Biomedical subjects

Dirk W Droste

Publications and source records attributed to Dirk W Droste.

30 records · Page 2Linked to original sources

PubMed2003

Microembolus detection in four patients with Fabry's disease: further support for a primarily microangiopathic origin of early cerebrovascular symptoms.

Fabry's disease is a sex-linked recessive storage disorder leading to cerebrovascular symptoms in many cases. Whether the primary origin of cerebrovascular symptoms in these patients is due to autochthonous thrombosis of small vessels or embolic infarction from large vessels is under debate. Microembolic signals (MES) indicative of an active embolic source can be recorded by transcranial Doppler sonography. We report four patients (34, 44, 62 and 66 years old) with Fabry's disease from one kindred in whom we carried out microembolus detection recordings to disclose active embolic sources. Three of the patients had had transient focal neurological deficits. Two patients had angina pectoris and one had exercise dyspnea, but no patient had clear evidence of disease of the large coronary vessels or brain-supplying arteries. No MES were found in 1-hour recordings in any patients, supporting the hypothesis that early cerebrovascular symptoms arise from small vessel occlusion and not from embolic sources as an indicator of disease of large brain-supplying arteries or cardiac embolism.

Adult↗

PubMed2002

Mechanisms of acute cerebral infarctions in patients with middle cerebral artery stenosis: a diffusion-weighted imaging and microemboli monitoring study.

Although most therapeutic efforts and experimental stroke models focus on the concept of complete occlusion of the middle cerebral artery as a result of embolism from the carotid artery or cardiac chamber, relatively little is known about the stroke mechanism of intrinsic middle cerebral artery stenosis. Differences in stroke pathophysiology may require different strategies for prevention and treatment. We prospectively studied 30 consecutive acute ischemic stroke patients with middle cerebral artery stenosis detected by transcranial Doppler and magnetic resonance angiography. Patients underwent microembolic signal monitoring by transcranial Doppler and diffusion-weighted magnetic resonance imaging. Characteristics of acute infarct on diffusion-weighted magnetic resonance imaging were categorized according to the number (single or multiple infarcts) and the pattern of cerebral infarcts (cortical, border zone, or perforating artery territory infarcts). The data of microembolic signals and diffusion-weighted magnetic resonance imaging were assessed blindly and independently by separate observers. Diffusion-weighted magnetic resonance imaging showed that 15 patients (50%) had single acute cerebral infarcts and 15 patients had multiple acute cerebral infarcts. Among patients with multiple acute infarcts, unilateral, deep, chainlike border zone infarcts were the most common pattern (11 patients, 73%), and for single infarcts, penetrating artery infarcts were the most common (10 patients, 67%). Microembolic signals were detected in 10 patients (33%). The median number of microembolic signals per 30 minutes was 15 (range, 3-102). Microembolic signals were found in 9 patients with multiple infarcts and in 1 patient with a single infarct (p = 0.002, chi(2)). The number of microembolic signals predicted the number of acute infarcts on diffusion-weighted magnetic resonance imaging (linear regression, adjusted R(2) =0.475, p < 0.001). Common stroke mechanisms in patients with middle cerebral artery stenosis are the occlusion of a single penetrating artery to produce a small subcortical lacuna-like infarct and an artery-to-artery embolism with impaired clearance of emboli that produces multiple small cerebral infarcts, especially along the border zone region.

Acute Disease↗

PubMed2002

Microembolus detection by transcranial doppler sonography.

Microembolic signals can be detected by transcranial ultrasound as signals of high intensity and short duration. These signals represent circulating gaseous or solid particles. To optimize the differentiation from artefacts and the background signal and to facilitate the clinical use, several attempts have been made to automatize the detection of microemboli. Microemboli occur spontaneously in various clinical situations but their clinical impact and possible therapeutical implications are still under debate. This article provides a review of the actual literature concerning the current state of technical and clinical aspects of microembolus detection.

Artifacts↗

PubMed2002

Detection of microemboli in the subclavian vein of patients undergoing haemodialysis and haemodiafiltration using pulsed Doppler ultrasound.

