Y-shaped Silicone Research Articles

Expanded range of indications for Neuroform Atlas stent in the treatment of very small, wide-necked cerebral aneurysms

The purpose of this study was to investigate the range of indications for using the Neuroform Atlas stent. Between 2016 and 2020, we treated 20 females and 5 males for aneurysms with a diameter of less than 3 mm and an aspect ratio less than 1.5. The diameter of the parent arteries varied from 1.1 mm to 4.5 mm. There were 13 ruptured and 12 unruptured aneurysms. Double stent-assisted coiling was performed in 14 cases, and single stent-assisted coiling was performed in 11 cases. After deployment, the morphology of the Neuroform Atlas stents was analyzed in tapered or Y-shaped silicone tubes that simulated parent arteries. Radiological results were assessed 7 months and 2 years after the intervention using the Raymond-Roy scale. Clinical outcome was assessed 1 year after the intervention using the modified Rankin score. There were three fatal outcomes. One aneurysm was recoiled. The rate of class I aneurysm occlusion was registered in 21 patients at the last follow-up. At the end of the clinical follow-up period, a favorable outcome (modified Rankin scale 0 –1) was registered in nine patients with ruptured aneurysms. An analysis of the morphology of the stents deployed in the silicone tubes provided an explanation for the stability of the coil mass in the treated aneurysms. Our results suggest that the range of indications for use of the Neuroform Atlas stent can be expanded beyond the present range with regard to the diameter of the parent vessels and size of the aneurysms.

Modified silicone stent for the treatment of post-surgical bronchopleural fistula: a clinical observation of 17 cases

BackgroundBronchopleural fistula is a rare but life-threatening event with limited therapeutic options. We aimed to investigate the efficacy and safety of the modified silicone stent in patients with post-surgical bronchopleural fistula.MethodsBetween March 2016 and April 2020, we retrospectively reviewed the records of 17 patients with bronchopleural fistula and who underwent bronchoscopic placement of the Y-shaped silicone stent. The rate of initial success, clinical success and clinical cure, and complications were analyzed.ResultsStent placement was successful in 16 patients in the first attempt (initial success rate: 94.1%). The median follow-up time was 107 (range, 5–431) days. All patients achieved amelioration of respiratory symptoms. The clinical success rate was 76.5%. Of the 14 patients with empyema, the daily drainage was progressively decreased in 11 patients, and empyema completely disappeared in six patients. Seven stents were removed during follow-up: four (26.7%) for the cure of fistula, two for severe proliferation of granulomatous tissue and one for stent dislocation. No severe adverse events (i.e. massive hemoptysis, suture dehiscence) took place. Seven patients died (due to progression of malignancy, uncontrolled infection, myocardial infarction and left heart failure).ConclusionsThe modified silicone stent may be an effective and safe option for patients with post-surgical bronchopleural fistula patients in whom conventional therapy is contraindicated.

Modified silicone stent for difficult-to-treat massive hemoptysis: a pilot study of 14 cases.

BackgroundMassive hemoptysis is a life-threatening event with limited therapeutic options. Bronchoscopic placement of stents may offer an alternative option for massive hemoptysis. However, traditional silicone stents have not been customized, making it difficult to tailor to individual patient’s needs for achieving optimal hemostasis. To investigate the efficacy and safety of the modified silicone stent in patients with difficult-to-treat massive hemoptysis.MethodBetween May 2016 and November 2018, we enrolled 14 patients who underwent bronchoscopic placement of the modified silicone stent, which was fabricated manually based on the Y-shaped silicone stent by tailoring and suturing on site. We recorded the technical success, clinical success, and complications. Patients were followed up for recording the recurrence of massive hemoptysis and complications.ResultsPlacement of the modified silicone stent was successful in all 14 patients with a mean duration of 69.6 minutes (technical success rate: 100%). After stenting, no further massive hemorrhage episodes recurred in 12 patients (clinical success rate: 85.7%). Two cases suffered from recurrent hemoptysis in 4 and 6 days after stenting, respectively. The main complications were sputum plugging, granuloma proliferation and pulmonary infection such as pneumonia. There were no adverse events of stent migration and suture dehiscence. After a median follow-up of 5.8 (range, 0.3–21.3) months, three patients withdrew and seven patients succumbed. Only one patient died of uncontrolled pneumonia which was possibly related to stent placement.ConclusionsThe modified silicone stent is an effective and safe gate-keeping therapeutic option for difficult-to-treat massive hemoptysis.

