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Biomedical subjects

D Didier

Publications and source records attributed to D Didier.

At least 37 records · Page 2Linked to original sources
PubMed1997

Cost-effectiveness of noninvasive diagnostic aids in suspected pulmonary embolism.

BACKGROUND: Noninvasive instruments such as plasma D-dimer measurement (DD) and lower-limb compression ultrasonography (US) are being increasingly advocated to reduce the number of necessary angiograms in patients having suspected pulmonary embolism (PE) and a nondiagnostic lung scan. We therefore designed a decision analysis model (1) to evaluate the cost-effectiveness of combining these noninvasive diagnostic aids with lung scan and angiography in the diagnosis of PE and (2) to determine the optimal sequence and combination of tests taking into account the clinical probability of PE. METHODS: We performed a cost-effectiveness analysis based on literature data, including data from a management study in our institution. Six diagnostic strategies were compared with the reference, ie, lung scan followed when nondiagnostic (low or intermediate probability) by angiography. In all strategies, PE was ruled out by a normal or near-normal scan, a negative DD (plasma level below 500 micrograms/L), or a negative angiogram. Pulmonary embolism was diagnosed and anticoagulant treatment was undertaken in the presence of a high-probability lung scan, deep vein thrombosis showed by US, or a positive angiogram. In case of a nondiagnostic scan (low or intermediate probability), patients could be either treated or not treated, or undergo other tests, according to the selected strategy. RESULTS: Under baseline conditions (prevalence of PE, 35%), strategies combining DD and US with lung scan, angiography being done only in case of an inconclusive noninvasive workup (DD level > 500 micrograms/L, normal US, and nondiagnostic lung scan), were most cost-effective. This approach yielded a 9% incremental cost reduction and a 37% to 47% decrease in the number of necessary angiograms compared with the reference strategy (scan +/- angiography). For patients with a low clinical probability of PE (< or = 20%), withholding treatment from those with a low-probability lung scan without performing an angiogram proved safe and highly cost-effective (30% cost reduction), provided US showed no deep vein thrombosis. CONCLUSION: The DD test and US are cost-effective in the diagnostic workup of PE, whether performed after or before lung scan, thus allowing centers devoid of lung scanning and/or angiography facilities to screen patients with suspected PE and avoid costly referrals. In patients with a low clinical probability, a low-probability lung scan, and a normal US, treatment may be withheld without resorting to angiography.

Algorithms↗
PubMed1996

Diagnosis of pulmonary embolism by a decision analysis-based strategy including clinical probability, D-dimer levels, and ultrasonography: a management study.

BACKGROUND: Assessment of the clinical probability of pulmonary emboli sm, plasma D-dimer measurement, and lower-limb venous compression ultrasonography have all been advocated in the workup of suspected pulmonary embolism, to minimize the requirement for pulmonary angiography in patients with nondiagnostic lung scans. However, their contribution has not been assessed prospectively. METHODS: Three hundred eight consecutive patients who came to the emergency department with suspected pulmonary embolism were managed according to a diagnostic protocol that included clinical probability assessment, lung scan, and sequential noninvasive tests: plasma D-dimer measurement by enzyme-linked immunosorbent assay (a concentration <500 microgram/L ruled out pulmonary embolism) and lower-limb B-mode venous compression ultrasonography (a positive finding was diagnostic of venous thromboembolism). Patients without pulmonary embolism according to the diagnostic workup did not receive anticoagulant treatment. The safety of this approach was assessed by a 6-month follow-up. RESULTS: of the 308 patients, 106 (34%) had a diagnostic lung scan (normal in 43 and high probability in 63). For the remaining 202 patients, noninvasive workup was diagnostic in 125 (62%). Pulmonary embolism was ruled out by a low clinical probability and a nondiagnostic scan in 48 patients and a D-dimer level less than 500 microgram/L in 53; pulmonary embolism was established by a high clinical probability and a nondiagnostic scan in seven patients and by a finding of a deep vein thrombosis on ultrasonography in 17. Therefore, only 77 of these 202 patients underwent pulmonary angiography (negative in 55; positive in 22). At 6-month follow-up (completed for 99.4% of the study population), only two of the 199 patients in whom the diagnostic protocol had ruled out pulmonary embolism (1.0% [95% confidence interval, 0.1 to 3.6]) had a thromboembolic event (pulmonary embolism, one; deep vein thrombosis, one). CONCLUSIONS: This decision analysis strategy yielded a definitive noninvasive diagnosis in 62% of patients with a nondiagnostic scan and appears to be safe.

