Andreas Valentin

Detection of patent foramen ovale by transcranial contrast Doppler ultrasound.

Abstract The results of recent studies suggest that paradoxical embolism through a right-to-left shunt may more often be the cause of stroke than was previously supposed. Especially in young patients with otherwise unexplained stroke, the prevalence of a patent foramen ovale has been significantly higher (54 and 56%) than in asymptomatic control subjects (10%). 1,2 Currently, contrast echocardiography together with a Valsalva maneuver is the only noninvasive method that reveals this defect. 3,4 Based on the accurracy of transcranial Doppler sonography in the detection of intracerebral emboli during carotid endarterectomy, 5 we investigated whether the route of paradoxical cerebral embolism through patent foramen ovale may be traced reliably by transcranial contrast Doppler sonography.

Evaluation of vasomotor reactivity by transcranial Doppler and acetazolamide test before and after extracranial-intracranial bypass in patients with internal carotid artery occlusion.

Background and Purpose The aim of this trial was to evaluate the effectiveness of extracranialintracranial bypass with respect to vasomotor reactivity in patients with internal carotid artery occlusions and absent vasomotor reactivity, comparing them with a control group treated conservatively. Methods To test vasomotor reactivity in 104 patients with unilateral occlusion of the internal carotid artery, we measured blood flow velocity in the middle cerebral artery by transcranial Doppler sonography both at rest and after injection of acetazolamide. Among the 39 patients who failed to show increased mean blood flow velocity after the acetazolamide test distal to an occluded internal carotid artery by ≥10%, 14 subjects subsequently underwent extracranial-intracranial bypass surgery (group A) and 14 age- and sex-matched subjects in whom no such procedure was done composed the control group (group B). Follow-up examinations were performed 3–6 months postoperatively and in the control group 3–6 months after initial examination. Results Baseline values of the mean blood flow velocity at rest on the affected side were reduced in both groups compared with the contralateral healthy side (group A, 46.0±15.1 cm/sec; group B, 48.1±16.7 cm/sec) and revealed only a marginal increase after acetazolamide. The contralateral side showed a normal blood flow velocity at rest and an adequate response to acetazolamide in both groups. On the follow-up examination group A demonstrated a normalized vasodilatory capacity. Blood flow velocity increased significantly after acetazolamide from 41.9±13.1 cm/sec to 53.5±16.0 cm/sec (p<0.002). In group B, the compromised vasomotor reactivity remained unchanged. Conclusions Our results demonstrate that transcranial Doppler sonography together with the acetazolamide test can identify subjects with reduced vasomotor reactivity distal to an occluded internal carotid artery, who may improve hemodynamically by an extracranial–intracranial bypass.

Embolic stroke by compression maneuver during transcranial Doppler sonography.

Background and Purpose Embolic complications during ultrasound examinations are a rare cause of neurological deficits. The present case documents the occurrence of embolism by a nonobstructive compression maneuver during transcranial Doppler examination, resulting in a minor stroke. Case Description A 63-year-old man suffered from recurrent transient ischemic attacks. Duplex sonography showed a small echogenic plaque at the right carotid bifurcation. During transcranial Doppler studies with a reverberating compression maneuver of the right common carotid artery low in the neck, multiple emboli signals were detected, and the patient developed a left-sided hemiparesis with slurred speech. Funduscopy revealed cholesterol emboli in the inferior temporal arteriole of the right eye. These findings suggested embolization as the cause of the stroke. Conclusions Compression maneuvers should not be performed in patients with recent neurological symptoms, even in the case of only small lesions in the extracranial carotid territory.

Sex-Related Differences in Acetazolamide-Induced Cerebral Vasomotor Reactivity

BACKGROUND AND PURPOSE Cerebral vasomotor reactivity can easily be assessed reliably by measuring vasodilatory response to acetazolamide by transcranial Doppler sonography. The aim of this study was to confirm the hypothesis that female sex is associated with an increased cerebrovascular flow reserve. METHODS Blood flow velocity of the middle cerebral artery was measured by transcranial Doppler sonography in 36 healthy sex- and age-matched subjects. After the initial blood flow velocities were recorded, the subjects received 14.3 mg/kg body wt acetazolamide, ie, 1 g/70 kg, intravenously. The measurements were repeatedly performed at 5-minute intervals starting 10 minutes after injection and lasting for 30 minutes. The highest measured flow velocities were used for further analysis. RESULTS In both groups mean blood flow velocity increased significantly after acetazolamide (women, from 60.2 +/- 12.5 to 89.9 +/- 14.4 cm/s, P < .006; men, from 54.5 +/- 18.8 to 75.7 +/- 24.5 cm/s, P < .02). The difference in mean blood flow velocity after acetazolamide between groups of women and men was statistically significant (P < .02). CONCLUSIONS Female subjects show an increased vasodilatory response to the acetazolamide test compared with men.

