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Biomedical subjects

G Deklunder

Publications and source records attributed to G Deklunder.

At least 19 recordsLinked to original sources
PubMed2003

Impairment of endothelial function in patients with spontaneous cervical artery dissection: evidence for a general arterial wall disease.

BACKGROUND AND PURPOSE: Cervical artery dissection (CAD) accounts for 10-20% of ischemic strokes in young adults. Although trauma and preexisting disorders of the arterial wall are the main predisposing factors, most CADs are considered 'spontaneous'. We hypothesized that CAD could originate in systemic vascular disease bound to the intima-media interface without clinical signs. If this hypothesis is true, endothelium-dependent vasodilation would be impaired in response to a physiological stimulus such as an increase in blood flow. METHODS: Flow-mediated arterial dilation was studied in 65 consecutive patients with spontaneous CAD: 26 with carotid artery dissection (ICAD), and 39 with vertebral artery dissection (VAD). CAD patients with vascular risk factors, trivial or obvious cervical trauma, or connective tissue disease were excluded. Twenty-three patients with ischemic stroke of unknown cause were included as controls. Using high-resolution ultrasonography, brachial artery diameter was measured at rest, during post-ischemic hyperemia (flow-mediated endothelium-dependent dilation), and after sublingual glyceryl trinitrate spray (endothelium-independent dilation). RESULTS: The mean +/- SD values of the flow-mediated vasodilation index were 5.7 +/- 6.2% in ICAD, 5.0 +/- 9.3% in VAD and 13.2 +/- 6.5% in controls (p < 0.0005), without any difference between ICAD and VAD. Endothelium-independent dilation mean values were 21.5 +/- 9.5% in ICAD, 25.1 +/- 12.5% in VAD, and 20.8 +/- 8.4% in controls, without a significant difference between groups (p = 0.49). CONCLUSIONS: These results give evidence of impaired endothelium-dependent vasodilation in CAD patients that is not the result of stroke, and suggest that an underlying abnormality of the arterial wall layers may predispose to CAD.

Adult↗
PubMed2003

[Value of sonographic contrast agents in the evaluation of the cerebral arteries].

Stroke is a frequent and severe disorder. Most strokes are ischemic in nature and 20% are due to atherosclerosis of the cerebral arteries. Sonographic examination plays a key role in the diagnosis and management of patients with cerebrovascular disease. However, shortcomings can be encountered in the ultrasound evaluation of cervical and intracranial arteries. Contrast agents are known to improve the signal / noise ratio and they can therefore compensate for these shortcomings in most cases. They have proved to be helpful in unfavorable examinations in daily practice. Moreover, their use increases the accuracy and the potential of the technique especially in the intra-cranial examination, increasing the role of ultrasound techniques.

Carotid Artery Diseases↗
PubMed2001

Anterior chordal transection impairs not only regional left ventricular function but also regional right ventricular function in mitral regurgitation.

BACKGROUND: Preservation of annuloventricular continuity through the chordae tendinae aims to maintain left ventricular (LV) function and thus improve postoperative prognosis. This study was designed to prospectively investigate the effect of anterior chordal transection on global and regional LV and right ventricular (RV) function in mitral regurgitation (MR). METHODS AND RESULTS: Sixty-five patients with severe MR underwent radionuclide angiography before and after either mitral valve (MV) repair (42 patients) or replacement with anterior chordal transection (23 patients). LV and RV ejection fractions (EF) were determined at rest. Both ventricles were divided into 9 regions to analyze regional EF and the effect of anteromedial translation related to surgery. After surgery there was a significant decrease in LVEF (P=0.038) and an increase in RVEF (P=0.036). However, LVEF did not change after MV repair (63.8+/-9.9% to 62.6+/-10.3%), whereas RVEF improved (40.7+/-10.1% to 44.5+/-8.1%, P=0.027). In contrast, LVEF decreased after MV replacement (61.7+/-10.1% to 57.2+/-9.9%, P=0.03), and RVEF was unchanged (40.9+/-10.9% to 41.3+/-9.1%). LVEF 4 and 5, in the area of anterior papillary muscle insertion, were impaired after MV replacement compared with MV repair (region 4, 77.6+/-16.7% versus 87.7+/-10.8%, P=0.005, and region 5, 73.9+/-19.3% versus 89.9+/-13.1%, P<0.001). Moreover, anterior chordal transection led to a significant impairment in the apicoseptal region of the RV (RVEF 4, 50.3+/-15.6% versus 59.3+/-13.8%, P=0.02). CONCLUSIONS: Anterior chordal transection during MV replacement for MR impairs not only regional LV function but also regional RV function.