BACKGROUND: The pathophysiology leading to pulmonary side effects during haemodialysis and haemodiafiltration is not yet fully understood. Chronic microembolization, which can be demonstrated by pulsed Doppler ultrasound, may be one cause. METHODS: The study cohort consisted of 24 long-term dialysis patients undergoing haemodialysis (n=21) and online-haemodiafiltration (n=3), respectively. The subclavian vein downstream to the venous access was investigated during different phases of the procedure using a 2-MHz pulsed ultrasound device. RESULTS: In all periods investigated (connection, dialysis, disconnection), numerous microembolic signals (MES) were found in the subclavian vein. The numbers of MES detected during haemodiafiltration (314-709 MES per 10 min) were higher than during haemodialysis (0-81 MES per 10 min). CONCLUSIONS: The composition (gaseous or solid) and origin (pump, tubing system or shunt) of the microemboli detected remains unclear. Chronic microembolization may be one cause of pulmonary complications of haemodialysis and haemodiafiltration. The detection method described in this article will help us to better understand this process and to determine what role microemboli might play in pulmonary and central nervous system disorders. It may also help to optimize the devices and techniques used.

Adult↗

PubMed2002

Circulating microemboli in 33 patients with intracranial arterial stenosis.

BACKGROUND: Intracranial arterial stenosis is a rare cause of stroke in Caucasians. Detection of clinically silent circulating microemboli by transcranial Doppler sonography is now widely investigated in patients with carotid artery disease in the hope to identify patients at increased risk for stroke. METHODS: In 33 patients with intracranial internal carotid (n = 12), middle cerebral (n = 18), posterior cerebral (n = 2), or basilar artery stenosis (n = 1), we performed a 1-hour microembolus detection downstream to the stenosis in the middle or in the posterior cerebral artery, respectively. The stenosis was assessed by transcranial Doppler and duplex ultrasound. 18 patients had been symptomatic in the dependent territory. RESULTS: Five patients with ischaemic symptoms within the last 8 days and with a peak systolic flow velocity of > or =210 cm/s in the stenosis showed microembolic signals at a rate of 3-25 events/h, despite effective anticoagulation. All these 5 patients had a lesion pattern on cranial CT or MRI scan suggesting embolic origin. All the asymptomatic patients (n = 15) and all the patients with a peak systolic intrastenostic velocity of 160 to <210 cm/s (n = 13) did not show microembolic signals at all. CONCLUSION: Microembolic signals occur in recently symptomatic patients with high-grade intracranial arterial stenosis indicated by a sonographically measured stenotic peak flow velocity of > or =210 cm/s. Therapeutic anticoagulation was not sufficient to suppress microemboli formation.

Adult↗

PubMed2002

Evaluation of progression and spread of atherothrombosis.

Symptomatic atherothrombosis in one vascular bed is usually indicative of disseminated disease. Indeed, involvement of multiple beds is common in everyday clinical practice, and these patients are at much higher risk of ischaemic events. The prevention of manifestations following atherothrombosis is therefore an important therapeutic goal in these patients. Some causative risk factors demonstrate affinities to particular arterial domains. Cigarette smoking, for example, is particularly associated with atherothrombotic involvement of the pelvic and lower limb arteries, whereas arterial hypertension is associated with the intracranial cerebral arteries. The degree, spread and progression of atherosclerosis can be assessed using various non-invasive and invasive modalities: high-resolution Doppler ultrasound, ankle-brachial index (ABI) measurement, magnetic resonance (MR), computed tomography (CT) and intra-arterial angiography. Indicators of atherothrombotic risk include increased carotid artery intima-media thickness, microembolic signals on transcranial Doppler ultrasonography and low ABI. There is a strong rationale for the inclusion of the ABI measurement as part of the routine clinical examination to assess the cardiovascular risk in patients with identified risk factors. Furthermore, detection of a low ABI should serve as a trigger for patient management with aggressive antiplatelet therapy. The generalized nature of atherothrombosis and the methods for evaluating the spread of disease are illustrated through the case history of a patient with disseminated atherothrombotic disease.

Diagnosis, Differential↗

PubMed2002

Contrast transcranial Doppler ultrasound in the detection of right-to-left shunts: comparison of Echovist-200 and Echovist-300, timing of the Valsalva maneuver, and general recommendations for the performance of the test.