Adolescent↗
PubMed1996

Blunt injury to the ascending aorta: three patterns of presentation.

BACKGROUND: Injury to the ascending aorta is a rare lesion that may present in various forms. A thorough analysis of this lesion is lacking in the literature. This study was undertaken to delineate the prevalence and modes of presentation of injuries to the ascending aorta after blunt trauma and to suggest guidelines for management. METHODS: A retrospective analysis of autopsies performed in our department of forensic medicine on blunt trauma victims from 1984 to 1993 and a literature review of autopsy series were undertaken to delineate the prevalence and relevant characteristics of this injury. A cash report from our institution and a review of the literature were used to provide information regarding clinical presentations of this injury and treatment approaches. RESULTS: Three modes of presentation were encountered. (1) Presentation at autopsy: The prevalence of injury to the ascending aorta after a traffic accident was 2% in our autopsy series. Among 13 patients with this injury 12 had other associated, potentially lethal lesions. A massive hemopericardium was present in two patients only. In autopsy series the incidence of injury to the ascending aorta in patients with an injury to the aorta ranged from 0% to 23%. (2) CLINICAL PRESENTATION: Twenty-one patients were treated surgically and reported in the literature. Fourteen presented with a pseudoaneurysm and seven with a chronic sinus of Valsalva fistula. One patient with a pseudoaneurysm presented with signs of cardiac tamponade and required immediate decompression; the others were hemodynamically stable. Seven patients had a cardiac lesion (valve tear in six and cardiac contusion in one), and three had an arch vessel lesion. Aorta repair was performed under cardiopulmonary bypass in every patient. (3) Incidental presentation: Seven patients with a traumatic tear of the aortic valve presented an incidental lesion of the ascending aorta. It was a subadventitial hematoma in three patients and an intimal and medial tear in four patients. Aortic tears were reinforced by direct suture. CONCLUSIONS: Injury to the ascending aorta after blunt trauma is rare but lethal mostly from associated injuries. Survivors may appear in stable condition and present mostly with pseudoaneurysms of the ascending aorta or sinus of Valsalva fistula. Associated lesions to the heart and arch vessels should be looked for. Repair of the ascending aorta injury is performed under cardiopulmonary bypass.

Adolescent↗
PubMed1996

[Treatment of post-coronarography femoral false aneurysm by compression, guided by Doppler echography].

MATERIAL AND METHODS: We evaluated the role of color Doppler US-guided compression in the non-invasive treatment of femoral artery pseudoaneurysms after cardiac catheterization, including 22 PTCA procedures. The diagnosis of 32 pseudoaneurysms in 32 patients was accomplished by detection of the typical US-Doppler pattern consisting of the swirling color Doppler flow and the "to and fro" pulsed Doppler waveform at a mean 3.6 days (1 to 14) after the cardiac catheterization. Thirteen patients had multiple cavity pseudoaneurysms (2 to 4). All the patients immediately underwent compression therapy. RESULTS: Treatment was successful in 42/49 cavities (86%) and 25/32 patients (78%), usually after 1 to 3 compression cycles of 6 to 8 minutes duration. Only one recurrence was noted at the 24 hour US-Doppler follow-up. In all cases, pain relief during compression was an excellent clinical sign of hemostatic plug formation and conversion from pseudoaneurysm to simple hematoma. Failures occurred among patients under high dose anticoagulants in spite of 4 to 10 compression cycles. COMMENTARY: In conclusion, color Doppler US-guided compression of post-cardiac catheterization pseudoaneurysms should be the first line therapeutic modality, even in cases of multiple cavities and among patients under effective anticoagulation therapy.

Adult↗
PubMed1996

Segmental arterial calcification and atheromatosis in a limb with venous angiodysplasia (Klippel-Trenaunay syndrome).