Cardiac Surgical Procedures↗
PubMed2000

Echocardiographic follow-up after Ross procedure in 100 patients.

The Ross procedure could provide an ideal aortic valve replacement method in children and young adults. We evaluated midterm echocardiographic results to assess pulmonary homograft function as well as pulmonary autograft dimensions and function. In all, 105 patients (26 women and 79 men) underwent the Ross procedure; median age at implant was 29 years. All patients underwent free root replacement. Transvalvular gradients and autograft dimensions were measured at 3 levels (annulus, sinuses of Valsalva, and proximal aorta) at discharge, at 6 months, and annually thereafter. Perioperative mortality was 4.7%. The mean period for echocardiographic follow-up in 100 patients was 32.7 months (range 0.5 to 7 years), during which 4 noncardiac-related deaths occurred. Two patients underwent late reintervention. No moderate or severe regurgitation was recorded. There was 1 case of mild homograft regurgitation and 4 of mild autograft regurgitation at late follow-up. Autograft peak gradients were low and reproducible (5 +/- 2.8 mm Hg at discharge vs 5.5 +/- 3.5 mm Hg at last follow-up, p = NS). Homograft peak gradients increased significantly without severe obstruction (7.8 +/- 5.7 mm Hg at discharge vs 15.8 +/- 9.2 mm Hg at last follow-up). The diameter of the autograft annulus was stable during follow-up, whereas autograft dimensions at sinuses and proximal aorta increased significantly. One group of patients was identified with sinus diameter increases >20% (group A). The 90 remaining patients were classified into group B. The only parameter significantly different between the 2 groups was the sinus diameters measured at discharge (1.74 cm/m2 (group A) vs 1.92 cm/m2 (group B); p = 0.036). In 100 patients and with echocardiographic follow-up for up to 7 years, the Ross procedure showed excellent results. For 10% of patients, we observed a 20% dilation of sinus diameters, but in only 3 patients (3%) was this beyond the upper normal limit.

Adolescent↗
PubMed2000

Effects of myocardial contractility on microemboli production by mechanical heart valves in a bovine model.

Microemboli caused by mechanical heart valves have the potential to cause cerebrovascular events. We investigated the effects of myocardial contractility and heart rate on microemboli production in association with conventional and experimental mechanical heart valves implanted in the mitral position in a bovine model. In 10 calves, the mitral valves were replaced with mechanical valves. Doppler recordings were analyzed for high-intensity transient signals, which are ultrasound reflections from circulating microemboli. The animals were studied at rest, during pacing at 160 bpm, after dobutamine infusion, and after esmolol infusion. The incidence of high intensity transient signals was expressed as signal frequency (signals per hour) and as signal rate (signals per 100 heart cycles). With a 68% increase in the heart rate, signal frequency increased by 135%, but signal rate increased by only 41 %. With a 144% increase in myocardial contractility, signal rate increased by 264 %. With a 31 % decrease in contractility, signal rate decreased by 62 %. We conclude that microemboli production by mechanical heart valves varies with myocardial contractility and heart rate. The fact that contractility affects the incidence of high-intensity transient signals suggests that the microemboli are gaseous in nature, that their production is pressure driven, and that cavitation is a possible cause. It is likely that mechanical heart valve design is responsible for the quantity of microemboli production.

Adrenergic beta-Agonists↗
PubMed2000

[Supra-aortic arteries angioplasty and stenting: an ultrasonographic follow up].

