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Biomedical subjects

W G Daniel

Publications and source records attributed to W G Daniel.

At least 109 records · Page 6Linked to original sources
PubMed1997

[Endovascular stent in spontaneous arteriovenous fistula of the common iliac artery].

In a 64 years old patient with increasing oedema of the legs and massive untreatable ascites, colour coded duplex sonography and angiography revealed a wide arteriovenous fistula (AVF) of unknown origin between right common iliac artery and vein. Avoiding surgical intervention, the AVF was eliminated by applying an endovascular stent covering the site of the fistula. After intervention oedema and ascites disappeared, and colour doppler half a year later showed a good long term result.

Angiography↗
PubMed1995

Atrial septal aneurysm in adult patients. A multicenter study using transthoracic and transesophageal echocardiography.

BACKGROUND: An atrial septal aneurysm (ASA) is a well-recognized abnormality of uncertain clinical relevance. We reevaluated the clinical significance of ASA in a large series of patients. The aims of the study were to define morphological characteristics of ASA by transesophageal echocardiography (TEE), to define the incidence of ASA-associated abnormalities, and to investigate whether certain morphological characteristics of ASA are different in patients with and without previous events compatible with cardiogenic embolism. METHODS AND RESULTS: Patients with ASA were enrolled from 11 centers between May 1989 and October 1993. All patients had to undergo transthoracic and transesophageal echocardiography within 24 hours of each other; ASA was defined as a protrusion of the aneurysm > 10 mm beyond the plane of the atrial septum as measured by TEE. Patients with mitral stenosis or prosthesis or after cardiothoracic surgery involving the atrial septum were excluded. Based on these criteria, 195 patients 54.6 +/- 16.0 years old (mean +/- SD) were included in this study. Whereas TEE could visualize the region of the atrial septum and therefore diagnose ASA in all patients, ASA defined by TEE was missed by transthoracic echocardiography in 92 patients (47%). As judged from TEE, ASA involved the entire septum in 100 patients (51%) and was limited to the fossa ovalis in 95 (49%). ASA was an isolated structural defect in 62 patients (32%). In 106 patients (54%), ASA was associated with interatrial shunting (atrial septal defect, n = 38; patent foramen ovale, n = 65; sinus venosus defect, n = 3). In only 2 patients (1%), thrombi attached to the region of the ASA were noted. Prior clinical events compatible with cardiogenic embolism were associated with 87 patients (44%) with ASA; in 21 patients (24%) with prior presumed cardiogenic embolism, no other potential cardiac sources of embolism were present. Length of ASA, extent of bulging, and incidence of spontaneous oscillations were similar in patients with and without previous cardiogenic embolism; however, associated abnormalities such as atrial shunts were significantly more frequent in patients with possible embolism. CONCLUSIONS: As shown previously, TEE is superior to the transthoracic approach in the diagnosis of ASA. The most common abnormalities associated with ASA are interatrial shunts, in particular patent foramen ovale. In this retrospective study, patients with ASA (especially with shunts) showed a high frequency of previous clinical events compatible with cardiogenic embolism; in a significant subgroup of patients, ASA appears to be the only source of embolism, as judged by TEE. Our data are consistent with the view that ASA is a risk factor for cardiogenic embolism, but thrombi attached to ASA as detected by TEE are apparently rare.

Case-Control Studies↗
PubMed1995

The safety of intracoronary ultrasound. A multicenter survey of 2207 examinations.

