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C Ranke

Publications and source records attributed to C Ranke.

At least 19 recordsLinked to original sources
PubMed1999

[Angiology update].

Explore the source record for details and available documents.

Cerebrovascular Disorders↗
PubMed1999

Standardization of carotid ultrasound: a hemodynamic method to normalize for interindividual and interequipment variability.

BACKGROUND AND PURPOSE: Accurate carotid Doppler examination is an important issue in the light of large endarterectomy trials, but recommended cutoff values for detection of >70% stenosis vary widely. Standardization of diagnostic criteria should consider patient variation and instrument variability. METHODS: We prospectively analyzed various Doppler parameters in 44 patients undergoing carotid angiography to evaluate whether normalization through individual reference measurements from the common carotid artery or the distal internal carotid artery could improve accuracy. For assessment of interindividual and interequipment variability, we performed repeated measurements of 40 carotid arteries in 21 patients. Two color-coded duplex ultrasound systems were compared for machine variability estimation: Hewlett Packard SONOS 2500 and ATL Ultramark 9 HDI. RESULTS: Intrastenotic divided by distally recorded mean blood flow velocity (mean velocity ratio) showed the closest correlation with angiography: R2=0.93. Mean velocity ratio >5 was 97% sensitive and 98% specific for detection of >70% carotid stenosis. Intrastenotic blood flow velocities were significantly different between the 2 duplex systems (0.22+/-0.16 versus 0.17+/-0. 11 m/s; P<0.001), whereas mean velocity ratio values did not differ significantly. Interobserver variation expressed as 95% CI for predicted stenosis between 2 observers was 13.6% (peak systolic velocity) and 15.4% (mean velocity ratio). CONCLUSIONS: A mean velocity ratio using distal reference measurement in the internal carotid artery can normalize for interindividual and interequipment variability.

Aged↗
PubMed1998

[Pseudoaneurysm with associated arteriovenous fistula after transfemoral puncture].

BACKGROUND: Local vascular complications after transfemoral cardiac catheterization occur with an incidence of 5%. Most commonly these lesions are pseudoaneurysms, av-fistulas, arterial dissections or direct vascular injuries. Undiagnosed vascular lesions can lead to fatal consequences especially in patients with chronic heart failure by av-fistula with significant shunt volume. CASE REPORT: We report a vascular complication of combined pseudoaneurysm and av-fistula originated from the pseudoaneurysm. The lesion was diagnosed by color Doppler ultrasound. CONCLUSION: The suspicion of a vascular lesion after vascular catheterization should immediately lead to color Doppler ultrasound. Noninvasive duplexsonography will lead to early diagnosis of vascular complications and prompt further surgical or conservative intervention with reduction of long-term sequela and morbidity.

Aged↗
PubMed1997

Blood flow velocity measurements for carotid stenosis estimation: interobserver variation and interequipment variability.

BACKGROUND: Because of the wide range of recommended threshold values for carotid stenosis graduation we performed a prospective study to determine interobserver and interequipment variability of quantitative blood flow velocity measurements. PATIENTS AND METHODS: We recorded absolute blood flow velocities and velocity ratios in 21 patients with carotid artery stenosis using two colour coded duplex ultrasound systems an ATL Ultramark 9 HDI, and a Hewlett Packard SONOS 2500 system. The ATL system was used for the interobserver variation study, where each patient was examined twice on the same day. The Doppler angle was recorded together with blood flow velocities (peak systolic velocity and mean maximum velocity from the velocity-time-integral both in the stenosis jet and 4-5 cm distally in the cranial portion of the internal carotid artery off poststenotic turbulences). RESULTS: The ATL system generated significantly higher blood flow velocity values as compared with the HP system (218 +/- 156 cm/s vs. 169 +/- 114 cm/s; p < 0.001). The Mean Velocity Ratio (the ratio of intrastenotic Vmean and poststenotic Vmean) was constant with both duplex systems. The HP system yielded 10% (Cl, 7-13%) lower predicted stenosis estimates than the ATL system with Vmax as the stenosis criterion. The stenosis estimates calculated from Mean Velocity Ratio values did not differ significantly. The 95% Cl for predicted diameter reduction between two observer was 13.6% (Vmax) and 15.4% (Mean Velocity Ratio). CONCLUSION: Because of significant interequipment differences of colour coded duplex ultrasound systems we recommend calculation of the Mean Velocity Ratio to avoid interpatient and interequipment variation of absolute flow velocities. According to our interobserver variability study, a change of more than 15% diameter reduction on follow-up examinations indicates disease progression or regression.

