Kimray-Greenfield vena cava filter: percutaneous introduction

Percutaneous interventions for pulmonary embolism

Pulmonary embolism (PE) ranks as a leading cause of in-hospital mortality and the third most common cause of cardiovascular death. The spectrum of PE manifestations varies widely, making it difficult to determine the best treatment approach for specific patients. Conventional treatment options include anticoagulation, thrombolysis, or surgery, but emerging percutaneous interventional procedures are being investigated for their potential benefits in heterogeneous PE populations. These novel interventional techniques encompass catheter-directed thrombolysis, mechanical thrombectomy, and hybrid approaches combining different mechanisms. Furthermore, inferior vena cava filters are also available as an option for PE prevention. Such interventions may offer faster improvements in right ventricular function, as well as in pulmonary and systemic haemodynamics, in individual patients. Moreover, percutaneous treatment may be a valid alternative to traditional therapies in high bleeding risk patients and could potentially reduce the burden of mortality related to major bleeds, such as that of haemorrhagic strokes. Nevertheless, the safety and efficacy of these techniques compared to conservative therapies have not been conclusively established. This review offers a comprehensive evaluation of the current evidence for percutaneous interventions in PE and provides guidance for selecting appropriate patients and treatments. It serves as a valuable resource for future researchers and clinicians seeking to advance this field. Additionally, we explore future perspectives, proposing "percutaneous primary pulmonary intervention" as a potential paradigm shift in the field.

Back to the Basics: Inferior Vena Cava Filters

Inferior vena cava filters are an important therapeutic option for patients with venous thromboembolism and contraindication to anticoagulation. Indications for filter placement have varied over the previous decades. This article discusses the history of inferior vena cava filter use, with a basic overview of technology and specific devices. Finally, this article reviews emerging filter design and technology. Understanding the basics of inferior vena cava filters is critical to building more robust clinical data for the purpose of improving patient outcomes.

Perforation of inferior vena cava and duodenum by strut of inferior vena cava filter: A case report

INTRODUCTION

An Inferior vena cava (IVC) filter is an intravascular filter that is implanted into the IVC to prevent pulmonary embolism in medical, surgical, and trauma patients. The insertion of an IVC filter is a relatively safe procedure, but rarely may be associated with symptomatic perforation of the IVC wall, particularly in the long term.

PATIENT CONCERNS AND DIAGNOSIS

A 74-year-old-woman with a medical history of IVC filter insertion visited the emergency department complaining of abdominal pain. A computed tomography scan showed perforation of the IVC wall and penetration into the duodenum by one of the filter's struts.

INTERVENTIONS

We performed a laparotomy to remove the IVC filter.

OUTCOMES

Postoperatively, the patient was admitted to the general ward. On hospital day 12, she was discharged without any complications. We followed her up and computed tomography did not show any abnormal findings six months after discharge.

LESSONS

There is currently no evidence testifying to the benefits of IVC filter removal. Detailed, evidence-based guidelines on the indications, timing and procedure for IVC filter removal are needed. Documenting cases of long-term complications of IVC filter s such as in this patient serve to accelerate the publication of updated guidelines and are aimed at improving outcomes of similar cases in the future.

Inferior Vena Cava Filters: Current Indications, Techniques, and Recommendations

The vena cava filter (VCF) is intended to prevent the progression of deep venous thrombosis to pulmonary embolism. Recently, the indications for VCF placement have expanded, likely due in part to newer retrievable inferior vena caval filters and minimally invasive techniques. This article reviews the available VCFs, the indications for use, the techniques for placement, and possible outcomes and complications.

Use of noncontrast computed tomography of the inferior vena cava for real-time imaging guidance for the placement of inferior vena cava filters