BACKGROUND: Intracoronary ultrasound (ICUS) is increasingly used in clinical practice to study the natural history of coronary artery disease and to assess the effects of intracoronary, catheter-based interventions. However, the risk associated with the procedure is not well documented. METHODS AND RESULTS: ICUS studies performed in 28 centers were retrospectively included; these centers agreed to contribute to the study among a total of 60 centers initially invited. Among the 2207 ICUS studies, 505 (23%) were performed in heart transplant recipients and 1702 (77%) in nontransplant patients. Indication for ICUS was diagnostic imaging in 915 (41%), drug testing in 244 (11%), and guidance for intracoronary interventions in 1048 patients (47%). There were no complications in 2034 patients (92.2%). In 87 patients (3.9%), complications occurred but were judged to be "not related" to ICUS by the operator. In 63 patients (2.9%), spasm occurred during ICUS imaging. In 9 patients (0.4%), complications other than spasm were judged to have a "certain relation" to ICUS, including acute procedural events in 6 (3 acute occlusion, 1 embolism, 1 dissection, and 1 thrombus) and major events in 3 patients (2 occlusion and 1 dissection; all resulting in myocardial infarction). In 14 patients (0.6%), complications with "uncertain relation" to ICUS were recorded, including acute procedural events in 9 (5 acute occlusion, 3 dissection, and 1 arrhythmia) and major events in 5 patients (2 myocardial infarction and 3 emergency coronary artery bypass surgery). The incidence of acute procedural or major complications judged to be associated with ICUS (uncertain relation or certain relation to ICUS) was compared in different patient groups. The complication rate was higher in patients with unstable angina or acute myocardial infarction (2.1% events) as compared with patients with stable angina pectoris and asymptomatic patients (0.8% and 0.4%, respectively; chi 2 = 10.9, P < .01). These complications were also more frequent in patients undergoing interventions (1.9%) as compared with transplant and nontransplant patients undergoing diagnostic ICUS imaging (0% and 0.6%, respectively; chi 2 = 13.5, P < .001). Adverse events were few, and no association was detected between these events and the size or type of ICUS catheter used. CONCLUSIONS: ICUS is associated with (but not necessarily the direct cause of) a minor acute clinical risk. Vessel spasm is the most frequent event occurring during ICUS. Other complications predominantly occur in patients with acute coronary syndromes and during guidance for intervention.

Adult↗
PubMed1995

Transesophageal versus transthoracic echocardiography in the evaluation of right atrial tumors.

The purpose of this study was to define the contribution of transesophageal echocardiography to the diagnosis of right atrial tumors in a large series of patients with this rare finding. Transesophageal echocardiography (TEE) has been found to be valuable in evaluating patients with intracardiac masses and has been shown to be superior to transthoracic echocardiography (TTE) in evaluating left heart masses. Between 1989 and 1993, 23 patients with either known tumors elsewhere or right atrial masses that were detected on TTE were evaluated with TEE. TEE studies were performed in the noninvasive cardiology laboratory. All patients were studied with 5 MHz biplane or omniplane transducers. The right atrium was evaluated for the presence, characteristics, extent, and attachment of any masses and for extension of these masses into the great vessels or other cardiac chambers. No complications occurred. Six patients had primary right atrial tumors. In 10 patients the tumors reached the right atrium via the inferior vena cava. Seven patients had malignant secondary tumors. TEE demonstrated three tumors not detected by TTE. Furthermore TEE provided 16 additional findings not seen on TTE. In conclusion, TEE is superior to TTE in the evaluation of right atrial tumors. TEE should be considered in patients with right atrial tumors even when these tumors have been demonstrated with TTE.

Adolescent↗
PubMed1995

Identification of patent foramen ovale permitting paradoxic embolism.

OBJECTIVES: We sought to analyze the morphologic and functional characteristics of the patent foramen ovale in patients with different clinical likelihoods for paradoxic embolism. BACKGROUND: The incidence of patent foramen ovale is increased in patients with otherwise unexplained arterial ischemic events. Because signs of venous thrombosis are absent in most patients, the diagnosis of paradoxic embolism is often questioned, even when patent foramen ovale is the only potential explanation for the ischemic event. METHODS: Seventy-eight patients with a patent foramen ovale detected by contrast transesophageal echocardiography were studied: 21 patients with an otherwise unexplained arterial ischemic event and clinical evidence implying paradoxic embolism (group I), 30 patients with an unexplained ischemic event but no clinical evidence for paradoxic embolism (group II) and 27 patients without an ischemic event (group III). RESULTS: During transesophageal contrast echocardiography, patients in group I had more severe right to left shunting (mean +/- SD 52 +/- 16% of the left atrial area filled with contrast medium) and a wider opening of the patent foramen ovale (7.1 +/- 3.6-mm separation between the septum primum and the septum secundum) than did patients in group II (35 +/- 15% and 4.4 +/- 3.2 mm, respectively, p < 0.001) or group III (23 +/- 12% and 3.0 +/- 2.0 mm, respectively, p < 0.001). The incidence of atrial septal aneurysm was similar in the three groups. Severe contrast shunting (> or = 50% of the left atrial area filled with contrast medium) and wide opening of the patent foramen ovale (> or = 5-mm separation) revealed a high sensitivity (71% and 86%, respectively) and high specificity (86% and 96%, respectively) for identification of group I patients. CONCLUSIONS: Right to left contrast shunting is more severe and opening of the patent foramen ovale is larger in patients with ischemic arterial events considered to be due to paradoxic embolism. In patients with a patent foramen ovale as the only potential cause for ischemic events and no signs of venous thrombosis, morphologic and functional variables assessed by transesophageal echocardiography may be helpful in estimating the likelihood of paradoxic embolism.

