Dysregulation of Endothelial Nitric Oxide Synthase Does Not Depend on Hemodynamic Alterations in Bicuspid Aortic Valve Aortopathy

Background

Bicuspid aortic valves (BAVs) predispose to ascending aortic aneurysm. Turbulent blood flow and genetic factors have been proposed as underlying mechanisms. Endothelial nitric oxide synthase (eNOS) has been implicated in BAV aortopathy, and its expression is regulated by wall shear stress. We hypothesized that if turbulent flow induces aneurysm formation in patients with a BAV, regional differences in eNOS expression would be observed in BAVs.

Methods and Results

Ascending aortic specimens were harvested intraoperatively from 48 patients with tricuspid aortic valve (19 dilated, 29 nondilated) and 38 with BAV (28 dilated, 10 nondilated) undergoing cardiac surgery. eNOS mRNA and protein concentration were analyzed at the convex and concave aortic wall. In nondilated aortas, eNOS mRNA and protein concentration were decreased in BAV compared with tricuspid aortic valve (all P<0.05). eNOS expression was increased in association with dilation in BAV aortas (P=0.03), but not in tricuspid aortic valve aortas (P=0.63). There were no regional differences in eNOS mRNA or protein concentration in BAV aortas (all P>0.05). However, eNOS expression was increased at the concave wall (versus convexity) in tricuspid aortic valve dilated aortas (all P<0.05).

Conclusions

Dysregulated eNOS occurs independent of dilation in BAV aortas, suggesting a potential role for aberrantly regulated eNOS expression in the development of BAV‐associated aneurysms. The absence of regional variations of eNOS expression suggests that eNOS dysregulation in BAV aortas is the result of underlying genetic factors associated with BAV disease, rather than changes stimulated by hemodynamic alterations. These findings provide insight into the underlying mechanisms of aortic dilation in patients with a BAV.

Elevated endothelin-1 level is a risk factor for nonocclusive mesenteric ischemia

OBJECTIVE

Nonocclusive mesenteric ischemia may occur after cardiac surgery, commonly in conjunction with the use of cardiopulmonary bypass. Some evidence suggests that endothelin-1 serum levels are increased in patients with mesenteric ischemia, but the association of endothelin-1 and nonocclusive mesenteric ischemia has not been studied. The objective was to investigate whether elevated levels of endothelin-1 could be found in patients exhibiting nonocclusive mesenteric ischemia.

METHODS

In an observational cohort study, nonocclusive mesenteric ischemia developed in 78 of 865 patients undergoing elective cardiac surgery. Control patients were identified from the cohort through 1:1 propensity score matching. Preoperative and postoperative endothelin-1 serum levels were determined by means of enzyme-linked immunosorbent assay. Odds ratios (with 95% confidence interval) were calculated by logistic regression analyses to determine the risk of endothelin-1 for the development of nonocclusive mesenteric ischemia.

RESULTS

Patients with nonocclusive mesenteric ischemia had higher preoperative (11.3 vs 9.3 pg/mL; P = .001) and postoperative (15.7 vs 11.1 pg/mL, P < .001) levels of endothelin-1 than the controls. The probability of developing nonocclusive mesenteric ischemia increased with each picogram/milliliter endothelin-1 level preoperatively (odds ratio, 1.29; 95% confidence interval, 1.12-1.49) and each picogram/milliliter postoperatively (odds ratio, 2.04; 95% confidence interval, 1.54-2.72). Receiver operating characteristic analyses showed that elevated endothelin-1 serum levels had a high accuracy to predict nonocclusive mesenteric ischemia (optimal cutoff value of 14.5 pg/mL, area under the curve of 0.77, sensitivity 51%, and specificity 94%).

CONCLUSIONS

Endothelin-1 seems to predispose patients undergoing cardiac surgery to develop nonocclusive mesenteric ischemia. In addition, it may be a useful marker to identify patients at risk for nonocclusive mesenteric ischemia after cardiac surgery.

GATA5 and endothelial nitric oxide synthase expression in the ascending aorta is related to aortic size and valve morphology

BACKGROUND

The pathogenesis of aortic dilatation in patients with congenital aortic valve anomalies is poorly understood. Recent studies suggest that alterations of gene expression may be related to ascending aortic aneurysm formation in these patients. Knockout of endothelial nitric oxide synthase (eNOS) and GATA5 is associated with bicuspid aortic valves in mice. To study the role of eNOS and GATA5 in human congenital aortic valve disease and aortic dilatation, we investigated their gene expression in aortic tissue from patients with unicuspid, bicuspid, and tricuspid aortic valves.

