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At least 631 records · Page 35Linked to original sources
PubMed1999

Evaluation of local platelet deposition during laser thermal angioplasty.

Laser thermal angioplasty is one of the brand-new transluminal interventions for arterial occlusive disease. And one of the most important prognostic factors of this intervention is the degree of local platelet deposition which causes the acute platelet thrombus and increases the proliferation of smooth muscle cells. The purpose of this study is to assess the degree of platelet deposition on the laser ablated area and to investigate the optimal conditions of laser ablation from the point of thrombogenesis. First of all, the laser ablations of various delivered energy were carried out on canine femoral arteries, then thrombus formation after laser ablation was evaluated with angioscopy. No thrombus was recognized on all ablated areas in the cases with a laser energy of 16 Joule (J) and 20 J. On the other hand, small thrombus on the ablated area was observed in 1 of 4 cases (25%) with that of 24 J, and in 2 of 4 cases (50%) with that of 30 J. Then, the degree of platelet deposition on the laser ablated area was evaluated with platelet labeled radioimmunoassay. Laser ablations were employed in canine femoral arteries varying delivered laser energy. There were no differences in the numbers of platelet deposition when the laser energy for one shot was within 24 J. The numbers of platelet deposition with a laser energy of 30 J and 45 J were significantly (p < 0.05) higher than those with a laser energy within 24 J. The numbers of platelet deposition were gradually increased related to the frequency of laser ablations, and the numbers of platelet depositions in 10 repeated laser ablations of 16 J and 20 J were significantly (p < 0.05) higher than that in single laser ablation of 16 J and 20 J. From the aspect of local platelet deposition, the optimal laser energy for one shot should be restricted within 24 J and the repeated ablation was the most appropriate method of laser thermal ablation.

Aluminum↗
PubMed2000

Semiclosed endarterectomy for long superficial femoral artery atherosclerotic occlusive disease. One-year angiographic results.

BACKGROUND: The anatomic results of endarterectomy of long occlusive lesions in the superficial femoral artery (SFA) are required for reconsidering this procedure and comparing the results with those of newly developed endovascular techniques. We designed a prospective study to determine the arteriographic findings one year after a successful semiclosed endarterectomy of long occlusive lesions in the SFA. METHODS: From January 1995 until July 1996, an endarterectomy in the SFA was attempted in 12 successive patients and was successfully performed in 10 patients (6 men and 4 women), with an average age of 73 years (range 66 to 90 years). Indications for successfully performed procedures were claudication in 6, non healing ulcer in 2, local gangrene in 2 patients. The mean length of the occlusion was 17 cm (12-33). Six patients had poor run-off with 0 to 1 patent tibial artery. The mean length of the endarterectomised segment was 31 cm (27-39). An angioscopy and an angiography were performed in all procedures. There were no postoperative complications. All patients had an angiography at 12 months or before because of ipsilateral disease. Primary angiographic patency was defined as patency of the treated artery with stenosis of less than 30%. A short stenosis was defined as <5 cm. These lesions were an indication of percutaneous balloon angioplasty (PTA) and the final results were listed as secondary patency. RESULTS: Angiography revealed 3 patent arteries, 5 short stenosis, 2 long stenosis and no occlusions. The primary patency rate was 30% at 12 months. The secondary patency was 80% with a mean follow-up of 19 months (ranging from 13 to 25 months). The mortality and amputation rate at 12 months was nil. CONCLUSIONS: Despite a modern intraoperative control, there was a high incidence of restenosis after semiclosed endarterectomy performed for long occlusive lesions of the SFA. As a result of a close surveillance and PTA, the secondary patency at one year was good. Before a widespread use of newly developed endovascular techniques, comparative patency studies with the mere endarterectomy should be performed. Endarterectomy followed by a PTA in cases of restenosis, is an alternative to bypass when the vein is not available.

Aged↗
PubMed2001

Present-day investigations cannot adequately determine the risk of acute coronary syndromes.

It is an important irony that present-day clinical stress testing methods including exercise electrocardiogram, stress echocardiography and even coronary angiography are not able to demonstrate vulnerable coronary plaques at risk of rupture. A vulnerable plaque may in fact be invisible on clinical stress test and perhaps only visualized directly through less available techniques such as coronary angioscopy. Landmark pathological studies have deepened our understanding of the mechanisms behind acute coronary syndromes over the last decade. Thrombosis plays a key role and is a unifying feature in the pathogenesis. Platelet-rich thrombus superimposed over the disrupted atherosclerotic plaque or eroded plaque endothelium, with or without fibrin-thrombus extension, is evident in post-mortem necropsy and angioscopic studies. However features which contribute to the risk of acute events lie in the atherosclerotic plaque itself. Plaque content and not plaque size is the important factor. Clinical stress testing demonstrates plaque size but not plaque content. A plaque will be prone to rupture if it has only a thin cap and a proportionally larger lipid core. In such a plaque there is preponderance of activated macrophages and T-lymphocytes, and high activity of matrix metalloproteinases. Smooth muscle cell proliferation and collagen synthesis are downregulated. These features may serve as possible targets for devising clinical methods to detect plaques at risk or for reversing the risk in vulnerable plaques.

