Active clinical trials for "Constriction, Pathologic"

We sought to determine whether the dual-source computed tomography assessment of aortic valve stenosis and coronary artery disease is equivalent to or even better than conventional invasive coronary angiography and transthoracic echocardiography.

Exertional angina is common symptom in patients with severe aortic stenosis (AS) without obstructive coronary artery disease (CAD). Although reduced myocardial flow reserve is one of the proposed explanations for angina, little is known about the pathophysiology. This study aimed that adenosine-stress cardiac magnetic resonance can be used for the assessment of myocardial perfusion reserve and suggest the pathophysiology of development of angina in patients with severe AS without obstructive CAD.

Aortic stenosis (AS) is the most common valve disease in the United States and most common indication for valve replacement surgery. Anatomical and hemodynamic severity of AS is insufficient for elucidating patients' prognosis. Therefore, the decision about the optimal timing of surgical intervention remains critical. However, the changes in structure and electrical activity of the cardiac muscle can be assessed by noninvasive imaging and electrocardiography (ECG). Degenerative myocardial changes characterized by fibrosis or collagen deposits are frequently observed in AS patients and have a negative impact on patient outcomes. In this project, our objective is to determine whether echocardiographic image analysis of integrated backscatter (IB), which can express changes in myocardial tissue composition (amount of fibrosis) based on its ultrasound reflectivity, global left ventricular (LV) load as measured by Zva, and ECG analysis of the duration of the QRS interval have a role in risk stratification for AS patients and to apply those methods to identify which patients would benefit from surgical intervention. The investigators hypothesize that 1) the severity of myocardial damage can discriminate the prognosis in patients with AS, and 2) IB, Zva, and QRS interval can be diagnostic measures of the severity of myocardial damage. The investigators will measure the severity of myocardial fibrosis using MRI (reference) in 50 patients and will test the diagnostic significance of IB (testing method). Zva, QRS duration, and conventional echocardiographic measures will also be tested for diagnosing severity of myocardial fibrosis.

The rate of success 12 months after surgery is reported to be 60-65% in patients with lumbar disc herniation and 60-70% in patients with spinal stenosis. At the Back Center Copenhagen, patients with persistent low back pain caused by lumbar disc herniation and spinal stenosis are treated by a multidisciplinary team comprising rheumatologists, physiotherapists, chiropractors, and social workers according to current guidelines. Therefore we have a unique opportunity to report the long term outcome in candidates for surgery, regardless of whether they have surgery or not, after having received optimal but unsuccessful nonsurgical treatment. The purpose of this study is to answer the following questions: 1) What is the proportion of patients operated upon after referral to surgical evaluation with positive MRI findings, persistent low back pain, and poor outcome following non-operative treatment? 2) What was the outcome in these patients 2 years following referral? 3) Where any baseline variables predictive of good or poor postsurgical outcome? 4) Where there any difference in outcome in patients with or without surgery?

The overall aim of this work is to assess the relationship between stroke risk and hemodynamic compensation strategies, as measured using a novel 3.0 Tesla MRI protocol, in patients with symptomatic intracranial (IC) steno-occlusive disease. Recent studies have shown high two-year ischemic stroke rates in symptomatic patients with IC arterial stenosis. Therapy for IC stenosis patients includes revascularization with angioplasty, IC stenting, or bypass, however identification of patients most likely to benefit from these more aggressive interventions, rather than medical management alone, has been problematic. Accurate measurements of hemodynamic compromise are likely required to better define stroke risk and guide treatment decisions. Specifically, in IC stenosis patients with compromised cerebral perfusion pressure (CPP), the extent of hemodynamic compromise reflects the autoregulatory capacity of vasculature to increase arterial cerebral blood volume (aCBV) and/or develop collaterals to supplement cerebral blood flow (CBF). The prevalence of CBF collateralization and aCBV autoregulation has been hypothesized to correlate uniquely with stroke risk, however the extent of this correlation has been debated. The critical barrier to stratifying stroke risk rests with a lack of (i) methodology for measuring multiple hemodynamic factors with high specificity and (ii) noninvasive approaches capable of monitoring longitudinal progression of impairment. The investigators have demonstrated the clinical utility of relatively new, noninvasive MRI approaches for assessing cerebrovascular reactivity (CVR), aCBV, and collateral CBF. The investigators hypothesize that stroke risk can be more completely evinced from collective measurements of these parameters. Therefore, the investigators propose to implement a novel, validated hemodynamic MRI protocol to assess tissue-level impairment and compensation strategies in patients with IC stenosis. Using a collective approach combining measurements of collateral CBF, aCBV and CVR in multiple brain regions, in conjunction with a statistical model incorporating the above variables as possible prognostic factors, the investigators will quantify the extent to which two-year stroke risk is associated with hemodynamic compensation mechanisms. The noninvasive and multi-faceted scope of this investigation is intended to expand the diagnostic stroke infrastructure and elucidate new hemodynamic prognostic indicators of stroke in this high-risk population.

To establish a registry in order to collect and analyze baseline and outcome data on patients with severe valvular stenosis treated with balloon valvuloplasty.

To use a new statistical method, the Logical Analysis of Data (LAD), to predict cardiac surgery risk.

