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Biomedical subjects

W Schoop

Publications and source records attributed to W Schoop.

At least 19 recordsLinked to original sources
PubMed1993

Recanalization of chronic arterial occlusions: low-speed rotational angioplasty. 5 years experience in peripheral and coronary vessels.

Chronic complete occlusions still represent the major technical limitation of percutaneous transluminal angioplasty, both in peripheral and coronary vessels. The clinical use of low-speed rotational angioplasty started in 1986 for the peripheral and in 1987 for the coronary arteries, and has already become part of the clinical routine in several centres. Up to now more than 350 patients with peripheral and 250 patients with coronary occlusions have been treated in Frankfurt; a multicentre questionnaire already contains information about 1,252 patients with peripheral vessel obstructions. In peripheral occlusions the acute success rate was more than 80% if low speed rotational angioplasty was used as the first attempt; after failure of conventional techniques still more than 60% of the vessels could be recanalized successfully. In addition to occlusions of the arteries of the lower limb, indications now may include the iliac artery and the subclavian artery. In each of the patients with chronic coronary occlusions an attempt with conventional techniques had failed before. Following a learning curve, which was also influenced by a better understanding of morphological preconditions, the acute success has now reached 70%. Both in patients with peripheral and those with coronary occlusions the technique turned out to be a safe procedure. Early angiographically documented long-term results in both indications are comparable with conventional balloon techniques. It is concluded that the use of low-speed rotational angioplasty (ROTACS) can improve the results of non-operative invasive treatment, both in peripheral and in coronary arteries.

Angioplasty↗
PubMed1993

[Effect of transient therapeutic occlusion on some hemodynamic parameters and walking distance].

The effect of a one hour lasting occlusion was studied by recording the ankle/arm pressure ratios at rest and during post-occlusive reactive hyperemia 30 min, 1 day, 3 days and 7 days after the procedure. Both parameters improved, reaching a maximum on the 7th day at which time the changes became statistically significant. Finally, a standardized walking distance test yielded a highly significant improvement when determined on the 7th day (mean increase in walking distance: 69%). Although the underlying mechanism is yet unclear, the positive therapeutic results and absence of side effects warrant further investigations to be focused on the mechanism as well as on practical implications related to the procedure itself to optimize the results.

Arterial Occlusive Diseases↗
PubMed1993

[Behavior of post-occlusion systolic blood pressure after long duration blockade. Effect of induced hypertension].

A suprasystolic blockade (300 mm Hg) was applied for 50 to 60 min to the thigh of the affected leg with a blood pressure cuff in 13 patients with occlusions of the femoral artery. Afterwards, the pre-postocclusive systolic pressure difference was clearly less in most patients than before the compression manoeuvre. This reduction of the systolic pressure gradient, which was greatest in the first hour and slowly decreased in subsequent days, is likely to be based on a dilatation of the collateral arteries. The reaction was especially pronounced in patients with isolated occlusion of the femoral artery. Since the entire collateral circulation is largely in the region of the cuff compression in these cases, the collateral dilatation might arise from the powerful and long lasting pressure. In 9 patients it was investigated whether an increase of systemic blood pressure induced by hypertension can be transduced more effectively to the postocclusive arterial system when the collateral arteries are "paralyzed". The heterogeneous results show that such an effect can evidently only be expected when the collateral circulation is restricted to the thigh. However, such conditions are probably not usual in poorly compensated stage IV following Fontaine, in which a temporary peripheral increase of blood pressure is likely to be reasonable for therapy.

Adult↗
PubMed1993

[Antibiotic concentrations after intravenous and retrograde intravenous injections].

In patients with peripheral arterial occlusive disease, it is difficult to attain an adequate antibiotic concentration in poorly perfused infected lesions. The antibiotic concentrations prevailing in the ulcer secretion with the different routes of administration were investigated in 7 patients. The patients received 1 g of cefotaxim on consecutive days: intravenously on the first day, intraarterially on the second day and by retrograde venous injection on the third day. Significantly higher concentrations in the secretion were found after retrograde venous antibiotic administration than after intravenous or intraarterial injection. Clinical experience up to now indicates that far better results of treatment can be attained if the antibiotic is administered by retrograde venous injection (in addition to the surgical measures required).

Biological Availability↗
PubMed1992

[Gingko biloba extract EGb 761 and pentoxifylline in intermittent claudication. Secondary analysis of the clinical effectiveness].

