Advanced embolization techniques

Migration of sclerosant material to the left renal vein following coil embolisation of a varicocele

Percutaneous testicular varicocele embolisation for symptomatic and subfertile males is often preferred over surgical ligation of the gonadal vein due to its minimally invasive approach and reduced complication rate. Glues, coils, vascular plugs, balloons and sclerosants are used in various combinations to achieve sufficient venous occlusion. Here, we report on the first known case of sclerosant material migration beyond the placement of an embolisation coil for treatment of a varicocele, resulting in a left renal vein thrombus. A man in his 20s presented to the emergency department 2 days following uncomplicated left varicocele embolisation with acute left-sided abdominal pain, found to have sclerosant material causing an ipsilateral non-occlusive left renal vein thrombus with extension towards his inferior vena cava on CT. He was treated with 3 months of anticoagulation and follow-up imaging at 3 months showed resolution of this thrombus without renal impairment.

Single Component Polymers, Polymer Blends, and Polymer Composites for Interventional Endovascular Embolization of Intracranial Aneurysms

Intracranial aneurysm is the abnormal focal dilation in brain arteries. When untreated, it can enlarge to rupture points and account for subarachnoid hemorrhage cases. Intracranial aneurysms can be treated by blocking the flow of blood to the aneurysm sac with clipping of the aneurysm neck or endovascular embolization with embolics to promote the formation of the thrombus. Coils or an embolic device are inserted endovascularly into the aneurysm via a micro-catheter to fill the aneurysm. Many embolization materials have been developed. An embolization coil made of soft and thin platinum wire called the "Guglielmi detachable coil" (GDC) enables safer treatment for brain aneurysms. However, patients may experience aneurysm recurrence because of incomplete coil filling or compaction over time. Unsatisfactory recanalization rates and incomplete occlusion are the drawbacks of endovascular embolization. So, the fabrication of new medical devices with less invasive surgical techniques is mandatory to enhance the long-term therapeutic performance of existing endovascular procedures. For this aim, the current article reviews polymeric materials including blends and composites employed for embolization of intracranial aneurysms. Polymeric materials used in embolic agents, their advantages and challenges, results of the strategies used to overcome treatment, and results of clinical experiences are summarized and discussed.

Vascular occlusion with 0.035-inch hydrogel expandable coils in congenital heart diseases and vascular anomalies

BACKGROUND

We present our experience with transcatheter vascular occlusion using 0.035-inch hydrogel expandable coils, which has been reported only in a few cases in the pediatric cardiology fields.

METHODS

This study is a retrospective analysis of all patients who underwent transcatheter embolization with 0.035-inch hydrogel coils at the Department of Pediatrics, Okayama University Hospital, between October 2018 and September 2020.

RESULTS

Twenty patients with a median age of 5.1 years (0.05-26.0 years) and a median weight of 13.8 kg (3.0-56.8 kg) were included. A total of fifty-four 0.035-inch hydrogel coils, including 35 Azur 35 and nineteen Azur CX 35 coils (Terumo, Tokyo, Japan), were successfully deployed in 22 target vessels. The target vessels consisted of 10 aortopulmonary collaterals, 8 veno-venous collaterals, and 4 pulmonary arteriovenous malformations. We achieved technical success in all the target vessels. In total, the mean target vessel diameter was 4.4 mm, the mean number of 0.035-inch hydrogel coils was 2.5 per vessel. The mean device to vessel ratio was 1.6 for the anchor coil and 1.2 for the additional coil. Post-implantation angiograms revealed that the primary occlusion rate was 18/22 (82%). There were no periprocedural complications.

CONCLUSIONS

The 0.035-inch hydrogel expandable coils are effective and safe in patients with congenital heart disease and vascular anomalies. These occlusion devices could be valuable options for interventional pediatric cardiologists.

Determination of the Frequency of Right and Left Internal Mammary Artery Embolization in Single Ventricle Patients: A Two-Center Study

Embolization of systemic to pulmonary artery collaterals to regulate pulmonary arterial flow or pressure of the cavopulmonary circulation in patients with single ventricle is a common practice. The relative incidence and impact of this practice on future interventions like coronary artery bypass grafting is poorly understood. This study aims to evaluate the frequency and implications of internal mammary artery (IMA) embolization in the single ventricle (SV) population. A retrospective chart review was performed of SV patients who underwent cardiac catheterization before and after Fontan procedure between February 2007 and 2017. Data were collected from two tertiary care centers in the Midwest. Of the 304 SV patients, 62 (20.4%) underwent embolization of one or more IMAs, whereas 242 (79.6%) did not. The rate of embolization of IMA was 40.5% in one center and 14.5% in the second center. Among patients who received IMA embolization, left internal mammary artery (LIMA) embolization was seen in 6 (9.7%) patients. Majority of patients underwent either right internal mammary artery (RIMA) embolization (n = 25; 40.3%) or RIMA and LIMA embolization (n = 27; 43.5%). IMA embolization in SV patients is common. Embolizing IMAs early in life will likely eliminate a valuable graft option for coronary artery bypass grafting should it be required in the future care of these patients. Multi-center, prospective, nation-wide studies are warranted to examine coronary artery disease in the SV population and true frequency of IMA embolization. Delineation of which IMAs were embolized is a necessary in surgical and cardiac intervention national data, such as Society of Thoracic Surgeons (STS) database. All measures should be taken to preserve IMAs patency, if deemed feasible and safe.

Design and biocompatibility of endovascular aneurysm filling devices

The rupture of an intracranial aneurysm, which can result in severe mental disabilities or death, affects approximately 30,000 people in the United States annually. The traditional surgical method of treating these arterial malformations involves a full craniotomy procedure, wherein a clip is placed around the aneurysm neck. In recent decades, research and device development have focused on new endovascular treatment methods to occlude the aneurysm void space. These methods, some of which are currently in clinical use, utilize metal, polymeric, or hybrid devices delivered via catheter to the aneurysm site. In this review, we present several such devices, including those that have been approved for clinical use, and some that are currently in development. We present several design requirements for a successful aneurysm filling device and discuss the success or failure of current and past technologies. We also present novel polymeric-based aneurysm filling methods that are currently being tested in animal models that could result in superior healing.

[Endovascular treatment of pulmonary sequestration with Amplatzer® vascular plugs]

Pulmonary sequestration is a rare malformation characterised by non-functioning lung tissue, separated from the tracheobronchial tree and with arterial supply from the systemic circulation. The classical therapeutic approach is surgical resection. In recent years, the endovascular embolisation technique is increasingly being used for the treatment of this disease. The embolisation materials used are coils and vascular plugs. The Amplatzer® vascular plug is a self-expandable cylindrical mesh device, particularly useful for the embolisation of large vessels with high flow. Three cases of pulmonary sequestration were treated by embolisation with Amplatzer® vascular plugs. In all cases the procedure was performed without complications, and the aortopulmonary collateral vessels were completely occluded. Our study provides new data on the safety and efficacy of pulmonary embolisation with Amplatzer® vascular plugs, and its preference over coils in the embolisation of large vessels.