Cardioplegia solution is used to arrest the cardiac activity during cardiopulmonay bypass.

Types-

ST Thomas I (Maccarthy)

• Nacl-144mmol/l
• Kcl -20mmol/l
• Mgcl -16
• Cacl2 -2.4 meq/l
• NaHco3-
• Procaine-1.0
• pH – 5.5-7.0
• osmolarity -300-320

 

ST Thomas II (Plegisol)

• Nacl -110
• Kcl -16
• Mgcl -16
• Cacl2-1.2
• NaHco3 -10
• pH- 7.8
• osmolarity -285-300

 

MYOCARDIAL PROTECTION STRATEGIES

• Anaesthetic agents
• Nanovolemic hemodilution
• Non cardioplegia medication
• Neutrophil depletion
• Ischaemic preconditioning
• Offpump revascularization

 

CARDIOPLEGIA  DELIVERY SYSTEM

SrNo		PROS	CONS
1	Antegrade	simple,mimics normal flow	Requires competent aortic valve, advanced CAD
2	Retrograde	obviates limitations form Aortic insufficiency And CAD, Does not improve Conduict of surgery , augments dearing	Catheter  placement can be difficult. Complex
3	Throng conduits	Allows antegrade protection of Areas of CAD , obviates limitation from AR and CAD Allows, need to pressure aortic root too or interrupt surgery	Requires conduit , right coronary distribution poor , complex
4	integreated	maintain uniform distribution of cardioplegia	Complexity
5	Blood	Provides substrate for metabolic demands of myocardium.High colloid oncotic pressure increase. Avoid cellular edema. Oxygen carrying capacity, Buffering action,Similar in electrolyte. Compositiom and osmolarity Free radical scavenging ability	Cost,Complexity ,   Viscosity Left shift of O2 curve   High O2 and substrate Not required.
6	CRYSTALLOID	Inexpensive , simplicity , availability	large volume of crystalloid, No buffering , No O2 carrying capacity
7	MICROPLAGIA	Large volume of cardioplegia but minimum crystalloid volume According to quantification of quadriplegia delivery	cost , complexity

 

Ability to further modify cardioplegia with additives

	ADDITIVE	FUNCTION
1	K+ / Mg+/procaine	immediate arrest
2	Hypothermia 10-20 degree celcius	decrease  metabolism
3	Glucose	as substrate for metabolism
4	O2/blood	substrate
5	Glutamate / asparatate	substrate
6	Hco3/THAM/Phosphate	buffer
7	FFP/Albumin	colloid osmotic pressure increases and decreases  oedema.
8	Methylprednisolone	decreases edema

 

Delivery  schedule

Pros	Cons
1.Intermittant- improved exposure,Low cardioplegia solution	increase in interval in dosing causes my-ocardial acidosis
2.Continuous- Normal perfusion	operative field  disturbances.
Increase post op LV Function,Decrease ionotropic  support post op	complexity of delivery,

 

 

ADDITIVES:

Nicorandil: Adenosine triphosphate sensitive K+ channels opener

Opens K+ channel, cardiacarrest can be achieved with kess toxic doses of K+ containing cardioplegia

Preconditioning agent

	PROS	CONS
Nicorandil	less cardioplegia and K+requirement Reduced peri operative Coronary spasm Pre conditioning,  reduced  need for catecholamine use in post op.	Cost
L Arginine	decrease cytokine levels. decreses myocardial enzyme levels Reduced need for catecholamine use postop Reduced pulomary wedge pressure.	Cost complexity
Insulin	Increases survival and improved lt.ventriculat function.	Complexity, efficacy not clear.

 

NON CARDIOPLEGIA MEDICATIONS:

1. Erythropoeitin: protect for hypoxia and oxidative stress
2. N-acetyl cysteine : reactive O2 scavenger
3. Deferoxamine: iron chelator

 

	PROS	CONS
Anaesthetic Agents	Provide pre conditioning	unclear
Acute Normovolemic haemodilution	Less myocardial injury Cpk-mb release and decreased Ionotrope requirement Reduced incidence of atrial fibrillation and conduction block.	efficacy not clear anaemia
Neutrophil depletion	decrease post bypass VF Lower ionotropic use and post op cardiac enzyme	Cost   Compliance
Erythropoeitin	limits myocardial injury	Cost
N-acetyl cysteine	may reduce ocidative stress	Cost
Deferoxamine	decrease lipid peroxidation Increase myocardial protection Decrease post op wall motion abnormalities	Cost
Statins	increase NO release Anti oxidative properties

dr.ajita.