Intravascular ultrasound imaging: a current perspective

Catheter-based intravascular ultrasound imaging has evolved from a research tool to a device that has received Food and Drug Administration approval. Although it is currently employed as an adjunct to contrast angiography in both the peripheral and the coronary circulation, the indications for its use and its clinical utility have yet to be defined. Much of the research on the technique has explored its qualitative and quantitative capabilities to improve the assessment of atherosclerotic vascular disease. There is the hope that this imaging technique may ultimately improve the performance of endovascular interventions. This review describes the development of the technology from early in vitro validation studies to its present use in human subjects. Wherever possible, studies that validate the findings (that is, by comparison with histopathology results) of intravascular ultrasound are emphasized. Although there is great promise for this technology, limitations such as loss of image quality in severely diseased or heavily calcified vessels hinder its use. The application of imaging with endovascular intervention, imaging of intracardiac structures and the pulmonary circulation and new techniques such as computer image analysis are discussed.     

Aceruloplasminemia: new clinical,pathophysiological and therapeutic insights

Aceruloplasminemia is an autosomal recessive disease of iron overload associated with mutation(s) in the ceruloplasmin gene. We report here a new case of aceruloplasminemia in a woman who is a compound heterozygote for two new mutations. Besides this novel genotypic profile, this observation provides new insights on: (i) iron metabolism with normal erythroid repartition, in the absence of serum non-transferrin-bound iron and with an increase of 59Fe plasma clearance; (ii) hepatic abnormalities associated with the presence of iron-free foci; (iii) the therapeutic management of the disease, chronic subcutaneous infusion of deferrioxamine being remarkably effective at reducing hepatic iron overload.     

Intravascular and intracardiac ultrasound imaging: current research and future directions

Intravascular and intracardiac ultrasound imaging is a newly emerging catheter-based imaging modality with considerable promise. This review article presents the rationale behind attempts at developing intravascular imaging methods, the design features of intravascular instrumentation, the knowledge obtained with in vitro studies, the in vivo experience in humans, and the potential applications of intravascular imaging in arterial atherosclerosis. The feasibility of pulmonary artery imaging and the potential applications of intracardiac echocardiography are discussed. Finally, future directions in intravascular imaging are outlined.     

Intravascular ultrasound of the coronary arteries: Current applications and future directions

Although angiography is widely applied in the diagnosis of the coronary artery disease (CAD), studies have questioned the accuracy of radiographic methods. Miniaturized intravascular ultrasound devices offer several potential advantages, including a tomographic orientation and the ability to characterize atherosclerotic plaques. Two dissimilar technical approaches to transducer design have emerged: mechanically rotated devices and multi-element arrays, each yielding small coronary catheters (1.1–1.8 mm in diameter). Initial studies of coronary ultrasound have demonstrated few serious untoward effects. In most normal subjects, the vessel wall is laminar in appearance with an intimal leading edge and subintimal sonolucent layer averaging ≤0.20 mm in thickness. In most CAD patients, the thickness of the leading-edge or sonolucent zone is abnormally increased. Atherosclerotic abnormalities are frequently evident in segments with no angiographic lesion. At sites with a circular lumen shape, minimum diameter by ultrasound and angiography correlate closely, R = 0.93. At sites with an eccentric lumen, significant disagreement between angiography and ultrasound diameter is evident, R = 0.78. Correlation between angiography and ultrasound from percent stenosis is moderate, R = 0.63. Following balloon angioplasty percutaneous transluminal coronary angioplasty (PICA), morphologic findings include complex cracks, splits, and dissections, and minimum lumen diameter by angiography and intravascular ultrasound correlate poorly. Recent advances have improved the utility of coronary ultrasound, including smaller catheters and a device combining a miniature imaging transducer (1.16 mm) with a low profile balloon (0.028–0.033 inch). Important current limitations include inability to visualize the smallest coronaries and tight stensoses. The future of coronary ultrasound is promising, propelled by the unique capability of this modality to image atherosclerotic plaques directly.     

