Weibin Shi

Value of sublingual isosorbide dinitrate before isoproterenol tilt test for diagnosis of neurally mediated syncope.

Head-up tilt-table test is valuable in diagnosing type of syncope. Sensitivity varies in reports and is mostly poor. Isoproterenol or nitroglycerin is regularly used to increase head-up tilt-table test sensitivity. The aim of this study was to assess the value of sublingual isosorbide dinitrate administration before isoproterenol tilt test as a simple, practical test for diagnosis of neurally mediated syncope. Ninety-six patients (45 men and 51 women, mean age 42.5 years) with recurrent (median 4 times) loss of consciousness that remained unexplained after clinical and noninvasive assessment and 72 healthy volunteers (36 men and 36 women, mean age 40.1 years) were randomly divided into groups: isosorbide-isoproterenol test and isoproterenol test. During isosorbide-isoproterenol test, a positive response (syncope in association with sudden hypotension or bradycardia) occurred in 35 patients (72.9%) with unexplained syncope, an exaggerated response (minor symptoms in association with slowly increasing hypotension alone) occurred in 7 (14.6%), a negative response in 2 (4.2%), and drug intolerance in 4 (8.3%). During isoproterenol testing, these percentages were 52.1%, 16.7%, 25.0%, and 6.2%, respectively. Only 3 control volunteers (8.3%) had a positive response to isosorbide-isoproterenol test and 2 (5.6%) to isoproterenol test. The duration of the test and the time for syncope induction in the isosorbide-isoproterenol test were shorter than those in the isoproterenol test (24.84 +/- 5.15 vs 35.70 +/- 6.28 minutes [p <0.01]; 4.53 +/- 2.86 vs 6.27 +/- 4.11 minutes [p <0.05]). This study concluded that isosorbide-isoproterenol test could be valuable in diagnosing unexplained syncope for its high sensitivity, powerful specificity, and short duration.

Inhibitory effect of D1-like and D3 dopamine receptors on norepinephrine-induced proliferation in vascular smooth muscle cells

The sympathetic nervous system plays an important role in the regulation of blood pressure. There is increasing evidence for positive and negative interactions between dopamine and adrenergic receptors; the activation of the alpha-adrenergic receptor induces vasoconstriction, whereas the activation of dopamine receptor induces vasorelaxation. We hypothesize that the D1-like receptor and/or D3 receptor also inhibit alpha1-adrenergic receptor-mediated proliferation in vascular smooth muscle cells (VSMCs). In this study, VSMC proliferation was determined by measuring [3H]thymidine incorporation, cell number, and uptake of 3-(4,5-dimethylthiazol-2-yl)-diphenyltetrazolium bromide (MTT). Norepinephrine increased VSMC number and MTT uptake, as well as [3H]thymidine incorporation via the alpha1-adrenergic receptor in aortic VSMCs from Sprague-Dawley rats. The proliferative effects of norepinephrine were attenuated by the activation of D1-like receptors or D3 receptors, although a D1-like receptor agonist, fenoldopam, and a D3 receptor agonist, PD-128907, by themselves, at low concentrations, had no effect on VSMC proliferation. Simultaneous stimulation of both D1-like and D3 receptors had an additive inhibitory effect. The inhibitory effect of D3 receptor was via protein kinase A, whereas the D1-like receptor effect was via protein kinase C-zeta. The interaction between alpha1-adrenergic and dopamine receptors, especially D1-like and D3 receptors in VSMCs, could be involved in the pathogenesis of hypertension.

D1-like receptors inhibit insulin-induced vascular smooth muscle cell proliferation via down-regulation of insulin receptor expression.

