The effects of beta-blockers on dobutamine-atropine stress echocardiography: early protocol versus standard protocol

BACKGROUND: To study the effects of Beta-blockers during Dobutamine Stress Echocardiography (DSE) comparing the hemodynamic benefits of an early administration of atropine in patients taking or not Beta-blockers. METHODS: One hundred and twenty-one patients were submitted to dobutamine stress echocardiography for the investigation of myocardial ischemia. The administration of atropine was randomized into two groups: A or B (early protocol when atropine was administered at 10 and 20 mcg/kg/min of dobutamine, respectively) and C (standard protocol with atropine at 40 mcg/kg/min of dobutamine). Analysis of the effects of Beta-blockers was done regarding the behavior pattern of heart rate and blood pressure, test time, number of conclusive and inconclusive (negative sub-maximum test) results, total doses of atropine and dobutamine, and general complications. RESULTS: Beta-blocked patients who received early atropine (Group A&B) had a significantly lower double product (p = 0.008), a higher mean test time (p = 0.010) and required a higher dose of atropine (p = 0.0005) when compared to the patients in this group who were not Beta-blocked. The same findings occurred in the standard protocol (Group C), however the early administration of atropine reduced test time both in the presence and absence of this therapy (p = 0.0001). The patients with Beta-blockers in Group A&B had a lower rate of inconclusive tests (26%) compared to those in Group C (40%). Complications were similar in both groups. CONCLUSION: The chronotropic response during dobutamine stress echocardiography was significantly reduced with the use of Beta-blockers. The early administration of atropine optimized the hemodynamic response, reduced test time in patients with or without Beta-blockers and reduced the number of inconclusive tests in the early protocol

Perioperative risk stratification in non cardiac surgery: role of pharmacological stress echocardiography

Perioperative ischemia is a frequent event in patients undergoing major non-cardiac vascular or general surgery. This is in agreement with clinical, pathophysiological, and epidemiological evidence and constitutes an additional diagnostic therapeutic factor in the assessment of these patients. Form a clinical standpoint, it is well known that multidistrict disease, especially at the coronary level, is a severe aggravation of the operative risk. From a pathophysiological point of view, however, surgery creates conditions able to unmask coronary artery disease. Prolonged hypotension, hemorrhages, and haemodynamic stresses caused by aortic clamping and unclamping during major vascular surgery are the most relevant factors endangering the coronary circulation with critical stenoses. From the epidemiological standpoint, coronary disease is known to be the leading cause of perioperative mortality and morbidity following vascular and general surgery: The diagnostic therapeutic corollary of these considerations is that coronary artery disease – and therefore the perioperative risk – in these patients has to be identified in an effective way preoperatively

Usefulness of an accelerated transoesophageal stress echocardiography in the preoperative evaluation of high risk severely obese subjects awaiting bariatric surgery

<p>Abstract</p> <p>Background</p> <p>Severe obesity is associated with an increased risk of coronary artery disease (CAD). Bariatric surgery is an effective procedure for long term weight management as well as reduction of comorbidities. Preoperative evaluation of cardiac operative risk may often be necessary but unfortunately standard imaging techniques are often suboptimal in these subjects. The purpose of this study was to demonstrate the feasibility, safety and utility of transesophageal dobutamine stress echocardiography (TE-DSE) using an adapted accelerated dobutamine infusion protocol in severely obese subjects with comorbidities being evaluated for bariatric surgery for assessing the presence of myocardial ischemia.</p> <p>Methods</p> <p>Subjects with severe obesity [body mass index (BMI) >40 kg/m²] with known or suspected CAD and being evaluated for bariatric surgery were recruited.</p> <p>Results</p> <p>Twenty subjects (9M/11F), aged 50 ± 8 years (mean ± SD), weighing 141 ± 21 kg and with a BMI of 50 ± 5 kg/m²were enrolled in the study and underwent a TE-DSE. The accelerated dobutamine infusion protocol used was well tolerated. Eighteen (90%) subjects reached their target heart rate with a mean intubation time of 13 ± 4 minutes. Mean dobutamine dose was 31.5 ± 9.9 ug/kg/min while mean atropine dose was 0.5 ± 0.3 mg. TE-DSE was well tolerated by all subjects without complications including no significant arrhythmia, hypotension or reduction in blood arterial saturation. Two subjects had abnormal TE-DSE suggestive of myocardial ischemia. All patients underwent bariatric surgery with no documented cardiovascular complications.</p> <p>Conclusions</p> <p>TE-DSE using an accelerated infusion protocol is a safe and well tolerated imaging technique for the evaluation of suspected myocardial ischemia and cardiac operative risk in severely obese patients awaiting bariatric surgery. Moreover, the absence of myocardial ischemia on TE-DSE correlates well with a low operative risk of cardiac event.</p

Relative abundance of the human mitochondrial transcription system and distinct roles for h-mtTFB1 and h-mtTFB2 in mitochondrial biogenesis and gene expression