PURPOSE: Ultrasonographic follow up of patients with supra-aortic arteries angioplasty and stenting was performed to determine the normal characteristics and to detect restenosis or thrombosis at the repair site. MATERIAL AND METHODS: Twenty-eight patients were followed. The delay between the procedure and the ultrasonographic examination was 1 to 5 years. There were 32 procedures: 7 carotid angioplasties with stenting; 32 vertebral angioplasties (2 stentings), 2 brachiocephalic artery angioplasties (1 stenting); 1 subclavian artery angioplasty. The ultrasonographic examination included morphological and bilateral flow analysis. The usual criteria were measured. Special attention has been given to the morphological aspect of the stents. RESULTS: All of the carotid stents were patent. No restenosis appeared during the follow up. A parietal thickening was observed in one patient without significant reduction of the arterial lumen. There were one vertebral and one brachiocephalic stent thrombosis. The results of the ultrasonographic examinations correlated well with magnetic resonance imaging. CONCLUSION: The ultrasonographic follow up of supra aortic arteries angioplasty and stenting is feasible. An early examination is recommended after the vascular procedure to control the efficacy of the repair and to detect and quantify the residual lesions. This phase is compulsory for an optimal long term follow up.

Adult↗
PubMed1999

[Clinical results of angioplasty of the renal arteries in renovascular arterial hypertension. A retrospective study in 113 patients].

The aim of the study was to evaluate the clinical results of percutaneous transluminal renal angioplasty in a population of 113 consecutive hypertensive patients who underwent endoluminal revascularization for angiographically significant renal artery stenosis. Retrospective analysis of the case records of 104 patients showed that systolic blood pressure (SBP) and diastolic blood pressure (DBP) decreased significantly 6 months after angioplasty (-20.9 mmHg and -8.4 mmHg respectively; p = 0.0001). This decrease was maintained until 19.8 months after the procedure. In cases with suboptimal revascularization (persistence of a residual stenosis more than 30%), only the SBP decreased significantly at 6 months (from 177 mmHg to 156.1 mmHg; p = 0.0061); when DBP decreased from 91.4 mmHg to 86.1 mmHg (NS) at 6 months, and fell to 80.9 mmHg (p = 0.026) at 19.8 months (after the performance of a second transluminal angioplasty for 41% patients of this group due to restenosis). Twenty-nine patients presented a restenosis of the renal artery 6 months after the initial procedure. In this group, only SBP decreased significantly at 6.1 months and at 18.7 months (from 171.9 mmHg to 156.1 mmHg and 146.5 mmHg respectively; p = 0.0064 and p = 0.0001). DBP decreased significantly only at 18.7 months (-12.6 mmHg; p = 0.0001), after a second renal angioplasty in 23 patients (79%). In the 60 patients without restenosis at 6 months, SBP and DBP decreased significantly at 6.1 and 18.7 months. No significant variation of creatinine levels was observed. These results confirm the utility of percutaneous transluminal renal angioplasty for the treatment of renovascular hypertension.

Angioplasty, Balloon↗
PubMed1998

Can cerebrovascular microemboli induce cognitive impairment in patients with prosthetic heart valves?

Doppler ultrasonography can be used to detect the presence of emboli in the cerebral arterial circulation. Emboli can be produced by different sources and can be of different nature: solid elements as thrombi, platelet aggregates or atheromatous material, or gaseous when they are produced during the decompression phase of diving or during extracorporeal circulation (ECC) procedures. A more recent source of emboli has been found in the mechanical prostheic heart valves (MHV). The emboli generated by MHV are likely of gaseous nature and are found in the middle cerebral artery blood flow at a variable rate, where they are detected by transcranial Doppler sonography. The mechanism of production of these microbubbles may be related to the rapid leaflet motion especially at closure when very high local pressure gradients appear, which may be able to provoke a release of the disolved blood gas. Solid element emboli constitute a major cause of cerebrovascular disease and particularly stroke. Conversely, gaseous emboli coming from ECC or MHV are considered as clinically silent. Nevertheless, cognitive alterations have been reported after ECC. As the MHV carriers are chronically submitted to embolic events, it can be assumed that cognitive impairments may occur also in these patients. A preliminary study was designed to inpatients attention and memory in patients with normally functioning MHV and microemboli, with biological prosthesis and in normal subjects. In the two groups of patients, episodic memory was significantly altered relatively to the control group. In the MHV carriers group, a significant decrease in working memory performance was observed relatively to the two other groups. These results confirm a long term effect of the microembolization occuring during ECC and point out the effect of the chronic exposition to microemboli.