Aged↗
PubMed1996

[Angiology update].

Explore the source record for details and available documents.

Angioplasty, Balloon↗
PubMed1995

[Angiology update].

Explore the source record for details and available documents.

Angioplasty, Balloon↗
PubMed1995

[A nomogram of duplex ultrasound quantification of peripheral arterial stenoses. Studies of the cardiovascular model and in angiography patients].

BACKGROUND AND METHODS: Blood flow velocity measurements were performed with duplex ultrasound in vitro (flow phantom) and in 62 patients who underwent angiography due to peripheral vascular disease. RESULTS: Intrastenotic peak systolic velocity (PSV) divided by proximally recorded PSV (peak velocity ratio, PVR) exhibited a strong correlation with percent diameter reduction: r2 = 0.86; N = 106 stenoses. A PVR value > or = 2.4 indicated a more than 50% stenosis with a sensitivity of 87% and a specificity of 94%. Calculation of PVR may normalize for patient variation and allow noninvasive quantification of lumen narrowing with high sensitivity and specificity. The intraobserver variability (95% CI) of stenosis quantification using PVR values was 10%. A nomogram simplifies estimation of lumen narrowing after measurement of intrastenotic and proximal PSV values. CONCLUSION: Quantification of peripheral artery stenoses can be performed easily and noninvasively with duplex ultrasound using the peak velocity ratio (PVR).

Aged↗
PubMed1994

Controlled trial of high- versus low-dose aspirin treatment after percutaneous transluminal angioplasty in patients with peripheral vascular disease.

Percutaneous transluminal angioplasty of aortoiliac and femoropopliteal atherosclerotic lesions can provide long-lasting hemodynamic improvement. High-dose aspirin is commonly prescribed as reocclusion prophylaxis, but low doses would be preferable because of fewer adverse effects. We performed a double-blind, randomized, controlled clinical trial in patients with peripheral vascular disease with lesions appropriate for angioplasty. We compared the efficacy and side effects of two doses of aspirin (50 mg vs. 900 mg daily) during a period of 12 months after angioplasty. A total of 359 patients were evaluated: 175 were randomly assigned to treatment with 900 mg aspirin daily and 184 to 50 mg aspirin daily. Thirty-nine patients developed restenosis at the angioplasty site; the cumulative percentage of event-free survival after 1 year (patency rate) was 85% in 900 mg group and 84% in 50 mg group. An equivalence test showed the two groups equivalent with respect to restenosis rates (P = 0.0003 for an equivalence region of < 10% difference. Nine patients (5%) in the 900 mg group had serious gastrointestinal side effects (peptic ulcer, 8; erosive gastritis requiring transfusion, 1) compared to two ( peptic ulcer) in the 50 mg group (P = 0.03). The results of our study show that a dose of 50 mg aspirin a day is as effective as 900 mg for the prevention of restenoses after lower limb angioplasty, and that severe gastrointestinal side effects are less frequent.

Aged↗
PubMed1993

[Dose-dependent side effects of acetylsalicylic acid therapy. Results of a prospective randomized clinical study in patients with peripheral arterial occlusive disease].

