Transcatheter Electrocoagulation Research Articles

Experimental evaluation of a new instrument for transcatheter electrocoagulation.

A new coaxial electrode catheter design has been tested in 19 renal arteries of pigs with excellent results, i.e. 100 per cent thrombosis. One vessel ruptured. The electrode (anode) is situated on a thin inner catheter and after electrolysis it is pulled back into a shielding outer catheter. This should reduce downstream embolization. Usual currents have been 8 to 10 mA at 10 V and doses of 16 to 36 C have been used depending on the size of the artery. In the single case of rupture of the vessel a current of 20 mA was used. The method appears to be ready for clinical testing.

Evaluation of embolization distal to arterial occlusion by transcatheter electrocoagulation (TCEC) and Gianturco coils.

A technique was developed to evaluate the degree of embolization distal to arterial occlusion by transcatheter electrocoagulation (TCEC) and Gianturco coils. The kidneys of mongrel dogs were used to collect emboli distal to conventional TCEC or Gianturco coil occlusion of the renal arteries. TCEC controls (TCEC setup without current), normal kidneys, kidneys embolized with autologous clot, and kidneys whose renal arteries were surgically ligated were evaluated for comparison. The renal vasculature was flushed and then fixed by glutaraldehyde infusion. The kidneys were filled with a barium gelatin mixture and examined both radiographically and pathologically. The four normal kidneys and the four ligated kidneys gave a characteristic complete filling of the vascular web, while filling defects were evident in the following conditions: 3/12 TCEC controls; 26/34 with TCEC occlusion; 6/10 with Gianturco coils; and 11/11 with autologous clot. An excellent correlation existed between radiographic intraluminal filling defects and grossly and microscopically identified emboli.

Experimental Pulmonary Infarction in Dogs

Transcatheter electrocoagulation of the pulmonary artery was used to successfully create experimental pulmonary infarcts in 15 of 16 dogs. The animals were evaluated from one to 13 weeks by chest radiography, computed tomography (CT), angiography, and pathologic examination. The abnormal densities in the dogs' lungs cleared in two to three weeks. The majority of the chest radiographs were normal in two weeks, and all were normal after three weeks. Prior to sacrifice, CT showed abnormal densities in the lungs in only two of eight animals. CT proved to be more sensitive than chest radiography for showing the densities in the lungs due to pulmonary infarction.

Experimental Pulmonary Infarction in Dogs

Transcatheter electrocoagulation of the pulmonary artery was used to successfully create experimental pulmonary infarcts in 15 to 16 dogs. The animals were evaluated from one to 13 weeks by chest radiography, computed tomography (CT), angiography, and pathologic examination. The abnormal densities in the dogs' lungs cleared in two to three weeks. The majority of the chest radiographs were normal in two weeks, and all were normal after three weeks. Prior to sacrifice, CT showed abnormal densities in the lungs in only two of eight animals. CT proved to be more sensitive than chest radiography for showing the densities in the lungs due to pulmonary infarction.

Effect of increasing current and decreasing blood flow for transcatheter electrocoagulation (TCEC).

Arterial occlusion by direct-current transcatheter electrocoagulation (TCEC) has been developed experimentally and used successfully in clinical situations. The major shortcoming of the technique has been the lengthy time necessary for occlusion of larger arteries. In the present study we attempted to decrease the time necessary for TCEC occlusion of the renal and femoral arteries of heparinized mongrel dogs. The results showed that the occlusion time could be significantly decreased, either by increasing the TCEC current from 15 ma to 30 or 60 ma, or by using a Meditech balloon catheter to occlude the artery during TCEC. The combination of higher current and simultaneous balloon occlusion consistently produced permanent occlusion of arteries up to 7 mm in diameter in 15 minutes or less. Balloon occlusion with TCEC is significantly faster than without this modification and makes the technique of TCEC more applicable for human use and for continued experimental study than any previous refinements.

Transcatheter electrocoagulation of the pulmonary artery: an experimental model in dogs for studying pulmonary thrombosis.

