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Biomedical subjects

M Zwaan

Publications and source records attributed to M Zwaan.

52 records · Page 3Linked to original sources
PubMed1990

[CT diagnosis of the elbow joint].

The normal anatomy of the elbow joint is described. Diverse pathologic joint alterations, e.g. fractures and dislocations, osteochondritis, inflammatory changes, and ulnar nerve lesion are demonstrated. Particular attention is paid to three-dimensional (3D-) reconstruction of demonstrable pathologic findings.

Arthritis↗
PubMed1989

[MR tomography of the elbow joint].

MR examinations of the elbow joint of three healthy subjects and a comparison with corresponding sections of anatomical preparations show that MR tomography enables not only an excellent differentiation of muscles, tendons and of the articular capsule, but will also visualise vessels and nerve tracts. MR tomography proved superior to the conventional methods in demonstration of separate fragments and inflammatory changes in the bone on examining 11 pathological elbow joints: congenital malformation, osteochondritis dissecans, ostitis, ulnar and radial nerve lesions, completely healed radius fracture and epicondylitis of the radial and ulnar humerus. Epicondylitis could not be demonstrated by MR. Magnetic resonance tomography seems to be the only method that enables direct visualisation of the nerve paths at the elbow joint.

Elbow Joint↗
PubMed1989

[Comparison of 2 positive and 1 negative oral contrast media for abdominal CT diagnosis].

In a prospective randomised study three groups of 30 patients each were subjected to CT of the entire abdomen. The oral intestinal contrast media used were iodine solution (2%), barium suspension (1.5%) and paraffin emulsion (25%). The results were evaluated according to imaging, artifacts, ability to assess the intestinal wall, taste and side effects. All three contrast media are suitable for marking the gastrointestinal tract; paraffin shows advantages in the upper part of the tract and is the only medium that enables assessment of the wall, while causing the lowest rate of artifacts. Barium has a high acceptance and the best tolerance of all contrast agents.

Barium Sulfate↗
PubMedDate not supplied

MR-guided placement of a temporary vena cava filter: technique and feasibility.

The purpose of this paper was to investigate the feasibility of MR-guided insertion of a temporary vena cava filter on an open low-field imager. In vivo procedures were performed on four anesthetized pigs using a common nonferromagnetic temporary vena cava filter and a special prototype guidewire developed for vascular interventions guided by low-field MRI. Breath-hold spoiled gradient-echo sequences (fast low-angle shot [FLASH]) with flow compensation were used for position monitoring of the passively visualized intravascular devices. Using the described technique and equipment, all steps of the procedure were feasible in the MR unit. Practicability of the procedure seems to be sufficient for clinical purposes but was inferior compared to the conventional technique of filter placement.

Animals↗
PubMedDate not supplied

Central venous access ports placed by interventional radiologists: experience with 125 consecutive patients.

PURPOSE: To assess safety and function of central venous port systems implanted percutaneously in the interventional radiology suite. METHODS: One hundred and twenty-five consecutive ports in 123 patients were evaluated retrospectively. One hundred and twenty ports were implanted via the subclavian vein. RESULTS: Technical success was 100%. Fourteen patients (11.2%) experienced immediate procedural complications, all minor (pneumothorax 1.6%). During follow-up (4-343 days, mean service period 97.8 days), nine complications occurred, six of which were major. These were three port infections which led to hospitalization and port removal, one chamber penetration through the skin, and two port occlusions. Port removal as a result of complications was performed in six patients. Altogether, 20 complications occurred within a total of 11,056 days of service, which means 1.8 events per 1000 days of service. CONCLUSION: Percutaneous implantation of central venous port systems is safe and easy to perform. Complication rates of this study compare favorably with those of other radiological and surgical series.

Administration, Cutaneous↗
PubMedDate not supplied

Temporary vena cava filters and ultrahigh streptokinase thrombolysis therapy: a clinical study.

PURPOSE: To assess the efficacy of temporary vena cava filters in patients undergoing ultrahigh-dose streptokinase thrombolysis for iliocaval thrombosis and to determine therapy success and filter and therapy complications. METHODS: Forty-five patients were studied regarding extension and characteristics of thrombosis, duration, success, and complications of thrombolysis therapy, filter type, access route, pulmonary embolisms, and filter complications. RESULTS: Complete recanalization was achieved in 57% of cases. Filters were inserted predominantly via a transbrachial route. One fatal pulmonary embolism (2%) occurred 1 day after starting thrombolysis. No other pulmonary embolism was noted. Other complications were induced by thrombolysis alone (n = 12), thrombolysis and filter (n = 9), and filter alone (n = 11). CONCLUSION: Fatal pulmonary embolisms as a complication of ultrahigh-dose treatment of pelvic or caval thrombosis can not safely be prevented by the temporary vena cava filters currently available. Filter design needs to be improved.