Gene expression analysis of cardiovascular diseases: novel insights into biology and clinical applications

Although the contribution of genetics to complex cardiovascular diseases such as atherosclerosis has been accepted for quite some time, full and detailed knowledge of the individual causative genes has been elusive. With the advent of genomic technologies and methods, the necessary tools are now available to begin pinpointing the genes that contribute to disease susceptibility and progression. One approach being applied extensively in candidate gene discovery is gene expression analysis of human and animal tissues using microarrays. The genes identified by these genomic studies provide valuable insight into disease biology and represent the initial steps toward the development of diagnostic tests and therapeutic strategies that will substantially improve human health. This paper highlights the progress that has been made in using gene expression analysis cardiovascular genomic research and the potential for applying these findings in clinical medicine.     

Intravascular ultrasound in the current percutaneous coronary intervention era

The use of intravascular ultrasound (IVUS) in the cardiac catheterization laboratory has continued to evolve since its introduction nearly 15 years ago. In this review, the authors discuss the current strategies regarding the use of this imaging modality during percutaneous coronary interventions. Although routine IVUS guidance of interventions is unnecessary, the tomographic perspective provided by this modality can be very informative in selected cases. It remains unknown whether the use of emerging IVUS-based technologies such as elastography or spectral analysis is feasible for identification of vulnerable plaques.     

Gene expression analysis of cardiovascular diseases: novel insights into biology and clinical applications.

Although the contribution of genetics to complex cardiovascular diseases such as atherosclerosis has been accepted for quite some time, full and detailed knowledge of the individual causative genes has been elusive. With the advent of genomic technologies and methods, the necessary tools are now available to begin pinpointing the genes that contribute to disease susceptibility and progression. One approach being applied extensively in candidate gene discovery is gene expression analysis of human and animal tissues using microarrays. The genes identified by these genomic studies provide valuable insight into disease biology and represent the initial steps toward the development of diagnostic tests and therapeutic strategies that will substantially improve human health. This paper highlights the progress that has been made in using gene expression analysis cardiovascular genomic research and the potential for applying these findings in clinical medicine.     

Thalidomide: current and potential clinical applications

More than three decades after its withdrawal from the world marketplace, thalidomide is attracting growing interest because of its reported immunomodulatory and anti-inflammatory properties. Current evidence indicates that thalidomide reduces the activity of the inflammatory cytokine tumor necrosis factor (TNF)-alpha by accelerating the degradation of its messenger RNA. Thalidomide also inhibits angiogenesis. Recently, the drug was approved for sale in the United States for the treatment of erythema nodosum leprosum, an inflammatory complication of Hansen's disease. However, it has long been used successfully in several other dermatologic disorders, including aphthous stomatitis, Beh?et's syndrome, chronic cutaneous systemic lupus erythematosus, and graft-versus-host disease, the apparent shared characteristic of which is immune dysregulation. Many recent studies have evaluated thalidomide in patients with human immunodeficiency virus (HIV) infection; the drug is efficacious against oral aphthous ulcers, HIV-associated wasting syndrome, HIV-related diarrhea, and Kaposi's sarcoma. To prevent teratogenicity, a comprehensive program has been established to control access to the drug, including registration of prescribing physicians, dispensing pharmacies, and patients; mandatory informed consent and education procedures; and limitation of the quantity of drug dispensed. Clinical and, in some patients, electrophysiologic monitoring for peripheral neuropathy is indicated with thalidomide therapy. Other adverse effects include sedation and constipation. With appropriate safeguards, thalidomide may benefit patients with a broad variety of disorders for which existing treatments are inadequate.     

Endoscopic ultrasound and the liver: current applications and beyond

The diagnosis and management of many gastrointestinal conditions has been augmented by the development of endoscopic ultrasound. Its role in the diagnosis and management of liver disease has been somewhat limited, but with the rapid development of therapeutic advancements it has quickly emerged as a useful tool in the management of complex hepatic conditions. This includes its use in the management of complications of portal hypertension as well as its use in liver lesions and cancer. In this paper, we review case studies, case series and trials for hepatic applications of endoscopic ultrasound to provide an overview of its utilization in this field and demonstrating its more novel applications for future use.     