Arteriosclerosis↗
PubMed2001

[Identification of unstable coronary atherosclerotic plaques].

The mechanisms of atherogenesis are better understood and the detection of atherosclerosis has improved with the different diagnostic methods currently available. However, it is almost impossible at present to differentiate high risk, unstable or vulnerable plaques from quiescent or stable plaques of atherosclerosis. This is a crucial problem given the banality of atherosclerosis on the one hand, and, on the other hand, the serious consequences (acute coronary syndromes, cerebrovascular accidents) of thrombotic occlusion at the site of an atherosclerotic plaque. It has now been established that the composition of the plaque is more important than the degree of stenosis, a fundamental concept in the risk of plaque rupture, precipitating the cascade of reactions leading to uncontrolled thrombosis. Consequently, new imaging techniques should address the problem of analysing the composition of atheromatous plaques. Endovascular ultrasonography, fast CT, angioscopy, nuclear imaging techniques and MRI are so many promising tools. However, non-invasive techniques should be distinguished from invasive ones. In all probability, it will be the former which will turn out to be the most useful diagnostic aid in pauci or asymptomatic patients. This article reviews the different imaging techniques under evaluation for the identification of risk of plaque rupture.

Angiography↗
PubMed1975

[Cardiovascular pathology in dermatomyositis].

Among 110 patients with dermatomyositis cardiovascular pathology was found in 77, and only in 37 of them it was attributable to the underlying pathology. In all of these patients myocardial lesions were found, that manifested themselves most frequently by non-specific ECG changes. Cardiac insufficiency and arrhythmias were revealed less frequently, mainly during exacerbations of the pathological process. Only in one patient endocarditis was diagnosed, and in two others elements of chronic cor pulmonale due to pneumonitis. In 18 patients signs of moderate myocardial dystrophy developed after a long-term therapy with corticosteroid hormones. A study of the central haemodynamics in 20 patients with dermatomyositis revealed a tendency towards a hyperkinetic state of the circulation in those patients who had the most sereve muscle syndrome. Angioscopy of the bulbar conjunctiva revealed the changes that persisted even during the remission period, achieved by means of active steroid therapy.

Adolescent↗
PubMed2002

[Non-invasive coronary angiography by multislice computed tomography: a new diagnostic method?].

A significant improvement in the noninvasive evaluation of coronary anatomy has been obtained after the introduction of the new high-speed multislice computed tomography systems. Images are reconstructed using retrospective ECG-gated protocol along with contrast analysis and three-dimensional display algorithms. The 8 detectors and the reduced tube rotation time of last-generation scanners allow the coverage of the entire heart during a single breath-hold following an intravenous bolus of 120 ml of nonionic contrast. Faster computer software offers submillimeter resolution reconstructions and increased post-processing capabilities, such as quantitative angiography, virtual angioscopy, and calcium score evaluation. At least in this phase of technical development the visualization of side branches of coronary vessels seems to advantage multislice computed tomography with respect to nuclear magnetic resonance and electron-beam computed tomography in the challenge for clinical noninvasive evaluation of coronary microcirculation.

Aged↗
PubMed2002

Intravascular ultrasound assessment of blood vessel morphology.

Intravascular ultrasound (IVUS) is an invasive imaging technique, characterized by the ability to depict the tomographic section of blood vessels' lumen and wall. Thus, it enables the performance of a unique in-vivo assessment of the luminal area and three-layer wall morphology, as well as atherosclerosis within the vessel. The typical composition of an IVUS image and the measurements of observed structures have been shown to correlate well with histology and angioscopy in several in vitro studies. The existing data on intravascular imaging of the aorta are scant. In this study, the preliminary results of in-vitro IVUS examination of human descending aorta morphology are presented, with reference to the corresponding histological section.

Aorta↗
PubMed2003

[Diagnosis with helical CT and echocardiography of patients with suspected chronic thromboembolic pulmonary hypertension].