The investigators plan to collect 30 participants with internal carotid artery stenosis to observed the relationship between the degree of internal carotid artery stenosis and fundus vessels （and blood flow）density before operation, and compared with participants without internal carotid artery stenosis.The fundus blood flow density will be observed after intervention operation in order to see whether the operation is effective to improve the density of fundus vessels and blood flow or not.

Introduction: Lumbar spinal stenosis is a common cause of low back and leg pain in elderly impacting physical activity and quality of life. Initial treatments are non-surgical options. If unsuccessful, surgery is advocated. The literature is not clear as to the outcome of surgery when compared to non-surgical treatment, and the optimal time for surgery is not explicit. Materials and analysis: This observational study is designed to investigate the course of treatment, compare effectiveness of surgical and non-surgical treatment in patients with lumbar spinal stenosis, and identify prognostic factors for outcome in the context of current clinical practice. Prospectively registered data on treatment, outcome and patient characteristics are collected from nationwide registers on health and social issues, a clinical registry of people with chronic back pain and hospital medical records. Primary outcome is change in physical function measured by the Zurich Claudication Questionnaire. Secondary outcomes are changes in symptom severity, pain-related function, health-related quality of life, and general self-efficacy. All outcomes are measured at baseline, 6 months and 12 months follow up. Comparisons on these variables will be made between those who undergo surgery for lumbar spinal stenosis and those not receiving surgery at 12 months follow up according to different analysis populations. Prognostic factors include treatment allocation, back and leg pain intensity, comorbidity, duration of symptoms, pre-treatment function, self-rated health, income, general self-efficacy and magnetic resonance imaging graded compression of central stenosis. Ethics and dissemination: The study has been evaluated by The Regional Committees on Health Research for Southern Denmark (S-20172000-200) and notified to the Danish Data Protection Agency (17/30636). All participants provide consent. Findings will be disseminated in peer-reviewed publications and presented at national and international conferences following the guidance from the STROBE and PROGRESS statement. Potential sources of bias will be addressed using ROBINS-I.

Aortic stenosis is the most common valve disease requiring surgery in the Western world. It is defined by progressive calcification and fibrosis of the valve leaflets and restricted valve opening. This in turn exposes the heart muscle (left ventricle) to increasing pressure leading to heart muscle thickening (left ventricular hypertrophy, LVH) to normalise wall stress and maintain heart output (stroke volume). The only treatment available is relief of pressure overload by surgical or minimally invasive valve replacement (TAVI). Transthyretin (TTR) amyloidosis is a condition characterised by deposition of insoluble transthyretin protein (a small protein tetramer produced in the liver) in various tissues, predominantly in the heart. Although there are inherited forms caused by specific TTR gene mutations, most cases occur in older individuals with non-mutated TTR (wild-type). The finding of TTR plaques in elderly individuals is relatively common; in a post-mortem study 22-25% of patients over the age of 80 had evidence of cardiac amyloid deposition. However, there is significant progressive amyloid accumulation in a small percentage of individuals leading to heart muscle thickening and heart failure. No medical treatments are currently licensed although several agents are at advanced stages of clinical trials. As both the above conditions are increasingly common in the elderly population and characterised by increased heart muscle thickening, there is the potential for them to coexist unrecognised in individual patients. The prevalence of cardiac amyloidosis in clinical populations with significant aortic stenosis is not known however small series have estimated somewhere in the region of 6-29%. Other data have suggested that patients with aortic stenosis and concurrent cardiac amyloidosis have an adverse prognosis even despite AVR. It is therefore important to identify aortic stenosis patients with coexistent amyloidosis both in terms of predicting prognosis and because it may influence decisions about whether to proceed to valve intervention. PET/MR is an emerging technique, which combines the excellent temporal and spatial resolution of MRI with the sensitive molecular imaging of PET. PET/MR has significant advantages over PET/CT (the currently more widely used approach) in that it offers superior tissue characterisation, improved correction for cardiac and respiratory motion and major reductions in radiation exposure. Whilst there are concerns about its ability to provide reliable attenuation correction of the PET data, these issues appear to have been largely overcome with recent techniques proposed by our group. MR is also more naturally suited to the imaging of certain tissues in the body compared to CT including the left ventricular myocardium. In aortic stenosis, MRI has become the gold-standard technique for examining the heart muscle (myocardium) with the unique ability to assess its tissue composition. In particular both late gadolinium enhancement (LGE) and T1 mapping based techniques are able to detect heart scarring (fibrosis) which act as biomarkers of left ventricular decompensation and are strongly associated with poor patient outcomes. CMR is also the gold-standard non-invasive technique for detecting cardiac amyloid, which is associated with both a characteristic pattern of LGE and high native T1 values. However it is not currently able to differentiate between the two different types of cardiac amyloid TTR and AL amyloidosis, which have different prognoses and treatments. Preliminary studies conducted by our group have suggested that 18F-NaF PET when added to CMR can make this distinction on the basis that this tracer binds to TTR deposits but not AL deposits, may be able to differentiate between the two. Importantly we have also used the same PET tracer as a marker of calcification activity in the aortic valve, demonstrating its ability to predict disease progression and cardiac events. In this study, we will investigate whether PET/MR could be used as "one-stop" imaging in aortic stenosis in whom valve intervention is being considered to assess in detail functional and structural properties of both the valve and myocardium and identify cases of significant cardiac TTR amyloid deposition.