Multiple Fatal Pulmonary Embolism During Polymethyl-Methacrylate Vertebroplasty With Successful Percutaneous Retrieval of a Large Cement Fragment
a Sección de Hemodinámica, Servicio de Cardiología, Hospital de Cruces-Barakaldo, Vizcaya, Spain
To the Editor,
A 74-year-old man with high blood pressure, dyslipidemia, and diabetes, who had been evaluated in our unit 13 months earlier for atrial fibrillation, underwent cardioversion with no apparent structural heart disease. One month later he was diagnosed with T4N3M0-stage adenocarcinoma of the lung and received chemotherapy and radiation therapy. In February 2011, the patient was hospitalized for intense lumbar pain of 10 days’ duration. Computerized tomography identified a compression fracture of the second lumbar vertebra (L2) due to metastasis.
The neuroradiology team opted for vertebroplasty. With the patient under general anesthesia and prone decubitus, the procedure began with diagnostic vertebrography, immediately followed by bilateral transpedicular vertebroplasty in L2 introducing radiopaque bone cement (Biomet Bone Cement V, BIOMET®). This is prepared by dissolving a powder containing methyl methacrylate (MMA), zirconium dioxide, and benzoyl peroxide in a 10ml flask with MMA solution and dimethyl toluidine, which is then cooled. We obtained good results in the vertebra (Figure 1A). However, we identified millimetric MMA fragments in both lungs and one larger, round fragment in a segmental branch of the inferior left lobule (Figure 1B).
Figure 1. A: transpedicular vertebroplasty; introducing cement in L2. B: selective pulmonary arteriography; inferior left lobule segmental branch occlusion; scattered microembolisms (arrows). C: cement embolus in right lung segmental branch. D: snare catheter capture and passage of catheter+fragment through tricuspid valve.
We requested that the cardiac catheterization laboratory remove these. After positioning the patient in supine decubitus and using right femoral vein access, a 30cm 20 Fr XLCFW 20.0-38-30 Endostent (COOK®) delivery catheter–with 2 cuts made in the distal end–was deployed. With a multipurpose catheter, we accessed the pulmonary artery and performed selective angiography, enabling us to locate the cement fragment in the segmental branch (Figure 1B). We deployed a straight guidewire distally, followed by the catheter. This was replaced by a 15mm Amplatz Goose-Neck (ev3®) snare catheter, opened and retracted over the cement, closing the snare to fix the fragment. While keeping a hold on this, we slowly retrieved the catheter and fragment but at the level of the tricuspid valve it embolized and impacted in an inferior right branch lobule (Figure 1C). We repeated the capture maneuver in this lobule and at the second attempt passed the tricuspid valve without difficulty (Figure 1D) and drew the cement into the sheath with no resistance thanks to the 2 cuts we had previously made (Figure 2A). With the cement fixed in the interior, we withdrew the entire sheath and, once on the table, extracted the MMA fragment by cutting the sheath lengthwise (Figure 2B).
Figure 2. A: 20 Fr sheath; detail of longitudinal cuts. B: rounded, 1cm diameter morphology of cement.
The patient was admitted to intensive care and underwent thoracic computerized tomography which confirmed millimetric fragments remained in the inferior and suprahepatic vena cavae and segmental branches of both lungs.
Despite several attempts to disconnect the ventilator, this was not possible. The patient presented pneumonia for Staphylococcus aureus, which was treated with antibiotics initially leading to improvement. In the following days his condition worsened with severe respiratory insufficiency with hypoxemia and respiratory acidosis; he was labeled as having acute respiratory distress. Clinical course was bad, with low blood pressure and oligoanuria, and the patient died 12 days after the procedure.
Vertebroplasty and kyphoplasty with MMA are well-known techniques and one of the complications is loss of material, which occurs in up to 70% of cases. How MMA accesses the venous system is unclear although direct injection into iliolumbar or epidural veins may be the cause. Vertebra are highly vascularized by intraosseous veins with a network that connects to paravertebral and extradural plexuses. Moreover, osteoporotic compression destroys the vertebral body, permitting direct shunting of MMA fragments to the venous system and pulmonary circulation.1 Hence, pulmonary embolisms appear in 23% of computerized tomography studies.2
Treatment of this complication ranges from anticoagulation therapy to surgical embolectomy in severe cases.3 Our review of the literature revealed a recent case of pulmonary embolism of MMA following vertebroplasty with percutaneous retrieval.4 Bose et al.4 captured the fragment with a snare catheter and surgically retrieved it from the femoral vein.
In our patient, as well as the major accumulation, percutaneously retrieved, multiple pulmonary embolizations occurred. These, together with the patient's lung condition, influenced the outcome.
In addition to the embolism-occlusion process, we describe a fatal outcome to respiratory distress following surgical embolectomy.3 The MMA microparticles activate the inflammatory-anaphylactic cascade and endothelial permeability is altered with activation of the complement system and liberation of histamine.5, 6
Faced with vertebroplasty complicated by a pulmonary event, this type of embolism should be expected. The process may be severe and the outcome fatal, as in the present case. Accumulations of a certain size can be retrieved percutaneously.
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