Switching the Standard for Cardiac Surgery

May 2019

Over the years, there has been a dramatic increase in the number of elderly and multimorbid patients. For cardiac surgery, this patient population is associated with increased perioperative mortality, prompting the need for improved processes and procedures. 

In a study published earlier this year in The Journal of Thoracic and Cardiovascular Surgery, researchers in Austria sought to improve myocardial protection for this patient population by changing the standard depolarizing solution used during cardiac surgery.
Currently, depolarizing solutions - administered as intermittent, oxygenated blood - are considered standard for myocardial protection during cardiac surgery.
However, these potassium based depolarizing solutions can lead to intracellular Na+ accumulation with subsequent elevation in myocyte Ca2+ loading, resulting in contracture and cell death.
Previous work by the same group showed the feasibility of using a polarizing solution. In this later study, the authors sought to extend their initial work by testing the polarizing and depolarizing solutions in a clinically - relevant porcine model of cardiopulmonary bypass, in which they compared coronary and arterial cellular health.
Overall, the authors describe comparable myocardial protection between the groups, showing that arterial and coronary creatine kinase-MB (CK-MB), a marker of muscle damage, remained similar between groups. Additionally, they reported that biochemical, structural, and hemodynamic data were also comparable.
With the help of TriLink’s CleanTag® Small RNA Library Prep technology, the researchers were able to extend their findings and report that two of 238 miRNAs, miR-708-5p and miR-122, were significantly different.
miR-708-5p, which was recently identified as an anti-inflammatory miRNA in endothelial and vascular smooth muscle cells, was significantly increased in the group that received the polarizing solution.
In addition, miR-122, which has been shown to correlate to cardiac troponin-I, a marker for acute myocardial infarction and progression of heart failure, was also significantly different between experimental animals, though not associated with a particular cardioplegic solution. After confirming that miR-122 correlated to cardiac troponin-I under these experimental conditions, the authors suggested that miR-122 may be a potential biomarker of ischemia-reperfusion injury following cardiac surgery.
While the authors were careful to identify several limitations of the study, they ultimately concluded that the results confirm the non-inferiority of polarized versus depolarized arrest.

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