BACKGROUND AND METHODS: In 359 patients with peripheral arterial occlusive disease who had undergone percutaneous transluminal angioplasty (PTA), a randomized double-blind, controlled clinical study was done to investigate the tolerability of acetyl salicylic acid (ASA) given for reocclusion prophylaxis. A comparison was made between a conventional daily dose of 900 mg ASA and a dose of 50 mg ASA. RESULTS: Within an observation period of one year following PTA, 35 patients (20%) in the 900 mg group, and 32 patients (17%) in the 50 mg group left the trial because of side effects (p = NS). Under the higher dose, however, severe gastrointestinal side effects (ulcer, haemorrhagic gastritis requiring transfusion) were significantly more common (nine patients delta 5.1% vs two patients delta 1.1%, respectively; p = 0.03). Overall, 107 patients (30%) reported subjective side effects such as upper abdominal pain, a sensation of fullness or nausea during the course of the trial. 62 of these patients were from the 900 mg group (35%) as compared with 45 patients (24%) in the 50 mg group (p = 0.02). Self-scoring of epigastric pain on the basis of a visual analogue scale revealed a score of 1.3 (95% confidence interval 0.9 to 1.6) in the 900 mg group and 0.8 (95% confidence interval 0.6 to 1.0) in the 50 mg group. The subjective pain intensity showed a uniform time course for all three types of symptom, with a maximum after three months. CONCLUSION: Our results confirm the superior tolerability of the lower dose, in particular in elderly patients. For long-term treatment, the smallest possible effective dose should be chosen.

Aged↗
PubMed1993

Dose-dependent effect of aspirin on carotid atherosclerosis.

BACKGROUND: Antiplatelet treatment with aspirin is well established as secondary prophylaxis after a transient ischemic attack or minor ischemic stroke, but the effect of aspirin treatment on the course of carotid atherosclerosis is unknown. We investigated the effect of aspirin on the initial stages of carotid atherosclerosis. METHODS AND RESULTS: Patients were recruited from a prospective, randomized, double-blind clinical trial to compare two doses of aspirin (900 mg versus 50 mg daily) with regard to restenoses after lower limb angioplasty. Of the 383 patients admitted to the angioplasty trial, 27 patients with 104 small carotid atheroma (< 50% lumen narrowing) were examined at entry and after 1 year of aspirin treatment with the use of a high-resolution ultrasound duplex system. Disease progression and regression were defined by a change of maximal plaque area (as measured by longitudinal ultrasound sections) of more than 2 SDs of the method. The change in plaque area was significantly different for the treatment groups: Average plaque size remained unchanged after treatment with 900 mg aspirin daily but increased markedly after treatment with 50 mg aspirin daily (p = 0.011). There were significantly more lesions in the 50-mg group showing progression than in the 900-mg group (23 plaques [47%] versus 13 plaques [24%], p = 0.025). Ultrasonic disappearance of a lesion was observed only in the 900-mg group in nine cases (seven soft plaques and two ulcerative plaques, p = 0.018). The six patients on 50 mg aspirin who continued smoking during the study showed significantly more progression compared with the seven nonsmokers in the 50-mg group (17 plaques [59%] versus six plaques [30%], p = 0.038). CONCLUSIONS: The results of our study indicate that aspirin treatment slows carotid plaque growth in a dose-dependent fashion, with a dose of 900 mg daily more efficient than 50 mg daily.

Aspirin↗
PubMed1992

Duplex scanning of the peripheral arteries: correlation of the peak velocity ratio with angiographic diameter reduction.

The correlation of the peak systolic velocity (PSV) and the peak velocity ratio (PVR, calculated as intrastenotic PSV divided by proximally recorded PSV) with percent diameter reduction was studied in 62 patients with peripheral arterial occlusive disease. PSV values correlated well with angiographic diameter reduction (r = 0.81, n = 106 stenoses), but due to large variability the sensitivity and specificity in the detection of greater than 50% stenoses were only 66% and 80% (for a cutoff value of 180 cm/s). The PVR showed less interindividual variability and exhibited a strong correlation with percent diameter reduction (r = 0.93,n = 106 stenoses). A 2.4 fold increase of the peak systolic velocity values with respect to the proximal site (i.e., PVR = 2.4) or more indicated a more than 50% stenosis with a sensitivity of 87% and a specificity of 94%. Figures for PVR are provided to quantitate the degree of stenoses in the 50-99% range. Calculation of PVR may normalize for patient variation and allow noninvasive quantification of lumen narrowing with high sensitivity and specificity.

Arterial Occlusive Diseases↗