Asymmetric dimethylarginine and coronary collateral vessel development

Asymmetric dimethylarginine: Is it a risk facgtor in the repair of aortic coarctation?

BACKGROUND

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, causes endothelial dysfunction which is an important risk factor for mortality in adult cardiovascular diseases. We aimed to investigate whether there was a relationship between the aortic cross-clamping (ACC) time and serum ADMA level in aortic coarctation surgery and importance of the serum ADMA level as a marker of mortality and morbidity.

METHOD

Twenty-two patients undergoing surgery for aortic coarctation in the neonatal and early infant period were included in the study, and the patients were divided into two groups according to the aortic cross-clamping time (Group I: <20-min, Group II: >20-min).

RESULTS

In Group I, preoperative and postoperative mean ADMA values of the patients were 0.57 ± 0.78 and 0.54 ± 0.83 µmol/L, respectively. In Group II, preoperative and postoperative mean ADMA values of the patients were 0.69 ± 0.93 and 1.10 ± 0.30 µmol/L, respectively. Preoperative-postoperative change of ADMA correlates with ACC time (r = .802, p < .005) and duration of postoperative inotropic support (r = .719, p < .05). Also a high correlation has been found between the ACC time and duration of inotropic support in both groups (r = .689, p < .05).

CONCLUSION

Perioperative serum ADMA levels could be used as a prognostic bio-marker in the patients undergoing aortic coarctation repair. Treatments to reduce serum ADMA levels can be valuable for preventing mortality and morbidity which develop after surgeries in a transient ischemia setting by clamping the aorta.

L-Arginine-Nitric Oxide-Asymmetric Dimethylarginine Pathway and the Coronary Circulation: Translation of Basic Science Results to Clinical Practice

By 1980, it was thought that we already knew most of the major mechanisms regulating vascular tone. However, after the somewhat serendipity discovery that endothelium is involved in mediation of relaxation to acetylcholine, a whole new world opened up and we had to rewrite our concept regarding vascular function and its regulation (not to mention many other fields). The new player was an endothelium derived relaxing factor, which molecular constitution has been identified to be nitric oxide (NO). This review summarizes the major molecular steps concerning how NO is synthetized from L-arginine. Also, the fate of L-arginine is described via the arginase and methylation pathways; both of them are affecting substantially the level and efficacy of NO. In vitro and in vivo effects of L-arginine are summarized and controversial clinical findings are discussed. On the basis of the use of methylated L-arginines, the vasomotor effects of endothelial NO released to agonists and increases in flow/wall shear stress (a major biological stimulus) is summarized. In this review the role of NO in the regulation of coronary vascular resistance, hence blood flow, is delineated and the somewhat questionable clinical use of NO donors is discussed. We made an attempt to summarize the biosynthesis, role, and molecular mechanisms of endogenously produced methylated L-arginine, asymmetric dimethylarginine (ADMA) in modulating vascular resistance, affecting the function of the heart. Additionally, the relationship between ADMA level and various cardiovascular diseases is described, such as atherosclerosis, coronary artery disease (CAD), ischemia/reperfusion injuries, and different types of coronary revascularization. A novel aspect of coronary vasomotor regulation is identified in which the pericardial fluid ADMA and endothelin play putative roles. Finally, some of the open possibilities for future research on L-arginine-NO-ADMA signaling are highlighted.

Association between Hemogram Parameters and Coronary Collateral Development in Subjects with Non-ST-Elevation Myocardial Infarction

OBJECTIVE

Coronary collateral development (CCD) predicts the severity of coronary heart disease. Hemogram parameters, such as mean platelet volume (MPV), eosinophil, red cell distribution width, and platelet distribution width (PDW), are supposed novel inflammatory markers. We aimed to compare hemogram parameter values in patients presenting with non-ST-elevation myocardial infarction (NSTEMI) with adequate or inadequate CCD.

METHODS

A total of 177 patients with NSTEMI undergoing coronary arteriography were enrolled and divided into two groups based on the development of CCD: one group with adequate CCD (n=88) and the other with impaired CCD (n=89).

RESULTS

Baseline demographics and clinical risk factors were similar between the groups. Hemogram parameters were not significantly different between the two groups. However, compared to the inadequate CCD group, the median PDW was significantly higher in the adequate CCD group, 17.6 (1.4) vs. 17.8 (1.6) p=0.004. In a multivariate analysis, PDW (p=0.001, 95% CI for OR: 0.489(0,319-0,750) was found to be significantly different in the adequate CCD group compared to the inadequate CCD group. Pearson's correlation analysis revealed that PDW was significantly correlated with the Rentrop score (r=0.26, p<0.001).

