Current use of low-osmolality contrast agents: results of a survey

Members of the Society of Cardiovascular and Interventional Radiology and the Society of Uroradiology were surveyed to assess both current practice and determinants of use of low-osmolality contrast agents (LOCA). Of 715 questionnaires mailed, 229 were returned (32%). Many indicated that the responses referred to the practice of a group, rather than to an individual. Two thirds of the responses indicated that the choice of agent was made by the radiologist alone; one third shared the decision with administrators. Approximately 40% of respondents use written guidelines, but this percentage was higher when administrators were involved in the decision. Almost all (99%) obtained written informed consent--one third for all procedures that use contrast material and two thirds for angiographic studies only. Four percent noted the availability of LOCA in obtaining consent. Overall, LOCA were used for most angiographic procedures by 38% and for most IV studies by only 9% of respondents. All used them for at least some angiographic studies, and all but 2% used them for some IV studies. The major indications for use in both angiographic and IV studies were a prior major (but not minor) reaction and renal dysfunction. Anticipated patient discomfort also was important for intraarterial use. LOCA were used most often for peripheral and pulmonary arteriography. When LOCA were used, nonionic agents were preferred to low-osmolality ionic dimeric contrast agents for coronary angiography and venography, but this preference was essentially reversed for peripheral arteriography. This survey suggests that IV use of LOCA is much less frequent than intraarterial use and that use is individualized to certain risk factors and certain examinations. Guidelines for use are often in place, but this is clearly not universal. The importance of informed consent for use of contrast agents and of the appropriate role for LOCA remains unsettled.     

Observations on the ultrastructure and function of the so-called “microfold” or “membraneous” cells (M cells) by means of peroxidase as a tracer

Summary 79 NMRI mice and Wistar rats were used for ultrastructural investigations of the sequential uptake of horseradish peroxidase (HRP) by M cells. In addition the ultrastructure of the so-called tuft-cells was reported.HRP, a foreign protein antigen, was applied either by injection (Owen 1977), or by stomach tube. After variable exposure times (5 min to 3 h) segments of the distal small intestine, containing Peyer's patches, mesenteric lymph nodes and liver tissue were removed. After fixation, they were reacted with H₂O₂-3,3-diaminobenzidine tetrachloride and were examined by light and electron microscopy for HRP reaction products. The uptake of HRP mainly occurs through the M cells in the dome epithelium of Peyer's patches with a continual transport of the antigenic material into lymphoid cells, macrophages, and dendritic reticulum cells. In the 3 h specimens a few single HRP-positive lymphoid cells can be observed within the efferent lymphatics of Peyer's patches. In addition, a continual uptake of HRP by necrobiotic enterocytes was observed. It has also been shown that after 3 h HRP is located inside the Kupffer cells of the liver. These findings also support the presumption that antigenic material can be transmitted via the portal circulation. However, definite, quantitatively and permanently recorded uptake of HRP by brush border cells was not be observed.To exclude a toxic effect of the applied HRP on the enterocytic epithelium additional resorptive-physiological investigations were performed using the in vivo-perfusion-recirculation method and in vitro-accumulation of L-phenylalanine.This study was supported by a grant from Deutsche Forschungsgemeinschaft (Ot 53/4-6)     

Bronchial artery embolization to control hemoptysis: A review

Bronchial artery embolization has become an established technique in the management of massive or recurrent hemoptysis. The clinical background, methods, and results of this procedure are discussed, as are the potential complications and their prevention.     

Clinical significance of PlA polymorphism of platelet GP IIb/IIIa receptors during long-term VAD support

BACKGROUND: Although bleeding and thromboembolism remain major complications after implantation of ventricular assist devices (VADs), no standard anticoagulation protocols are available. Genetic polymorphism of platelet glycoprotein IIb/IIIa may contribute to the development of complications. The present study demonstrates a relationship between the PlA genotype and postoperative complications in patients implanted with pulsatile and axial flow VADs. METHODS: The PlA genotype was determined in 41 consecutive patients treated with a VAD who received anticoagulation with phenprocoumon and aspirin. Pulsatile Novacor (Novacor Corp, Oakland, CA) and Berlin Heart VADs (Berlin Heart, Berlin, Germany) were implanted in 28 patients and the axial flow MicroMed DeBakey VAD (MicroMed Technology, Inc, Houston, TX) in 13. The relationship between the PlA genotype, the anticoagulation regime, and bleeding and thromboembolic events was analyzed. RESULTS: There were no differences between patients with the A1A1 and A1A2 genotype regarding demographic characteristics, weight, or infection episodes. The international normalized ratio (INR), platelet activation tests, and doses of aspirin and dipyridamol before events were similar in both groups. Patients with the A1A1 genotype developed more bleeding complications (39% vs 0%, p = 0.021), while patients with the A1A2 genotype showed a tendency toward more thromboembolic events (13% vs 30%, p = 0.33). With regard to different types of VAD, patients with the axial flow DeBakey VAD and the A1A1 genotype developed significantly more bleeding complications (70% vs 0%, p = 0.033). CONCLUSIONS: In patients with a long-term VAD determination of PlA polymorphism and subsequent adjustment of the anticoagulation regime may lead to a reduction of bleeding and thromboembolic complications.     

Thrombolysis of occluded femoropopliteal grafts

In a series of 44 occluded femoropopliteal grafts, streptokinase was used for thrombolytic therapy in 22 cases and urokinase in 22 cases. In most cases, thrombolytic agents were administered via an indwelling arterial catheter directly into the proximal thrombus. The catheter tip was advanced as thrombolysis occurred. Compared with streptokinase infusions, urokinase bolus injection followed by infusion had better results (77% vs 41%) and fewer complications (23% vs 50%). During thrombolytic infusion, concomitant heparin infusion was usually used to reduce the frequency of thrombus formation on the infusion catheter or recurrent thrombosis of the graft, once the tip of the infusion catheter was advanced distally. Follow-up in 23 of 26 successful cases showed that 11 of the grafts remained open at an average follow-up of 12 months or until the patient died. The 12 grafts that reoccluded remained open an average of 3 months. In none of the 18 failures was simple surgical thrombectomy or thrombectomy with graft revision effective in revascularizing the distal limb. The advantages of thrombolysis compared with thrombectomy are less trauma to the graft, which is especially important in vein grafts, and improved distal runoff due to lysis of infrapopliteal thrombus. Even among cases considered failures in this series, the surgical approach was often simplified because of partial thrombolysis. Thrombolysis requires a considerable amount of time, effort, and expense, but in certain patients where thrombectomy is indicated for the treatment of occluded femoropopliteal grafts this technique offers important advantages.     

Evaluation of optimized biplane pulmonary cineangiography

Biplane pulmonary cineangiograms utilizing a short cine pulse width and automatic brightness control were performed in 47 patients during normal respiration. The diagnostic quality of the arteriograms was categorized as good in 33 patients, fair in 12 patients, and poor in two patients. Of the 18 patients in whom pulmonary emboli were identified, cineangiography displayed certain diagnostic features to advantage, including motion of emboli in ten and respiratory scissoring of vessels overcoming vascular superimposition in three. Optimized pulmonary cineangiography is an acceptable alternative to serial film pulmonary angiography for the diagnosis of pulmonary embolism.     

Recent advances in contrast agents

Intravascular contrast agents are remarkably safe and inexpensive. With the recent approval of three new low-osmolality, high-cost contrast media, questions arise as to toxicity, side effects, and choice of particular agents for particular patients and examinations. This article examines the nature and the etiology of the effects of all currently available contrast agents in order to achieve an improved understanding of the relative advantages, disadvantages, and utility of each.