Multivariate Analysis-Based Prediction Rule for Pulmonary Embolism

The diagnosis of pulmonary embolism (PE) is still an unresolved problem. The aim of this prospective observational study was to derive and validate a prediction rule (PEscore) by which PE can be diagnosed by easily obtainable and rapidly available investigations. Included were consecutive patients with a clinical suspicion of PE admitted to a community hospital. Risk factors and clinical and instrumental investigations were registered. PE was diagnosed by angiography, scintigraphy, or autopsy. In 168 patients, PE was either diagnosed (angiography, n = 28; autopsy, n = 18) or excluded (angiography, n = 12; scintigraphy, n = 99; autopsy, n = 11). Based on the results of clinical and instrumental findings, a PEscore was derived by a multiple regression analysis, calculated as: [0.29 x proven leg vein thrombosis (0 = no, 1 = yes)] + [0.25 x ECG right heart strain (0 = no, 1 = yes)] + [0.22 x neck vein distension (0 = no, 1 = yes)] + [0.20 x dyspnoea (0 = no, 1 = yes)] + [0.13 x suspicious chest X-ray (0 = no, 1 = yes)] - [0.17 (constant)]. The PEscore was tested further in 139 subsequent cases. In these patients, the PEscore was 0.65+/-0.17 (diagnosed PE, n = 47) and 0.18+/-0.17 (excluded PE, n = 92), respectively (p = 0.0001). Depending on a given PE-score, the level of probability of PE can be assessed. Calculation of the PEscore can be helpful in clinical decisions when PE is suspected.

Effects of naftidrofuryl in patients with intermittent claudication.

In a randomized, double-blind, placebo-controlled study in patients with peripheral arterial occlusive dis ease stage IIb of Fontaines classifica tion, the efficacy of naftidrofuryl, a vasoactive substance, was investi gated. Forty patients — 31 men and 9 women with an average age of 62.98 ± 10.65 years — were admitted to the study. All had a history of claudica tion for at least six months. The du ration of the trial was eighteen weeks. After a washout period of two weeks the patients received either two times 400 mg naftidrofuryl or two identical placebo tablets daily for eight weeks. Subsequently a cross over from verum to placebo and vice versa was carried out and the alter native medication was administered for another eight weeks. Clinical results were evaluated by measuring painfree and maximal walking distance by treadmill test at a speed of 3.2 km/h and an inclina tion of 12°. Systolic ankle pressure and brachial pressure were measured by Doppler ultrasound, and ankle/ arm pressure ratio was calculated. Treadmill test, Doppler ultrasound examination, and laboratory data analysis were performed at the begin ning of every study period, every four weeks during and at the end of the study. Results. The patients in both groups showed an initial homogeneity of age, risk factors, concomitant dis eases, walking distance, and Doppler indices. After eight weeks naftidro furyl resulted in a statistically signifi cant increase in painfree (p < 0.02) and maximal walking distance (p < 0.05). The placebo-treated group showed only a slight, statistically nonsignificant increase in both pain free and maximal walking distance. After crossover the administration of naftidrofuryl produced a further in crease in painfree walking distance (p < 0.05), whereas in the group crossed over to placebo, both pain free and maximal walking distance remained unchanged. Systolic ankle blood pressure and ankle/arm pres sure ratio showed no significant al terations in both groups within the study period. The authors conclude that naftidrofuryl is an efficient va soactive drug, which significantly im proves walking distance in patients with peripheral arterial occlusive dis ease stage IIb.

Initial experience with intravascular ultrasound imaging during carotid endarterectomy.