Transcatheter electrocoagulation (TCEC) has been shown to produce permanent arterial occlusion. This study was performed to evaluate the potential of using TCEC of the pulmonary artery as an experimental model of pulmonary thromboembolism. Fourteen lobar or first-order pulmonary arteries were occluded in ten dogs in the acute studies. Eight pulmonary arteries were occluded in eight dogs that were sacrificed 25 to 85 days after TCEC. There were permanent occlusions in seven, and all seven evidence of pulmonary infarction. The animals tolerated the procedure well. The technique may have merit as an experimental model for studying pulmonary thrombosis and infarction.

Vessel occlusion with transcatheter electrocoagulation: negative results.

Vessel occlusion with transcatheter electrocoagulation: negative results.

Transcatheter vessel occlusion: Selection of methods and materials

Transcatheter vessel occlusion (TCVO) is increasingly used for control of hemorrhage, palliative and preoperative tumor embolization, organ function ablation, and obliteration of arteriovenous fistulae and malformations. Methods for TCVO include transcatheter electrocoagulation, "staining" with contrast, the use of balloon-tipped catheters, and embolization. The choice of method and material depends on whether proximal occlusion of feeding vessels or arteriocapillary occlusion is desired, the vascular anatomy of the lesion, the safety with which the lesion can be embolized, and the type of lesion being treated. Embolization is the most frequently employed modality. Available materials include autologous tissue, absorbable hemostatics, synthetic particulates, and liquid polymers. Each material has advantages and disadvantages that make it desirable in certain situations and less useful in others. Complications of TCVO may be disastrous, but can be avoided with careful attention to detail. The specific features of the lesion determine the choice of materials and techniques.

A bipolar electrode for vascular electrocoagulation with alternating current.

A bipolar electrode for transcatheter electrocoagulation with alternating current is described. This electrode avoids the problem of variation of the electric impedance of the monopolar electrode/ground plate system. It allows quick, safe, and reliable endovascular occlusion of vessels.

Vessel Occlusion with Transcatheter Electrocoagulation: Initial Clinical Experience

Transcatheter electrocoagulation (TCEC) was used for vessel occlusion in combination with embolization by Gelfoam and/or Ivalon in six patients in whom other interventional or surgical techniques were considered dangerous or unfeasible. The technique was effective in decreasing or obliterating the blood supply to variously located lesions in all cases. The only complications were small skin burns in one patient and a small ulceration of the upper lip in another.

The effect of drug-induced thrombocytopenia on direct-current transcatheter electrocoagulation.

Direct-current transcatheter electrocoagulation in vitro produced substantial clots in thrombocytopenic blood in dogs. The splenic artery was occluded in 3 dogs following ristocetin-induced thrombocytopenia. This procedure may produce effective vessel occlusion in patients with platelet-poor blood.

Transcatheter electrocoagulation: a therapeutic angiographic technique for vessel occlusion.

Previous work has shown that localized electrocoagulation of blood vessels using direct current applied by catheter placed electrodes is feasible. In vitro and in vivo experiments showed that clot size and thrombosis of vessels are directly related to the product of the amount and duration of the current. Surgically created splenic hemorrhage was well controlled in 9 of 10 animals. The vessels remained permanently occluded after electrocoagulation in 8 of 9 animals. Pathological studies of all the vessels showed intimal damage at the sites of occlusion. These experiments indicate that clot formation may be a product of both intimal damage and platelet attraction to the positive electrode. The technique has advantages over embolization since no foreign material is injected and a localized clot is produced at the tip of the guidewire. There are certain disadvantages and further refinements must be developed to establish transcatheter electrocoagulation as a useful clinical technique for vessel occlusion.

Experimental Closure of Arteriovenous Fistula by Transcatheter Electrocoagulation.

Introduction of a small electric current by way of a catheter-placed electrode can completely occlude experimentally produced arteriovenous fistula. The occlusion appears permanent and without morbidity in experimental animals. This technique might be clinically useful in obliterating an arteriovenous fistula and controlling gastrointestinal hemorrhage.

Transcatheter Electrocoagulation of Blood Vessels

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