Bioprosthesis↗
PubMed1998

Microemboli in cerebral circulation and alteration of cognitive abilities in patients with mechanical prosthetic heart valves.

BACKGROUND AND PURPOSE: It has been shown previously that cerebral microemboli may occur frequently in patients with a normal mechanical heart valve (MHV) without prior history of stroke. Some arguments strongly suggest that these microemboli have a gaseous origin. In other circumstances such as extracorporeal circulation or decompression in divers, it has been demonstrated that cerebral microbubbles could lead to some deterioration in cognitive functions. Therefore, we have studied attention and memory, which are among the most impaired cognitive functions as demonstrated in previous studies, in patients with an MHV. METHODS: Three groups of 12 volunteers each were composed of patients with an MHV and embolic signals in the cerebral circulation (group 1), patients with biological prostheses (group 2), and healthy subjects (group 3). Groups were carefully matched for age and verbal intellectual abilities. For each group, a transcranial Doppler examination was performed and a set of cognitive tests assessing sustained and selective attention and episodic and working memory was administered. RESULTS: The mean embolic rate was 29 per hour in patients with an MHV. No embolus was detected in the other 2 groups. Episodic memory was significantly modified in both groups 1 and 2 compared with the control group for tasks that required high-processing resources. Working memory performance was significantly decreased in MHV patients. No between-groups differences were observed for the other parameters. CONCLUSIONS: Alteration of episodic memory can be attributed to a long-term effect of the surgical procedure. Deterioration of working memory can be related to the presence of cerebral microemboli in MHV patients.

Aged↗
PubMed1997

Diagnosis of acute lower limb deep venous thrombosis with ultrasound: trends and controversies.

Acute deep venous thrombosis of the lower limb is a common and threatening condition whose clinical diagnosis is known to be unreliable. Sonography has gradually superseded venography as the primary diagnostic procedure. A review of the medical literature shows that sonography offers a high level of sensitivity and specificity in symptomatic patients but suffers from a lack of sensitivity at the calf level and in asymptomatic patients. Technologic progress, as well as increased operator experience, may improve sensitivity. Nevertheless, several critical issues remain unresolved, such as the significance of free-floating thrombi, the usefulness of calf and bilateral examination, the criteria that are essential to the diagnosis, the risk of compression sonography, and sonography's role in the direct detection of venous emboli.

Acute Disease↗
PubMed1997

Cervical artery dissections.

Cervical artery dissection (CAD) accounts for up to one fifth of ischemic strokes occurring before 45 years. Their increasing recognition is probably due to an increased clinical awareness of this condition in patients with painful ischemic events. The internal carotid artery is the most commonly affected vessel. Cerebral ischemia is the most serious consequence of a CAD. It may be due to hemodynamic factors or emboli. The enlargement of the artery may lead to a direct compression of the lower cranial nerves. CAD typically occurs in young adults with a mean age of 40 years with a male:female ratio of 1.5. After exclusion of traumatic cases, the average annual incidence rate of CAD is 2.6 per 100,000, but the reported incidence figures in the literature are likely to be an underestimation of the incidence of CAD. A spontaneous dissection is assumed when no or only minor trauma preceded the onset. However, the differentiation between spontaneous and traumatic dissections is artificial because of a continuum between both forms. The pathogenesis of dissections remains unknown in most cases. However, traumas and primary diseases of the arterial wall are the main predisposing factors. The clinical presentation of spontaneous dissections of the internal carotid artery includes cerebral ischemia, cervical or cranial pain, Horner's syndrome and cranial nerve palsy; CAD may also be silent. Brainstem ischemic deficits and occipital pain are the most common findings in vertebral artery dissections, but these features may be biased because the most benign and the most severe cases may escape detection. The favorable natural history of CAD emphasizes the need for a noninvasive approach to the detection, monitoring and follow-up. This noninvasive approach can be obtained by means of CT scan, MRI, magnetic resonance angiography and ultrasonography, although angiography remains the gold standard for the diagnosis of arterial dissections. Follow-up studies suggest a fairly good overall prognosis in adults and in children. In many centers, CAD are treated by heparin at the acute stage, although the benefit of such a potentially dangerous treatment has never been proven by a randomized trial.