Clinical trials on the efficacy of EGb 761 and pentoxifylline are summarized in the context of their methods and results and compared with each other. All placebo-controlled, randomized and double-blind studies with the major target objective of "pain-free walking distance" were selected. The pentoxifylline studies were adopted from a survey of the existing literature in the English language, which has been brought up to date via DIMDI research. The studies on both active substances are fraught with similar difficulties as to method, and are not different as regards their quality. The increase in walking distance is highly variable, especially in the pentoxifylline studies. On average through each and all of the studies on both preparations, an increase of 45% (EGb 761) or 57% (pentoxifylline) in relation to initial values is here found. No differences in the documentation of efficacy and the clinical efficacy were discovered between the two substances, both of which are registered as effective substances in the treatment of peripheral arterial occlusion (pAO) in accordance with the Federal German Drugs Law (Arzneimittelgesetz, AMG) of 1976.

Dose-Response Relationship, Drug↗
PubMed1991

[Spontaneous course of peripheral, stenosing arteriosclerosis and the effect of catheter interventions].

Peripheral obliterating arteriosclerosis tends to progress. If it was previously a mainly unilateral disease, similar alterations on the opposite side are to be expected in the near future. This applies in particular to the most frequent incidence, occlusion of the femoral artery, which only rarely remains unilateral. Clinical symptoms of stenotic lesions are often found in the still-patent femoral artery, and the tendency to complete obliteration can be appraised from these lesions. The progression appears to be slower in patients in whom endogenous risk factors are present than in patients in whom smoking is regarded as the crucial factor. In the region of the pelvic arteries, the tendency to bilateral obliteration is considerably less. Stenoses of the iliac artery also have a less pronounced tendency to occlusion than do stenoses of the femoral artery. Manifestation of the disease in a different segment of the artery is far rarer and mostly develops proximal to the already existing obliteration. Occasional regressions of the stenoses probably result from the reduction of thrombotic deposits. Catheter interventions may affect the spontaneous course in various ways. It appears possible that the imminent complete obliteration can be delayed or prevented by stretching of the stenosis. After elimination of an isolated arterial occlusion, the collateral dilatation regresses. If a further obliteration is situated distal to the reopened section of the artery, an additional collateral dilation develops there. A reobliteration develops relatively frequently after catheter recanalization of the femoral artery and may have an unfavorable effect on the further course.

Angioplasty, Balloon↗
PubMed1990

[Concentration of cefotaxime in the exudate from ischemic ulcer after systemic and regional administration].

We evaluated the concentration of cefotaxime in the exudate from ischemic leg ulcers in 9 subjects with severe obstructive arterial disease. The administration of the drug was either systemic (1 g in 250 ml of saline given in 30 min) or regional at a vein of the foot while a tourniquet was applied at the level of the thigh during 30 min. Hygroscopic discs were used to collect samples of ulcer exudate at hourly intervals for 4 hr. Cefotaxime concentration was determined by HPL chromatography. A significantly greater concentration of antibiotic was obtained with regional as compared to systemic administration (46 +/- 16 vs 25 +/- 14, p less than 0.01) and a greater percentage of patients attained MIC 90. A stable concentration of the drug was observed during the 4 hr period indicating a decreased rate of elimination of the antibiotic from the ulcer tissue. Thus, regional administration of antibiotics affords greater concentration than systemic administration, for treatment of ischemic leg ulcers.

Adult↗
PubMed1990

[Antibiotic treatment for diabetic foot. Advantages of intravenous regional route as alternative for systemic route].

Diabetic angiopathy prevents adequate access of antibiotic agents to septic areas of the diabetic foot. We treated 22 such patients with antibiotics infused through a superficial vein associated to tourniquet occlusion of the limb (Group A). A control group of 47 patients, similar in age, sex and severity of diabetes received conventional systemic therapy (Group B). 45% of the patients exhibited occlusive arterial disease. Surgery was performed by the same team in both groups. Group A received regional anesthesia at the same time of the first antibiotic infusion. Group B received general or spinal anesthesia. Amputation was required in 5% of patients in Group A compared to 30% of patients in Group B (p < 0.02). Hospital stay was also significantly shorter in patients from Group A. No complications of this form of therapy were observed. Thus, regional antibiotic therapy may improve prognosis and facilitate management in patients with septic diabetic foot.

Adult↗
PubMed1990

[Which therapeutic measures ensure good long-term results in arterial occlusive disease?].

The lumen-opening methods reconstructive operation, angioplasty and thrombolysis achieve their best long-term results in the region of the large iliofemoral arteries. After elimination of occlusions in arteries situated more peripherally, reobliterations are more frequent and not uncommonly associated with a deterioration in the course of the disease. Of the conservative measures, long-term benefit is to be expected primarily from continuous training. Pharmacotherapy with anticoagulants or inhibitors of thrombocyte function (acetylsalicylic acid) is likely to be successful in certain patients.