BACKGROUND AND PURPOSE: Cardiac right-to-left shunts (RLS) can be identified by transesophageal echocardiography (TEE) as well as by transcranial Doppler ultrasound (TCD) using contrast agents, such as Echovist-200 or Echovist-300 in conjunction with a Valsalva maneuver (VM) as provocation procedure. Both Echovist preparations are in use. Currently, the appropriate timing of the VM is still under debate. METHODS: Sixty-four patients were investigated by both TEE and bilateral TCD of the middle cerebral arteries. The following protocol was applied in a randomized way: (1) no VM, (2) VM for 5 s starting with the beginning of Echovist-300 injection, (3) VM for 5 s starting 5 s after the beginning of Echovist-300 injection, (4) VM for 5 s starting 10 s after the beginning of Echovist-300 injection, and (5) VM for 5 s starting 5 s after the beginning of Echovist-200 injection. RESULTS: In 27 patients, an RLS was demonstrated by both TEE and contrast TCD (shunt-positive). Twenty-two patients were negative in both investigations, no patient was positive on TEE but negative on TCD, 15 patients were only positive on at least one TCD investigation but negative on TEE. Tests 3 and 5 were the most appropriate ones; test 3 was slightly superior to test 5. CONCLUSIONS: TCD using Echovist-300 or Echovist-200 is a sensitive method to identify TEE-proven cardiac RLS. To achieve the best diagnostic accuracy, the VM should be performed for a duration of 5 s starting at 5 s following the beginning of contrast injection.

Adult↗

PubMed2002

Therapy of Sneddon syndrome.

We report the case of a young woman with progressive cognitive decline and epilepsy. She showed ischemic cerebrovascular disease and proximal livedo racemosa. Antiphospholipid antibody (aPL) could not be detected and there were no microemboli on continuous transcranial Doppler ultrasonography monitoring. Histology of cerebral vessels showed intimal hyperplasia in small leptomeningeal venous vessels and micronecrosis of grey and white matter. We subsequently made the diagnosis of aPL-negative Sneddon Syndrome (SNS). Anticoagulation with warfarin could not be initiated because of a drug-resistant epilepsy with the risk of falls and subsequent bleeding; immunosuppression with steroids and azathioprine was ineffective, as was initial antiplatelet therapy with clopidogrel alone. However, when we intensified antiplatelet therapy by combining clopidogrel and ASS, a slowing of disease progression, as assessed by neuropsychological testing and magnetic resonance imaging, was noted on a follow-up after 6 months. Therapeutic options in SNS in both aPL-positive and aPL-negative patients with SNS are discussed.

Adult↗

PubMed2002

Optimizing the technique of contrast transcranial Doppler ultrasound in the detection of right-to-left shunts.

BACKGROUND AND PURPOSE: A cardiac right-to-left shunt (RLS) can be identified by transesophageal echocardiography and transcranial Doppler ultrasound (TCD) with contrast agents and a Valsalva maneuver (VM) as a provocation procedure. This article applies the modalities of these tests detailed in previous studies to a large patient cohort and compares 2 contrast agents (saline and Echovist-300). METHODS: Eighty-one patients were investigated by both transesophageal echocardiography and bilateral TCD of the middle cerebral arteries. The following protocol with injections of 10 mL agitated saline was applied in a randomized way: (1) no VM, (2) VM for 5 seconds starting 5 seconds after the beginning of contrast injection, and (3) repetition of the test with VM if the first test with VM was negative. The VM was performed for 5 seconds starting exactly 5 seconds after the beginning of saline injection. Thereafter, the same protocol was repeated with 10 mL Echovist-300 instead of saline. RESULTS: Thirty-one patients had a cardiac RLS. The Echovist-300 investigation disclosed all these 31 shunts, but saline disclosed only 29 of them. Twenty-two had an RLS only in at least 1 of the above TCD tests, some of them even with a considerable shunt volume. CONCLUSIONS: Contrast TCD performed with Echovist-300 but not with saline yields a 100% sensitivity to identify transesophageal echocardiography-proven cardiac RLSs. The TCD test should be repeated if negative the first time. This article gives detailed information for the optimization of the contrast TCD technique. Extracardiac shunts detected only during contrast TCD can have a considerable shunt volume and may allow for paradoxical embolism.

Adult↗

PubMed2002

Detection of carotid artery stenosis by in vivo duplex ultrasound: correlation with planimetric measurements of the corresponding postmortem specimens.