Fibrotic airway stenosis following radiotherapy in patients with adenoid cystic carcinoma.

Radiotherapy is usually administered to the central airway in patients with unresectable adenoid cystic carcinoma (ACC). The purpose of this study was to describe the outcomes of endobronchial intervention in patients with airway stenosis following radiotherapy for ACC. Moreover, we investigated the incidence and contributing factors for airway stenosis following radiotherapy for ACC. Forty-seven patients with ACC, who underwent radiotherapy of the tracheobronchial tree from January 1995 to December 2011, were reviewed retrospectively. Fibrotic airway stenoses were diagnosed using three-dimensional computed tomography, flexible bronchoscopy or both. Eleven (23%) of the 47 patients with ACC suffered fibrotic airway stenosis following radiotherapy and received bronchoscopic intervention. The median interval from radiotherapy to diagnosis of fibrotic airway stenosis was 7 months. Low forced expiratory volume in 1 s (FEV1), FEV1 /forced vital capacity and brachytherapy were verified as factors contributing to radiotherapy-induced airway stenosis. Bronchoscopic intervention provided both symptomatic relief and improvement of lung function, and no procedure-related death or major complication was observed. Insertion of a straight silicone stent was required in 10 patients (91%), and 4 (36%) eventually received Y-shaped silicone stents. The stents, once implanted, could not be removed in any of the patients; stents were well-tolerated for a prolonged period in all patients. Fibrotic airway stenosis following radiotherapy in patients with ACC is often found. Bronchoscopic intervention, including silicone airway stenting, was a safe and useful method for treating radiotherapy-induced fibrotic airway stenosis in patients with ACC.

Compact Polarization Beam Splitter Based on Surface Plasmon Polariton Silicon Waveguide

A compact polarization beam splitter (PBS) based on a silicon waveguide-silver nanoribbon-silicon waveguide is proposed and demonstrated numerically by utilizing the evanescent coupling between a strip-nanowire and a nanoslot waveguide. Two-dimensional (2-D) FDTD simulations were performed to elucidate the properties of surface plasmon polaritons (SPPs) in this device made from silicon-metal-silicon, and were found to agree well with the theoretical predictions. TE and TM polarized light are respectively separated into two different output ports of Y-shaped silicon waveguide in which the coupling efficiency is 62% and 45% for 1.55μm wavelength, respectively. The proposed PBS structure could be utilized to develop ultracompact optical polarization modulating device for large-scale photonic integration and optical information processing.

A Novel Effective Y-Shaped Silicon Stent for Treating Canalicular Laceration

Purpose: To introduce the novel effective Y-shaped silicon stent for treating canalicular laceration. Methods: Fifty-four canalicular laceration cases (54 eyes) underwent the lacrimal surgery using the novel Y-shaped silicon stents were collected, and the stents were removed 3 months after surgery. All cases were followed up for 12 months. The operability of stenting and removing the stent were assessed. The data we collected during each follow-up are: stent position and integrity, aesthetic results, the discomfort, the symptom of epiphora, the patency of lacrimal passage, complications, and patient’s satisfaction. Results: The stenting time was 14.3±5.8 min and the time of removing it was 1.8±0.5 min. Both of the operability of stenting and removing were accessed to be easy in more than 94.4% cases. All stents were in position and integrated. 51 cases (94.4%) had no problems on aesthetic results. Three patients (5.4%) complained about the discomfort. Two cases (3.7%) had the symptom of epiphora, which were obstructed after removing the stents. Fifty-two cases (96.3%) were with patent canaliculus and satisfied with the surgery and symptom improvement. Only 5 cases (9.3%) had complications. Conclusion: The novel Y-shaped silicon stent is an effective stent for treating canalicular laceration.

