Search PubMed⌕ Search

Biomedical subjects

F Mahler

Publications and source records attributed to F Mahler.

At least 37 records · Page 2Linked to original sources
PubMed2000

Stent placement in ostial and nonostial atherosclerotic renal arterial stenoses: a prospective follow-up study.

PURPOSE: To compare the results of balloon percutaneous transluminal renal angioplasty (PTRA) and stent placement in atherosclerotic ostial, proximal, and isolated truncal stenoses. MATERIALS AND METHODS: Between January 1994 and April 1998 the authors prospectively followed up 163 consecutive patients with 200 atherosclerotic renal arterial lesions after primary PTRA or primary stent placement. Duplex ultrasonography was performed 1 day and 3, 6, and 12 months later. RESULTS: The primary 12-month PTRA patency rates were 34% (21 of 33 atherosclerotic lesions) for ostial stenoses, 65% (20 of 60) for proximal stenoses, and 83% (five of 30) for truncal stenoses (chi(2) value, 15.63; P <.001). The corresponding stent patency rates were 80% (four of 21), 72% (nine of 34), and 66% (five of nine), respectively (chi(2) value, 4.11; not significant). Significant stent-related reduction in risk of restenosis was limited to the ostial stenoses (P =.002). CONCLUSION: Renal arterial stent placement considerably improves patency in ostial stenoses, but compared with the technically successful PTRA, it does not significantly improve primary patency in proximal and isolated truncal renal arterial stenoses.

Adult↗
PubMed2000

Influence of the ultrasound contrast agent Levovist on human nailfold capillary microcirculation.

Little is known about the behavior of ultrasound contrast microbubbles in human capillaries. The evaluation of circulatory effects of echo contrast media may bring valuable information for the interpretation of echo contrast phenomena in the human myocardium. In 12 healthy volunteers (aged 31 +/- 6.7 years; five women), nailfold capillaries were examined by means of TV microscopy. The authors investigated acral microcirculation at rest and after local cold application with and without saccharide-based microbubbles (10 mL Levovist 300 mg/mL IV). The mean blood flow velocity at rest was 1.18 +/- 0.18 mm/s (mean value +/-1 SD) and 1.11 +/- 0.11 mm/s (mean value +/- 1 SD) after the injection of Levovist (ns). One minute after local cold exposure a decrease of the blood flow velocity by 61% before and by 75% after intravenous Levovist was found. In both groups the cold-induced decrease of blood flow velocity was statistically significant (p<0.01), whereas there was no significant difference in flow reaction between the two groups. No wall adhesion of blood cells or extravasation of contrast into the surrounding tissue was detected. After intravenous injection of a regular dose of saccharide-based microbubbles Levovist, no change of blood cell flow velocity and no wall adhesion or extravasation could be found at rest and after cold application in human nailfold capillaries. Since microcirculatory flow characteristics in the finger nailfold capillaries are not influenced by Levovist, it might be assumed also that myocardial blood flow behavior remains unchanged, so that this contrast agent may be used as a flow tracer for cardiac investigation.

Adult↗
PubMed1999

Stenting of the peripheral, renal and supraaortic arteries and the aorta.

In spite of the limited experience with the newer types of stents (covered stents, stent grafts) and the resultant reservations, this development is one of the most fascinating features of the last decade and opens new perspectives for vascular medicine and endovascular surgery in the near future. At present stents in the aortoiliac region, including the origin of renal arteries, appear to fulfil their promise. In the femoropopliteal and crural region there are still unresolved problems (relapse rate around 50%), and stents should be implanted only in salvage situations. However, primary application of stents cannot be recommended even in the unproblematic regions, due to the possibility of stent-induced intimal hyperplasia and the high cost of the devices. In other more controversial regions such as the carotid arteries, the application is still experimental and should be performed under controlled study circumstances.

Aged↗
PubMed1999

A prospective, randomized evaluation of nonsurgical closure of femoral pseudoaneurysm by compression device with or without ultrasound guidance.

