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Page 2 of 9 Pragliola et al. Vessel Plus 2019;3:22 I http://dx.doi.org/10.20517/2574-1209.2019.003

mitral procedures performed in 2016 were minimally invasive and the isolated aortic valve procedures, the
second most common cardiac operation, undergoing key-hole surgery have a steady increase. Clearly we are
facing more complex procedures and worse clinical characteristics of our patients. This can imply longer
cross clamp times which is a well-known risk factor in cardiac surgery. On the other hand the available
cardioplegic solutions to protect the heart need to be repeated every 10 to 20 min or continuously infused
in a retrograde fashion through the coronary sinus. Although the results with the current cardioplegias are
consistently good, some surgeons, in particular those who have focused in minimally invasive procedures,
are searching for a “solution” which could combine effective and consistent long lasting myocardial protection
with easy of deliver.

In the last few years, when its original the patent expired, the paediatric del Nido cardioplegia (DNC) has
been increasingly used in adult patients . This cardioplegia allows for an interval between infusions up to
[2]
90 min and has some unique features that appear to be promising to the adult cardiac surgeons.

The DNC is a 1:4 blood cardioplegia which can be classified as a modified depolarizing cardioplegia,
containing Lidocaine and Magnesium. Clinically it has been validated in valve surgery and at the moment,
[3]
in low risk coronary patients . We hereby are summarizing the basic concepts behind its formulation and
[4]
use, along with the available evidence in the adult patients.

DEVELOPMENT OF DNC
For long time paediatric cardiac surgeons had to rely on the common adult cardioplegic solutions to operate
on their patients. However, the crystalloid solutions in use in the 80’s and early 90’s had controversial
results in young populations with, for instance, the St Thomas solution being reported either effective [5]
or ineffective . Although infant and paediatric hearts have some distinctive histologic and metabolic
[6]
features, a “dedicated” cardioplegia was missing. Histologically the paediatric heart has a poorly developed
sarcoplasmatic reticulum , fewer mitochondria, a higher concentration of poly unsaturated fatty acids [8]
[7]
in the cell membrane and a deficient free radical scavenge system with less active superoxide dismutase,
catalase and glutathione reductase . In addition these hearts depends more on the extracellular calcium for
[9]
contraction. At Pittsburgh University Hospital the team led by Pedro J. del Nido focused on many of these
aspects and developed a solution preventing the intracellular accumulation of Calcium, providing effective
free radicals scavenge whit maintenance of the anaerobic glycolysis and assuring effective buffering during
prolonged periods of cardiac arrest. A detailed description of the development of the cardioplegia is available
in the literature .
[10]

COMPONENTS
The DNC is a 1:4 Blood to Crystalloid solution with additional components to achieve depolarized arrest and
mitigate the effects of temporary myocardial ischemia [Table 1].

Plasmalyte a solution
The Plasma Lyte A (Baxter Health Care Corp. Deerfield, IL USA) solution forms the crystalloid base of the
+
DNC. It is an extracellular (Na 140 mEq, K 5 mEq/L) solution with a final pH of 7.4 and an osmolarity
+
of 294 mOsm/L. It is commonly used as a fluid volume replacement infusion in many clinical conditions.
Noticeably it does not contain glucose.

Potassium
Similarly to other common depolarizing solutions, the final content of K ions in the DNC is about 24 mEq/L
+
which is obtained from the basal content of Plasma-Lyte (5 mEq) plus the added 26 mEq and an assumed
4.5 mEq/L from the patient’s blood.