We report a case with segmental arterial calcification and atheromatosis of the superficial femoral artery in a patient with venous angiodysplasia (Klippel-Trenaunay syndrome). Pathogenesis remained unclear. A short hemodynamically significant stenosis within the calcified segment was treated by angioplasty requiring high balloon pressure and was complicated by an arterio-venous fistula. This fistula could successfully be closed by a dacron-covered endovascular prosthesis (Cragg-stent). There is little experience with covered stents to close arterio-venous shunts and our case may encourage further use in this indication.

Adult↗
PubMed1995

Preoperative diagnosis of a pulmonary artery sarcoma.

A pulmonary artery sarcoma was diagnosed preoperatively by magnetic resonance imaging enhanced with gadolinium and confirmed by percutaneous computed tomographic guided needle biopsy. Accurate preoperative diagnosis allowed planned curative surgery with removal of the right ventricular outflow tract and reconstructive surgery using a cryopreserved homograft.

Adult↗
PubMed1995

[Evaluation of congenital cardiopathies].

In this article, the different MRI methods used for the evaluation of congenital heart diseases are described and the role of this technique in complement to the other classical methods such as echocardiography and cardiac catheterization. Description of the MRI techniques is first realized, then the contribution of MRI in different types of congenital heart disease is specified with emphasizing of the specificity of the method in each case, particularly in complex diseases.

Aortic Coarctation↗
PubMed1995

Standard views in cardiac multimodality tomographic imaging.

In cardiology, it is often necessary to acquire more than one type of image to investigate a given clinical problem of a single patient. Images obtained from different imaging modalities are usually recorded and displayed in different orientations, at different positions, and at different scale factors. It is then necessary for the physician to mentally integrate the image information from the different imaging modalities. This phenomenon is particularly true with tomographic imaging techniques that allow complete freedom of the acquisition plane. In particular, when comparing images obtained from ultrasound, computed tomography, magnetic resonance imaging, positron-emission tomography, and single-photon emission computed tomography. The purpose of this article is to propose a standard set of slice orientations that could be easily applied to all modalities. Such common views could greatly facilitate the user's perception of the regional abnormalities observed in the different imaging modalities. This standardization is certainly useful for clinical application but also for every research study that requires a comparative evaluation of the different imaging modalities. Although exact registration of the images from the different modalities requires sophisticated computer programs, the simple reference method in plane positioning proposed here based on plane orientation according to the cardiac geometry can certainly provide a practical and convenient method for the reasonably accurate image registration required for visual comparative studies.

Diagnostic Imaging↗
PubMed1994

Right atrial thrombosis associated with central venous catheters in children with cancer.

Right atrial thrombosis (RAT) is infrequently diagnosed in children with cancer. Once RAT is documented, medical fibrinolysis or surgical thrombectomy is recommended. A RAT was documented in a child with lymphoma and was successfully lysed with recombinant tissue-type plasminogen activator. The case is presented and therapeutic options reviewed.

Antineoplastic Agents↗
PubMed1994

Collagen application versus manual compression: a prospective randomized trial for arterial puncture site closure after coronary angioplasty.

OBJECTIVES: This study evaluated the safety and efficacy of a newly developed puncture-sealing device consisting of subcutaneous bovine collagen application designed to facilitate local hemostasis after coronary angioplasty. BACKGROUND: The most common local hemostatic procedure after coronary angioplasty consists of heparin discontinuation and delayed sheath removal followed by mechanical compression at the puncture site. METHODS: Between December 1991 and February 1993, 124 patients undergoing coronary angioplasty with either a 6F guiding catheter followed by a heparin infusion for > 12 h or a 7F or 8F guiding catheter with optional heparin infusion were prospectively randomized to either delayed sheath removal followed by manual compression (n = 62) or sheath removal immediately after angioplasty combined with bovine collagen application for puncture site closure (n = 62). Half of the collagen plugs were delivered using measured and half using estimated skin-artery distance. Clinical and duplex sonographic evaluations of the puncture site were performed 24 h later. RESULTS: No significant difference in the incidence of local hematomas was observed. Major complications were false aneurysm, venous thrombosis and arterial occlusion. The incidence of false aneurysm was the same in both groups (4 [7%] of 62). Venous thrombosis (2%) and arterial occlusion (2%) were each recorded in one patient, both in the collagen application group. CONCLUSIONS: Sheath removal and collagen application with this new vascular hemostasis device used directly after coronary angioplasty are not superior to delayed sheath removal after heparin discontinuation followed by mechanical compression. Arterial collagen sealing with this device in its current form is associated with a small but worrisome risk of arterial occlusion.