Appropriate placement of an inferior vena cava (IVC) filter necessitates imaging of the renal veins because when an IVC filter is deployed its tip should be at or below the inferior aspect of the inferiormost renal vein. Traditionally, imaging during placement of IVC filters has been with conventional cavography and fluoroscopy. Recently, intravascular ultrasound has been used for the same purpose but with additional expense. Morbidly obese patients often exceed the weight limit of fluoroscopy tables. In addition, short obese patients are at risk of falling from narrow fluoroscopy tables. For such patients, computed tomography (CT) guidance is a viable alternative to conventional fluoroscopic guidance. IVC placement was performed in the CT suite for two obese patients who exceeded the weight limits of the available fluoroscopy tables. In one case, a Vena-Tech filter (Braun Medical, Melsungen, Germany) was placed using CT fluoroscopy. In the second case, a Recovery (Bard, Murray Hill, NJ) filter was placed using intermittent limited z-axis scanning. In the first case, the filter was placed below the level of the renal veins and above the confluence of the iliac veins, which is acceptable placement. In the second case, with refinement of technique, the filter tip was placed less than 1 cm below the inferiormost renal vein, which is considered optimal placement. CT of the IVC precisely images the renal veins and can characterize their number and their confluence with the IVC. CT guidance is a viable alternative to fluoroscopic guidance for the placement of IVC filters in morbidly obese patients.

Placement of vena cava filter via percutaneous puncture of the great saphenous vein

The aim of this study was to investigate the feasibility and safety of vena cava filter (VCF) placement via percutaneous puncture of the great saphenous vein (GSV) in the prevention of pulmonary embolisms. Using ultrasound positioning, VCF placement via percutaneous puncture of the GSV was performed on 12 patients with deep vein thrombosis (DVT) in the lower extremities. Transcatheter thrombolysis was conducted simultaneously. The postoperative filter position, puncture wound recovery and fluency of the GSV were observed. All filters were successfully released, with accurate positioning. No hematoma was observed at the puncture point during the perioperative period. In certain patients, local petechiae appeared around the puncture point during the thrombolysis period, which did not require special treatment. Re-examination using ultrasound revealed unobstructed blood flow in the GSV. VCF placement via percutaneous puncture of the GSV is a new filter placement method. The feasibility and safety of this method for the prevention of pulmonary embolisms has been demonstrated in a small number of sample cases.

Inferior vena caval filters: 5 years of experience in a tertiary care center

BACKGROUND AND OBJECTIVES

Interruption of the Inferior Vena Cava (IVC) is recommended in certain cases to prevent Pulmonary Embolism (PE). Reported data on the efficacy and rate of complications vary considerably.

PATIENTS AND METHODS

We conducted a retrospective analysis of patients who had a temporary or permanent IVC filter inserted at our institution during the past 5 years.

RESULTS

Seventy-seven of 225 patients (34%) with Venous Thrombosis (VT) had an IVC filter inserted. Deep vein thrombosis and PE were the most common causes for anticoagulation. Bleeding was the reason for IVC filter insertion in 48 (62%). The only complication found was the breaking of a temporary filter during removal related to the procedure. However, 3 patients (out of 10) had a recurrence of VT after prolonged discontinuation of anticoagulation.

CONCLUSIONS

Our criteria for indication of IVC filter insertion are in line with current standard of care. The immediate and delayed complications caused by IVC filter insertion was low. Active bleeding was the most common indication for filter insertion, whereas inherited thrombophilia was relatively common.

Vena cava filters: an update

Venous thromboembolism is a major health problem that results in significant long-term complications and mortality. The management of venous thromboembolism is complex and can be particularly challenging when pharmacological therapy alone cannot be effectively utilized. Vena cava filters provide protection from pulmonary embolism for patients in whom therapeutic anticoagulation is contraindicated or inadequate. Recent innovations in caval interruption have included the use of alternative imaging modalities for filter insertion and the emergence of devices designed to allow temporary caval filtration. These developments have been accompanied by a controversial increase in the use of vena cava filters for prophylactic indications in the absence of venous thromboembolism. In addition to a brief historical perspective on caval filtration, this update reviews the indications for vena cava filter insertion, associated complications, methods of caval imaging and filter insertion and current FDA-approved devices.

Inferior Vena Cava Filters in Venous Thromboembolism

Vena cava filters have been used for the prevention of pulmonary embolism in patients with venous thromboembolism since the 1930s. Historically, vena cava filters were used in patients with either a contraindication to or a complication of systemic anticoagulation or in those with recurrent pulmonary embolism despite adequate anticoagulation. However, indications for placement have broadened even in the absence of support from randomized controlled trials as the deployment procedure became less complex. With more recently available optional retrievable filters, physicians have another valuable tool to use for the treatment of venous thromboembolism in patients who are not candidates for systemic anticoagulation or, perhaps, more importantly, have only a temporary indication for filtration. As with permanent filters, there is a clinical need for robust clinical studies to establish appropriate indications and define long-term outcomes because there are only case series to guide the current usage of such filters.