Intracoronary ultrasound imaging: methods and clinical applications

OBJECTIVE: To review the development of intracoronary ultrasound, its current utility and the impetus for its continued development as a coronary imaging modality. DATA SOURCES: English-language literature (1966 to 1999) was searched in the MEDLINE database with the key words 'ultra- sound', 'intravascular' and 'intracoronary', and limited to human studies. In addition, an online public access catalogue was searched using the subject headings 'cardiovascular diseases - therapy', 'heart diseases' and 'vascular diseases'. STUDY SELECTION AND DATA EXTRACTION: Articles relating to the history of intravascular or intracoronary ultrasound, methods and materials employed, advantages and disadvantages, safety issues and future directions of research in the area of intracoronary ultrasound were selected. DATA SYNTHESIS: Intracoronary ultrasound has been shown to improve upon demonstrated weaknesses of coronary angiography. This imaging technique, while invasive, has not been associated with significant, acute adverse effects and has proved to be useful in guiding interventions, and evaluating the mechanism and extent of their success. Technological limitations with respect to the equipment employed, and the acquisition, processing and display of images are the subject of intense research focus because they hinder more widespread clinical use of intracoronary ultrasound. CONCLUSIONS: Intracoronary ultrasound has emerged as a safe and useful tool in the visualization of the coronary vasculature. Technological limitations and questions about long term safety are a concern. Its ability to overcome the inherent limitations of coronary angiography, and to guide and evaluate coronary interventions supports the notion that this technique will continue to assume an ever-expanding role in interventional cardiology.     

Intravascular ultrasound: limitation and prospects

The aims of intravascular ultrasound (IVUS) are visualization of the arterial wall, characterization of the arterial plaque, measurement of vessel diameter and endoluminal procedure assessment. The main sources of errors are: limitation of resolution, distortion of images due to non uniform angular velocity of mechanical type transducers, overestimation or underestimation of cross sectional area secondary to eccentric position or non coaxial orientation of the catheter. Awareness of these problems may prevent misinterpretations. Combined balloon imaging catheters, forward-looking sector scanners and ultrasound imaging guide wires may be achieve by miniaturization of transducers. Three dimensional imaging, blood flow quantification, local elasticity of tissues may be achieve by new softwares.     

Postprandial glycemia--review of current pathophysiological, epidemiological and clinical aspects

One of the most difficult current medical problems is the growing epidemics of diabetes mellitus. The contemporary treatment aims not only to secure the patients survival and to protect from the acute symptoms but also to avoid the occurrence of the chronic complications of the disease. This paper contains a review of the role that postprandial hyperglycemia plays in the treatment of diabetes mellitus especially type 2. Authors summarize findings of pathophysiological and epidemiological macroangiopathy studies that indicate the use of prandial glucose regulation in clinical practice. This review contains discussion of postulated mechanism in which short-lasting increases in plasma glucose concentration can damage vessel wall lead to atherosclerosis. Epidemiological studies showing the strong correlation between postprandial (and post-challenge) plasma glucose levels with cardiovascular endpoints are also discussed. Moreover, in this paper the reader may find a discussion on practical aspects of postprandial hyperglycemia monitoring in the treatment of diabetic patient, focusing at the relationship between prandial glycaemia and long term glycaemia control expressed by HbA(1c) measurements. The guidelines for monitoring postprandial glycaemia are also included. The modern therapeutic possibilities aiming post-prandial hyperglycaemia are also showed.     

Stress echocardiography: current methodology and clinical applications

Stress echocardiography is commonly employed for the clinical management of known or suspected coronary artery disease. This review discusses the accuracy of the technique, which is equivalent to that of competing imaging techniques, as well as its overall role in patient management. The utilization of stress echocardiographic modalities in clinical presentations, such as chest pain, congestive heart failure, and valvular heart disease, and preoperative risk assessment, as well as determining myocardial viability, are discussed.