Successful Silicon Stent for Life-Threatening Tracheal Wall Laceration

We report an 86-year-old woman with a large tracheal laceration caused by tracheal intubation at cardiopulmonary arrest who underwent a successful stent procedure. Tracheal laceration developed in the membranous portion longitudinally 6 cm in length to 2 cm above the carina. Following 9 days' tracheal intubation, a Y-shaped silicon stent was inserted over the lacerated trachea. Four months after the stenting procedure, we removed the Y-shaped silicon stent from the healed membranous wall. The patient returned to daily life without requiring thoracotomy.

Tracheobronchoplasty for the treatment of tracheobronchomalacia

Patients with tracheobronchomalacia (TBM) typically present with dyspnea, recurrent infections, intractable cough, or retained secretions. Airway stabilization may be accomplished with silicone stenting, which provides patients with symptom relief in a minimally invasive manner. However, this technique is not without complications, which mostly occur by 3 weeks. Surgical stabilization is the definitive treatment of TBM. We review the evaluation of TBM and options for treatment.

Theoretical Study of Atomic Structure and Elastic Properties of Branched Silicon Nanowires

The atomic structure and elastic properties of Y-shaped silicon nanowires of "fork"- and "bough"-types were theoretically studied, and effective Young moduli were calculated using Tersoff interatomic potential. The oscillation of fork Y-type branched nanowires with various branch lengths and diameters was studied. In the final stages of the bending, the formation of new bonds between different parts of the wires was observed. It was found that the stiffness of the nanowires is comparable with the stiffness of Y-shaped carbon nanotubes.

Clinical Application of the Natural Y Stent in the Management of Benign Carinal Stenosis

The Y-shaped structure of the carinal bifurcation causes difficulties in the treatment of carinal stenosis. We describe a new Y-shaped silicone stent, called the Natural Y stent. We investigated its clinical efficacy through a review of patients with benign carinal stenosis who undewent consecutive Natural Y stent placement. Between January 2004 and February 2008, 11 patients underwent ballooning, neodymium:yttrium-aluminum-garnet laser resection, or bougienation (by rigid bronchoscopy) to dilate the airway, followed by placement of the Natural Y stent. The underlying etiologies of carinal stenosis included posttuberculosis stricture in 7 patients (64%), postintubation stenosis in 2 (18%), and postoperative malacia in 2 (18%). All patients reported subjective symptomatic relief immediately after stent placement. No procedurally related deaths or immediate major complications occurred. Stent-related late complications included granulation tissue formation (64%) and mucostasis (18%, defined as > or = 50% narrowing). The median duration of overall stent placement was 439 days (range, 119 to 1729 days). The stents were successfully removed in 4 patients (36%) after a median of 409 days. The Natural Y stent provides an effective and feasible therapeutic modality in patients with benign carinal stenosis, with or without previous thoracic airway interventions.

Synthesis of straight Y-shaped SiO x nanorods by a simple thermal evaporation method

The straight Y-shaped silicon oxide [ SiO x ( 1 < x < 2 )] nanorods have been synthesized on Si wafers by thermal evaporation of mixed powders of silica and carbon nanofibers at 1300 ∘C and condensation on an Si substrate without assistance of any catalyst. The synthesized products were characterized by means of scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, and Raman spectrum. The results suggested that the straight Y-shaped nanorods are amorphous and consist only of silicon oxide, and these rods with diameters about 50–200 nm have a neat smooth surface. The growth of such silicon oxide nanorods may be a result of the second nucleation on the surface of rods causing a change in the growth direction of silicon oxide nanorods developed.