Human mitochondrial transcription requires the bacteriophage-related RNA polymerase, POLRMT, the mtDNA-binding protein, h-mtTFA/TFAM, and two transcription factors/rRNA methyltransferases, h-mtTFB1 and h-mtTFB2. Here, we determined the steady-state levels of these core transcription components and examined the consequences of purposeful elevation of h-mtTFB1 or h-mtTFB2 in HeLa cells. On a per molecule basis, we find an ∼6-fold excess of POLRMT to mtDNA and ∼3-fold more h-mtTFB2 than h-mtTFB1. We also estimate h-mtTFA at ∼50 molecules/mtDNA, a ratio predicted to support robust transcription, but not to coat mtDNA. Consistent with a role for h-mtTFB2 in transcription and transcription-primed replication, increased mitochondrial DNA and transcripts result from its over-expression. This is accompanied by increased translation rates of most, but not all mtDNA-encoded proteins. Over-expression of h-mtTFB1 did not significantly influence these parameters, but did result in increased mitochondrial biogenesis. Furthermore, h-mtTFB1 mRNA and protein are elevated in response to h-mtTFB2 over-expression, suggesting the existence of a retrograde signal to the nucleus to coordinately regulate expression of these related factors. Altogether, our results provide a framework for understanding the regulation of human mitochondrial transcription in vivo and define distinct roles for h-mtTFB1 and h-mtTFB2 in mitochondrial biogenesis and gene expression that together likely fine-tune mitochondrial function

Relevance of tissue Doppler in the quantification of stress echocardiography for the detection of myocardial ischemia in clinical practice

In the present article we review the main published data on the application of Tissue Doppler Imaging (TDI) to stress echocardiography for the detection of myocardial ischemia. TDI has been applied to stress echocardiography in order to overcome the limitations of visual analysis for myocardial ischemia. The introduction of a new technology for clinical routine use should pass through the different phases of scientific assessment from feasibility studies to large multicenter studies, from efficacy to effectiveness studies. Nonetheless the pro-technology bias plays a major role in medicine and expensive and sophisticated techniques are accepted before their real usefulness and incremental value to the available ones is assessed. Apparently, TDI is not exempted by this approach : its applications are not substantiated by strong and sound results. Nonetheless, conventional stress echocardiography for myocardial ischemia detection is heavily criticized on the basis of its subjectivity. Stress echocardiography has a long lasting history and the evidence collected over 20 years positioned it as an established tool for the detection and prognostication of coronary artery disease. The quantitative assessment of myocardial ischemia remains a scientific challenge and a clinical goal but time has not come for these newer ultrasonographic techniques which should be restricted to research laboratories

Early and long-term outcome of elective stenting of the infarct-related artery in patients with viability in the infarct-area: Rationale and design of the Viability-guided Angioplasty after acute Myocardial Infarction-trial (The VIAMI-trial)

BACKGROUND: Although percutaneous coronary intervention (PCI) is becoming the standard therapy in ST-segment elevation myocardial infarction (STEMI), to date most patients, even in developed countries, are reperfused with intravenous thrombolysis or do not receive a reperfusion therapy at all. In the post-lysis period these patients are at high risk for recurrent ischemic events. Early identification of these patients is mandatory as this subgroup could possibly benefit from an angioplasty of the infarct-related artery. Since viability seems to be related to ischemic adverse events, we initiated a clinical trial to investigate the benefits of PCI with stenting of the infarct-related artery in patients with viability detected early after acute myocardial infarction. METHODS: The VIAMI-study is designed as a prospective, multicenter, randomized, controlled clinical trial. Patients who are hospitalized with an acute myocardial infarction and who did not have primary or rescue PCI, undergo viability testing by low-dose dobutamine echocardiography (LDDE) within 3 days of admission. Consequently, patients with demonstrated viability are randomized to an invasive or conservative strategy. In the invasive strategy patients undergo coronary angiography with the intention to perform PCI with stenting of the infarct-related coronary artery and concomitant use of abciximab. In the conservative group an ischemia-guided approach is adopted (standard optimal care). The primary end point is the composite of death from any cause, reinfarction and unstable angina during a follow-up period of three years. CONCLUSION: The primary objective of the VIAMI-trial is to demonstrate that angioplasty of the infarct-related coronary artery with stenting and concomitant use of abciximab results in a clinically important risk reduction of future cardiac events in patients with viability in the infarct-area, detected early after myocardial infarction

Providing perioperative care for patients with hip fractures

Providing perioperative care for patients with hip fractures can present major challenges for the anaesthesiologist. These patients often have multiple comorbidities, the deterioration of any one of which may have precipitated the fall. A careful balance has to be achieved between minimising the time before operation and spending time to optimise their medical status. This review will present insights into preoperative patient assessment and optimization in this group of patients from the anaesthesiologists’ perspective. In particular, it will highlight important medical issues of concern that may alter anaesthetic risks and management. With a greater understanding of what these issues are, potentially a more prompt and integrated approach to managing these patients may be made. Hopefully, this would result in minimising last minute cancellations due to medical reasons for these patients

Prognostic implications of negative dobutamine stress echocardiography in African Americans compared to Caucasians

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