CT fluoroscopic guided insertion of inferior vena cava filters

The value and use of inferior vena cava (IVC) filters is well documented and has been growing since the first reported filter placement in 1973 and the first percutaneous insertion in 1982. Access routes now include both jugular veins, both ante-cubital veins and both femoral veins. However, all insertions require some form of imaging, usually fluoroscopy, to identify the location of the filter with respect to the IVC and the renal veins. We describe two cases where the patients' weight was significantly greater than the weight limit of the angiography table, necessitating insertion under CT fluoroscopic guidance.

TrapEase™ Vena Cava Filter: A Case of Filter Migration and Pulmonary Embolism After Placement

Inferior vena cava filters provide an alternative method of protection against pulmonary embolism in situations where anticoagulation either fails or is contraindicated. These filters are easily placed, with a relatively minor risk of complications. Currently, we know of only one reported case of filter migration using the TrapEase filter. We present a case report of a migrating TrapEase filter, as well as pulmonary embolism after TrapEase filter placement. This complication developed in a 31-year-old trauma patient who developed bilateral popliteal deep vein thromboses and an initial pulmonary embolus while on low molecular weight heparin.

Update on inferior vena cava filters

The ravages of thromboembolic disease continue to plague patients despite improvements in diagnostic imaging and anticoagulation regimens. In certain cases, standard medical therapy for thromboembolism is contraindicated, results in complications, or fails to adequately protect patients from embolic insults. These patients are treated with insertion of inferior vena cava (IVC) filters. Although it appears that IVC filters do reduce long-term pulmonary embolism (PE) rates, there may be a higher associated incidence of IVC thrombosis and lower-extremity deep venous thrombosis (DVT) than with anticoagulation alone. This article will address attributes of the theoretical ideal IVC filter, recently introduced IVC filters, complications of use of IVC filters, and results of recent IVC filter studies. Alternative sites for filter placements are then reviewed, along with use of temporary and retrievable IVC filters and use of IVC filters for prophylactic situations.

Preliminary results of the new 6F TrapEase inferior vena cava filter

The TrapEase filter is a permanent, symmetric nitinol filter that can be deployed through a low-profile sheath. Although the TrapEase is enjoying an increasing market share of inferior vena cava (IVC) filters, there are still limited clinical follow-up data on its use. This study is a retrospective review of 189 consecutive infrarenal TrapEase filters placed at our institution. The study included 80 men and 109 women, with an average age of 73 years (24-102). The most common indication for filter placement was a contraindication to warfarin. In total, 13% of the patients were treated with warfarin. The filter was successfully deployed in all cases, via the right femoral vein in 57% of the patients, via the left femoral vein in 32%, and via the right internal jugular vein in 11%. Follow-up studies were performed as clinically indicated. During the investigation, there were three cases of IVC thrombosis (1.5%) and one case of retroperitoneal hemorrhage potentially caused by filter placement. Two of the thrombosis cases resulted in serious sequelae. This study also represents the first report of a symptomatic pulmonary embolism (PE) after TrapEase filter placement. While this investigation does demonstrate a low overall complication rate of this new device, it raises the concern of an increase in IVC thrombosis rate.

Long-term Follow-up of Percutaneous Vena Cava Filters: a Prospective Study in 100 Consecutive Patients

OBJECTIVES

the long-term outcome in following insertion of inferior vena cava (IVC) filters remains unclear.

DESIGN

prospective study.

MATERIAL AND METHODS

one hundred consecutive patients received percutaneous vena cava filters between 1988 and 1993. The patients underwent clinical examination, abdominal X-rays and duplex ultrasound of the IVC, right internal jugular vein and legs after a mean follow-up duration of 38+/-11 months.

RESULTS

forty patients died after implantation (median 11.3 months; IQR: 1.8--20.4 months). The cause of death was known in 33 cases, and pulmonary embolism (PE) was suggested in three. Multivariate analysis revealed the mortality rate to be significantly higher in cancer patients (relative risk of 2.13). The 3-year survival was 20% for cancer patients and 71% for patients without cancer. Among the 60 living patients, thrombi were trapped in the filter in 10 cases, the filter tilted in four, was malpositioned in five and migrated in 29. These incidents were recorded as asymptomatic complications, as opposed to seven IVC thromboses and 23 recurrent lower limb thromboses, which were considered as symptomatic complications.