Adult↗
PubMed1997

[Helical x-ray computed tomography of renal arteries. Apropos of 300 patients].

PURPOSE: To evaluate the role of helical CT angiography (CTA) in the detection of renal artery stenosis in hypertensive patients. MATERIALS AND METHODS: We studied 300 hypertensive patients (50 prospectively and 250 consecutively) with CTA and arteriography (n = 118). Helical acquisition (collimation 3 mm; pitch = 1, 20 seconds acquisition time) was performed 20-45 seconds after contrast injection (300 mgl/ml; 120 ml, 4 ml/sec). Transverse axial views and 3D reconstructions were analyzed (360 degrees interpolation algorithm, 1 mm overlapped). RESULTS: In the prospective series, CTA sensitivity was 100% for main renal artery stenoses and specificity was 98.2%; however 7/32 renal accessory arteries were not visualized. In the 300 patients studied, seventy-four stenoses were detected. There were 5 false-positive and 5 false-negative studies. Secondary hypertension was detected in 26% of patients (including 14 cases of adrenal hyperplasia). CONCLUSION: CTA is a promising technique for the detection of renal artery stenosis in hypertensive patients.

Adult↗
PubMed1996

Pulse wave velocity measurement by cross-correlation of Doppler velocity signals. Application to elderly volunteers during training.

Pulse wave velocity (PWV) measurement is widely used for the indirect assessment of arterial wall distensibility. In order to improve its measurement technique, we built a system performing the calculation of the cross-correlation function of Doppler velocity signals. In 12 normal subjects and 10 patients, the mean difference between duplicate measurements was 0.7 +/- 7.8% (NS). We tested this technique in 15 elderly volunteers before and after a three months training period. Brachial and tibial systolic blood pressure decreased respectively from 18.1 +/- 2.2 kPa to 16.7 +/- 1.9 kPa (p = 0.008) and from 21.1 +/- 3.4 kPa to 18.4 +/- 2.5 kPa (p = 0.003), while lower limb PWV decreased from 8.96 +/- 1.26 to 7.92 +/- 1.22 m.s-1 (p = 0.016). Therefore, automatic PWV measurement using the cross-correlation technique allows to demonstrate training induced changes in PWV, although concomitant changes in blood pressure must be considered in their interpretation.

Adult↗
PubMed1996

Helical CT angiography compared with arteriography in the detection of renal artery stenosis.

OBJECTIVE: The aim of the study was to improve the accuracy and detection rate for renal vascular lesions on helical CT angiography with an improved acquisition protocol and postprocessing. SUBJECTS AND METHODS: Fifty hypertensive patients (man age, 53 years old) referred because of clinical suspicion on renal artery stenosis were prospectively studied with digital renal arteriography and helical CT angiography. A 20-sec helical scan (collimation, 3 mm; pitch, 1) was obtained after injection of contrast medium. Interpretation was base on transverse sections, shaded-surface-display and maximum-intensity-projection reconstructions, and two-dimensional multiplanar reconstruction cuts obtained from shaded-surface-display reconstructions. RESULTS: Arteriography visualized 131 renal arteries (including 32 accessory arteries). Sixteen had significant (greater than 50% in diameter) stenosis. On helical CT angiography, 14 of these 16 stenoses were detected; two were missed (false-negatives), and two additional stenoses (false-positives) were reported. Sensitivity and specificity were 88% and 98%, respectively. Considering only main renal arteries, the sensitivity and the specificity of helical CT angiography were 100% and 98%, respectively. Helical CT angiography detected Conn's syndrome, which was responsible for hypertension, in two other patients. CONCLUSION: The accuracy and detection rate for renal artery stenosis on helical CT angiography compared with arteriography is improved with the described protocol.