CONCLUSIONS

We suggest that since PDW is an index that is inexpensive and easy to assess, it could serve as a marker of CCD in patients with NSTEMI.

Catheter-directed intra-arterial thrombolysis for lower extremity arterial occlusions

Catheter-directed intra-arterial thrombolysis (CDT) is a rational treatment method in patients with acute/subacute and even some chronic occlusions of lower extremity arteries and bypass grafts having salvageable limb ischemia. Immediate vessel patency can be achieved with an acceptable complication rate in many patients, especially those with fresh thrombus or emboli. It can be also an adjuvant treatment modality for endovascular interventions for chronic occlusions. There is no standard method of CDT including thrombolytic agent dose and technique. Selection of treatment strategy should be based on individual judgment based on viability of limb, lesion characteristics, and risks of hemorrhage.

Repetitive ischemia increases myocardial dimethylarginine dimethylaminohydrolase 1 expression

Pharmacologic inhibition of nitric oxide production inhibits growth of coronary collateral vessels. Dimethylarginine dimethylaminohydrolase 1 (DDAH1) is the major enzyme that degrades asymmetric dimethylarginine (ADMA), a potent inhibitor of nitric oxide synthase. Here we examined regulation of the ADMA-DDAH1 pathway in a canine model of recurrent myocardial ischemia during the time when coronary collateral growth is known to occur. Under basal conditions, DDAH1 expression was non-uniform across the left ventricular (LV) wall, with expression strongest in the subepicardium. In response to ischemia, DDAH1 expression was up-regulated in the midmyocardium of the ischemic zone, and this was associated with a significant reduction in myocardial interstitial fluid (MIF) ADMA. The decrease in MIF ADMA during ischemia was likely due to increased DDAH1 because myocardial protein arginine N-methyl transferase 1 (PRMT1) and the methylated arginine protein content (the source of ADMA) were unchanged or increased, respectively, at this time. The inflammatory mediators interleukin (IL-1β) and tumor necrosis factor (TNF-α) were also elevated in the midmyocardium where DDAH1 expression was increased. Both of these factors significantly up-regulated DDAH1 expression in cultured human coronary artery endothelial cells. Taken together, these results suggest that inflammatory factors expressed in response to myocardial ischemia contributed to up-regulation of DDAH1, which was responsible for the decrease in MIF ADMA.

Association of circulating angiogenesis inhibitors and asymmetric dimethyl arginine with coronary plaque burden

BACKGROUND

Chronic kidney disease (CKD) is an independent risk factor for the development and severity of coronary artery disease (CHD) and endothelial dysfunction. There is an increase in the circulating angiogenesis inhibitors endostatin (END), thrombospondin-2 (TSP), angiopoietin-2 (ANG) and the nitric oxide (NO) inhibitor asymmetric dimethyl arginine (ADMA) in CKD patients. The aim of this study was to evaluate associations of the serum level of these factors and of the related angiogenesis inhibitor, endoglin (ENG), with burden of coronary atherosclerosis.

METHODS

One hundred twenty-two patients undergoing coronary angiography were recruited from the cardiac catheterization lab at a single center. The total burden of coronary plaque (mm(2)) and the presence of coronary collaterals were quantified using quantitative coronary angiography (QCA). Serum levels of angiogenesis inhibitors were measured by ELISA (ENG, END, and ANG), Luminex assay (TSP), or HLPC (ADMA), respectively. Associations with plaque burden and coronary collateral supply were analyzed in multi-variable linear and logistic regression models.

RESULTS

There was no significant association found between levels of circulating ADMA, ENG, END, ANG, or TSP and coronary plaque burden or collateral formation.

CONCLUSIONS

Our findings suggest that associations of circulating END, ENG, TSP, and ANG with cardiovascular mortality are unlikely to be mediated via direct effects on coronary plaque formation or by inhibition of collateral formation. Whether associations of these factors with mortality are mediated via local concentrations, myocardial tissue, or intra-plaque expression of these factors or by an effect on plaque vulnerability merits additional investigation.

Association between brachial-ankle pulse wave velocity and the ratio of l-arginine to asymmetric dimethylarginine in patients undergoing coronary angiography

BACKGROUND

Endothelial dysfunction causes vasomotor dysregulation and vascular stiffening in addition to structural changes. By influencing NO synthesis, deficiency of l-arginine relative to asymmetric dimethylarginine (ADMA), which is an l-arginine derivative that acts as a competitive NO synthase inhibitor, may lead to the promotion of arterial stiffness. This study investigated the relationship between the l-arginine/ADMA ratio and brachial-ankle pulse wave velocity (baPWV), an indicator of arterial stiffness.