METHODS

Samples from 84 patients (33 tricuspid, 32 bicuspid, and 19 unicuspid) were harvested intraoperatively from the ascending aorta. GATA5 and eNOS expression was determined by real-time polymerase chain reaction.

RESULTS

GATA5 and eNOS expression in the aortic wall from patients with unicuspid aortic valves (GATA5: mean [M], 2.14; standard deviation [SD], 1.72; eNOS: M, 3.40; SD, 3.83) was significantly higher than in tricuspid aortic valves (GATA5: M, 1.12; SD, 0.80; eNOS: M, 1.00; SD, 0.74; each p < 0.05). Patients with bicuspid aortic valves (GATA5: M, 1.29, SD, 1.33; eNOS: M, 1.66; SD, 1.31) had a significantly higher eNOS expression than patients with tricuspid aortic valves (p < 0.05). The expression levels of eNOS and GATA5 correlated positively with each other and negatively with the ascending aortic diameter.

CONCLUSIONS

Our data suggest that GATA5, possibly through upregulation of eNOS, plays a role in the development of aortic dilatation in patients with unicuspid and bicuspid aortic valves. The differential gene expression in patients with unicuspid compared with bicuspid aortic valves suggests that the pathogenesis of both aortic valve anomalies may be different.

Identification of reference genes for quantitative RT-PCR in ascending aortic aneurysms

Hypertension and congenital aortic valve malformations are frequent causes of ascending aortic aneurysms. The molecular mechanisms of aneurysm formation under these circumstances are not well understood. Reference genes for gene activity studies in aortic tissue that are not influenced by aortic valve morphology and its hemodynamic consequences, aortic dilatation, hypertension, or antihypertensive medication are not available so far. This study determines genes in ascending aortic tissue that are independent of these parameters. Tissue specimens from dilated and undilated ascending aortas were obtained from 60 patients (age ≤70 years) with different morphologies of the aortic valve (tricuspid undilated n = 24, dilated n = 11; bicuspid undilated n = 6, dilated n = 15; unicuspid dilated n = 4). Of the studied individuals, 36 had hypertension, and 31 received ACE inhibitors or AT1 receptor antagonists. The specimens were obtained intraoperatively from the wall of the ascending aorta. We analyzed the expression levels of 32 candidate reference genes by quantitative RT-PCR (RT-qPCR). Differential expression levels were assessed by parametric statistics. The expression analysis of these 32 genes by RT-qPCR showed that EIF2B1, ELF1, and PPIA remained constant in their expression levels in the different specimen groups, thus being insensitive to aortic valve morphology, aortic dilatation, hypertension, and medication with ACE inhibitors or AT1 receptor antagonists. Unlike many other commonly used reference genes, the genes EIF2B1, ELF1, and PPIA are neither confounded by aortic comorbidities nor by antihypertensive medication and therefore are most suitable for gene expression analysis of ascending aortic tissue.

Early results with annular support in reconstruction of the bicuspid aortic valve

OBJECTIVE

Repair of the bicuspid aortic valve may be performed in aortic regurgitation and aneurysm. Dilatation of the atrioventricular junction has been identified as a risk factor for repair failure, and we have used suture annuloplasty to correct atrioventricular junction enlargement. The objective was to compare the early results of aortic repair with and without annuloplasty.

METHODS

Between November 1995 and January 12, a total of 559 patients were treated with bicuspid aortic valve repair for predominant regurgitation (n = 389), aortic aneurysm (n = 158), or acute dissection (n = 12). Isolated valve repair (aortic valve repair) was performed for aortic valve regurgitation with preserved aortic dimensions (n = 208) and sinotubular junction remodeling plus valve repair for aortic aneurysm and preserved root size (n = 116). Root remodeling was used for dilatation involving the root (n = 235). In 193 patients, dilatation of the atrioventricular junction (>27 mm) was corrected with suture annuloplasty.

