K
High K= 20 ml
| Low K= 20 ml
