Archive for the ‘Vena Cava’ Category

Indications and Discussion
No technique can be evaluated without establishing an “ideal” standard. In our view, such an ideal caval interruptive approach would incorporate the following features: (1) The procedure should be applicable with safety and efficacy by physicians of reasonable skill after modest periods of training. (2) The procedure should be performed without general anesthesia and with minimal patient invasion. (3) The approach should not interfere, acutely, with caval blood flow to a significant degree. (4) All potential emboli above a defined size (eg, 2 mm diameter) should be prevented. (5) Acute and chronic complications of the procedure (eg, bleeding, caval thrombosis) should be minimal. (6) The approach should be applicable despite concurrent anticoagulant or thrombolytic therapy. (7) The interruption should be reversible. alta white teeth whitening Read the rest of this entry »

The Greenfield Vena Cava Filter: Caval PerforationCaval Perforation
As stated previously, when the filter springs open during insertion, its struts engage the wall of the vena cava with some force. Penetration of the caval wall by the sharp anchoring prongs is necessary to prevent filter migration. Whether the prongs actually perforate the cava is not documented, but there have been no reported complications attributed to this. However, strut perforation can take place in a minority of cases, particularly if there is angled insertion, or if an effort is made to alter the position of a filter after it has been extruded. Methods used to assess filter position have included computerized tomography, ultrasound, and venacavography. Strut perforation has been the potential cause of two retroperitoneal hematomata, one case mimicking intestinal obstruction, and one case of reversible hematuria. Long-term experience with patients both treated and untreated with anticoagulants has not revealed other complications. generic wellbutrin Read the rest of this entry »

Anticoagulation
Anticoagulation remains the primary therapy for deep venous thrombosis. Caval filtration serves to protect the patient from one complication of this disease (pulmonary embolism) but has no effect on venous thrombosis. Therefore, anticoagulation should be administered as usual if no contraindication exists. While he prefers to discontinue heparinization briefly prior to insertion, Greenfield contends that anticoagulation is not an absolute contraindication to filter placement. This assertion is supported by the experience of Gomez et al who routinely administered 7,500 units of heparin immediately prior to venotomy in those patients without contraindication and noted no increase in complications. In the two reported cases of retroperitoneal hematoma in association with a filter, both patients received excessive anticoagulation therapy. In one of the cases, the patient underwent laparotomy 18 months later (for another condition), at which time, one arm of the filter was noted to have perforated the I VC. The actual timing could not be proven, and the earlier bleed would suggest that the perforation took place during or shortly after insertion. There is no other evidence that patients receiving anticoagulation therapy are at increased risk of caval hemorrhage. starlix 60 mg Read the rest of this entry »

The Greenfield Vena Cava Filter: Recurrent Pulmonary EmbolismRecurrent Pulmonary Embolism
The purpose of caval filtration is to prevent pulmonary embolism. One of the arguments against the use of the Mobin-Uddin umbrella, and indeed, all other devices which can lead to caval occlusion, is that future embolization may take pace through extensive venous collateral circulation. In addition, the presence of a foreign surface in the blood stream may activate clotting, and the “protector” may then become the seed from which future embolic episodes grow. medicine-against-diabetes.net Read the rest of this entry »

Operative Complication
Most series documenting operative complications were compiled prior to the changes made in 1983, changes designed to improve certain reported complications of insertion: oblique placement, clot formation during insertion, and difficult accurate placement into the infrarenal IVC. Anecdotal reports substantiate these improvements. Therefore, these early reports likely represent “worse case” scenarios. We have pooled reports of 463 attempted insertions from ten different series.- Of 463 attempts, 12 filters could not be placed due to technical or anatomic problems. Twenty-three filters were misplaced into locations, including the suprarenal IVC, renal vein, iliac veins, and the right ventricle. buy glucotrol online Read the rest of this entry »

The Greenfield Vena Cava Filter: Operative TechniqueOperative Technique
Anatomic definition of a patients IVC is mandatory prior to filter placement, as the device has a finite maximal diameter. In addition to congenital abnormalities in the venous system, cavae with diameters greater than 28 mm (so-called “megacavae”) may be encountered. Indeed, the one report of significant proximal filter migration was due to inadvertent placement in a massively dilated segment of the IVC. Venocavography will also alert the physician to the presence of clot in the IVC or the renal veins. Such clot may prevent the struts of the filter from completely opening and engaging the caval wall. This situation, once recognized, can be dealt with by suprarenal filter placement. Read the rest of this entry »

Mobin-Uddin Filter
In order to appreciate the development of the Greenfield filter, it is necessary to understand what has previously been available. The Mobin-Uddin filter was the first widely used transvenous device, having been introduced in the 1960s. It resembles an umbrella and consists of six stainless steel spokes radiating from a central hub. A thin fenestrated Silastic sheet covers the metal on each side but allows protrusion of the spokes by 2 mm. In its original design, the filter expanded to 23 mm in cross-sectional diameter, having been developed in such fashion based on autopsy studies of human vena cava morphology. However, due to filter migration in man, the filter was increased in size to its current 28 mm. This has helped reduce the number of proximally migrating filters but has not eliminated the problem. In one report 20 of 1,981 (1 percent) of 23 mm filters proximally migrated vs two of234 (0.85 percent) 28 mm filters; and in another report, 0.4 percent of the 28 mm filters migrated. This filter is efficacious in preventing pulmonary embolism; however, complications have been recognized, including caval thrombosis in 33 to 85 percent of patients, proximal migration of the filter resulting in death, venous stasis sequelae related to filter placement, and a higher than expected rate of recurrent pulmonary embolism perhaps related to the high incidence of caval thrombosis. natural breast enhancement Read the rest of this entry »

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