Experience with the helix cava filter.
A new caval filter of helico-spiral geometry (Helix-Filter) was implanted in 13 patients for the prevention of pulmonary embolism (PE). The indications for implantation were: recurrent PE despite adequate anticoagulation (5 cases) or contraindication to anticoagulation (3 cases), incomplete local therapeutic fibrinolysis after severe paracentral PE (2 cases), and prophylaxis in high risk patients (3 cases). Implantation was effected by the saphenous/femoral vein approach in 12 patients, and via the right atrial appendage during open heart surgery in one instance. There were no intraoperative technical problems and in no case was the filter misplaced. During the follow-up period (mean 14.8 months, maximum 28 months) no filter-related complications were encountered. One patient with an exceptionally enlarged vena cava, due to abnormal renal vein inflow, had a fatal recurrent PE despite high dosage heparinization. One patient with an event-free follow-up died 12 months after filter placement from unrelated diseases. The remaining 11 patients are free of symptoms with no recurrent PE, no deterioration of venous circulation or presence of caval thrombosis. Emboli trapped at the filter were documented in 2 patients; spontaneous resolution occurred in one case. Experimental and early clinical results indicate that the hemodynamically optimal design of the Helix-Filter permits controlled and uniform luminal filtering with high patency. As such, it represents an alternative and highly promising solution to the problem of "mechanical" prevention of pulmonary embolism in selected patients.