Objective Vascular smooth muscle cell (VSMC) proliferation is central to the development of vascular diseases, including hypertension, which is regulated by numerous hormones and humoral factors. Our previous study showed that the stimulatory effect of norepinephrine on VSMC proliferation is inhibited by D1-like receptors and the D3 dopamine receptor, a member of the D2-like receptor family. Insulin is a proliferative hormone but it is not known if there is any interaction between insulin and D1-like receptors. We hypothesized that Dl-like receptors may have an inhibitory effect on the insulin-induced VSMC proliferation; aberrant insulin and Dl-like receptor functions could be involved in the pathogenesis of essential hypertension. Methods VSMC proliferation was determined by [3H]-thymidine incorporation; insulin receptor mRNA and protein expressions were determined by RT-PCR, immunoblotting, and immunohistochemistry. Results Insulin increased VSMC proliferation in immortalized aortic A10 cells, determined by [3H]-thymidine incorporation. Although the D1-like receptor, by itself, had no effect on VSMC proliferation, stimulation with fenoldopam, a D1-like receptor agonist, inhibited the stimulatory effect of insulin. The inhibitory effect of fenoldopam on insulin-mediated VSMC proliferation was receptor specific, because its effect could be blocked by SCH23390, a D1-like receptor antagonist. Fenoldopam also inhibited insulin receptor mRNA and protein expression, which was time dependent and concentration dependent. A PKC or MAP kinase inhibitor blocked the inhibitory effect of fenoldopam on insulin receptor expression, indicating that PKC and MAP kinase were involved in the signaling pathway. Conclusion The inhibitory effect of D1-like receptors on insulin-mediated VSMC proliferation may play an important role in the regulation of blood pressure.

Noninvasive measurement of cardiac output during 6-minute walk test by inert gas rebreathing to evaluate heart failure.

Objective The objective of this study was to assess the clinical value of cardiac output (CO) measurements using the inert gas rebreathing (IGR) method during the 6-minute walk test (6MWT) in evaluation of chronic heart failure (CHF). Methods and results A total of 56 CHF patients in our hospital who conformed to the Framingham CHF diagnostic criteria were recruited to this study from October 2007 to February 2009. Subjects were asked to complete a 6MWT and a bicycle exercise test. The CO was measured during both tests using IGR. B-type natriuretic peptide (BNP) levels and the left ventricular ejection fraction (LVEF) were measured at rest. The 6MWT did not correlate with BNP, LVEF, peak cardiac output (PCO), or CO during the 6MWT (CO6MWT). A negative correlation between CO6MWT and BNP as well as a strong correlation between CO6MWT and PCO was observed. When atrial fibrillation and valvular heart disease patients were excluded, CO6MWT and LVEF became significantly correlated. After grouping patients into tertiles according to their PCO values, the PCO remained correlated with CO6MWT within each group. The mean difference between CO6MWT and PCO decreased with decreases in the mean PCO in each group. No significant differences were found in the third tertile (PCO < 10.1 L/min). Conclusions The IGR method during 6MWT is safe and reliable to evaluate cardiac function in patients with CHF.

Inhibitory effect of D1-like dopamine receptors on neuropeptide Y-induced proliferation in vascular smooth muscle cells.

Proliferation of vascular smooth muscle cells (VSMCs) is thought to have a key role in the development of atherosclerotic lesions. Neuropeptide Y (NPY), norepinephrine and dopamine are sympathetic neurotransmitters. NPY has been particularly shown to stimulate proliferation of VSMCs. NPY, norepinephrine and dopamine are all sympathetic transmitters. In our previous study, we found that in the presence of the dopamine receptor, the α1-adrenergic receptor-mediated VSMC proliferation is reduced. We hypothesize that the activation of the D1-like receptor might inhibit the NPY-mediated VSMC proliferation. In our present study, we found that NPY, mainly via the Y1 receptor, increased VSMC proliferation. This was determined by [3H]-thymidine incorporation, in a concentration (10−11 to 10−8u2009m)-dependent manner. In the presence of the D1-like receptor agonist, fenoldopam (10−12 to 10−5u2009m), the stimulatory effect of NPY on VSMC proliferation was reduced. The involvement of the D1-like receptor was confirmed when the inhibitory effect of fenoldopam was reversed in the presence of the D1-like receptor antagonist SCH-23390 (10−8u2009m). Moreover, the inhibitory effect of fenoldopam on NPY-mediated VSMC proliferation was also blocked in the presence of the PKA inhibitor 14–22 (10−6u2009m). Protein kinase A activator 8-(4-chlorophenylthio) adenosine-3,5-cyclic monophosphorothioate, Sp-isomer sodium salt (10−6u2009m) could simulate the stimulatory effect of fenoldopam. It indicated that the inhibitory effect of D1-like receptors on NPY-mediated VSMC proliferation may have an important role in the regulation of blood pressure or prevention of atherosclerosis.