Femoral artery pseudoaneurysm (PA) is a significant complication following diagnostic or therapeutic catheterization. The treatment of choice for femoral artery PA is freehand ultrasound-guided compression repair (UGCR). An alternative method is compression by mechanical devices. The study evaluated the mechanical compression device (FemoStop) with (G1) or without (G2) ultrasound guidance for initial placement in a randomized fashion. Thirty-eight patients (20 women, 18 men) age 40 to 85 (mean 54) years with clinical signs of PA underwent diagnostic color Doppler ultrasound. Randomization yielded 19 patients each for G1 and G2. PA occurred after 12 diagnostic cardiac catheterizations, 18 coronary stent implantations or balloon angioplasties, 2 electrophysiology procedures, and 6 peripheral percutaneous transluminal angioplasties. The G1 protocol was successful in 15 of 19 patients (79%), with a mean compression time of 28 min. The three other patients were treated successfully with UGCR. Only one patient needed vascular surgery. The G2 protocol was successful in 14 of 19 patients (74%) with a mean compression time of 33 min. The failed patients were treated successfully: three with UGCR and two with the same mechanical compression device now positioned under ultrasound control. Compression therapy with the compression device (FemoStop) for iatrogenic femoral pseudoaneurysm does not require ultrasound guidance for positioning. Cathet. Cardiovasc. Intervent. 47:304-309, 1999.

Aged↗
PubMed1999

PTA of the subclavian and innominate arteries: long-term results.

BACKGROUND: To investigate the long-term clinical and duplex sonographic results of percutaneous transluminal angioplasty (PTA) of the subclavian and innominate arteries, and the potential of a new double balloon technique to avoid cerebrovascular thromboembolism. PATIENTS AND METHODS: Forty-three PTAs were performed on 38 subclavian, four innominate arteries and one subclavian-subclavian bypass in 37 patients. In three instances a protective double balloon technique was used. Indication for the intervention was: subclavian steal syndrome (n = 14 [38%]), upper extremity arterial insufficiency (n = 26 [70%]), peripheral thromboembolism (n = 8 [22%]) and PRIND/stroke (n = 3 [8%]). Analysis of long-term follow-up (median 15, range 2 to 100 months) was possible of 28 patients including duplex sonographic assessment in 23 patients. The cumulative patency rate was calculated by means of life-table analysis. RESULTS: Technical success was achieved in 36 endovascular procedures (84%). Minor peripheral catheter complications occurred in three interventions (7%), cerebrovascular thromboembolism in four (9%). No cerebrovascular complications were seen using the double balloon technique. On final check-up 4 patients (14%) suffered from subclavian steal syndrome, 3 (11%) from mild upper extremity arterial insufficiency and one (4%) from rest pain. Duplex sonography showed no stenosis in 12 of 23 patients (52%) and a stenosis of less than 50% in 8 (35%). The life-table analysis showed a secondary cumulative patency rate of 72% after 100 months with all restenoses occurring within 24 months. CONCLUSIONS: PTA of the subclavian and innominate arteries appears to be a useful alternative to surgery with a low complication rate. The long-term patency rate of 72% is comparable to results of other series. In high risk situations cerebrovascular complications may be reduced using the new double balloon technique.

Adult↗
PubMed1999

New system for image analysis in nailfold capillaroscopy.

For quantitative evaluation of human TV nailfold capillary microscopy a new semi-automated image-analyzing system called "CapiShape" is presented. Skeletons and boundaries of capillaries are obtained by a special image processing algorithm to describe the shape of capillaries. In addition to conventional parameters such as diameters and loop widths for the size of single capillaries, new non-size parameters related to surface area and the skeletons are calculated. To describe capillary distribution in a nailfold, the ratio of distance between capillaries to its projection in the X axis, and area percentage are indicated. With different operators and different orientations of the camera, the measured differences in diameters and loop widths are smaller than 1.5 microm, and in area percentage smaller than 1.0%. As practical examples, applications of CapiShape to patients with scleroderma showed marked, significant differences in capillary size between patients and controls, patients with diabetes differed significantly in non-size parameters from controls. CapiShape is specially designed for clinical applications, and besides the usual measures new parameters for describing nailfold images may be developed. CapiShape is safe and easy to use for diagnosis, routine examination, and quantitative follow-up studies.

Adult↗
PubMed1998

Pseudoaneurysm of femoral artery after catheterisation: treatment by a mechanical compression device guided by colour Doppler ultrasound.

BACKGROUND: Femoral artery pseudoaneurysm is a significant complication in patients undergoing diagnostic or therapeutic catheterisation. First choice treatment for pseudoaneurysm is freehand ultrasound guided compression repair, which is time consuming and uncomfortable for the patient and operator. AIM: To explore a mechanical compression device (FemoStop) as an alternative treatment for iatrogenic femoral artery pseudoaneurysm. METHODS: Fourteen patients with pseudoaneurysm were considered for treatment with FemoStop after a brief freehand ultrasound guided compression repair to confirm the compressibility of the lesion. The FemoStop compression was applied for 20 minutes. The result was controlled with colour Doppler ultrasound, and a second cycle of 20 minutes followed if necessary. RESULTS: FemoStop compression was successful in 13 of the 14 patients. The mean compression time was 33 minutes (range, 20-60). The mean number of compression periods was 1.6 (range 1-3). FemoStop compression was successful in all 11 patients not taking anticoagulants and in two of three patients receiving anticoagulants. The mean compression time in patients given oral or intravenous anticoagulants was longer (50 v 27 minutes). Colour Doppler ultrasound 12 hours after the procedure indicated no recurrence of pseudoaneurysm in the 13 patients with initial success. CONCLUSIONS: FemoStop compression for iatrogenic pseudoaneurysm is feasible, and as safe and effective as freehand ultrasound guided compression repair. It is more comfortable for the patient and operator, and probably more economical than freehand compression.