CONCLUSION

long-term major complications are not frequent. As expected, cancer was the only factor predicting mortality. IVC filters seem effective in preventing PE.

Deep venous thrombosis after percutaneous insertion of vena caval filters

PURPOSE

A large multicenter study has recently questioned the overall clinical efficacy of vena caval filters, especially when inserted prophylactically, because of the subsequent development of deep venous thrombosis (DVT) at the insertion site. We examined the incidence of this complication with newer, smaller diameter percutaneous devices.

METHODS

We reviewed our vascular surgery and interventional radiology clinical registries to identify patients in whom a femoral percutaneous vena caval filter had been placed from 1993 to 1998. This list was cross referenced with patients who had undergone lower extremity venous ultrasound scan examinations for the diagnosis of DVT in the vascular laboratory within a 60-day period before and after the insertion of the filter device.

RESULTS

A total of 35 patients during this 5-year period had timely follow-up venous duplex scan studies performed. The indications for filter placement were DVT in 16 patients (46%), pulmonary embolus in 13 patients (37%), DVT and pulmonary embolus in three patients (9%), and prophylactically in three patients (9%) at high risk for thromboembolization. Of the patients with documented thromboembolic events, 91% (29 of 32) had contraindications to anticoagulation therapy, and the remaining 9% (3 of 32) represented failure of anticoagulation therapy. A Greenfield filter was used in 13 patients (37%), a Simon Nitinol filter was used in 11 patients (31%), and a VenaTech filter was used in nine patients (26%). The other two patients (6%) had a Bird's Nest filter inserted. At a mean follow-up period of 12 +/- 2 days (median, 6 days), there was a 40% (14 of 35) incidence of proximal DVT in venous segments without evidence of thrombus before filter insertion. The majority (71%; 10 of 14) occurred in the common femoral vein, with three located in the superficial femoral vein and one in the external iliac vein. The lowest incidence of DVT was seen with the Greenfield and Bird's Nest filters as compared with the smaller Simon Nitinol and VenaTech filters (20% vs 55%; P < .05). The highest incidence of thrombosis occurred in patients with pre-insertion pulmonary emboli (50%; 8 of 16) as compared with those patients with DVT (38%; 6 of 16) and prophylactic insertion (0%; 0 of 3). However, the subgroups were too small to attain statistical significance.

CONCLUSION

There is a continuing and significant incidence of new DVT development ipsilateral to the percutaneous femoral insertion site of vena caval filters. The smaller diameter filters are not associated with a lower incidence of femoral thrombosis.

Right internal jugular vein approach as an alternative in balloon pulmonary valvuloplasty

Transjugular balloon pulmonary valvuloplasty was safely and successfully performed in five patients, two of whom had severe right heart failure. Crossing the stenotic pulmonary valve from the right internal jugular vein was consistently easy and quick. This approach should be considered whenever difficulties are experienced or anticipated in the femoral approach.

Prophylactic vena cava filter insertion in selected high-risk orthopaedic trauma patients

OBJECTIVES

(a) To determine the incidence and risk factors for the development of pulmonary embolism in orthopaedic trauma patients and (b) to determine whether prophylactic vena cava filters are efficacious against pulmonary edema in high-risk patients.

DESIGNS

Before and after trial on the incidence of pulmonary embolism in the orthopaedic trauma population before and after the introduction of prophylactic vena cava filters.

SETTING

Tertiary care level I trauma center.

PATIENTS

Thirty-five patients received prophylactic vena cava filters. These patients had a long bone and pelvic, multiple long bone fractures, or a complex (Kane's III or IV) pelvic fracture with at least one additional risk-factor at an age of > 55 years and an Injury Severity Score of > 16 or requiring prolonged (> 6 weeks) immobilization.

INTERVENTION

Thirty-five patients had vena cava filters placed (32 titanium Greenfield filters, Medi-tech/Boston Scientific, Watertown, MA; and three Bird's Nest filters, Cook Bloomington, IN). Most filters (n = 33) were placed percutaneously in radiology.

