What are the dosing, composition, and administration guidelines for Delnido cardioplegia in adult cardiac surgery?

Del Nido Cardioplegia in Adult Cardiac Surgery

Del Nido cardioplegia can be used safely in adult cardiac surgery with a single-dose approach for procedures with aortic cross-clamp times under 90 minutes, but requires redosing every 60-90 minutes for longer procedures, though it shows no mortality or major morbidity advantage over conventional blood cardioplegia. 1

Composition and Preparation

Del Nido cardioplegia is a crystalloid-based solution mixed with blood in a 4:1 ratio (4 parts crystalloid to 1 part blood), which is the opposite of conventional blood cardioplegia 2, 3. The solution contains:

• High potassium concentration (8-20 mEq/L) for depolarized arrest
• Lidocaine to prolong hyperpolarization and provide antiarrhythmic effects
• Components to prevent intracellular calcium overload

Dosing Strategy

Initial Dose

• 1000-1200 mL administered as a single bolus 4
• Delivered cold via antegrade route into the aortic root at 60-100 mmHg pressure 1
• Can be given directly into coronary ostia with pressure monitoring

Redosing Protocol

For cross-clamp times <90 minutes:

• Single dose is sufficient without redosing 1

For cross-clamp times >90 minutes:

• Administer 500 mL maintenance doses every 60 minutes 4
• Critical threshold: Do not exceed 70 minutes between the second and third doses 5
• Time after second infusion >69.5 minutes correlates with significantly higher myocardial injury markers 5

For cross-clamp times >100 minutes:

• Most patients (82.9%) require initial dose plus one redose
• 17.1% require two or more redoses 5

Redosing Options

Two acceptable strategies exist for maintenance doses 6:

• Full-dose (FD): 1:4 blood to crystalloid ratio (same as initial)
• Dilute: 4:1 blood to crystalloid ratio (similar to conventional blood cardioplegia)

Both strategies show no statistical difference in mortality or major outcomes, though dilute redosing more commonly requires retrograde delivery 6.

Administration Routes

Antegrade delivery (most common):

• Directly into aortic root proximal to cross-clamp
• Pressure: 60-100 mmHg
• Cardiac arrest achieved in 30-60 seconds 1

Retrograde delivery:

• Via coronary sinus catheter
• Flow: 200-400 mL/min
• Pressure: 30-50 mmHg (avoid higher pressures to prevent venous injury)
• Slower arrest induction (2-4 minutes)
• Important caveat: Inadequate right ventricular protection with retrograde-only delivery 1

Combined antegrade + retrograde:

• Use in complex cases with extended cross-clamp time, severe coronary disease, poorly developed collaterals, or aortic insufficiency 1

Clinical Evidence and Limitations

Efficacy Data

The 2019 EACTS/EACTA/EBCP guidelines note that evidence for del Nido superiority over conventional approaches is insufficient 1. A meta-analysis of 1,501 adult patients showed:

• No reduction in mortality (RD 0,95% CI -0.01 to 0.01; p=0.53)
• No difference in myocardial enzyme release (SMD 0.16,95% CI -0.41 to 0.08; p=0.18)
• No difference in hospital length of stay (SMD 0.10,95% CI -0.26 to 0.05; p=0.18)

Advantages

• Shorter cross-clamp times due to less frequent redosing interruptions 4
• Reduced hemodilution compared to conventional blood cardioplegia 3
• Lower transfusion requirements 3
• Reduced defibrillation requirements due to lidocaine's antiarrhythmic effects 3
• Lower troponin T levels in some studies 7

Disadvantages in Prolonged Ischemia

For cross-clamp times >90 minutes with single-dose strategy 8:

• Significantly higher postoperative troponin I levels
• Elevated lactate at 4 hours post-CPB
• Increased defibrillation requirements
• Higher vasoactive-inotropic scores (VIS)
• Compromised myocardial electrical stability

Guideline Recommendations

The 2019 and 2024 EACTS/EACTA/EBCP guidelines recommend:

• Patient-centered myocardial protection strategies based on clinical condition and procedural complexity rather than fixed institutional protocols (Class I, Level C) 1, 9
• Blood cardioplegia should be considered in selected patients with anemia, low body surface area, chronic kidney disease, or undergoing complex procedures to reduce hemodilution, bleeding, and transfusion requirements (Class IIa, Level B) 1, 9

Clinical Decision Algorithm

Use del Nido cardioplegia when:

1. Expected cross-clamp time <90 minutes in low-risk cases
2. No severe coronary disease or aortic insufficiency
3. Desire to minimize surgical interruptions

Avoid or use with caution when:

1. Complex procedures with expected cross-clamp >180 minutes
2. Severe coronary disease requiring guaranteed distribution
3. Significant aortic insufficiency (consider retrograde component)

Monitoring requirements:

• Intraoperative TOE assessment of RV and LV function pre- and post-CPB (Class I, Level B) 9
• Review RV/LV function and cardiac enzyme release within 24 hours postoperatively (Class I, Level C) 9

Critical Pitfalls to Avoid

1. Do not use single-dose strategy for cross-clamp times >90 minutes - significantly increases myocardial injury 5, 8
2. Do not delay third dose beyond 70 minutes after second infusion 5
3. Do not rely on retrograde-only delivery - inadequate RV protection 1
4. Do not exceed 50 mmHg pressure with retrograde delivery - risk of coronary venous injury 1
5. Do not assume superiority over blood cardioplegia - outcomes are equivalent in most studies 1