Background and Purpose To assess the feasibility of intravascular ultrasound imaging during carotid endarterectomy. Methods Intravascular ultrasound imaging was performed during carotid endarterectomy in eight patients using an over-the-wire catheter system with a 30-MHz ultrasound probe. In vitro studies were carried out before the intraoperative application, paying special attention to visualization of the wall layers of normal carotid arteries, structures of more or less diseased vessels, and surgically placed materials such as patch, suture material, and fibrin glue. Although intravascular ultrasound failed to distinguish between intima and media in areas of normal intima, fibrotic and calcified plaques were detected clearly. Dacron patch as well as sutures were identified as highly reflective structures. Results In seven of the eight patients studied, intravascular ultrasound yielded cross-sectional images of good quality allowing identification of the vessel layers and the structures at the endarterectomy site. In all patients the three layers of the vessel wall were clearly differentiated and the transition zone between the site of endarterectomy and the genuine vessel appeared smooth without intimal flaps or residual arteriosclerotic plaques. In one patient severe eccentric thickening of the media was detected in the distal internal carotid artery. Neither damage of the vessel layers by the shunt nor thrombus formation in the operating area and the internal carotid artery were detected. Conclusions Intravascular ultrasound lends itself as a potentially valuable method of quality control during carotid endarterectomy. The method seems to enable an accurate evaluation of the endarterectomy site and the search for residual plaques.

Ischemic Stroke and Splenic Rupture in a Case of Streptococcus bovis Endocarditis

ABSTRACT A 58-year-old man with an acute stroke suffered from splenic rupture. Streptococcus bovis was found in blood cultures, and gram-negative cocci were found in the infarcted spleen. Hemorrhagic transformation of the stroke occurred. Echocardiography showed aortic endocarditis. Cardiac surgery was not performed because of concern about cerebral bleeding. The patient died due to cerebral rehemorrhage after 3 weeks.

Intravascular ultrasound imaging of Guenther vena caval filters

Abstract The percutaneous implantation of vena caval filters has gained acceptance as a means of preventing pulmonary embolism in patients with contraindications to or inefficiency of oral anticoagulants. In the past years, we predominantly used the Guenther filter. Its stainless steel wires are formed into a helical basket and anchoring struts. 1 Our experience with 62 patients showed that this device prevents pulmonary embolism effectively. However, cranial and caudal migration of the filter, perforation of the caval wall by the struts, and breakage of the struts have been reported. In 39% of cases, thromboemboli were found inside the filter by computed tomography, but computed tomographic imaging does not allow differentiation between trapped emboli and genuine thrombi. 2 Intravascular ultrasound has demonstrated reliable implementation in the diagnosis of peripheral arterial diseases. 3,4 McCowan et al 5 examined 6 different vena caval filters in vitro and in vivo, and found this method to be superior to both external ultrasound and cavography in detecting thrombi in the filter or vena cava. The present study was performed to assess the implementation of intravascular ultrasound imaging of Guenther basket filters, while paying particular attention to both the detection of trapped or genuine thromboemboli, and the diagnosis of filter perforation and breakage of struts.

Different Effects of Beta-1-Adrenergic Blocking Agents With ISA or Without ISA on Peripheral Blood Flow

Until recently beta-adrenergic blocking agents were considered contraindicated in peripheral arterial occlusive disease (PAOD). However, in recent years several studies have failed to show negative effects on peripheral blood flow. It was the aim of this study to compare the effects of celiprolol, a beta-1-adrenergic blocking agent with intrinsic sympathomimetic activity (ISA), and of metoprolol, a beta-1-adrenergic blocking agent without ISA, on peripheral blood flow of patients with and without PAOD. In an acute trial 24 patients (group I: 12 patients with PAOD stage I and II; group II: 12 patients without PAOD received a single dose of 200 mg celiprolol or 200 mg metoprolol in a double-blind crossover design. Celiprolol induced no significant changes in calf and skin blood flow at rest or during reactive hyperemia. Basal vascular resistance (BVR) and minimal vascular resistance (MVR) were not affected. Metoprolol, however, significantly reduced muscle blood flow and increased BVR in both groups. Subsequently the patients were treated in a randomized double-blind design with a daily dose of 200 mg celiprolol or metoprolol for three weeks. In long-term treatment skin and muscle blood flow at rest and during reactive hyperemia, BVR, and MVR were not affected by celiprolol. Metoprolol significantly lowered calf blood flow at rest in patients with PAOD; other parameters remained unchanged. In patients without PAOD, metoprolol caused a significant decrease of calf blood flow at rest and an increase of BVR. Calf blood flow during reactive hyperemia, as well as skin blood flow at rest and during reactive hyperemia, showed no significant changes. Our results suggest that celiprolol— owing to its ISA or other mechanisms not yet clarified—in contrast to other beta-1-adrenergic blocking agents without ISA, neither reduces muscle blood flow nor increases BVR.