Chronic Thromboembolic Pulmonary Hypertension (CTEPH) is a serious disease with a very high mortality after variable periods of time. Early diagnosis of CTEPH is critical because thromboendarterectomy can improve survival, hemodimamics and functional capacity. Based on our experience we have performed a review of diagnostic techniques. Echocardiography, pulmonary angiography, fiberoptic angioscopy, helical CT an MRI. For each diagnostic procedure we have analysed its accuracy, invasiveness and easiness of use. We conclude that currently the most useful techniques are echocardiography (to asses pulmonary hypertension), and helical CT which is a good alternative to pulmonary angiography and can detect very specific findings such as dilatation of central pulmonary arteries, eccentric localized thrombi and mosaic attenuation of the pulmonary parenchyma. Even more accurate findings can be expected by the use of multislice CT, which could allow to asses the degree of narrowing of the pulmonary vessels and bronchial circulation.

Aged↗
PubMed1992

[Bronchial cancer: how can the anatomic mediastinal extension of the tumor be estimated?].

Determining the precise extension of a bronchial carcinoma is essential to decide the treatment and appreciate the outcome. Computed tomography (CT) remains the reference method for the evaluation of mediastinal invasion by tumor. It seems reasonable to purpose CT for every operable tumor after radio bronchoscopic examination (except for peripheral T1 tumor without contact with the pleura). The place of MRI is not yet definitely established. But one can expect it to be better defined in the years to come because of technical improvement. However MRI could be performed in place of CT or complementary to CT in some cases: tumor of pulmonary apices, tumor in contact with diaphragm cardiac cavities or large mediastinal vessels, suspicion of vertebral invasion. MRI is also indicated first in cases of contra indication to iodine injection. There is no more indication to angiographic examinations for the staging of bronchogenic carcinoma. Other imaging methods have to be evaluated in this field: i.e. esophagoscopy, endovascular, ultrasound or angioscopy.

Carcinoma, Non-Small-Cell Lung↗
PubMed1992

[Vascular endoprosthesis. A new indication in the surgery of the iliac artery].

We have used endoprosthesis (Palmaz Schatz) after balloon angioplasty of iliac arterial stenoses or thromboses, in order to increase the immediate patency and to prevent the recurrence of stenosis. Our series gathers 24 patients operated with endovascular procedures over a period of 2 years: 22 men, 2 women--extreme ages 42 to 78 years, average age 63.5 years--Clinical stage: 22 at stage I, 1 at stage III, 1 at stage IV. Arteriographic findings: 8 primary iliac lesions (6 stenoses and 2 thromboses), 11 external iliac lesions (stenoses). All these lesions were atheromatous. One of them had recurred after angioplasty. Usual technique: balloon angioplasty of the stenosis, assessment on a fluoroscopic screen and angioscopy of the result, decision to insert the Palmaz Stent if defects are seen on the image. Repatency of impassable lesions with a YAG laser was carried out in 2 cases. The indication of an endoprosthesis was established on the basis of the radiological image in 17 cases, of the angioscopic image in 4 and systematically in 10 cases of recurrence of stenosis, iliac thrombosis or associated surgery. Associated surgery: 2 femoropopiteal bypass grafts, 3 femorofemoral bypass grafts, 1 deep plasty, 1 superficial femoral recanalization with laser, 1 lymbar sympathectomy. Postoperative results: 1 death due to MI (78-year-old diabetic woman), 1 thrombosis treated with femorofemoral bypass. Middle-term results: after 6 to 24 months, average time lapse 13 months. The comparison of the ankle pressure indices and of the pre- and postoperative sonographic findings shows an indisputable hemodynamic improvement.

Adult↗
PubMed1992

[Present possibilities of use of intravascular ultrasound examinations].

Catheter intravascular imaging is currently used as an adjunct to contrast angiography and angioscopy in peripheral and coronary arteries. At present the smallest catheters are 3.0 F (1.0 mm). Frequencies used are from 10 to 40 Mz, which allow high resolution imaging of structures close to the transducer. Mechanical and phased array systems are used, introduced either on the wire or through fine plastic catheter. More recent is the monorail system improving the flexibility and tracking of the mechanical systems. The review presents current status of catheters and diagnostic possibilities. Normal arteries have typical three layered appearance (intima, media, adventitia). Ultrasound can be reliably used to distinguish abnormal vascular segments. Atherosclerotic plaques can be subclassified on the basis of plaque composition. Thrombus is characterized by granular appearance with varying sonographic gray levels. Dissection and intimal flaps are also visualized by intravascular ultrasound. Potential utility of intravascular ultrasound in the assessment of endovascular interventions and its limitations are discussed.

Blood Vessels↗
PubMed1992

Thrombus formation on ruptured atherosclerotic plaques and rethrombosis on evolving thrombi.

