Norepinephrine transporter expression is inversely associated with glycaemic indices: a pilot study in metabolically diverse persons with overweight and obesity.

OBJECTIVE: The objective of this study was to examine the cross-sectional relationship between the expression of norepinephrine transporter (NET), the protein responsible for neuronal uptake-1, and indices of glycaemia and hyperinsulinaemia, in overweight and obese individuals. METHODS: Thirteen non-medicated, non-smoking subjects, aged 58 ± 1 years (mean ± standard error of the mean), body mass index (BMI) 31.4 ± 1.0 kg m-2, with wide-ranging plasma glucose and haemoglobin A1c (HbA1c, range 5.1% to 6.5%) participated. They underwent forearm vein biopsy to access sympathetic nerves for the quantification of NET by Western blot, oral glucose tolerance test (OGTT), euglycaemic hyperinsulinaemic clamp, echocardiography and assessments of whole-body norepinephrine kinetics and muscle sympathetic nerve activity. RESULTS: Norepinephrine transporter expression was inversely associated with fasting plasma glucose (r = -0.62, P = 0.02), glucose area under the curve during OGTT (AUC0-120, r = -0.65, P = 0.02) and HbA1c (r = -0.67, P = 0.01), and positively associated with steady-state glucose utilization during euglycaemic clamp (r = 0.58, P = 0.04). Moreover, NET expression was inversely related to left ventricular posterior wall dimensions (r = -0.64, P = 0.02) and heart rate (r = -0.55, P = 0.05). Indices of hyperinsulinaemia were not associated with NET expression. In stepwise linear regression analysis adjusted for age, body mass index and blood pressure, HbA1c was an independent inverse predictor of NET expression, explaining 45% of its variance. CONCLUSIONS: Hyperglycaemia is associated with reduced peripheral NET expression. Further studies are required to identify the direction of causality.

Management strategies for recurrent vasovagal syncope.

Vasovagal syncope (VVS) is the commonest cause of recurrent syncope and has a high level of morbidity in both young and elderly patients. Diagnosis and treatment are often unsatisfactory despite the fact that syncope has a lifetime cumulative incidence of 35%. A detailed history can often yield an accurate diagnosis in most young patients. Older patients are more likely to present in an atypical manner and although the yield is low, a more comprehensive diagnostic assessment may be needed. It is important to identify patients with low supine systolic blood pressure who are prone to recurrent VVS. These patients represent a distinct subtype of VVS and may respond to a tailored therapeutic approach. Treatment options for VVS are limited because of a paucity of randomized trials. The backbone of therapy is educating the patient, avoiding precipitating factors, maintaining hydration and the application of physical counter-pressure manoeuvres. Drug therapy is rarely warranted; however, fludrocortisone, alpha-agonists, such as midodrine and dihydroergotamine, and selective serotonin reuptake inhibitors may be helpful in some patients. Permanent cardiac pacing is rarely needed and randomized trials do not support its use.

The valve of Vieussens: an important cause of difficulty in advancing catheters into the cardiac veins.

INTRODUCTION: The coronary sinus and cardiac veins are useful conduits for the passage of electrode catheters for mapping the origin of cardiac arrhythmias. However, sometimes it is difficult to advance catheters an adequate distance into the cardiac veins. The aim of this study was to determine the reasons for this. METHODS AND RESULTS: In 50 cadaveric hearts, a deflectable 7-French electrode catheter was passed from the right atrium into the coronary sinus and advanced to the anterior interventricular portion of the great cardiac vein (GCV). Causes of obstruction were determined. The catheter was obstructed by the valve of Vieussens in 23 of 50 hearts (46%). Once the valve was negotiated, obstruction was caused by an acute bend in the GCV in 28 of 50 hearts (56%). Clinical studies were undertaken in 10 patients in whom electrode catheters could not be advanced as far as required. Using contrast venography, the most frequent cause of obstruction was determined to be the valve of Vieussens in 8 of 10 cases (80%). An acute bend in the GCV caused obstruction in 2 cases (20%). CONCLUSIONS: The valve of Vieussens is a frequent cause of obstruction to passage of a catheter in postmortem and in vivo studies. An acute bend in the vein, with or without lodgment in a tributary, is the other common cause. In adults, venous luminal diameter is not a cause of obstruction to the passage of a 7-French catheter in the coronary sinus or proximal GCV.

Postpartum avulsion of the terminal ileal wall in Crohn's disease.

A case of acute perforation of the terminal ileum induced by avulsion of the bowel wall in a segment of acutely inflamed Crohn's disease is presented. This case is unusual in that the avulsion developed after delivery following the rapid retraction of the uterus which had been compressing a small localized perforation and abscess. A review of the literature has failed to demonstrate a similar case report.