Adult↗
PubMed1998

A New Approach to Plaque Removal: The Redha-Cut Device.

PURPOSE: To prospectively determine the safety, feasibility and efficacy of a new atherectomy device. Methods. Seventy patients with 93 symptomatic femoro-popliteal lesions underwent percutaneous atherectomy with Redha-cut, a metallic, flexible catheter. The device works on pull-back with two umbrella-like blades and enables cutting, retaining and removing of material. Quantitative analysis of the angiograms was performed. RESULTS: Obtaining of atherectomized samples was successful in all cases. The mean atherectomy time was 5 +/- 2 minutes. The stenoses were reduced from 74 +/- 2.3% before to 26 +/- 2% after atherectomy (p < 0.001). Subsequent PTA, which was performed to optimize the results, further decreased the degree of stenosis to 17% (p > 0.5). No perforations, acute closure or early re-thrombosis occurred. Cumulative patency rates according to the findings of non-invasiveive examinations were 83% at 6 months and 66% at 12 months. Conclusions. The Redha-cut device is a simple, safe and efficacious tool for biopsy sampling and atherectomy. Further studies randomizing patients either to balloon or atherectomy are planned to compare this technique with others in regard to long-term patency.

Journal Article↗
PubMed1998

Power-based colour coded duplex sonography for evaluation of calf veins.

BACKGROUND: Power-based colour coded duplex sonography (PD) has been described to display lower flow velocities compared to frequency-based colour coded duplex sonography (CD). This study was undertaken to study the clinical usefulness of PD in the evaluation of calf veins in suspected deep vein thrombosis. METHODS EXPERIMENTAL DESIGN: A prospective, comparative study. SETTING: University hospital, Switzerland. PATIENTS AND MEASURES: CD of the complete deep venous system and complementary PD of paired calf veins were performed in 50 consecutive patients with clinically suspected DVT. All except three patients, with failed vein puncture at the dorsum of the foot, had a venography used as reference test for confirmatory diagnosis of DVT. RESULTS: Complete identification of calf veins increased from 80.5% using CD to 97.9% using complementary PD (p=0.007). Overall accuracy to detect an acute calf DVT was 96% (95% Ci, 85-99%) and 95% (95% CI, 83-99%), respectively. Accuracy was 95% (95% CI, 83-99%) using CD vs 94% (95% CI, 82-98%) using PD in posterior tibial, 87% (95% CI, 74-95%) vs 85% (95% CI, 71-94%) in anterior tibial, and 95% (95% CI, 83-99%) vs 96% (95% CI, 85-99%) in peroneal veins. Chronic post-thrombotic changes (10.6%) were more reliably recognized using CD (accuracy 83% [95% CI, 72-94%]) compared to PD (accuracy 66% [95% CI, 59-85%]) due to tissue motion artifacts and inability to discriminate the direction of blood flow. CONCLUSIONS: PD used complementary with CD is capable of significantly improving identification of paired calf veins without loss of diagnostic accuracy in the diagnosis of acute DVT.

Blood Flow Velocity↗
PubMed1998

Discrepancy of clinical and angiographic results in the follow-up of percutaneous transluminal renal angioplasty (PTRA).

BACKGROUND: To investigate the value of recurrent hypertension as indicator for renal artery patency after PTRA clinical and angiographic follow-up results were analysed. PATIENTS AND METHODS: results of 66 follow-up angiographies and blood pressure measurements were available in 55 patients after technically and clinically successful PTRA. Out of 43 patients with atherosclerosis, in 33 was recurrent hypertension present, and in ten patients none. Of 12 angiographies in patients with fibromuscular dysplasia nine were done because of recurrent hypertension. RESULTS: In atherosclerosis, 21 (64%) out of 33 patients with recurrent hypertension showed a re-stenosis by > 70%, and 12 (36%) none. Out of the ten follow-up angiographies performed in patients with no recurrence, two showed an unexpected stenosis. In fibromuscular dysplasia, stenoses were present in seven cases (77%). Four of them were at the site of PTRA (44%), while three were at a new site (33%). The follow-up angiographies in three patients with no recurrence showed patent arteries. Out of 11 further angiographies carried out because of hypertension after repeated PTRA, only three revealed re-stenosis. CONCLUSIONS: In only about 35% of all patients with recurrent hypertension re-stenosis was shown in angiography but in 15% of asymptomatic patients. Recurrence of hypertension after PTRA and renal artery stenosis is not well correlated. Thus, follow-up should be performed not only clinically but also by direct examination of renal artery patency such as by ultrasound.

