Neutrophil Elastase Inhibitor Sivelestat Attenuates Myocardial Injury after Cardioplegic Arrest in Rat Hearts

Do we correctly calculate doses of cardioplegia during aortic valve replacement procedures? A preliminary report

Introduction

Intraoperative myocardial protection during aortic valve replacement (AVR) for aortic stenosis (AS) is of paramount importance for outcomes. The dose of cardioplegia is usually calculated with reference to body mass.

Aim

To assess whether such a strategy should be applied to all AS patients undergoing AVR.

Material and methods

The study included 94 patients who underwent elective isolated AVR in cardiopulmonary bypass with cold cardioplegic arrest, with a mean age of 65.4 ±7.8 years. They were divided into two subgroup: A with an infusion of high (above median) and subgroup B with a low (below median) volume of cardioplegia indexed for left ventricular mass (LVM). Their doses were referred to the maximal postoperative release of cardiac troponin I (cTnI max). Eventually, it was examined whether the extent of intraoperative myocardial injury translated into long-term survival stratified according to the Kaplan-Meier method.

Results

The mean volume of cardioplegia was 1381 ±279 ml (4.9 ±1.6 ml/g of LV myocardium). cTnI max was much higher in group A than in group B (medians: 14.918 vs. 9.876 μg/l; p = 0.005). Moreover, a negative correlation between the index cardioplegia volume and cTnI max (r = 0.345) was noted. The five-year probability of survival in subgroup A (95.7%) was significantly better than that in subgroup B individuals (82.6%, p = 0.044).

Conclusions

Calculating cardioplegic doses during AVR solely based on body mass may be suboptimal and have a significant impact on postoperative outcomes.

Neutrophil degranulation and myocardial infarction

Myocardial infarction (MI) is one of the most common cardiac emergencies with high morbidity and is a leading cause of death worldwide. Since MI could develop into a life-threatening emergency and could also seriously affect the life quality of patients, continuous efforts have been made to create an effective strategy to prevent the occurrence of MI and reduce MI-related mortality. Numerous studies have confirmed that neutrophils play important roles in inflammation and innate immunity, which provide the first line of defense against microorganisms by producing inflammatory cytokines and chemokines, releasing reactive oxygen species, and degranulating components of neutrophil cytoplasmic granules to kill pathogens. Recently, researchers reported that neutrophils are closely related to the severity and prognosis of patients with MI, and neutrophil to lymphocyte ratio in post-MI patients had predictive value for major adverse cardiac events. Neutrophils have been increasingly recognized to exert important functions in MI. Especially, granule proteins released by neutrophil degranulation after neutrophil activation have been suggested to involve in the process of MI. This article reviewed the current research progress of neutrophil granules in MI and discusses neutrophil degranulation associated diagnosis and treatment strategies.

Role of Neutrophils on the Ocular Surface

The ocular surface is a gateway that contacts the outside and receives stimulation from the outside. The corneal innate immune system is composed of many types of cells, including epithelial cells, fibroblasts, natural killer cells, macrophages, neutrophils, dendritic cells, mast cells, basophils, eosinophils, mucin, and lysozyme. Neutrophil infiltration and degranulation occur on the ocular surface. Degranulation, neutrophil extracellular traps formation, called NETosis, and autophagy in neutrophils are involved in the pathogenesis of ocular surface diseases. It is necessary to understand the role of neutrophils on the ocular surface. Furthermore, there is a need for research on therapeutic agents targeting neutrophils and neutrophil extracellular trap formation for ocular surface diseases.