Tailoring cardioplegia delivery circuits with modular heart-lung machines: A narrative review

Cardioplegia remains a cornerstone of myocardial protection during cardiac surgery; however, the configuration of its delivery circuit, particularly priming volume and blood-synthetic surface area, can exert a measurable influence on patient outcomes. Oversized or non-tailored circuits inherently increase hemodilution, inflammatory activation, and coagulation disturbances, effects that are especially pronounced in neonates and small children, whose circulating blood volume is limited. Advances in modular heart-lung machine (HLM) technology have introduced the possibility of tailoring cardioplegia circuits to patient size and procedural requirements, aligning mechanical design with physiological principles.

A narrative review was conducted using PubMed, Scopus, and Google Scholar for studies published between January 1976 and July 2025. Search terms included "cardioplegia," "myocardial protection," "cardioplegia circuit," "priming volume," "modular heart-lung machine," "microplegia," "del Nido cardioplegia," and related keywords. The search identified 286 records; after duplicate removal and eligibility screening, 22 studies were included in the final qualitative synthesis. Evidence was analyzed according to four domains: priming volume and blood conservation, contact surface area and inflammation, modularity and circuit customization, and physiological implications of delivery strategy.

Cardioplegia delivery circuit design appears to be a clinically relevant but underrecognized component of myocardial protection. Modular HLM platforms provide a practical approach to reduce circuit complexity and adapt extracorporeal circulation to individual patient requirements. Further prospective multicenter studies are needed to define the impact of modular cardioplegia circuits on clinical outcomes.

Modular HLM technology provides a flexible and physiologically grounded platform for tailoring cardioplegia delivery to individual patient profiles. Standardizing weight-banded modular configurations and implementing routine monitoring of priming volume-to-weight ratios could improve consistency in practice and serve as a foundation for prospective studies. The cumulative evidence suggests that extending modular principles to the cardioplegia circuit represents an underutilized but promising opportunity to enhance both pediatric and adult cardiac surgical outcomes.