Efficacy and indications of transradial and transfemoral approaches for peripheral artery stent implantation

The transradial approach (TRA) has become an attractive alternative to the transfemoral approach (TFA) in percutaneous coronary intervention. To date, however, these two approaches have not been systematically compared in various percutaneous peripheral artery interventions (PPAIs). In the present study 258 patients with peripheral artery disease that underwent PPAI via the TRA (n=75) or the TFA (n=183) were analyzed. Clinical factors and outcomes in these two groups were compared. The puncture time was significantly longer (P<0.05) and the prevalence of artery vasospasm significantly higher (P<0.05) in patients who underwent PPAI via the TRA rather than via the TFA. However, the complication rate was significantly lower (P<0.05) and the artery compression time (P<0.05) and time bedridden (P<0.05) were significantly shorter via the TRA than via the TFA. These results suggest that PPAI via the TRA was associated with a lower complication rate, and shorter artery compression time and bedridden time than PPAI via the TFA. The TRA may be preferable for bilateral vertebral artery stenosis, whereas the TFA may be preferable for interventional treatment of carotid and subclavian artery stenosis. Therefore, the catheter length, artery support and push force should be comprehensively considered before choosing the TRA or TFA in the interventional treatment of renal artery stenosis.

The characteristics of coronary stenosis in 11,267 patients from Southwest China: a retrospective study

The characteristics of coronary stenosis vary among the different countries or areas. 11,267 patients who have undergone coronary angiography (CAG) from three Southwest China hospitals were investigated. Patient characteristics, coronary stenosis and stent-implant information were recorded and analyzed according to two criteria: “visible stenosis” and “≥u200950% stenosis”. The patients who have undergone CAG increased year by year, with patients from 60 to 69 years-old taking the highest ratio (34.69%). Based on the “≥u200950% stenosis” criteria, the stenotic frequency was 40.54% for Southwest China patients getting CAG. Only 8.14% patients sufferedu2009≥u20093 stenotic vessels, while 11.58 and 20.82% patients had 2 or 1 stenotic vessel, respectively. However, when using the “visible stenosis” criteria, the stenotic frequency increased to 64.68%. The prevalence of stenosis increased with age based on the “visible stenosis” criteria. There were more male patients with stenosis than female except patients over 80xa0years old. The stenosis affected almost all main coronary arteries and their branches, with the most affected artery being the left anterior descending artery. There were 3246 cases (28.8%) implanted with 5423 stents with a concurrent age-dependent increasing tendency for stent-implant frequency and average implanted stent number. The numbers of patients who have undergone CAG and suffered from CVD increased rapidly. In these patients, positive rate of CAG was 64.67%, which increased to 72.2% in patients over 60-years old. The incidence of ≥u200975% stenosis and multiple stenosis increased with age, however it should be noticed there were 18.93% for ≥u200975% stenosis and 19.52% for multiple stenosis in patients under 40xa0years old.

Multiple‑site bleeding at pleural adhesions and massive hemothorax following percutaneous coronary intervention with stent implantation: A case report

An elderly male patient with coronary heart disease underwent coronary angiography, which revealed bilateral severe coronary artery stenosis. Four stents were implanted, and at 5 h post-surgery, typical hemorrhagic shock appeared. Echocardiography verified heavy bleeding in the right thoracic cavity. Emergency angiography excluded injury or perforation of the coronary artery, aorta, right subclavian artery and brachiocephalic artery. Considering the patients history of chronic obstructive pulmonary disease and severe cough during the operation, it was suspected that hemothorax was induced by a blood vessel rupture in the pleura. Video-assisted thoracic examination confirmed the tearing of pleural adhesion bands and bleeding at three sites in the pulmonary pleura and parietal pleura. According to the reported case, bleeding as a result of the laceration of pleural adhesions is an important cause of hemothorax that should be considered after exclusion of other common causes of pleural hemorrhage.