MAIN OUTCOME MEASURES

(a) Morbidity related to filter insertion, (b) incidence of pulmonary embolism in orthopaedic trauma population compared with historical controls who did not receive filters, and (c) patency of filters.

RESULTS AND CONCLUSIONS

Minimal morbidity was related to prophylactic vena cava filter insertion. There was a significant (p < 0.04); (Fisher's exact) decrease in the incidence of pulmonary embolism in the orthopaedic trauma population as a whole after the use of prophylactic vena cava filters. Follow-up ultrasound showed a 1 and 2-year inferior vena cava patency rate of 93.6% +/- 6.2% by life table analysis. We conclude that selected use of prophylactic vena cava filters in orthopaedic trauma is safe and decreases the incidence of pulmonary embolism.

Early duplex scan evaluation of four vena caval interruption devices

PURPOSE

Transvenous inferior vena cava (IVC) filters are used successfully for prevention of pulmonary embolism (PE), but early thrombotic complications such as insertion site thrombosis (IST) and inferior vena cava thrombosis (IVCT) may occur after placement. The frequency of these complications has been uncertain particularly for the wide variety of newer devices. This study was performed to prospectively evaluate IST and IVCT with color-flow venous duplex ultrasound scanning after four IVC filters were placed: the birds' nest filter, the titanium Greenfield filter, the stainless steel Greenfield filter, and the Simon nitinol filter.

METHODS

Percutaneous IVC filters were placed in 174 patients over a 21-month period. A birds' nest filter was used in 39 (22%) cases, a titanium Greenfield filter in 67 (39%) cases, a stainless steel Greenfield filter (25%) in 43 patients, and a Simon nitinol filter in 25 (14%) cases. Filters were placed for major deep venous thrombosis in 113 (63%) patients, after PE in 26 (15%) patients, and with prophylaxis in 35 (20%) patients. All patients had color-flow venous duplex ultrasound scanning of the insertion site and the inferior vena cava 7 to 10 days after placement or before discharge to document IST or VCT.

RESULTS

Early IST occurred in 43 (24.7%) cases, and early IVCT was observed in 20 (12%) cases in this series. No significant difference was found in the incidence of IST or IVCT among the four filter types used. The incidence of IVCT was significantly higher in patients having filters placed for PE. Men were more likely to receive a prophylactic filter than women in this study, but thrombotic complications were not related to patient sex. Thrombosis was seen with equal frequency at all insertion sites used. No patient died of PE after filter placement during the study period.

CONCLUSIONS

The incidence of thrombotic complications for all devices was higher than has generally been reported. No IVC filter used in this study demonstrated superior performance with regard to these thrombotic complications. As vena cava interruption devices are developed or significantly modified, prospective objective analysis of associated thrombotic complications will allow logical selection for clinical use.

Utilization patterns with inferior vena cava filters: surgical versus percutaneous placement

PURPOSE

To determine whether more inferior vena cava (IVC) filters were used after interventional radiologic placement methods became available, and if so, whether this increase could be due to expansion of indications.

PATIENTS AND METHODS

A retrospective analysis of the number of filters placed, the method of placement used, the indications for placement, and patient survival was performed during the 3 years before and the 3 years after 1989, the first year filters were placed percutaneously at the authors' institution.

RESULTS

From 1986 through 1988, 35 filters were all placed by surgeons in the operating room. From 1990 through 1992, 201 filters were all placed by radiologists in the special procedures suite. In the surgery group, 13 of 35 filters (37%) were placed for contraindications to anticoagulation therapy, 12 (34%) were placed for complications of anticoagulation, and nine (26%) were placed for recurrent thromboembolic disease despite anticoagulation. One filter was placed because of a free-floating thrombus in the IVC. In the radiology group, 98 of 161 patients (60%) underwent placement for contraindications to anticoagulation, 25 (16%) experienced complications of anticoagulation, 28 (17%) experienced recurrent thromboembolic disease, and nine (6%) had a free-floating thrombus. The 6-month survival in patients treated before 1989 was 80% versus 43% after 1989.

CONCLUSION

At the authors' institution, filters are now placed exclusively by interventional radiologists. The overall indications for placement remain unchanged. The increase in utilization appears primarily related to more frequent placement in severely ill patients who may not experience considerably improved survival but may benefit from a substantial reduction in the risk of hemorrhagic complications.