METHODS AND RESULTS

This cross-sectional study enrolled 74 patients (62 men, 12 women; mean age, 67±10 years) undergoing elective coronary angiography. A total of 54 (73%) patients had coronary artery disease. Serum l-arginine and ADMA were measured by high-performance liquid chromatography with fluorescence detection. The ratio of l-arginine to ADMA and the serum l-arginine level was associated with baPWV in univariate regression analysis (l-arginine/ADMA ratio: β=-0.323, p=0.005; l-arginine: β=-0.247, p=0.034). In addition, baPWV was related to blood hemoglobin concentration, hematocrit, brain natriuretic peptide level, symmetric dimethylarginine, renal function, blood pressure, and heart rate. In multivariate analysis, the l-arginine/ADMA ratio was a significant predictor of baPWV (β=-0.310, p<0.001). In subgroup analyses, the l-arginine/ADMA ratio was associated with baPWV in elderly patients (n=46, β=-0.359, p=0.004), and in younger patients (n=28, β=-0.412, p=0.006).

CONCLUSION

A low l-arginine/ADMA ratio may be associated with high baPWV in patients undergoing coronary angiography.

Increased serum bilirubin level is related to good collateral development in patients with chronic total coronary occlusion

OBJECTIVE

Bilirubin is a bile pigment with potent anti-oxidant properties; in previous studies it has been reported to be negatively associated with coronary artery disease (CAD). Although elevated serum bilirubin concentrations may protect against endothelial dysfunction, it is not clear whether higher serum bilirubin levels (SBLs) in physiological ranges may work in favor of good collateral development in patients with chronic total coronary occlusion (CTO).

METHODS

The study population consisted of patients who underwent coronary angiography with a suspicion of CAD. Patients who had CTO in at least one major coronary artery were included. Coronary angiograms of 179 eligible patients from our database were reanalyzed and 110 of them had good collateral development and 69 had poor collateral development according to the Cohen-Rentrop method.

RESULTS

Patients with good collateral development had a lower fasting plasma glucose level (FPG) (p=0.024) and higher SBLs in comparison to patients with poor collateral development (p<0.001). The number of CTO vessels (p=0.013) and left ventricular ejection fraction (EF%) were higher in good collateral group than poor collateral group (p=0.017). In multivariate analysis, FPG negatively (odds ratio [OR]: 0.981, p=0.003) and SBL (OR for per 0.1-mg/dL increase: 1.832, p<0.001) and the number of CTO vessels (OR: 5.642, p=0.007) were positively related to coronary collateral development.

CONCLUSION

This study suggests that higher bilirubin levels within relatively normal ranges were related with favorable coronary collateral growth in patients with CTO. SBL may be responsible for the difference in coronary collateral vessel development among different patients with coronary artery disease. The anti-inflammatory and anti-oxidant properties of bilirubin may mediate this effect.

Growth differentiation factor 15 and coronary collateral formation

BACKGROUND

The coronary collateral circulation can reduce sudden cardiac death,myocardial cell loss,and infarct size.Growth differentiation factor 15(GDF-15),a member of the transforming growth factor-beta (TGF-beta) superfamily,has been reported to have a prognostic predicting value in coronary artery disease.

HYPOTHESIS

GDF-15 can be related with the extent of collateral formation.

OBJECTIVE

Growth differentiation factor 15 (GDF-15), a member of the transforming growth factor-beta (TGF-beta) superfamily, has been reported to have a prognostic predicting value in coronary artery disease. We sought to investigate whether GDF-15 is related to coronary collateral development in patients with coronary heart disease.

METHODS

A cross-sectional study was performed in 201 patients, who were admitted for selective coronary angiography. Patients were divided into 3 groups based on Rentrop's classification of coronary collaterals. Group 1: patients with coronary collateral presence, which was defined by Rentrop's grade 1-3 collateral development. Group 2: patients with grade 0 collateral development. Group 3: control group were patients with a normal coronary angiogram. The levels of plasma GDF-15, asymmetric dimethylarginine (ADMA), and soluble Fms-related tyrosine kinase-1 (sFLT-1) were compared among the 3 groups.

RESULTS

There were significant statistical differences in plasma sFLT-1, ADMA, and GDF-15 concentrations among the different collateral groups. The correlations between Rentrop's grade and the cytokines were significant. A positive correlation was found between Rentrop's grade and GDF-15 (r = 0.187, P < 0.05). The correlations between the levels of plasma sFLT-1, ADMA, and Rentrop's grade were significant, with the correlation coefficient of r = 0.181, P < 0.05 (sFLT-1) and r = - 0.646, P < 0.001 (ADMA), respectively.

CONCLUSIONS

Our findings suggest that GDF-15 levels increase with the extent of collateral formation. In that case, the patients with a higher level of GDF-15 may predict more severe coronary stenosis, which has a higher probability to develop collaterals.