Adult↗
PubMed1995

Multiplane transoesophageal echocardiography detection of a papillary fibroelastoma of the aortic valve causing myocardial infarction.

Primary aortic valve tumours are rare. A patient is reported with a papillary fibroelastoma attached to the edge of the right coronary aortic cusp. This tumour was diagnosed by multiplane transoesophageal echocardiography after the patient experienced an acute inferolateral myocardial infarction. Multiplane transoesophageal echocardiography was useful to visualize and identify the precise point of attachment of the tumour, enabling cardiac surgeons to plan aortic valve repair rather than replacement.

Aortic Valve↗
PubMed1995

Echocardiographic assessment of vegetations in patients with infective endocarditis: prognostic implications.

Today, echocardiography is the most important technique next to clinical findings and blood cultures in the diagnosis of infective endocarditis. The sensitivity of echocardiography, particularly the transesophageal approach, for detection of vegetations and endocarditis related valvular destructions is high. In addition, echocardiographic findings may have some prognostic implications. The size and mobility of vegetations stratifies endocarditis patients into a high risk group for arterial embolism. In particular, mobile vegetations attached to the mitral valve with a maximal diameter > 10 mm may be prone to embolic events. Furthermore, increase in size of vegetations during antimicrobial treatment may identify patients with no, or at least a prolonged, healing process. Also, a lack of increase in the echo density of vegetations under adequate antibiotic treatment may indicate a poor healing process and may necessitate more aggressive management. The demonstration of paravalvular abscesses by echocardiography, particularly by transesophageal echocardiography, identifies a subgroup of patients who will need urgent cardiac surgery before widespread tissue destruction has occurred.

Echocardiography, Transesophageal↗
PubMed1995

Evaluation of endocarditis and its complications by biplane and multiplane transesophageal echocardiography.

Echocardiography is currently the method of choice for the diagnosis of endocarditis-associated vegetations or complications such as abscess formation. Thereby, the transesophageal approach (TEE) is clearly superior to precardial echocardiography and, at present, biplane TEE can be considered as the standard TEE technique. Compared with the monoplane technique, biplane TEE provides additional qualitative and quantitative information concerning the presence and amount of valvular destruction. Multiplane TEE facilitates (and abbreviates) the examination procedure, and may be helpful for easier detection of small initial abnormalities, those developing on native valves with preexisting lesions, or on prosthetic valves. It allows more accurate measurements and three-dimensional reconstruction of vegetations and abscess areas and provides more anatomical details of the disease. However, it remains to be shown by future studies if multiplane TEE will identify endocarditis-associated lesions more frequently than the biplane technique doses.

Echocardiography, Transesophageal↗
PubMed1994

Contrast-enhanced intravascular ultrasound: validation of a new technique for delineation of the vessel wall boundary.