Adult↗
PubMed1996

A prospective study of helical computed tomography angiography versus angiography for the detection of renal artery stenoses in hypertensive patients.

OBJECTIVE: To compare helical computed tomography angiography with arterial digital subtraction angiography in the diagnosis of renal artery stenoses. METHODS: Fifty hypertensives (24 men; mean age 53 years) were prospectively studied with computed tomography (Somaton Plus S, Siemens) and digital angiography (double-blind evaluation). Computed tomography was performed both in the sequential (the length of the abdomen) and in the helical (6 cm around renal arteries) modes during injection of 120 cm3 contrast medium. RESULTS: Digital angiography visualized 16 significant (< 50% on quantitative angiography) stenoses (16/131 renal arteries, including 32 accessory), in 14 (28%) patients. On helical computed tomography, 16 stenoses were detected, in 49 patients (16/122 renal arteries, seven accessory arteries were not identified because they were located out side the scan area); two patients had false-positive helical computed tomography results. The computed tomography sensitivity, specificity, positive and negative predictive values were 87.5% (14/16), 98.2% (111/114), 87.5% and 98.2%, respectively. In the sequential mode, two cases of bilateral adrenal hyperplasia, two aortic aneurysms and one renal neoplasm were detected. None of these patients had renal artery stenosis. CONCLUSIONS: Helical computed tomography is a suitable new non-invasive diagnostic modality for the detection of renal artery stenosis or adrenal pathology. With continued development and evaluation computed tomography could prove useful as a screening tool or as a replacement for digital angiography in patients with possible secondary hypertension.

Adolescent↗
PubMed1996

Transcranial high-intensity Doppler signals in patients with mechanical heart valve prostheses: their relationship with abnormal intracavitary echoes.

BACKGROUND AND AIMS OF THE STUDY: In preceding studies, we reported that abnormal Doppler signals of high intensity (HITS) were frequently found in the cerebral arteries of patients with prosthetic mechanical heart valves. These signals should be attributed either to air microbubbles, possibly due to cavitations or to solid emboli elements. On the other hand, the presence of abnormal intracardiac echoes has been reported in patients with mechanical valves. These echoes should be also attributed to air microbubbles or to formed elements. Although in vitro experiments are in favor of the first explanation, the discussion of their origin remains open. METHODS: Among patients subjected to a transesophageal echocardiography (TEE), we selected subjects with mechanical prosthetic heart valves, according to the following criteria: (i) normally functioning valves; (ii) bright echoes suggesting microbubbles, inside the prosthetic valve and/or upstream from it (left ventricular outflow tract or left atrium); (iii) no morphological lesions that could generate solid microemboli at the prosthetic level; (iv) normal carotid arteries, as investigated by color echo-Doppler. RESULTS: Twenty patients were selected: 11 men and nine women of age range 40-64 years. They were implanted with mechanical heart valves (24 Saint-Jude Medical, three Björk-Shiley and one CarboMedics) in the mitral position (10), aortic position (two), or mitral and aortic position (eight) for periods ranging from 10 days to 17 years. There was no major left ventricular dysfunction (mean end-diastolic diameter 51.8 mm; mean ejection fraction 59%). The mean diameter of the left atrium was 46.1 mm. All but three patients were in sinus rhythm; seven had presented with a transient ischemic attack or amaurosis within the six months preceding the investigation. Immediately after TEE, Doppler signals were recorded on the middle cerebral arteries (MCA) during 10 minutes on each side, and the abnormal Doppler signals were counted. Seventeen subjects (85%) exhibited HITS repetition rate from 0.2 to 5.5 per min. CONCLUSION: The percentage of patients with HITS in a non-selected group with mechanical heart valves was about 50%, as observed in previous studies. It appears that in a selected group of patients the percentage with HITS is consistently higher. Therefore, HITS and abnormal intracardiac echoes could have a common origin.

Adult↗