RESULTS

Hospital mortality was 0.5% (n = 3); 2 patients required pacemaker implantation. Reoperation was necessary for recurrent regurgitation (n = 54) or stenosis (n = 2); 10-year freedom from reoperation was 82% but was inferior after isolated valve repair (70%, P = .007) compared with the 2 other techniques. Application of suture annuloplasty improved 3-year freedom from reoperation after isolated repair (84%) to 92% (P = .07). In all groups, the proportion of patients with no or trivial regurgitation was significantly higher with annuloplasty.

CONCLUSIONS

Preservation of the bicuspid aortic valve is feasible in many patients. Long-term stability of the repaired valves is good; the negative impact of a dilated atrioventricular junction can be reduced by suture annuloplasty.

[Transesophageal echocardiography in cardiogenic shock in acute posterior wall infarct with rupture of the papillary muscles]

A 63-year-old male patient suffered an acute myocardial infarction entirely confined to the posterior wall. As symptoms persisted and cardiogenic shock developed immediate heart catheterization was performed, which demonstrated an occlusion of the left circumflex branch. Right-heart catheterization demonstrated an enlarged v-wave. Thus, acute infarct associated mitral regurgitation was suspected. In the catheterization laboratory transesophageal echocardiography including Doppler- and contrast echocardiography was then performed, which revealed the diagnosis of posterior papillary muscle rupture. The patient proceeded immediately to emergency surgery during which mitral valve replacement with a St. Jude prothesis was performed in addition to venous bypass revascularization of the occluded and a further stenosed coronary artery. The postoperative follow-up was without any complications and the patient recovered satisfactorily from the acute event. This case demonstrates the excellent diagnostic utility of emergency transesophageal echocardiography in the situation of infarct related myocardial rupture, which has to precede the life-saving operation.

[The venous aneurysm]

Venous aneurysms are rare: only 311 cases of venous aneurysms and 56 cases of aneurysms in vein transplants have been reported since 1939 to date. 62% of the patients suffering from venous aneurysms were less than 40 years of age. The most frequently involved vessels were the internal jugular vein (n = 56), the portal vein (n = 28), the v. saphena magna (n = 30) the popliteal vein (n = 23), the azygos vein (n = 22) and the vena cava superior (n = 20). The diameters of the aneurysms were between 1 and 16 cm. Symptoms, if at all noticeable, depend on the localisation of the aneurysm, but they are unspecific in the majority of cases. The most frequent finding was the space- occupying growth seen in 190 patients (52%). Pulmonary embolisms originating from venous aneurysms were seen in 19/311 (6.1%), a rupture of an aneurysm in 4/311 (1.2%) of the venous aneurysms and 5/56 (8.9%) of the aneurysms in transplant veins, respectively. and were fatal in 1 (0.3%) and 2 (3.6%) of the cases, respectively. Of the 205 patients who were operated on, 3 (1.5%) died from intraoperative complications.

["Coral reef" arteriosclerosis: computed tomographic and angiographic findings]

Patients suffering from "coral reef arteriosclerosis" are presented, the lesions being visualised via CT and angiography. This disease is characterised by an almost complete occlusion of the median ventricular aorta due to extreme, irregularly structured calcareous masses in the vascular lumen. The review of the literature points to the possible aetiology and pathogenesis of this disease pattern.

[Local fibrinolytic therapy of vascular occlusions in the pelvic-leg area and the upper extremity]

Seventy-three patients with vascular occlusions in the pelvis or lower limbs and three patients with upper limb lesions were treated by local low dose fibrinolysin, with strict control of any possible bleeding tendencies. Adequate recanalisation was obtained in 56 patients (73.6%). In ten patients, the occlusion recurred while the patient was still in hospital. After four to six months, 37 of the 56 (67%) of the vessels were still patent. In 18 patients, peripheral emboli resulted in some deterioration, but in 15 of these cases this could be treated successfully by operation. The methods and indications of local fibrinolysis therapy and the problems associated with it are discussed.

[Computed tomography of malignant stomach tumors]

Forty-four patients with malignant disease of the stomach (41 carcinomas, three non-Hodgkin lymphomas) and two patients with chronic gastric ulcers were examined by computer tomography before undergoing surgery. The ulcers, the non-Hodgkin lymphoma and the carcinomas stages pT2 to pT4 were easily demonstrated, as well as 66% of carcinomas in stage pT1. In addition to the primary tumour, it was possible to recognise lymph node and organ metastases. Two of the 46 patients were not submitted for surgery because of extensive metastases.