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Abstract
To adequately protect immature hearts during periods of ischemia necessitated by cardiac surgery, Pedro del Nido developed a novel cardioplegia formulation, called 1:4 del Nido cardioplegia, which arrested the heart to reduce myocardial energy demand and utilized supportive additives to help resume normal function upon reperfusion. Traditional 1:4 del Nido cardioplegia has been shown in numerous research studies to offer improved myocardial protection over many common cardioplegia formulations while possessing a favorable redosing strategy. Adoption of 1:4 del Nido cardioplegia has therefore become common in the United States in both pediatric and adult cardiac surgery centers, although many clinicians still hold reservations toward its associated hemodilution. In recent years, the desire to develop a cardioplegia formula that has the benefits of 1:4 del Nido cardioplegia without the perceived negative effects of hemodilution has led clinical sites to begin experimentation with a microplegia variant of del Nido, called Micro del Nido, that replaces the crystalloid component of 1:4 del Nido cardioplegia with whole blood from the cardiopulmonary bypass circuit.
Before Micro del Nido cardioplegia is adopted on a wider scale, it would be beneficial to have additional evidence supporting its safety and efficacy, specifically in relation to the more proven formulation of 1:4 del Nido cardioplegia. To support this goal, this project reviewed the historic origins of cardioplegia, the causes and severity of ischemic injury, the mechanisms of action of cardioplegia additives, and the perceived negative effects of hemodilution. A literature review was conducted that found limited studies about the safety and efficacy of Micro del Nido. In an attempt to provide additional evidence supporting its adoption, a retrospective study was initiated at Ascension Columbia St. Mary’s Hospital in Milwaukee, which transitioned from 1:4 del Nido cardioplegia to Micro del Nido cardioplegia for adult single valve repair and replacement surgeries. Unfortunately, the study was unable to be completed as planned due to data accessibility and integrity concerns, leading to a final recommendation of further comparative studies, specifically prospective studies where confounding factors can be reduced.