Cardioplegia between Evolution and Revolution: From Depolarized to Polarized Cardiac Arrest in Adult Cardiac Surgery

Abstract

Despite current advances in perioperative care, intraoperative myocardial protection during cardiac surgery has not kept the same pace. High potassium cardioplegic solutions were introduced in the 1950s, and in the early 1960s they were soon recognized as harmful. Since that time, surgeons have minimized many of the adverse effects by lowering the temperature of the heart, lowering K+ concentration, reducing contact K+ time, changing the vehicle from a crystalloid solution to whole-blood, adding many pharmacological protectants and modifying reperfusion conditions. Despite these attempts, high potassium remains a suboptimalway to arrest the heart. We briefly review the historical advances and failures of finding alternatives to high potassium, the drawbacks of a prolonged depolarized membrane, altered Ca2+ intracellular circuits and heterogeneity in atrial-ventricular K+ repolarization during reanimation. Many of these untoward effects may be alleviated by a polarized membrane, and we will discuss the basic science and clinical experience from a number of institutions trialling different alternatives, and our institution with a non-depolarizing adenosine, lidocaine and magnesium (ALM) cardioplegia. The future of polarized arrest is an exciting one and may play an important role in treating the next generation of patients who are older, and sicker with multiple comorbidities and require more complex operations with prolonged cross-clamping times.

St. Thomas Modified Cardioplegia Effects on Myoblasts’ Viability and Morphology

“…It was also found that AQP7 deficiency, protected myocardial cells [22]. The other studies demonstrated that cardioplegic arrest is also strictly related to the altered calcium and potassium ions circuits, and finally, prolonged membrane depolarization [6]. In this study, neonatal rat myoblasts were used as a model of extremely sensitive cells, and ST2C based cardioplegia was used in this in vitro model to estimate cell conditions.…”

“…The high serum concentration of potassium depolarizes the cell membrane suppressing the electric and mechanical activity of cardiomyocytes, causing cardiac arrest [3][4][5]. Cardioplegic solutions can induce cytotoxic effects because of the increased content of potassium ions or its anionic salts [6]; thus, this composition is still improved and developed. There are two types of cardioplegia used in the clinical practice based on the crystalloid solutions (e.g., Btertschneider's formula or St. Thomas' Hospital formula) and so-called blood cardioplegia (one of its components is the patient's blood).…”

“…There are two types of cardioplegia used in the clinical practice based on the crystalloid solutions (e.g., Btertschneider's formula or St. Thomas' Hospital formula) and so-called blood cardioplegia (one of its components is the patient's blood). There are also newly developed polarizing solutions containing adenosine, lidocaine, and magnesium (ALM), which also can protect coronary vasculature and enhance an inflammatory response [6]. Cardioplegia is administered to the coronary vessels just after the cross-clamping of the aorta.…”

Temperature-Related Effects of Myocardial Protection Strategies in Swine Hearts after Prolonged Warm Ischemia

“…In our experimental setting, we did not observe any additional benefit of adding adenosine to the warm cardioplegia, as there were no significant differences in the antioxidant enzyme activity among the groups. Further studies should be conducted, as the combination of adenosine with lidocaine and Mg 2+ (known as ALM cardioplegia) has shown promising results as a fully polarizing cardioplegia in human trials [57].…”

The Role of Purinergic Signaling in Heart Transplantation

“…The cardioprotective effect of adenosine has long been recognized, and all four adenosine receptors have been implicated. Adenosine is used as an additive in blood cardioplegia to induce a more rapid polarized cardiac arrest via the A1 receptors ( 106 , 107 ). A polarized membrane potential during initial reperfusion may minimize intracellular Ca 2+ overload and reduce cardiac IRI.…”