Effect of Transradial Catheterisation on Patency Rates of Radial Arteries Used as a Conduit for Coronary Bypass.

BACKGROUND: Transradial catheterisation is known to be associated with occlusion of the radial artery with an estimated incidence of 2-10% (1). There are very few studies looking at the patency of radial artery as a bypass graft after utilisation for catheterisation. METHODS: We conducted a retrospective review of patients undergoing coronary artery bypass grafting (CABG) utilising a radial artery graft. RESULTS: Long term patency rates were 59% in radial artery grafts utilised for catheterisation prior to CABG, compared to 78% if it were not (p= 0.035). CONCLUSION: Patency rates of radial artery grafts are significantly lower when the same radial artery was utilised for angiography prior to coronary artery bypass grafting (CABG).

Differential roles of caveolin-1 in ouabain-induced Na+/K+-ATPase cardiac signaling and contractility.

Binding of ouabain to cardiac Na+/K+-ATPase initiates cell signaling and causes contractility in cardiomyocytes. It is widely accepted that caveolins, structural proteins of caveolae, have been implicated in signal transduction. It is known that caveolae play a role in Na+/K+-ATPase functions. Regulation of caveolin-1 in ouabain-mediated cardiac signaling and contractility has never been reported. The aim of this study is to compare ouabain-induced cardiac signaling and contractility in wild-type (WT) and caveolin-1 knockout (cav-1 KO) mice. In contrast with WT cardiomyocytes, ouabain-induced signaling e.g., activation of phosphoinositide 3-kinase-α/Akt and extracellular signal-regulated kinases (ERK)1/2, and hypertrophic growth were significantly reduced in cav-1 KO cardiomyocytes. Interactions of the Na+/K+-ATPase α1-subunit with caveolin-3 and the Na+/K+-ATPase α1-subunit with PI3K-α were also decreased in cav-1 KO cardiomyocytes. The results from cav-1 KO mouse embryonic fibroblasts also proved that cav-1 significantly attenuated ouabain-induced ERK1/2 activation without alteration in protein and cholesterol distribution in caveolae/lipid rafts. Intriguingly, the effect of ouabain induced positive inotropy in vivo (via transient infusion of ouabain, 0.48 nmol/g body wt) was not attenuated in cav-1 KO mice. Furthermore, ouabain (1-100 µM) induced dose-dependent contractility in isolated working hearts from WT and cav-1 KO mice. The effects of ouabain on contractility between WT and cav-1 KO mice were not significantly different. These results demonstrated differential roles of cav-1 in the regulation of ouabain signaling and contractility. Signaling by ouabain, in contrast to contractility, may be a redundant property of Na+/K+-ATPase.

Cardioprotective role of ischemic postconditioning in acute myocardial infarction: a systematic review and meta-analysis.

BACKGROUND: Evidence suggests that ischemic postconditioning (IPoC) may reduce the extent of reperfusion injury. We performed a meta-analysis of randomized controlled trials, which compared the role of IPoC during primary percutaneous coronary intervention (PCI) to PCI alone (control group) in ST-segment elevation myocardial infarction. METHODS: Several databases were searched, which yielded 19 studies. The outcomes of interest were measures of myocardial damage (serum cardiac enzymes and infarct size by imaging) and left ventricular function (left ventricular ejection fraction and wall motion score index). Mean difference (MD) and standardized mean difference (SMD) were used to assess the treatment effect. An inverse variance method was used to pool data into a random-effects model. RESULTS: Ischemic postconditioning demonstrated a decrease in serum cardiac enzymes (SMD -0.48, 95% CI -0.92 to -0.05, I(2) = 92%), reduction in infarct size by imaging (SMD -0.30, 95% CI -0.58 to -0.01, I(2) = 80%), wall motion score index (MD -0.19, 95% CI -0.29 to -0.09, I(2) = 44%), and showed improvement in left ventricular ejection fraction (IPoC 52 ± 0.4, control 49.7 ± 0.4) (MD 2.78, 95% CI 0.66-4.91, I(2) = 69%). All included studies were limited by high risk of performance and publication bias. CONCLUSIONS: Ischemic postconditioning during PCI in ST-segment elevation myocardial infarction appears to be superior to PCI alone in reduction of both myocardial injury or damage and improvement in global and regional left ventricular function. The effect seems to be more pronounced when a greater myocardial area is at risk. Given the limitations of the current available evidence, additional data from large randomized controlled trials are warranted.

The diagnostic accuracy of Doppler echocardiography in assessment of pulmonary artery systolic pressure: a meta-analysis.

BACKGROUND: Transthoracic echocardiography is commonly used to estimate pulmonary arterial systolic pressure (PASP) and to diagnose pulmonary hypertension (PH). However, some recent studies have questioned the accuracy of Doppler echocardiography (DE) in the assessment of PASP. The present meta-analysis was performed to estimate the accuracy, sensitivity, and specificity of DE in the assessment of PASP. METHODS: A literature search and data extraction of English and non-English articles reported from May 1984 to January 2009 was performed independently by 2 investigators using MEDLINE and EMBASE databases. Articles were included if they compared DE with right heart catheterization (RHC) in the assessment of PASP. Nine articles met our criteria and were included in our meta-analysis. We conducted a meta-analysis of the results of these articles using fixed- and random-effect models to estimate the accuracy, sensitivity, and specificity of DE in the assessment of PASP. RESULTS: The correlation between PASP estimated by DE and RHC ranged from (r = 0.65, P < 0.001) to (r = 0.97, P < 0.001). The pooled sensitivity, specificity, and accuracy of DE for the diagnosis of PH were 88% (95% confidence interval [CI], 84-92%), 56% (95% CI, 46-66%), and 63% (95% CI, 53-73%), respectively. CONCLUSION: DE is a useful noninvasive modality to screen for PH and can reliably determine whether PASP is normal, mildly elevated, or markedly elevated. However, abnormal results from DE need to be confirmed by RHC.