Angiography in patients with unstable angina or myocardial infarction with subtotal coronary occlusion often reveals eccentric stenoses with irregular borders, suggesting ruptured atherosclerotic plaques and thrombosis, as documented by angioscopy and at autopsy. We have simulated and studied these processes in an ex vivo perfusion chamber and in an in vivo swine model. Our results suggest that specific local factors at the time of plaque disruption influence the degree of thrombogenicity, the stability of the growing thrombus, and, therefore, possibly also the various clinical syndromes. These factors can be divided into two groups: local vessel wall-related factors and systemic factors with local action at the area of risk. These factors include the following. 1) Exposed substrate-related effects: Plaque rupture produces a rough surface and stimulates the development of occlusive thrombus in proportion to the degree of damage. 2) Fluid dynamics-related factors: The more severe the stenotic lesion after plaque rupture, the higher the local shear rate, resulting in enhanced platelet deposition and thrombus formation. 3) Vasoconstrictive effects: Vasospasm is an important contributor to the pathogenesis of ischemic heart disease. 4) Systemic factors: There is clinical and experimental evidence to suggest that various systemic factors at the time of plaque rupture may enhance thrombogenicity (i.e., levels of epinephrine, levels of serum cholesterol, impaired fibrinolysis). We have investigated the role of residual thrombus on the process of rethrombosis and found that a residual thrombus is a very thrombogenic surface that may significantly contribute to reocclusion even in heparinized blood. Using recombinant hirudin as a pharmacological tool in our flow studies, we observed that rethrombosis is partially caused by thrombin bound to fibrin in the original thrombus, because the effect is abolished by the specific thrombin inhibitor.

Angina, Unstable↗
PubMed1992

[A case of superior vena cava syndrome due to extensive venous thrombosis of an idiopathic nature].

A 37-year-old man was admitted with facial edema and right arm swelling. Venography, computed tomography and magnetic resonance imaging showed massive organizing thrombi in the superior vena cava and bilateral internal jugular as well as subclavian veins, and showed no mass lesions occluding the veins in the mediastinum. Angioscopy demonstrated a white thrombus at the entrance of the right subclavian vein. All results of blood coagulation tests were normal. The patient was diagnosed as having superior vena cava syndrome caused by idiopathic venous thrombosis. Anti-coagulant therapy with intravenous tissue plasminogen activator injection and continuous urokinase and heparin infusion into the thrombi through a catheter were not effective in lysing the thrombi. Collateral circulation gradually developed and his symptoms decreased. We decided to follow this patient on warfarin medication because of the difficulty in removing the thrombi surgically.

Adult↗
PubMed1992

[The state of development of interventional cardiology in Austria].

3,157 PTCA were performed in Austria in 1991, this is 27% more compared to 1990. Prognosis for 1992 is another 27 to 30% more. Frequency of PTCA exceeded bypass surgery in 1990 for the first time in Austria. WHO-guidelines of 1,000 interventions per year and 1 million inhabitants will be achieved in Austria by 50% in 1992. In this context it is worth while to state, that installation of further cathlabs is recommended preferably within established centers including established heart surgery. The following NON-POBA-PTCA-techniques ("New devices") were used in Austria for the first time: Atherectomy, stent, lasers, TEC, ROTABLATOR, ROTACS, magnum wire and angioscopy accounted for 11.3% of all PTCA cases in Austria recently. A total of 447 valvuloplasties were performed in Austria until now, frequency of pulmonary and mitral valvuloplasties is increasing, that of aortic valve interventions decreasing. High frequency, Radiofrequency and Direct current Ablations of supraventricular- and ventricular- or WPW-arrhythmias were performed in 184 patients in Austria until now. In 247 patients with rare conditions, interventions like atrioseptostomy, implantation of umbrellas, etc. were performed. State of interventional cardiology in Austria is appropriate, compared to other European countries.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

Aortic and peripheral vascular disease: a clinician's point of view.

In vascular surgery specific treatment depends on an accurate diagnosis. History of the patient and clinical examination will determine the severity of the disease and provide an approximate localization. Non-invasive tests will refine diagnosis. Mostly used nowadays are color duplex, spiral computed tomography and magnetic resonance angiography. The latter is particularly indicated in patients with renal insufficiency and contrast allergy. Regarding invasive tests intra-arterial angiography remains the gold standard for precise visualization of vascular pathology with the exception of aneurysmal disease. Endovascular ultrasonography and angioscopy are mainly used for evaluation of a specific treatment.

Angiography↗
PubMed2004

Non-invasive coronary angiography with multislice computed tomography. Technology, methods, preliminary experience and prospects.