BACKGROUND AND PURPOSE: The correct detection and quantification of carotid artery disease are of decisive impact on patient prognosis and adequate treatment. In this study, we evaluated the ability of ultrasonography to detect and to grade carotid artery stenosis through a comparison of the in vivo ultrasound findings with the planimetric analysis of the corresponding postmortem specimens. METHODS: Shortly before their death, 59 critically ill neurological patients (mean age, 70 years) were prospectively examined by extracranial and intracranial Doppler sonography and color-coded duplex ultrasound. Carotid stenosis was classified by hemodynamic and morphological ultrasound criteria. Carotid specimens were removed in toto during autopsy. Under standardized conditions, specimens were redistended, sectioned, and histologically processed. Computerized planimetric measurements of the arteries were carried out and compared with the ultrasound findings. Correlation of the ultrasound and postmortem planimetric findings was available in 93 carotid bifurcations. RESULTS: Through both techniques, 46 carotid arteries were found to be normal. Steno-occlusive carotid lesions ranged from 8.5% to 100% lumen reduction. Overall, r=0.96 and adjusted R(2)=0.90. For the steno-occlusive carotid lesions, r=0.91. CONCLUSIONS: Extracranial and intracranial Doppler and color-coded duplex ultrasound permits reliable detection and quantification of carotid artery stenoses and occlusions even under difficult examination conditions in critically ill patients.

Adult↗

PubMed2002

Carotid artery auscultation--anachronism or useful screening procedure?

Carotid bruits are supposed to indicate the presence of high-grade common carotid or extracranial internal carotid artery stenosis in a large proportion of patients. Using a stethoscope, we prospectively auscultated 273 carotid arteries of 145 patients blinded to the results of a complete extracranial and intracranial Doppler investigation including extracranial color-coded duplex ultrasound. Fifty-four arteries showed stenosis of > or = 50%-99%, or occlusion of the extracranial internal or the common carotid artery. In 25 of these arteries, a bruit was present. In 9 out of 16 patients with extracranial stenosis from 70%-99%, a bruit was detected. In one additional patient with a middle-grade external carotid artery stenosis, a bruit was also present. In seven additional patients, a bruit was present in the absence of any carotid artery stenosis, cardiac vitium or goiter. The sensitivity of carotid auscultation for the detection of a 70%-99% stenosis of the common or extracranial internal carotid artery was 56% and specificity was 91%. The positive predictive value of a bruit found during carotid auscultation was 27%, and the negative predictive value of a normal auscultation was 97%. Carotid auscultation is a useful screening procedure in the detection of carotid stenosis or occlusion, but requires confirmation by carotid ultrasound.

Adult↗

PubMedDate not supplied

Surgical closure of combined symptomatic patent foramen ovale and atrial septum aneurysm for prevention of recurrent cerebral emboli.

BACKGROUND: Patients with patent foramen ovale (PFO) have an undefined but certainly considerable risk of repeated cerebral ischemia due to paradoxical embolism. Especially, if a cerebrovascular event has already occurred and the combination with an atrial septum aneurysm (ASA) is present this risk increases tremendously. The aim of this study was to demonstrate that surgical closure of PFO in combination with an ASA is safe and useful in preventing recurrent strokes. METHODS: Ten patients with previous cerebral ischemia, proven by CT or MRI, and PFO in combination with an ASA were prospectively scheduled for surgical closure. Patients with extracardiac sources of embolic disease were excluded from this study. However, one patient suffered from a hypercoagulability syndrome. RESULTS: All patients (mean age 35.5 +/- 19.1 years) underwent direct suture of the PFO and plication of the ASA with the aid of cardiopulmonary bypass and cardioplegic arrest (n = 3) or ventricular fibrillation (n = 7). Mean operation time was 123.1 +/- 20.2 minutes; mean bypass time was 34.5 +/- 9.9 minutes. There was no mortality or significant postoperative morbidity. Mean hospital stay was 5.1 +/- 1.5 days. During a follow-up of >4 years, no recurrent stroke or transient ischemic attack occurred and no patient received anticoagulation therapy. CONCLUSION: Our data suggest that surgical closure of PFO in combination with ASA in patients with previous stroke is safe and efficacious to prevent recurrent strokes and avoids lifelong anticoagulation.

Adolescent↗