Angioplasty, Balloon, Coronary↗
PubMed1990

[Long-term arterial blockade and retrograde venous perfusion in peripheral arterial occlusive diseases].

The method of longterm artificial arterial blockade in patients with peripheral arterial occlusive disease (PAOD) opens new therapeutic possibilities. However, it is yet not clear if and how the suspected dilation of collateral arteries can be therapeutically used. The retrograde venous perfusion permits the transport of active substances in high concentrations into ischemic areas. The resulting temporary local damping or even blockade of sympathetic innervation can under certain conditions achieve therapeutic effects. A longterm arterial blockade can be performed even in case of trophic lesions. This permits treatment in stage IV of PAOD. It has been proved that antibiotics reach a lesion by retrograde venous perfusion faster and better than by systemic application, especially in badly compensated cases. However, sufficient experience on the therapeutic effect and possible side effects in stage IV is still lacking.

Arterial Occlusive Diseases↗
PubMed1989

[Doppler-ophthalmomanometry in patients with obstruction of the carotid arteries].

A novel noninvasive method to determine simultaneously ophthalmic artery pressure (OAP) and flow direction based on Doppler ultrasound principles is presented: ophthalmomanometry-Doppler (OMD). Studies performed on 25 angiographically proven normal subjects with direct recording of the internal carotid artery pressure (ICP) and indirect determination of the brachial artery pressure (BAP) demonstrated that OAP values assessed by the OMD device are highly correlated with simultaneous ipsilateral intraarterial systolic ICP measurements (r = 0.95, n = 10) and with simultaneous recordings of the BAP (r = 0.88, n = 15). In 50 patients presenting angiographically occlusions and 52 patients presenting angiographically stenoses (greater than 60%) of the carotid artery the measured Doppler ophthalmic pressure index (OPI = ratio of the ophthalmic to systemic blood pressure) was lower ipsilateral to an occlusion (0.46 +/- 0.08) than ipsilateral to a stenosis (0.54 +/- 0.08; p less than 0.001) of the carotid artery. In both it was clearly diminished compared to normal values (0.68 +/- 0.04; p less than 0.001). In carotid artery occlusions, the ipsilateral OPI was 0.46 +/- 0.06 for antegrade (n = 17) and 0.46 +/- 0.09 for retrograde (n = 28) ophthalmic artery flow. In carotid artery stenoses, the ipsilateral OPI was 0.55 +/- 0.07 for antegrade (n = 41) and 0.48 +/- 0.06 for retrograde (n = 9) ophthalmic artery flow (p less than 0.01). It is concluded that in carotid occlusions presenting a longer disease history extra-intracranial collateralisation via the ophthalmic artery are as efficient as a functional circle of Willis.

Blood Pressure Determination↗
PubMed1989

Doppler ophthalmic blood pressure measurement in the hemodynamic evaluation of occlusive carotid artery disease.

In 102 patients with angiographically proven occlusive carotid artery disease of 60-100% diameter reduction, Doppler ophthalmic artery pressure and blood flow direction were recorded by the recently developed ophthalmomanometry-Doppler technique. Among these 102 patients, 50 presented with complete carotid artery occlusions and 52 with carotid artery diameter stenoses of greater than or equal to 60%. Mean +/- SD Doppler ophthalmic artery pressure was 69 +/- 15 mm Hg ipsilateral to the occlusion and 86 +/- 18 mm Hg ipsilateral to a stenosis of the carotid artery (p less than 0.001). The mean +/- SD Doppler ophthalmic pressure index (ratio of the ophthalmic artery to systemic blood pressure) was lower ipsilateral to the occlusion (0.46 +/- 0.08) than ipsilateral to a carotid artery stenosis (0.54 +/- 0.08; p less than 0.001); in both, the index was clearly diminished compared with normal values (0.68 +/- 0.04; p less than 0.001). It is concluded that the intracranial hemodynamic consequences in the patients with occlusion are on average more profound than in the patients with stenosis. In carotid artery occlusions, the mean +/- SD ipsilateral ophthalmic pressure index was 0.46 +/- 0.06 for antegrade and 0.46 +/- 0.09 for retrograde ophthalmic artery blood flow. In carotid artery stenoses, the mean +/- SD ipsilateral ophthalmic pressure index was 0.55 +/- 0.07 for antegrade and 0.48 +/- 0.06 for retrograde ophthalmic artery blood flow (p less than 0.01). These results indicate that in carotid stenoses the collateral capacity of the ophthalmic artery is insufficient compared with intracranial collaterals, while in carotid occlusions the blood flow direction in the ophthalmic artery does not predict intracranial hemodynamic compensation.

Adult↗
PubMed1989

[Rotation angioplasty--clinical experiences in 83 patients with chronic arterial vascular occlusion].

