Clinical And Experimental Studies Of Cardiac Dysfunction In Sepsis

Objective The aim of this study was to analyze the causes, types, and prognosis of new-onset arrhythmias in sepsis, investigate the diagnostic value of neutrophil gelatinase associated lipocalin (NGAL) in septic myocardial damage and discuss the mechanism of mitochondria injury and NLRP3 inflammasome activation in cardiac dysfunction, and the effects of different doses of ulinastatin(UTI) on cardiac function in sepsis.Methods In part one we studied 748 patients who were admitted to the general ICUs between December 2012 and Aprial 2014. We analyzed the causes, types, and prognosis of new-onset arrhythmias using SPSS statistical software, in addition, also compared the risk factors for arrhythmias and prognosis between these two groups. In part two urine and blood samples were collected in 4 hours after admission, and brain natriuretic peptide (BNP) was immediately tested with blood samples. NGAL mRNA expression of monocyte in peripheral blood was detected by real-time quantitative PCR, the protein expression in the plasma and urine were detected by ELISA, and the differences of all the above indexes were compared among the three groups. In part three sixty five male Wistar rats were randomized into 5 groups, namely the control group (group A), sham-operation group (group B), cecal ligation puncture group (CLP group, group C), low-dose UTI group (group D) and high-dose UTI group (group E). at 48h after successful modeling, the levels of serum cTnI, BNP,TNF-a and IL-1β were measured with ELISA, and the myocardium of the left ventricle was sampled to examine the mRNA expression of NLRP3 and caspase-1 using RT-PCR, the poteinic expression of NLRP3 and caspase-1 using Western blotting, with the camparison of the differences between groups.Results In part one the new-onset arrhythmias were observed in 18.85% (n=141) of 748 patients. The main risk factors leading to arrhythmias included age, emergency operation, sepsis, acute respiratory distress syndrome (ARDS), cardiovascular disease, electrolyte disturbance, mechanical ventilation, application of vasoactive drugs and high APACHE II score on ICU admission. Arial fibrillation was the most frequent arrhythmias. ICU mortality in sepsis patients with new-onset arrhythmias was 29.50% compared with 13.66% in patients without new-onset arrhythmias (p<0.01). Among surviving sepsis patients, ICU stay for those with new-onset arrhythmias was longer than those without new-onset arrhythmias (17.10±9.30 vs 11.25±5.50, p<0.01).In part two there was a significant difference among the non cardiac dysfunction group, cardiac dysfunction group and the control group in NGAL mRNA and protein expression in plasma and urine, P< 0.05. NGAL protein expression in the blood and urine in cardiac dysfunction group were significantly different compared with those in non cardiac dysfunction group, P< 0.05, but there were no differences of NGAL mRNA expression between the two groups. In part three the cTnI, BNP, TNF-a and IL-1β significantly increased in the serum of sepsis rats. Histological examination showed a large number of myocardial cell edema, necrosis, inflammatory cell infiltration, mitochondria edema, and mitochondria structure damage in CLP group. Immunohistochemistry showed that NLRP3 and caspase-1 mRNA expression in rat myocardium in sepsis model were enhanced and protein expression of NLRP3 and caspase-1 enhanced in real RT-PCR and Western blot, and the levels correlated with cTnI, BNP, TNF-a, IL-1β.Levels of myocardial damage markers, inflammatory mediators, degree of tissue lesions, NLRP3 and caspase-1 of mRNA and protein expression in low dose and high dose UTI groups were all improved than CLP group. The change of pathology in high dose UTI group became light, NLRP3 and caspase-1 mRNA expression and protein expression were weaker than those in the low dose UTI group.Conclusions1.Sepsis was the main risk factor for arrhythmias, arial fibrillation was the most frequent arrhythmia in sepsis, new-onset arrhythmias increased the length of ICU stay and the risk of death.2.Serum BNP increased in sepsis patients, and more obviously in cardiac dysfunction. Blood and urine NGAL elevated in sepsis patients, and more obviously in cardiac dysfunction. NGAL was positively correlated with BNP, Combining with other cardiac markers, NGAL can be used as a marker of myocardial damage.3.The rat myocardium structures were changed, mitochondria structures were damaged, and the levels of serum myocardium markers were elevated in sepsis. Sepsis could induce myocardial damage. NLRP3 inflammasome activation and caspase-1 protein increase occured in the rat myocardium in sepsis, and their levels were relevant to inflammatory cytokines. NLRP3 inflammasome activation participated in the myocardial damage induced by sepsis. Ulinastatin can protect myocardial damage induced by sepsis, and the mechanisms involved in this protect effects may include inhibition of release of inflammatory cytokines such as TNF-a and IL-1β, and the down regulation of downstream cascade reaction of NLRP3 inflammasome activities.