Aged↗
PubMed1993

Influence of variability of interpretation of contrast venography for screening of postoperative deep venous thrombosis on the results of a thromboprophylactic study.

To assess interobserver variability of venography for screening for postoperative deep venous thrombosis (DVT), we used 185 bilateral ascending contrast venograms (366 lower limbs) which were performed using the long-leg film technique, in the frame of a trial of the efficacy of two low-molecular-weight-heparin fractions (initial evaluation). These venograms were submitted in a multicenter setting to three further readers who performed a serial scoring as DVT, no DVT or non-evaluable. DVTs were diagnosed in 78, 55 and 59/366 limbs (initial evaluation: 58). The proximal locations of DVTs were 16, 9 and 16 (initial evaluation: 15) and the non evaluable limbs 3, 5 and 18 (initial evaluation: 0). Apparent pairwise agreement between the three readers ranged from 87 to 90% (true coefficient of agreement Kappa 0.63-0.70). It ranged from 89 to 93% (Kappa 0.63-0.74) for the comparison between the readers and the initial evaluation. This considerable degree of disagreement among experienced readers should be taken into account in calculating sample sizes in prospective thromboprophylactic studies. Indeed, one of the two prophylactic regimens proved to be significantly (p = 0.012, p = 0.031, p = 0.049) or non-significantly (p = 0.073) superior to the other one depending upon the reading of venograms.

Contrast Media↗
PubMed1993

Unexpectedly high rate of phlebographic deep venous thrombosis following elective general abdominal surgery among patients given prophylaxis with low-molecular-weight heparin.

One hundred ninety-four patients undergoing elective general abdominal surgery were randomized in a single-blind study to receive one daily subcutaneous injection of a low-molecular-weight heparin, dalteparin sodium (2500 IU, n = 97) or nadroparin calcium (3075 IU, n = 97), two regimens that are approved in Europe to prevent deep venous thrombosis. On the eight postoperative day, bilateral ascending leg phlebography (n = 185) showed the presence of deep venous thrombosis in 45 cases (24.3%; 95% confidence interval, 18% to 31%), with a significantly higher rate (on intention-to-treat) among the patients who received the lower dosage (30 vs 15 deep venous thromboses). We conclude that the two regimens of low-molecular-weight heparin that were used in this study failed to prevent postoperative phlebographically proved deep venous thrombosis in one of four patients.

Abdomen↗
PubMed1993

Superparamagnetic iron oxide particles and positive enhancement for myocardial perfusion studies assessed by subsecond T1-weighted MRI.

Superparamagnetic iron oxide particles (SPIOs) are usually referred to as T2 MR contrast agents, reducing signal intensity (SI) on T2-weighted MR images (negative enhancement). This study reports the original use of SPIOs as T1-enhancing contrast agents, primarily assessed in vitro, and then applied to an in vivo investigation of a myocardial perfusion defect. Using a strongly T1-weighted subsecond MR sequence with SPIOs intravenous (IV) bolus injection, MR imaging of myocardial vascularization after reperfusion was performed, on a dog model of coronary occlusion followed by reperfusion. Immediately after the intravenous bolus injection of 20 mumol/kg of SPIOs, a positive signal intensity enhancement was observed respectively, in the right and left ventricular cavity and in the nonischemic left myocardium. Moreover, compared to normal myocardium, the remaining ischemic myocardial region (anterior wall of the left ventricle) appeared as a lower and delayed SI enhancing area (cold spot). Mean peak SIE in the nonischemic myocardium (posterior wall) was significantly higher than in the ischemic myocardium (anterior wall) (110 +/- 23% vs. 74 +/- 22%, Mann-Whitney test alpha < 1%, n1 = 6, n2-n1 = 0, U > 2). In conclusion, the T1 effect of SPIOs at low dose, during their first intravascular distribution, suggests their potential use as positive markers to investigate the regional myocardial blood flow and some perfusion defects such as the "no-reflow phenomenon."

Animals↗