Spontaneous coronary artery dissection: to treat or not to treat--2 atypical cases and a review of the literature.

Spontaneous coronary dissection is an unusual cause of acute coronary syndrome and sudden death, with a predilection for otherwise healthy young women. Presentation during the peri-partum period accounts for a quarter of the cases. We describe 2 cases of spontaneous coronary dissection with some atypical features. Both patients differed in their demographics, clinical presentations, and management strategies. Posited pathogenetic mechanisms for spontaneous coronary dissection are varied and remain poorly understood. Optimal management strategies depend on the vessels involved and the presence of ongoing symptoms. Patients who survive to presentation typically have a good prognosis.

Renal vein thrombosis: a case report.

The presenting symptoms of acute renal vein thrombosis (RVT) can often be confused with those of nephrolithiasis. Delayed diagnosis and treatment of RVT can result in catastrophic complications, including loss of renal function and pulmonary embolism. A high clinical suspicion and early imaging with computed tomography or magnetic resonance imaging will allow early initiation of therapy and prevention of thrombus extension in patients with RVT.

A Pilot Study to Assess Adenosine 5'-triphosphate Metabolism in Red Blood Cells as a Drug Target for Potential Cardiovascular Protection.

OBJECTIVE: To study the effect of exercise preconditioning on adenosine 5'triphosphate (ATP) metabolism in red blood cells and cardiovascular protection against injury induced by isoproterenol in vivo. METHODS: Male Sprague Dawley rats (SDR) were each exercised on a treadmill for 15 minutes at 10 m/min and 10% grade (n = 7) (LowEx), or 14 m/min and 22% grade (n = 8) (VigEx). Two hours after the exercise, each rat received a single dose of isoproterenol (30 mg/kg) by subcutaneous (sc) injection. Two separate groups of SDR were used as control: One received no exercise (n = 10) (NoEx) and the other received no exercise and no isoproterenol (n = 11) (NoIso). Serial blood samples were collected over 5 hours for measurement of ATP and its catabolites by a validated HPLC. Hemodynamic recording was collected continuously for the duration of the experiment. Data were analysed using ANOVA and t-tests and difference considered significant at p < 0.05. RESULTS: Exercise pre-conditioning (both LowEx and VigEx) reduced mortality after isoproterenol from 50% to < 30% (p > 0.05). It attenuated the rebound in blood pressure significantly (p < 0.05 between NoEx vs VigEx), attenuated the increase of RBC adenosine 5'-monophosphate (AMP) concentrations induced by isoproterenol, and also decreased the breakdown of ATP to AMP in the RBC (p < 0.05 vs NoEx). CONCLUSION: Exercise pre-conditioning decreased the blood pressure rebound and also breakdown of ATP in RBC after isoproterenol which may be exploited further as a drug target for cardiovascular protection and prevention.

Evaluation and management of acquired methemoglobinemia associated with topical benzocaine use.

Benzocaine is a widely used topical oropharyngeal anesthetic and has been reported to cause methemoglobinemia. We discuss benzocaine-induced methemoglobinemia and review the causes, presentation, and management of this serious complication. Treatment with methylene blue will result in reversal of methemoglobinemia and clinical recovery in most cases but needs to be used at appropriate doses in carefully selected individuals. Physicians who perform procedures involving the application of benzocaine for topical anesthesia need to rapidly identify and treat methemoglobinemia to avoid significant associated morbidity and mortality.

Cardiovascular antioxidant therapy: a review of supplements, pharmacotherapies, and mechanisms.

Oxidant stress plays an important role in the pathogenesis of atherosclerosis. In the late 1980s, biological studies demonstrated that oxygen-free radicals oxidize low-density lipoprotein-cholesterol, resulting in the creation of foam cells and inciting the cascade of biological events that ultimately result in the formation of atherosclerosis. In vitro studies showed the ability of antioxidant vitamins to scavenge free radicals and block the oxidation of low-density lipoprotein. This data was supported in vivo by early observational studies suggesting the benefit of antioxidants, particularly vitamin E, in the prevention of coronary artery disease. On the basis of these studies, the use of antioxidant supplements by the general population increased substantially and became a multibillion dollar industry. Despite strong biological evidence and promising observational data, more rigorous scientific evaluation did not support a causational relationship between vitamin supplements and lowering coronary artery disease risk. Several prospective, double-blind, placebo-controlled trials showed no benefit and possibly harmful effects. Therapies such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and statins, which are known to have benefit in preventing and treating atherosclerosis by reducing blood pressure and cholesterol, also have a "pleiotropic" effect in reducing the formation of reactive oxygen species (ROS). Advances in molecular biology and the study of ROS led to a better understanding of the mechanisms that govern their production and role in atherogenesis. This progress identified unforeseen pathways by which these drugs favorably alter the balance in ROS production, and have raised possibilities for future targeted therapies in the prevention of atherosclerosis.

Multiple coronary to pulmonary artery fistulas: a case report and review of the literature.

Coronary to pulmonary artery fistulae (CAF) are rare cardiac anomalies. The majority arise from the right coronary artery, with fistulae originating from the left anterior descending artery or from multiple arteries being less common. CAF are frequently asymptomatic and found incidentally on routine cardiac imaging. We present the case of a 61-year-old woman with multiple CAF who presented with progressive shortness of breath and chest pain and was ultimately treated successfully with trans-catheter coiling with marked improvement in symptoms. We also review the currently available literature regarding advances in diagnosis and treatment of CAF.