The recent technical developments in multislice computed tomography (MSCT), with ECG retro-gated image reconstruction, have elicited great interest in the possibility of accurate non-invasive imaging of the coronary arteries. The latest generation of MSCT systems with 8-16 rows of detectors permits acquisition of the whole cardiac volume during a single 15-20 s breath-hold with a submillimetric definition of the images and an outstanding signal-to-noise ratio. Thus the race which, between MSCT, electron beam computed tomography and cardiac magnetic resonance imaging, can best provide routine and reliable imaging of the coronary arteries in clinical practice has recommenced. Currently available MSCT systems offer different options for both cardiac image acquisition and reconstruction, including multiplanar and curved multiplanar reconstruction, three-dimensional volume rendering, maximum intensity projection, and virtual angioscopy. In our preliminary experience including 176 patients suffering from known or suspected coronary artery disease, MSCT was feasible in 161 (91.5%) and showed a sensitivity of 80.4% and a specificity of 80.3%, with respect to standard coronary angiography, in detecting critical stenosis in coronary arteries and artery or venous bypass grafts. These results correspond to a positive predictive value of 58.6% and a negative predictive value of 92.2%. The true role that MSCT is likely to play in the future in non-invasive coronary imaging is still to be defined. Nevertheless, the huge amount of data obtainable by MSCT along with the rapid technological advances, shorter acquisition times and reconstruction algorithm developments will make the technique stronger, and possible applications are expected not only for non-invasive coronary angiography, but also for cardiac function and myocardial perfusion evaluation, as an all-in-one examination.

Artificial Intelligence↗
PubMed1989

Transcatheter coronary artery diagnostic techniques including impedance-catheter and impedance-guidewire measurement of absolute coronary blood flow.

Interventional cardiology requires precise assessment of coronary anatomy and physiology. Unfortunately, however, important interventional decisions are frequently made on the basis of arteriographic data alone. Increasing evidence suggests that visual interpretation of coronary arteriographic studies is irreproducible, inaccurate, and poorly predictive of coronary physiology. Moreover, arteriography is of little value in assessing endothelial ulceration and mural thrombus, which are important pathophysiologic features of unstable angina and acute myocardial infarction. In response to these limitations, several diagnostic transcatheter techniques have been developed that allow more complete assessment of coronary physiology and function. These include fiberoptic angioscopy, reflection spectroscopy (which can combine automated laser therapy with diagnosis), ultrasonic catheterization, and translesional gradient determination. Doppler catheterization permits the assessment of overall coronary flow reserve with the aid of induced hyperemia, whereas subselective digital radiography allows the evaluation of regional coronary flow reserve. The coronary flow reserve, however, may be falsely lowered immediately after balloon dilation, because of endothelial injury, repeated ischemia, or the administration of vasoactive drugs. To circumvent this problem, we have developed impedance-catheter and impedance-guidewire systems that, by applying impedance technology and the principles of indicator dilution, are capable of measuring absolute coronary blood flow. For a flow indicator, we use 0.5 mL of glucose solution (D5W), which has little effect on intrinsic blood flow. The validity of this approach has been demonstrated in experimental and clinical studies. The impedance guidewire is less obstructive than the catheter system, so it probably will become the method with clinical application.

Journal Article↗
PubMed1992

Plaque fissure: the link between atherosclerosis and thrombosis.

The immediate cause of arterial, predominantly coronary thrombosis is almost always cracking or fissuring of the cap of an atheromatous plaque. This exposes collagen and lipids to the flowing blood and thereby initiates thrombotic platelet aggregation, almost immediately followed by coagulation. The thrombi tend to extend into the arterial lumen, causing obstruction to blood flow and clinical symptoms and signs. Evidence for this sequence of events comes, inter alia, from angiograms of patients with unstable angina and developing myocardial infarction. Direct angioscopy in life is also visualising mural thrombi over fissured plaques in atheromatous coronary arteries. We are investigating the initial development of atheromatous plaques liable to fissuring. The cap over such plaques covers a "lipid pool". We have discovered that one factor promoting the uptake of lipid, in the form of plasma low-density lipoprotein, is the concentration of circulating catecholamines (Cardona-Sanclemente LE, Gorog P, Born GVR (1992) J Physiol London, in press). We are also investigating the immediate cause(s) of plaque fissure. We have evidence for a complex interaction of different determinants, including the concentration of macrophages, presumably as foam cells, in the plaque caps (Lendon CL, Davies MJ, Born BVR, Richardson PD (1991) Atherosclerosis 87: 87).

Angina, Unstable↗