Multistep endobronchial-endovascular approach in recurrent acute respiratory failure caused by thoracic aneurysm

Clinical Summary A 78-year-old man with a history of TAA was admitted to the emergency department because of recurrence of respiratory failure. He was unconscious, with cyanosis and severe hypertension (220/ 120 mm Hg). On thoracic examination, wheezes were heard at the lower third of the left lung. Arterial blood gas analysis revealed an arterial oxygen partial pressure of 40 mm Hg, a carbon dioxide partial pressure of 120 mm Hg, and a pH value of 6.93. The patient was intubated and mechanically ventilated. Preoperative chest radiography and computed tomography showed a large aortic aneurysm with compression of the tracheobronchial tree (Figure 1). Fiberoptic bronchoscopy confirmed extrinsic compression of the trachea just proximal to the carina and a significant narrowing of the left main bronchial branch 3 to 4 mm below the carina. After stabilization, the patient was weaned by using sedatives and extubated. Because of coexisting disease (coronary artery disease, renal insufficiency, and chronic obstructive pulmonary disease), which made the patient not an ideal operative candidate, a multistep endobronchial-endovascular intervention was planned. In the first step the patient continued to spontaneously breathe. Sedation was achieved with intravenous remifentanil (0.1 g · kg 1 · min ) and propofol (3 mg · kg 1 · h ). A 14-mm covered endobronchial Nitinol stent (Ultraflex stent; Boston Scientific CO, Natick, Mass) was placed in the left main bronchus with the aid of a rigid bronchoscope. A second 13-mm Y-shaped silicon stent (Tracheobronxane; Novatech, Plan de Grasse, France) was placed in the carina and right main bronchus (Figure 2, A and B). In the second step the patient was placed in the supine decubitus position on a radiolucent table and draped sterilely for emergency left thoracotomy in case serious complications ensued. Cardiopulmonary bypass standby was available. General anesthesia was induced with intravenous remifentanil (0.5 g · kg 1 · min ), propofol (2 mg · kg 1 · h ), and cisatracurium (200 g · kg ) and maintained with remifentanil (0.25 g · kg 1 · min ), propofol (3 mg · kg 1 · h ), and cisatracurium (1.7 g · kg 1 · min ). Two 3636 C114T Medtronic Talent stent grafts (Medtronic, Santa Rosa, Calif) were implanted (Figure 2, A) by using the standard technique. The endotracheal tube was removed 2 hours later, and the patient was dismissed from the intensive care unit on postoperative day 1 and discharged on postoperative day 2 after an uncomplicated course. In the third step, on postoperative day 15, the carinal stent was removed, and a new stent (Polyflex stent; W. Rusch AG, Kernen, Germany) was positioned in the trachea (Figure 2, C). In the fourth step, on postoperative day 147, the tracheal stent was removed. A left main bronchus metal stent was left in place. At 1 year of follow-up, the patient is alive and functions independently. He remained asymptomatic, and no further episode of respiratory distress occurred (Figure 2, D).

Neurohistochemical analysis of regeneration in rat peripheral nerve after end-to-side neurorrhaphy

We investigated the regenerative capacity of motor nerves repaired by end-to-side or end-to-end neurorrhaphy, using choline-acetyltransferase (ChAT) activity measurement or histological analysis. The right medial gastrocnemius nerves (MGNs) of 62 male Fisher strain rats were transected and divided into three groups. In group 1, the distal ends of the MGN were coapted to the side of the lateral gastrocnemius nerve, using a Y-shaped silicone tube in end-to-side neurorrhaphy. In group 2, the nerve ends were reconnected by the traditional end-to-end technique. In group 3, the nerve ends were separated and remained unrepaired. The MGNs were sampled 1, 2, and 3 months postoperatively for histological examinations and ChAT activity measurement. The medial gastrocnemius muscle (MGM) was also sampled for histological evaluations. Axonal regeneration of MGN and the recovery of MGM to nearly normal histology and weight were observed in groups 1 and 2 3 months postoperatively. Although there were no significant differences in ChAT values between groups 1 and 2, the values were significantly larger than that of group 3 3 months postoperatively. These findings suggested that end-to-side neurorrhaphy would be an alternative treatment for peripheral nerve injury in certain clinical situations.