OBJECTIVES: We evaluated a new technique for delineation of the vessel wall surface during intravascular ultrasound imaging using echogenic contrast agents. BACKGROUND: Intravascular ultrasound is used for detection of complex vessel wall structures after catheter-based interventions; however, differentiation between the lumen and these wall structures can be difficult. METHODS: In 12 anesthetized dogs, intracoronary ultrasound was performed during intracoronary bolus injection (3 and 6 ml) of different contrast agents (hand-agitated saline solution, standard iohexol, sonicated iohexol, hand-agitated iohexol, SHU 454, SHU 508). Contrast intensity was quantified by videodensitometry, and contrast homogeneity was assessed qualitatively (grade 0 to 3). RESULTS: Peak contrast intensities for SHU 454 and SHU 508 (mean [+/- SD] 48 +/- 9 and 36 +/- 6 U, respectively) were higher compared with standard, sonicated or agitated iohexol (16 +/- 3, 28 +/- 7 and 20 +/- 3 U, respectively) or with agitated saline solution (17 +/- 4 U); intensities were higher for 6 ml compared with that for 3 ml. Contrast homogeneity was higher for SHU 508 (mean [+/- SD] 3.0 +/- 0) and SHU 454 (2.7 +/- 0.5) compared with the other agents (standard iohexol 1.2 +/- 0.4, sonicated iohexol 2.0 +/- 0.5, agitated iohexol 1.8 +/- 0.6, agitated saline solution 1.0 +/- 0.4). Exact delineation of the vessel wall surface was possible in 100% of SHU 508 and in 88% of SHU 454 injections compared with 13% of agitated iohexol and 8% of sonicated iohexol injections. Accurate surface delineation was never achieved with standard iohexol or agitated saline solution. Shadowing of parts of the vessel wall by contrast material occurred at peak intensity of 75% of SHU 508 and 46% of SHU 454 injections but not with the other agents. No adverse physiologic reactions were noted, except for transient negative inotropic effects after 6 ml of SHU 508. CONCLUSIONS: This preliminary study shows that delineation of the vessel wall boundary using echogenic contrast agents during intravascular ultrasound is safe and feasible. Because of higher contrast intensity and homogeneity, SHU 454 and SHU 508 are superior to other agents.

Animals↗
PubMed1994

Assessment of left atrial appendage function by biplane transesophageal echocardiography in patients with nonrheumatic atrial fibrillation: identification of a subgroup of patients at increased embolic risk.

OBJECTIVES: This study was conducted to identify a subgroup of patients with nonrheumatic atrial fibrillation with an increased risk for cardiogenic embolism by assessing left atrial appendage function. BACKGROUND: Patients with nonrheumatic atrial fibrillation have an increased risk for thromboembolic complications. The left atrial appendage is the most likely source for thrombus formation. It is likely that the appendage function (contraction, filling dynamics) is related to the pathogenesis of thrombus formation. METHODS: Twenty-nine patients with nonrheumatic atrial fibrillation (group I) underwent biplane transesophageal echocardiography. The maximal and minimal areas during a cardiac cycle and the peak emptying and filling velocities of the appendage were measured in both scan planes. For comparison, two additional groups were also analyzed. Group II consisted of 12 patients with chronic atrial fibrillation due to significant mitral stenosis, and group III consisted of 30 patients who were in sinus rhythm. RESULTS: Patients with nonrheumatic atrial fibrillation showed two distinct appendage flow patterns: either well defined peak filling and emptying waves (> or = 25 cm/s) with visible fibrillatory contractions of the appendage wall ("high flow profile") or irregular, very low, peak filling and emptying waves (< 25 cm/s) associated with almost no visible appendage contractions ("low flow profile"). The left atrial appendage function in the first subgroup resembles that seen in patients with sinus rhythm, whereas the appendage function in the latter subgroup resembles more the "static pouch" seen in patients with rheumatic atrial fibrillation. Events suggestive of cardiogenic embolism occurred in six patients from group I, five of whom were in the low flow profile subgroup (p < 0.05). The spontaneous echo contrast phenomenon was observed in 80% of the low flow profile subgroup but in only 5% in the high flow profile subgroup (p < 0.05). Three thrombi confined to the left atrial appendage were detected by transesophageal echocardiography in group I; all three of the patients were in the low flow profile subgroup. CONCLUSIONS: The assessment of left atrial appendage function by transesophageal echocardiography may be helpful to identify subgroups of patients with nonrheumatic atrial fibrillation with an increased risk of thrombus formation.

Atrial Fibrillation↗
PubMed1994

[Digoxin-induced constriction of epicardial coronary vessels in patients with coronary heart disease: reversibility by nitrates].