Venous thromboembolism in trauma patients

Venous thromboembolism is common in patients with multiple injuries. In addition to having endothelial injury, trauma patients are hypercoagulable and are often confined to bed, thus placing them at high risk for venous thromboembolic events. Duplex ultrasonography and impedance plethysmography are the most practical modalities to screen trauma patients for the presence of DVT. At present, there do not appear to be any effective means of preventing DVT in trauma patients, although low molecular weight heparin appears promising. In particularly high-risk patients vena cava filters have been used safely and effectively to prevent PE.

Evolution of a new device for the prevention of pulmonary embolism

The embolus trap (ET) is a new device that interrupts the inferior vena cava (IVC) for the prevention of pulmonary embolism. It has a central column from which six wires extend in two tiers. The adjacent wires are formed into loops with hooks at the distal ends that grip the vein wall. Each tier contains three wire loops, and the loops are staggered circumferentially between the tiers. The ET was implanted into the IVC in 26 dogs via a femoral or jugular venotomy. IVC patency was evaluated by venacavagrams. Autologous clots were embolized via the femoral vein to test the efficacy of the ET. The animals were followed for 1 to 4 months prior to postmortem examination. The ET remained patent in all animals and consistently trapped the thromboemboli while preserving blood flow. Lysis of the trapped emboli was observed in 4 to 6 weeks. There was no evidence of malpositioning, penetration through the vein wall, or migration of the ET.

Endovascular therapy of venous thromboembolic disease

This article discusses the background and status of inferior vena caval filtration and transvenous catheter techniques for pulmonary embolectomy in the management of venous thromboembolic disease.

LGM vena cava filter: objective evaluation of early results

One hundred one LG-Medical (LGM) vena cava filters were placed in 97 patients at four institutions. Placement was a complete technical success in 90% (91 of 101). In 6% of attempts, LGM filter insertion was complicated by incomplete opening of the filter. Pulmonary embolism after filter placement was not definitely demonstrated in any patient. The probability of inferior vena cava patency was 92% at 6 months after filter insertion. Thrombosis at the insertion site was seen in eight of 35 patients (23%) evaluated with duplex ultrasound or venography. Thrombus was observed in 37% of filters at follow-up examination, with cephalic extension of thrombus above the filter in 20% of all patients examined. Filter migration (greater than 1 cm) was seen in 12%; significant angulation was observed in only one patient (2%). In vitro experimentation demonstrated that incomplete opening of the LGM filter during placement can be avoided, in part, by brisk retraction of the insertion cannula. The low-profile introducer system of the LGM filter allows increased alternatives in selecting the site for filter insertion. The low-profile system also makes outpatient filter placement a possibility. No significant difference in the prevalence of thrombosis at the insertion site following LGM filter insertion was noted compared with previous results reported for percutaneous transfemoral placement of the Greenfield filter. The nonopaque sheath does not permit careful localization prior to filter deposition. Modification of the LGM filter to include a radiopaque sheath is suggested.

Surgical treatment of acute deep venous thrombosis

In patients with venous thrombotic disease and in whom anticoagulation or thrombolytic therapy is inappropriate, ineffective, or even contraindicated, insertion of vena caval filters or venous thrombectomy must be considered. The primary indication for the placement of vena caval filters is in patients who have developed a pulmonary embolus and in whom anticoagulation is either contraindicated or in whom anticoagulation must be discontinued because of the development of bleeding complications. At the present time, either the Greenfield filter placed through a jugular, femoral, or axillary venotomy or the bird's nest filter are appropriate and appear to be the most effective and least fraught with complications. The use of venous thrombectomy has waxed and waned over the last several decades. At the present time, the procedure is advocated mainly for lower limb venous thrombosis which is extensive enough to threaten limb viability. On occasion, it may be appropriate to extend the indications for venous thrombectomy to include femoral thrombosis of less than 10 days duration or iliac thrombosis of less than 3 weeks duration with floating thrombi at the level. Technical modifications which improve the patency of the obliterated veins which are predisposed to rethrombosis include the creation of a temporary arteriovenous fistula and meticulous care in removing the entire clot. The patient should be treated with anticoagulants postoperatively to prevent a recurrence of the problem. The main theoretical advantage of venous thrombectomy is a reduced incidence of postthrombotic syndrome. Objective data to support this contention do not exist.