Collateral sprouting mechanism after end-to-side nerve repair in the rat.

The collateral sprouting mechanisms of axons from an uninjured donor nerve after end-to-side nerve repair was investigated in motor nerves of rats, with special reference to the neurotrophins related to nerve regeneration. In addition, growth cone formation at the tip of the regenerating nerve was examined. A transected medial gastrocnemius nerve (MGN) was transferred to the side of an intact lateral gastrocnemius nerve (LGN) using a Y-shaped silicone tube. At 3, 7, or 14 days later, the MGN with the LGN was transected and was stained immunohistologically. Expression of neurotrophin-3 (NT-3) and Trk C (receptor of NT-3) was most significantly observed 3 days postoperatively around the site of coaptation. Brain-derived neurotrophic factor (BDNF) and Trk B (receptor of BDNF) was weakly detected at the coaptation site 3 days after-operation. Growth-associated protein 43 (GAP-43), which is a marker of growth cone formation, was observed at the site of coaptation in the LGN 7 days postoperatively and in the MGN at the site of coaptation at 14 days. We concluded that motor nerve regeneration due to collateral sprouting of axons after end-to-side nerve repair is possible. We thus demonstrated the involvement of at least one neurotrophin, NT-3, in the process of collateral sprouting of motor nerves.

Emergency stenting of malignant obstruction of the upper airways: long-term follow-up with two types of silicone prostheses.

We report on 10 patients with severe malignant "mixed-type" obstruction of the proximal trachea or distal trachea plus both main stem bronchi. They had far-advanced inoperable tumors (esophageal cancer in 4 patients, lung cancer in 3, and recurrent laryngeal, uvular, and thyroid cancers in 1 each). Emergency treatment consisted of a dilating bougie maneuver followed by the insertion of a large one-way (4 patients) or Y-shaped (6) silicone prosthesis. Subsequent to the intervention, there was long-lasting clinical improvement. The median survival from stent insertion was 8 months for all patients irrespective of tumor type; it was 5 months for lung carcinoma patients and 8 months for those with esophageal cancer. The results are in accordance with those of other studies using different therapeutic modalities. Stent exchange proved necessary in 5 patients. The main reasons were continuing tumor growth beyond the proximal and distal boundaries and recurrent productive bronchial infection. Patients died of pneumonia (4 patients), pulmonary lymphangitic spread (1), heart failure (2, one of whom also had pneumonia), and fatal hemorrhage (1). As of December 1995, 3 patients were still alive, 2, 5, and 8 months after stent implantation. As evidenced by clinical efficacy and length of palliation, endoscopic placement of silicone-based one-way and bifurcated prostheses in far-advanced tumor of the central airways is technically feasible and ethically justifiable.

Experimental study of hypoglossal facial anastomosis and accessory-facial anastomosis in guinea pigs