Adult↗
PubMed1997

Unusual pseudoaneurysms after catheterization: successful treatment by ultrasound-guided compression.

Postcatheterization pseudoaneurysms occur mostly in the femoral artery. Two patients (both women, aged 67 and 59 years) undergoing percutaneous transluminal angioplasty (PTA) at our institution presented pseudoaneurysms in unusual locations, one in the brachial and one in the popliteal artery. Because of good experiences with ultrasound-guided compression repair (UGCR) in the femoral artery, we also successfully performed this noninvasive treatment on the two patients. Follow-up at 28 and 12 months, respectively, after the procedure, showed no instances of recurrence. As with the excellent results of UGCR in the femoral artery, we believe that this new modality is also the treatment of choice in iatrogenic pseudoaneurysms of the arm and popliteal arteries.

Aged↗
PubMed1997

Discriminative microcirculatory screening of patients with refractory limb ischaemia for dorsal column stimulation.

OBJECTIVES: (1) To determine the proportion of patients with critical limb ischaemia refractory to invasive treatment that can be successfully treated by dorsal column stimulation (DCS), and (2) to identify potential responders to DCS by a simple test that is sufficiently predictive to limit the need for a prolonged trial stimulation period. PATIENTS AND METHODS: Twenty patients with chronic limb-threatening ischaemia were assessed by a battery of macro- and microcirculatory tests and a DCS trial of 1 week. Favourable response during the trial determined selection for long-term stimulation. RESULTS: During a mean observation period of 14 months, limb salvage rate (LSR) was 63% overall and 83% among patients selected after a favourable trial. Of the tests performed preoperatively, digital subtraction angiography, Doppler assessment, oscillometry, capillaroscopy, foot temperature, and transcutaneous partial pressure of oxygen (tcpO2) in the supine or sitting position did not adequately predict DCS response. The supine-sitting tcpO2 gradient (delta tcpO2) was a good predictor of DCS outcome, with an 88% LSR when delta tcpO2 > 15 Torr, dropping to 12% when delta tcpO2 < or = 15 Torr. CONCLUSIONS: DCS is a rewarding therapeutic option in selected patients with critical limb ischaemia. delta tcpO2 appears to reliably predict response to DCS and may obviate trial stimulation in most cases.

Adult↗
PubMed1997

Patency of percutaneous transluminal renal angioplasty: a prospective sonographic study.

Evaluation of percutaneous transluminal renal angioplasty (PTRA) is today based primarily on clinical criteria rather than direct investigation of luminal width. In this study, we examined renal blood flow by color-coded duplex sonography (CCD) in order to correlate blood pressure as well as renal function with the true renovascular patency. Fifty consecutive patients suspected of suffering from renovascular disease and treated by PTRA were included for a prospective sonographic study. In all PTRA was performed on 63 renal arteries. Thirty-seven patients were diagnosed to have atherosclerosis and 13 patients to have fibromuscular dysplasia (FMD). Examinations were performed using CCD before PTRA, and one day, three months, six months and 12 months after PTRA. If CCD showed a restenosis > or = 60%, CCD was non-conclusive or hypertension deteriorated, angiography and, if necessary, catheter re-intervention were performed. The primary patency rate after 12 months was 73%, and could be improved to 94% overall when treated restenosis (N = 22) were included. Restenosis was more frequent in patients with mild residual stenosis identified by CCD one day after PTRA (P = 0.002). There was neither a significant difference in the restenosis rate in patients with atherosclerosis versus FMD, nor in patients with ostial versus non-ostial lesions. Hypertension was improved or cured in 70% of patients with atherosclerosis, and in 85% of those with FMD. Nevertheless, hypertension deteriorated in 12% of the patients without restenosis, and no deterioration was present in 14% of the patients with restenosis. A decrease in serum creatinine levels by more than 15% was observed in 12 of 22 patients with impaired renal function and patent renal artery during follow-up. These results suggest that optimal therapeutic efficiency can be obtained using PTRA followed by systematic CCD.

Adult↗