Myocardial cytochrome oxidase activity increases with age and hypoxemia in patients with congenital heart disease

Children with single ventricle heart disease have a greater increase in sRAGE after cardiopulmonary bypass

INTRODUCTION

Reducing cardiopulmonary bypass (CPB) induced inflammatory injury is a potentially important strategy for children undergoing multiple operations for single ventricle palliation. We sought to characterize the soluble receptor for advanced glycation end products (sRAGE), a protein involved in acute lung injury and inflammation, in pediatric patients with congenital heart disease and hypothesized that patients undergoing single ventricle palliation would have higher levels of sRAGE following bypass than those with biventricular physiologies.

METHODS

This was a prospective, observational study of children undergoing CPB. Plasma samples were obtained before and after bypass. sRAGE levels were measured and compared between those with biventricular and single ventricle heart disease using descriptive statistics and multivariate analysis for risk factors for lung injury.

RESULTS

sRAGE levels were measured in 40 patients: 19 with biventricular and 21 with single ventricle heart disease. Children undergoing single ventricle palliation had a higher factor and percent increase in sRAGE levels when compared to patients with biventricular circulations (4.6 vs. 2.4, p = 0.002) and (364% vs. 181%, p = 0.014). The factor increase in sRAGE inversely correlated with the patient's preoperative oxygen saturation (Pearson correlation (r) = -0.43, p = 0.005) and was positively associated with red blood cell transfusion (coefficient = 0.011; 95% CI: 0.004, 0.017; p = 0.001).

CONCLUSIONS

Children with single ventricle physiology have greater increase in sRAGE following CPB as compared to children undergoing biventricular repair. Larger studies delineating the role of sRAGE in children undergoing single ventricle palliation may be beneficial in understanding how to prevent complications in this high-risk population.

Peripheral Blood Mononuclear Cells Mitochondrial Respiration and Superoxide Anion after Heart Transplantation

INTRODUCTION

The mitochondrial function of circulating peripheral blood mononuclear cells (PBMCs) is an interesting new approach to cardiac diseases. Thus, PBMC's mitochondrial respiration decreases in relation to heart failure severity. However, no data are available on heart-transplanted patients (Htx).

POPULATION AND METHODS

We determined PBMCs mitochondrial respiration by high-resolution respirometry (Oroboros Instruments) and superoxide anion production using electron paramagnetic resonance (Bruker-Biospin) in 20 healthy subjects and 20 matched Htx and investigated clinical, biological, echocardiographic, coronarography and biopsy characteristics.

RESULTS

PBMCs mitochondrial respiratory chain complex II respiration was decreased in Htx (4.69 ± 0.84 vs. 7.69 ± 1.00 pmol/s/million cell in controls and Htx patients, respectively; p = 0.007) and complex IV respiration was increased (24.58 ± 2.57 vs. 15.68 ± 1.67 pmol/s/million cell; p = 0.0035). Superoxide anion production was also increased in Htx (1.47 ± 0.10 vs. 1.15 ± 0.10 µmol/min; p = 0.041). The leucocyte-to-lymphocyte ratio was increased in Htx, whom complex II correlated with leucocyte number (r = 0.51, p = 0.02) and with the left ventricular posterior wall peak early diastolic myocardial velocity (r = -0.62, p = 0.005). Complex IV was increased in the two patients with acute rejection and correlated negatively with Htx's isovolumetric relation time (r = -0.45, p = 0.045).

DISCUSSION

Although presenting with normal systolic function, Htx demonstrated abnormal PBMC's mitochondrial respiration. Unlike immunosuppressive therapies, subclinical diastolic dysfunction might be involved in these changes. Additionally, lymphopenia might reduce complex II, and acute rejection enhances complex IV respirations.

CONCLUSION

PBMC's mitochondrial respiration appears modified in Htx, potentially linked to cellular shift, mild diastolic dysfunction and/or acute rejection.

Molecular Genetics of Lidocaine-Containing Cardioplegia in the Human Heart During Cardiac Surgery

BACKGROUND

During cardiac surgery with cardiopulmonary bypass, delivery of cardioplegia solution to achieve electromechanical cardiac quiescence is obligatory. The addition of lidocaine to cardioplegia has advantages, although its consequences at a molecular level remain unclear. We performed whole-genome RNA sequencing of the human left ventricular (LV) myocardium to elucidate the differences between whole-blood (WB) cardioplegia with and without addition of lidocaine (LC) on gene expression.

METHODS

We prospectively enrolled 130 patients undergoing aortic valve replacement surgery. Patients received high-potassium blood cardioplegia either with (n = 37) or without (n = 93) lidocaine. The LV apex was biopsied at baseline, and after an average of 74 minutes of cold cardioplegic arrest. We performed differential gene expression analysis for 18,258 genes between these 2 groups. Clinical and demographic variables were adjusted in the model. Gene ontology (GO) and network enrichment analysis of the retained genes were performed using g:Profiler and Cytoscape.

RESULTS

A total of 1,298 genes were differentially expressed between cardioplegic treatments. Compared with the WB group, genes upregulated in the LC group were identified by network enrichment to play a protective role in ischemic injury by inhibiting apoptosis, increasing transferrin endocytosis, and increasing cell viability. Downregulated genes in the LC group were identified to play a role in inflammatory diseases, oxygen transport, and neutrophil aggregation.

CONCLUSIONS

The addition of lidocaine to cardioplegia had pronounced effects on a molecular level with genes responsible for decreased inflammation, reduced intracellular calcium binding, enhanced antiapoptotic protection, augmented oxygen accessibility through transferrins, and increased cell viability showing measurable differences.