Chronic, total vascular occlusion represents the limit for use of balloon dilatation. Occlusions of the superficial femoral artery and popliteal artery of more than 10 cm in length have a low recanalization rate of 50 to 60% with conventional angioplasty. In iliac artery occlusions, in addition to a high rate of complications, the recanalization rate is only about 30 to 40%. Starting in 1984, we developed a slowly rotating (100 to 200 r.p.m.), electrically-driven, flexible catheter with a blunt tip, inside lumen and outer diameter of 2.2 mm for the purpose of recanalization (Figure 1). The theoretical basis was that such a catheter would seek the soft occluding thrombus as the path of least resistance. Since 1986, the procedure has been carried out in 56 patients with occlusion of the superficial femoral artery, 21 with occlusion of the popliteal artery and six with occlusion of the iliac artery. The duration of occlusion ranged between five and 48 months and the length of the occlusions between 5 and 35 cm (mean 12.5 cm); the patients were in Fontaine stage II and IV, the ankle arm-index ranged between 0 and 0.86 (mean 0,51). After antegrade or retrograde puncture of the common femoral artery and intra-arterial injection of 5,000 units of heparin, the rotation catheter was advanced through an 8F sheath through the occlusion by means of slow rotation (Figure 2). After contrast medium injection to document the intraluminal position of the catheter and the catheter exchange over a 0.35'' wire, the channel created was dilated.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

[Duplex ultrasound studies of the deep femoral artery].

In case of occlusion of the superficial femoral artery (SFA), the deep femoral artery (DFA) supplies the entire lower extremity. Not infrequently, the SFA occlusion is associated with stenosis of the origin of the DFA. The angiographic study of the origin of DFA is often unsatisfactory. The purpose of the present study was to develop objective criteria for the diagnosis of the DFA origin stenosis by duplex scanning. In 60 patients, we examined 75 femoral bifurcations by duplex scanning and compared them with the independently performed angiography. Group 1 (n = 20 DFA origins) consisted of 10 normal individuals. Group 2 (n = 30 DFA origins) consisted of 25 patients with angiographically proven SFA occlusion and normal DFA. Group 3 (n = 25 DFA origins) consisted of 25 patients with angiographically proven SFA occlusion and DFA orifice stenosis. We measured the maximal systolic and mean flow velocity in the orifice of the DFA at rest and during the maximal hyperemia following 3 min of ischemia of the lower leg. At rest, the maximal flow velocity in groups 1-3 was 60 +/- 15, 142 +/- 44, and 255 +/- 60 cm/s (p less than 0.01) and the mean flow velocity was 8 +/- 6, 32 +/- 9, and 96 +/- 42 cm/s (p less than 0.01). During hyperemia, the maximal and mean flow velocity for groups 1-3 was 59 +/- 15, 155 +/- 42, and 286 +/- 82 cm/s (p less than 0.01) and 8 +/- 5, 55 +/- 19, and 144 +/- 51 cm/s (p less than 0.01), respectively. An origin stenosis of the DFA is highly probable when at rest the mean and maximal velocity in the proximal DFA exceed 50 cm/s and 180 cm/s, respectively. These results show that duplex scanning is able to detect safely DFA origin stenosis. The increase in postischemic DFA flow velocity when SFA occlusion is present, helps to evaluate total flow resistance of the deep-outflow channels (run-off) thereby being useful in planning appropriate therapy.

Adult↗
PubMed1988

Results of low speed rotational angioplasty for chronic peripheral occlusions.

After experimental investigation using postmortem human arteries, 19 patients with chronic peripheral artery occlusions were treated with a new angioplasty technique between December 1986 and October 1987. In 17 patients the superficial femoral artery and in 2 patients the popliteal artery were completely occluded. The length of the occlusions ranged between 5 and 25 cm (mean 11). The duration--estimated according to patients' history--was 5 to 48 months (mean 17). In 5 patients, durations of up to 30 months had been documented by angiography. A flexible, blunt, motor-driven rotating catheter was introduced through an 8 or 9Fr sheath and rotational angioplasty was performed at low speeds (up to 200 rpm). In 11 of 14 patients in whom this new technique was used as the primary intervention, the occlusions could be successfully reopened. In 2 patients after failure of conventional techniques the rotating catheter could not bypass the preexisting dissections in the same intervention. In 2 of 3 further patients after failure of conventional techniques the occlusions could be successfully reopened in a second intervention after several weeks. In none of the 19 patients did a perforation occur. It is concluded that with the new technique chronic peripheral artery occlusions can be reopened with a high success rate and without the danger of arterial wall perforation. The method can also be used in patients in whom conventional techniques have failed.

Adult↗