Adolescent↗
PubMedDate not supplied

In vitro studies of temporary vena cava filters.

PURPOSE: To evaluate the clot trapping capacity of different temporary vena cava filters in a vena cava model. METHODS: A vena cava flow model was built using PVC tubing, a hemodialysis membrane and a pulsatile pump. Blood was imitated by a Dextran 40 solution. Five different temporary vena cava filters and two prototypes were tested using human thrombi. The mechanism of clot capture was observed. RESULTS: Decreasing rank order according to decreasing percentage of clots captured for the 21-mm diameter vena cava model was Cook (C) > Angiocor (A) > Cordis (CD) > Antheor (TF-6) > DIL for thrombi with a diameter of 3 mm and A > C > CD > TF-6 > DIL for 5-mm thrombi. In a cava with diameter of 28 mm, decreasing rank order was C > CD = A > TF-6 > DIL and C > CD = A > DIL > TF-6 for 3- and 5-mm thrombi, respectively. Two new prototypes, the TF-8 and TF-10 filters, achieved better results than the TF-6 filter and were in most conditions comparable to the A and CD filters. In most cases, thrombi were trapped between filter and cava wall. CONCLUSION: The vena cava flow model demonstrates significant differences in rates of clot capture (range 22%-98%) depending on cava diameter, thrombus size, and filter type.

Equipment Design↗
PubMedDate not supplied

Initial clinical experience with a new pulsed dye laser device in angioplasty of limb ischemia and shunt fistula obstructions.

Selective plaque ablation with laser radiation at 405-530 nm in vitro has been reported. We investigated the possibilities of a new pulsed dye laser device for in vivo recanalization of arteries in ischemic lower limbs and stenoses/occlusions of arterio-venous hemodialysis shunt fistulae. A specially designed 9F or 7F multifiber catheter was used for treatment of 10 patients with lower limb artery obliterations and 11 patients with malfunctioning hemodialysis access fistulae (HAF). The recanalization technical success was 5/5 in the iliac arteries (IA), 4/5 in the superficial femoral arteries (SFA), and 11/11 in the HAF. Early re-occlusions occurred in one SFA and one IA, respectively, caused by very bad run-off. There was one clinically insignificant SFA perforation. Additional balloon angioplasty was considered necessary in 10/16 lesions. Mean ankle-arm index increased from 0.68 to 0.97. With two exceptions all HAF patients were re-integrated in the dialysis program. Pulsed dye laser angioplasty promises to be an effective and fast method for plaque ablation/debulking. The first clinical experience confirms previous in vitro results. In particular laser recanalization may become the method of choice for treatment of rigid HAF obstructions and it seems to be superior to vascular surgery or balloon angioplasty alone.

Aged↗
PubMedDate not supplied

Non-absorbable fat-dense oral contrast agent for abdominal computed tomography.

Opacification of the gastrointestinal tract for CT scanning is usually achieved by oral administration of a diluted iodine solution or barium suspension. As high-density contrast agents often cause image degrading artifacts, we investigated the value of a paraffin-methylcellulose emulsion as an oral CT scanning agent. Diseases of the intestinum were clearly outlined with paraffin emulsion, and image degrading artifacts were virtually not encountered.

Administration, Oral↗
PubMedDate not supplied

Clinical experience with temporary vena caval filters.

PURPOSE: To look at the benefits and complications of different vena caval filters inserted prophylactically. Three temporarily implantable caval filter systems were used in 67 patients. MATERIALS AND METHODS: Twelve Cook filters (six transjugular, six transfemoral), 11 Angiocor filters (one transjugular, 10 transbrachial), and 44 Antheor filters (three transjugular, four transfemoral, 37 transbrachial) were successfully implanted. In known iliac vein or caval thrombosis, the prophylactic filters were placed during thrombolytic therapy in 46 cases, surgery in 17 cases, thrombosis in pregnancy in three cases, and high-dose heparinization without lysis in one case. RESULTS: One patient had a fatal pulmonary embolism during treatment; seven thrombi were detected in the filter. Other complications were caused either by the underlying therapy alone (one fatal outcome of abdominal aorta aneurysmal surgery, two cases of cerebral hemorrhage, two cases of retroperitoneal hematomas, two cases of streptokinase fever reactions, one compartment syndrome, two cases of macrohematuria), by the combination of therapy and caval filter implantation (three cases of groin hematomas, three cases of arm hematomas), or by filter implantation alone (two cases of subclavian vein thrombosis, one catheter infection, one dislocation, one air embolism, one basket rupture). The bleeding complications were related to the aggressive thrombolytic therapy and would have occurred without filter implantation. CONCLUSION: Because temporary caval filters have no long-term complications per se, their use seems sensible as long as there are stringent indications, including the presence of iliac vein or caval thrombosis and risk of thrombus mobilization. The Antheor filter system was the most convenient system for implantation.

Adolescent↗