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Reflux of embolic material during therapeutic transcatheter embolization is a potential complication which can result in occlusion of distal vascular beds. The conditions under which reflux was demonstrated in laboratory animals include (1) low flow states, (2) overvigorous flushing, (3) selective contrast injections, and (4) placement of embolic material too proximally. Balloon occlusion of the orifice of the vessel undergoing embolization protects against reflux and allows more homogenous embolization. Because of experience gained in the laboratory, therapeutic transcatheter embolization is now performed in patients with balloon catheter protection. Preliminary clinical experience is described.
Renal embolization was performed in 12 dogs using the Seldinger technique and microspheres 250 +/- 40 micrometer in diameter. Periodical arteriography, microangiographies and histological analysis was carried out to control the efficacy of embolization. As a result, renal arteries could be embolized wi. th microspheres, however, because of statistical distribution there were histologically anemic and normal parenchyma situated closely together. In more than 50% there was a reflux of microspheres which could only be detected by histological examination, while angiographies showed a totally normal vascular pattern. Microspheres should not be used in clinical embolization. Experimental investigation of embolization materials must almost embrace histological analysis.
Following extracorporeal circulation with a bubble oxygenator (Rygg-Kyvsgaard) silicone emboli were found in the brain-and-kidney-capillaries of all dogs evaluated. There was no obvious correlation between intensity of silicone embolism and pump time. No cellular reaction was seen around the anti-foam agent. Occasionally single small areas of embolic brain damage were found. During extracorporeal circulation and within a recovery period up to one hour no silicone excretion through the kidneys could be demonstrated. Systemic fat embolism occurred less frequent than previously reported. Use of a filter in the cardiotomy suction line reduced its intensity further. In neither of the various organs examined, disseminated intravascular thrombosis could be found.
Serum cholesterol, triglycerides, phospholipids, and lipoprotein levels were studied by electrophoresis in 43 trauma patients with multiple fractures of the lower extremities and pelvis. Ten healthy volunteers were used for control studies. The fat embolism syndrome was diagnosed in eight of the 43 patients. The lipid values of all the trauma patients were lower than the control values. A decrease in cholesterol and phospholipids was observed in the fat embolism patients during 4 days; these changes were not observed in the other trauma patients. The triglycerides of all the trauma patients increased slowly over a period of 4 days. Changes in the lipoprotein fractions after the trauma were minor. An early increase in the alpha1 lipbrotein fraction was noted in the fat embolism patients simultaneously with a decrease in the pre-beta lipoprotein fraction; the values of the other trauma patients were at the control levels. Normalization was observed in 6 hours. The lipid concentrations of plasma and serum did not change with filtration with 1.2, 5, and 8mum Millipore filters. No differences were noted between the femoral and cubital vein samples.
It has been postulated in recent years that idiopathic necrosis of the head of the femur may possibly be caused by arteriolar obstruction by fat emboli emanating from a fatty liver, which would act as a reservoir, due to various causes such as alcoholism and prolonged steroid therapy. A similar situation has been found in human pathology in post traumatic fat embolism. The writers have reviewed forty five cases of post traumatic fat embolism which had passed the pulmonary filter. All the cases were reviewed after a minimum of two years, since this is considered the minimum time within which necrosis can manifest itself radiologically. In none of these cases was there any evidence of necrosis of the head of the femur. These findings, supported by other critical considerations. do not lend support to the theory of fat embolism as a case of idiopathic bone necrosis.
It was found in previous investigations that during venous gas infusion at low rates (1--5 ml/min-1) circulatory and respiratory variables reached a constant level after about 10--15 min. The present study demonstrates that this steady state can be disturbed by changing the composition of the breathing gas mixture. Alteration from air to 21% O2 in helium rapidly increased the embolic effects up to a maximum within 1.5--2 min; in the next 5--8 min the circulatory and respiratory variables returned to their previous levels during air breathing. Reverse effects occurred when changing from 21% O2 in helium to air. Similar phenomena were seen after switching from air to pure oxygen and from 21% O2 helium to pure oxygen. However, the extent of the circulatory and respiratory changes differed depending on the composition of the respective alternating breathing gas mixtures and on the initial embolic level as determined by infusion rate and kind of infusion gas. Gas movements between intravascular bubbles and alveolar space might be responsible for these changes.
The case of a young woman, receiving oral contraceptives, who developed massive pulmonary embolism producing circulatory collapse and paradoxical arterial embolism through a patent foramen ovale is documented.. Limb viability was threatened. Emergency management included removal of arterial and pulmonary emboli, surgical closure of the patent foramen ovale, inferior caval partitioning, ovarian vein ligation, and short-term anticoagulation. Recovery was rapid and complete.
Various embolization cases are described, and these require certain embolization materials. In our experience Gelfoam particles are very well suited for gastrointestinal tract lesions. Ivalon shavings gave excellent results in congenital arteriovenous malformations with permanent occlusions. Bristle brushes are a new device for larger artery occlusion. Stainless steel coils in combination with silk tufts proved thrombosis of large AV fistuals or of aneurysms particularly of the splenic artery.
We examined the amount of fat that can be forced into the circulation by compression of femora and of heads of the tibia in the very moment of injury. By fractures of diaphyses no considerable reduction of the intraosseous space was achieved and no fat was expelled through the foramina nutritia before the hard cortical bone was splintered. However, considerable amounts of fat were expelled into veins, when the epiphyses of the femora or when the head of the tibia was compressed from medially and from laterally. Even by a purely manual compression some fat was forced to leave the spongiosa by the foramina nutritia. This is explained by the higher elasticity of the spongious bone, permitting a marked space reduction by compression even before a fracture sets in. The mechanism resembles the procedure of opacification of veins by contrast media, injected into the bone cavity under pressure. The significance of these findings for the pathogenesis of clinical fat embolism is discussed.
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The effects of long-term occlusion of branches of the celiac and renal arteries were studied in 13 pigs, using isobutyl 2-cyanoacrylate (ibc), the Gianturco-Anderson-Wallace wool coil, and lvalon. IBC permanently occluded 2- to 8-cm lengths of both vessels, including their branches so that collateral circulation was not able to preserve the tissue supplied by the occluded artery. Gastric ulcers, splenic and hepatic infarcts, and large, sterile biliary cysts were observed on postmortem examination. Permanent occlusion was also observed with the wool coil and lvalon, but the pathological results were much less deleterious. The authors conclude that IBC is presently unsafe for use in branches of the celiac artery.
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