Pulmonary embolism

Pulmonary embolism is a common medical problem whose incidence is likely to increase in our aging population. Although it is life-threatening, effective therapy exists. The treatment is not, however, without significant complications. Thus, accurate diagnosis is important. Unfortunately, the clinical manifestations of pulmonary embolism are nonspecific. Furthermore, in many patients the symptoms of an acute embolism are superimposed on underlying chronic heart or lung disease. Thus, a high index of suspicion is needed to identify pulmonary emboli. Laboratory parameters, including arterial oxygen tensions and electrocardiography, are as nonspecific as the clinical signs. They may be more useful in excluding another process than in diagnosing pulmonary embolism. The first radiologic examination is the chest radiograph, but the clinical symptoms are frequently out of proportion to the findings on the chest films. Classic manifestations of pulmonary embolism on the chest radiograph include a wedge-shaped peripheral opacity and a segmental or lobar diminution in vascularity with prominent central arteries. However, these findings are not commonly seen and, even when present, are not specific. Even less specific findings include cardiomegaly, pulmonary infiltrate, elevation of a hemidiaphragm, and pleural effusion. Many patients with pulmonary embolism may have a normal chest radiograph. The chest radiograph is essential, however, for two purposes. First, it may identify another cause of the patient's symptoms, such as a rib fracture, dissecting aortic aneurysm, or pneumothorax. Second, a chest radiograph is essential to interpretation of the radionuclide V/Q scan. The perfusion scan accurately reflects the perfusion of the lung. However, a perfusion defect may result from a variety of etiologies. Any process such as vascular stenosis or compression by tumor may restrict blood flow. In addition, areas of the lung that are not well ventilated will be poorly perfused. Thus, a ventilation scan and a chest radiograph are essential to optimal interpretation of the perfusion scan. Ventilation/perfusion scans are interpreted as degrees of probability of pulmonary embolism. Emboli are not present in patients with a normal V/Q scan. An embolus is unlikely (10%-15%) among patients with a low-probability V/Q scan. However, small emboli that are nonocclusive may be present, and pulmonary arteriography may be used to further evaluate patients with a high clinical suspicion of pulmonary embolus.(ABSTRACT TRUNCATED AT 400 WORDS)

Percutaneous placement of the Greenfield vena caval filter

During the period from August 1986 to August 1987, 50 patients underwent percutaneous placement of a Greenfield vena caval filter from the right femoral vein, left femoral vein, or right internal jugular vein at our institution. All 50 patients had a contraindication to anticoagulation therapy or had complications of anticoagulation for deep venous thrombosis or pulmonary emboli. The percutaneous placement was accomplished in the angiographic suite with use of local anesthesia and was well tolerated by all patients. Only three complications related to the percutaneous approach occurred during the short-term follow-up (3 months to 1 year). These complications were deep venous thrombosis of the leg in two patients and misplacement of the filter in one patient. The three patients tolerated these complications well. We conclude that placement of Greenfield vena caval filters can be readily accomplished by means of percutaneous entry. Our experience demonstrated minimal associated morbidity and no mortality.

First clinical results with a new caval filter

A new percutaneous inferior venacaval filter was used in 15 patients. The filter is constructed of stainless steel wires formed into a helical basket and anchoring legs. It can be inserted through a 10F catheter in an antegrade or retrograde fashion and can also be retrieved percutaneously. In a follow-up period of up to 13 months, the filter was well tolerated. One patient died of recurrent embolism despite filter protection. Local thrombogenicity was noted in 2 patients, but no other side effects were observed. Short-term heparinization following filter insertion is advisable. Heparin coating of the filter is under evaluation.

Unusual approaches for insertion of the Greenfield vena cava filter: the value of its approach through the jugulosubclavian junction

During the last four years, we have attempted 249 insertions of the Greenfield inferior vena cava filter using the right internal jugular vein. This approach was impossible in 31 patients (12.5%). Our first alternative was the insertion of the filter through the venous junction between the right internal jugular and right subclavian veins. If this latter technique was not possible we attempted the insertion of the Greenfield filter through the left internal jugular vein before using the retrograde femoral route which is associated with high morbidity. By these techniques we have been able to reduce the number of patients in whom it is impossible to achieve mechanical endocaval partial interruption to 2.4%.