Hypoglossal facial nerve anastomosis (XII-VII anastomosis) or accessory-facial anastomosis (XI-VII anastomosis) have been chosen for facial rehabilitation when the facial nerve is widely sacrificed and end-to-end anastomosis or nerve grafting is unavailable. However, no detailed study has been conducted to determine which donor nerve is better for the anastomosis procedure in view of regeneration of the facial nerve. To compare and evaluate nerve regeneration after XII-VII anastomosis and XI-VII anastomosis, animal models of these anastomoses were made in guinea pigs by using a Y-shaped silicon tube. The proximal cut-ends of the hypoglossal nerve and accessory nerve were suspended in the paired inlet limbs of a Y-shaped silicone tube with a 9-0 nylon suture, and the distal cut-end of the facial nerve was suspended in the single outlet limb in a similar manner. After 4 and 8 weeks, histological studies were carried out. An electrophysiological study of conduction velocity and amplitude of evoked electromyography were measured at 8 weeks postoperation. The nerve fibers regenerated from the hypoglossal nerve were significantly more numerous than those from the accessory nerve at both 4 and 8 weeks after anastomosis. The amplitude of evoked electromyography elicited from the hypoglossal nerve was greater than that from the accessory nerve, even though there is no significant difference in conduction velocities between the two anastomoses. The nerve regeneration by the cross-over procedure was influenced by many factors such as the number of nerve fibers in the donor nerve and the affinity between donor and recipient nerves. The number of nerve fibers in the hypoglossal nerve was significantly greater than that in the accessory nerve. However, there was no significant difference in the ratios of regenerated nerve fibers to the preoperative nerve fibers. Accordingly, we concluded that the affinity of the hypoglossal or accessory nerve to the facial nerve is a minor factor if it exists, and the difference in the fiber count in these nerves is a major factor in the outcome of nerve regeneration.

Emergency stenting of malignant obstruction of the upper airways: Long-term follow-up with two types of silicone prostheses*

Objective: We evaluated the long-term prognosis of stents placed on an emergency basis in the trachea and its bifurcation for malignant stenosis. Methods: We retrospectively analyzed all bronchologic treatments of obstructing airway lesions from January 1993 to December 1995. Results: We report on 10 patients with severe malignant "mixed-type" obstruction of the proximal trachea or distal trachea plus both main-stem bronchi. They had far-advanced inoperable tumor (esophageal cancer: n = 4; lung cancer: n = 3; recurrent laryngeal, uvula, and thyroid cancer: n = 1 each). Emergency treatment consisted of a dilating bougie maneuver followed by the insertion of a large one-way ( n = 4) or Y-shaped silicone prosthesis ( n = 6). After the intervention, there was a long-lasting clinical improvement. Median survival from stent insertion was 8 months for all patients irrespective of tumor type; it was 5 months for patients with lung carcinoma and 8 months for those with esophageal cancer. The results are in accordance with other studies using different therapeutic modalities. Stent exchange was necessary in five patients. Main reasons were continuing tumor growth beyond the proximal and distal boundaries and recurrent productive bronchial infection. Patients died of pneumonia ( n = 4), pulmonary lymphatic spread ( n = 1), cardiac failure ( n = 2), and fatal hemorrhage ( n = 1). As of December 1995, three patients were still alive 2, 5, and 8 months after implantation. Conclusions: As evidenced by clinical efficiency and length of palliation, endoscopic placement of silicone-based one-way and bifurcational prostheses in far-advanced tumor of the central airways is technically feasible and ethically justifiable. (J T HORAC C ARDIOVASC S URG 1996;112:859-66)

Partial Splenic Embolization with Y-Shaped Silicone Particles

We have developed an embolizing material consisting of Y-shaped silicone particles for partial splenic embolization. Wide spaces for blood flow are left around the particles when these are lodged in arterial branches. We embolized one kidney in each of 3 dogs with the particles and observed a slowly induced occlusion of renal arterial branches during one month. The particles were also used for partial splenic embolization in 14 patients. The average portion of infarcted spleen tissue 7 days after embolization was 51% calculated from CT images. In 6 patients who had CT both 2 and 7 days after embolization, the average rate of splenic infarction increased from 29% at 2 days to 60% at 7 days. Our patients required analgesics for only 2.3 days on average. The Y-shaped silicone particles by slowly occluding splenic arterial branches produce ischemia in a gradual fashion which may minimize the pain after embolization.

Partial Splenic Embolization with Y-Shaped Silicone Particles

Partial Splenic Embolization with Y-Shaped Silicone Particles

Partial Splenic Embolization with Y-Shaped Silicone Particles

Partial Splenic Embolization with Y-Shaped Silicone Particles