Heart diseases requiring glycoside therapy are often associated with coronary artery disease. This study evaluated quantitatively the effect of an intravenous bolus injection of digoxin (0.8 mg) on diameters of epicardial coronary arteries in 11 patients with coronary artery disease. Coronary angiograms were taken up to 30 min following intravenous administration of glycosides. The maximum decrease in mean diameters of angiographically normal coronary segments was 10.0 +/- 3.5% (p < or = 0.001) compared to control. Maximum reduction in minimal diameters of stenotic segments was 22.1 +/- 13.1% (p < or = 0.001). This vasoconstriction could be reversed with nitroglycerin. Thus, intravenous administration of digoxin induces vasoconstriction of normal and stenotic coronary arteries, which could cause ischemic complications in the presence of high-grade stenoses. Since digoxin-induced vasoconstriction could be reversed with nitroglycerin, concomitant vasodilator therapy is recommended.

Adult↗
PubMed1994

[The form of atherosclerotic coronary plaques: pathoanatomic concepts and new insights using intravascular ultrasound].

In addition to the degree of vessel obstruction and to the composition of the atheroma, the geometric shape of the plaque--in particular the presence of non-diseased wall segments--is an important factor in the pathophysiology and therapy of coronary heart disease. The relevance of the plaque shape has been emphasized by pathoanatomic studies in the late 1970s. The in vivo assessment of the plaque shape using coronary angiography has major limitations: The lumen silhouette obtained by angiography does not accurately reflect the histologic extent of the plaque due to compensatory vessel enlargement, atrophy of the media, and diffuse plaque accumulation. In contrast, intravascular ultrasound (IVUS) allows direct, cross-sectional visualization of the plaque. Although this method has a small, but definite acute risk, it provides the first technique for in vivo assessment of the extent and shape of coronary plaque. In agreement with prior pathoanatomic investigations, IVUS studies have confirmed that the majority of advanced coronary plaques are located eccentrically in the vessel and that non-diseased wall segments are often present in these lesions. Using IVUS imaging, it has also been proven that in vivo relaxation of advanced coronary stenoses by vasodilatory drugs is mainly based on expansion of the non-diseased wall segment. IVUS studies have also shown that the presence of non-diseased wall segments may be important for the effect of intracoronary interventions: Balloon angioplasty of eccentric coronary lesions often causes dilatation of the non-diseased wall segments; immediate and chronic elastic recoil of these vessel segments may diminish the lumen gain from this procedure. During directional coronary atherectomy IVUS imaging of the exact location and shape of the plaque may limit subintimal tissue retrieval and thereby also reduce restenosis.

Angioplasty, Balloon, Coronary↗
PubMed1994

Transesophageal echocardiographic assessment of superior vena cava thrombosis in patients with long-term central venous hemodialysis catheters.

In some patients with end-stage renal failure, arteriovenous fistulas cannot be created due to poor vessel conditions. Alternatively, hemodialysis (HD) can be performed using long-term central venous catheters. However, these dialysis catheters are associated with a presently unknown risk of superior vena cava (SVC) thrombosis. We examined 20 patients (11 female, 9 male, age 29-83 years) 1-48 (mean 15) months after transjugular insertion of a permanent single lumen silicone rubber HD catheter. All patients underwent both transthoracic (TTE) and biplane transesophageal (TEE) echocardiography. TTE visualized the catheter only when its tip was localized in the right atrium (2 patients), but did not succeed in adequate imaging of the SVC. In contrast, TEE allowed high quality imaging of the SVC in all patients and detected a SVC thrombosis in 6 patients; in 3 of them, caval thrombosis was subtotal. One additional patient showed a thrombus attached to the catheter tip alone. Dwelling time of catheters since insertion in the SVC was not significantly different in patients with and without thrombosis. Reduced blood flow during HD was observed in 5 of 7 patients with catheter-associated thrombi but also in 4 of 13 patients without evidence for caval thrombosis by TEE. It is concluded that thrombotic occlusion of the SVC is frequent in patients with long-term central venous access; it does not necessarily correlate with clinical signs but can easily be detected by TEE. Patients with long-term central venous hemodialysis catheters should undergo transesophageal echocardiography at regular intervals.

Adult↗