Temporary stent placement with concurrent chemoradiation therapy in patients with unresectable oesophageal carcinoma: is there an optimal time for stent removal?

Objective

To investigate the influence of the timing of stent removal on the outcome of temporary stent placement with concurrent chemoradiation therapy in patients with unresectable oesophageal carcinoma.

Methods

Retrospective analysis was performed on 52 patients undergoing temporary stent placement. Stents were electively removed within 4 weeks in 15 patients (group A), 4–6 weeks in 17 patients (group B) and after 6 weeks in 20 patients (group C). Recurrent symptoms after stent removal, dysphagia score and overall survival periods were compared among the groups.

Results

Stent placement and removal were technically successful in all patients. The dysphagia score was significantly improved in all groups (P?<?0.001). In 19 patients (36 %), recurrent symptoms occurred 15–441 days after stent removal. In group A, recurrent obstruction was significantly higher than in groups B (P?=?0.049) and C (P?=?0.019). Incidence of oesophago-respiratory fistulas in group C was significantly higher than in group A (P?=?0.027). There was no significant difference in survival periods.

Conclusion

The ideal time for stent removal likely falls between 4 and 6 weeks following the start of palliative CCRT allowing the temporary stents to relieve dysphagia effectively in patients with unresectable oesophageal carcinoma.

Key Points

? Stents are usually required for unresectable oesophageal carcinoma ? Optimal timing of stent removal is 4–6 weeks after starting palliative CCRT. ? Early stent removal (<4 weeks) is associated with higher recurrence rates. ? Delayed stent removal (>6 weeks) is associated with greater oesophago-respiratory fistula development.     

Retrograde or antegrade double-pigtail stent placement for malignant ureteric obstruction?

AIM: To determine the optimum approach for double-pigtail stent placement in malignant ureteric obstruction. PATIENTS AND METHODS: Retrograde stent placement was attempted in a consecutive series of patients presenting with malignant ureteric obstruction. If retrograde stent placement was unsuccessful, percutaneous nephrostomy was performed immediately followed by elective antegrade stent placement. Identical digital C-arm fluoroscopy for image-guidance and conditions for anaesthesia and analgesia were employed for both retrograde and antegrade procedures. Identical 8 Fr (20-26 cm) double-pigtail hydrophilic coated stents were used for each approach. RESULTS: Retrograde placement was attempted in 50 ureters in 30 patients {19 male, 11 female, average age 61.4 yr (range 29-90 yr)} over a 24-month period. The success rate for retrograde ureteric stent placement was 50% (n = 25/50). Technical failures were due to failure to identify the ureteric orifice (n = 22), failure to cross the stricture (n = 1), failure to pass the stent (n = 1) and failure to pass a 4 Fr catheter (n = 1). Antegrade placement was attempted in 25 ureters with a success rate of 96% (n = 24/25). Failure in the one case was due to inability to cross an upper third stricture secondary to pyeloureteritis cystica. CONCLUSION: It is suggested that retrograde route should be the initial approach if imaging shows no involvement of ureteric orifice (UO), when nephrostomy is technically very difficult or in cases of solitary kidney. The antegrade route is preferred if imaging shows tumour occlusion of the UO or if there is a tight stricture very close to the uretero-vesical junction (UVJ) making purchase within the ureter difficult for crossing the stricture.     

Management of an acquired renal arteriovenous fistula with a vein-covered stent

A patient is presented who developed a renal arteriovenous fistula as a result of a percuta-neous nephrolithotomy procedure.This was successfully treated with the pereutaneous,intra-arterial insertion of vein covered 6 mm Pahnaz stents.The advantage of this technique is the preservation ofnormal renal parenehyma otherwise lost using intra-arterial embolization or surgery.     

Management of aorto-iliac occlusive vascular disease with the Memotherm self-expanding nitinol stent

This study reports on the application of the Memotherm nitinol self- expanding endovascularstent in the treatment of aorto-iliac occlusive vascular disease.Since it was released on the UK market inMarch 1994,the author has deployed 107 stents during 72 patient procedures,treating a total of 77 le-sions in 71 different patients.The lesions consisted of 21 total occlusions and 56 stenoses.The indicationfor stenting was primary in 83% of the lesions and seconday to unsatisfactory PTA in the remainder.Primary procedure success,defined as suceessful stent delivery combined with satisfactory arterial pa-tency,was achieved in 97%(n=75)of the lesions.Technical difficulties during deployment were ex-perienced with 3 stents(<3%).Complications were limided to 1 post-stent thrombosis and 6 minorgrion haematomata.Postprocedure assessment included clinical examination.A/B pressure ratios andpatient questionnaire.Clincal improvement in patient symptolns was recorded in 96% of the lesions.Based on these results and on additional personal experience of 125 stents of alternative design,the authorconcludes that the Memotherm nitinol stent represents a significant technical advance in stent design,facilitating the successful management of more complex and extensive aorto-iliac pathology.     

Noninvasive inductive stent heating: alternative approach to prevent instent restenosis?

RATIONALE AND OBJECTIVES: To test noninvasive inductive heating of implanted vascular stents as an alternative approach for reduction or prevention of neointimal hyperplasia. METHODS: Calorimetric pretests were performed to get an orientation on the different parameters of influence for inductive heating of stents. The field strength was set to a maximum of 90 kA/m within a frequency range from 80 kHz to 320 kHz. The electromagnetic field was emitted by a custom-made water-cooled copper winding antenna. A flow model for stent heating was set up to assess the increase in temperature of an expanded 316L stainless steel stent with typical coronary stent dimensions of 3.5 mm diameter and 14.5 mm in length, and in a second setup with 4.5 mm diameter and 13 mm in length, respectively. The stent was located in a bioartificial artery, simulated by a fibrinogen matrix with a defined number of vital cells. The system was exposed to a pulsating perfusion and to an electromagnetic field of 200 kHz over a period of 20 minutes and in a second setup to an electromagnetic field of 300 kHz and increasing intensity up to maximum power-output. Afterward, the artificial vessel was sliced and examined by fluorescence microscopy to evaluate the number and location of damaged cells. RESULTS: The calorimetric tests show an exponential correlation of energy uptake in the stent with an increase in frequency and a constant generator output. At a frequency of 80 kHz, the power uptake accounts for 0.1 W (250 kHz 1.0 W; 320 kHz 1.9 W, respectively). The flow tests confirmed feasibility to elevate the stent temperature from 37 degrees C body temperature to 44 degrees C at 200 kHz within 55 seconds. The temperature increase of the fluid passing the heated vessel region was only marginal (maximum of 0.5 degrees C). Cell necrosis after 20 minutes of treatment was not observed. In a second set-up with 4.5 mm stent diameter, a frequency of 300 kHz and with maximum power output, the stent temperature was increased to 80 degrees C and there was extensive necrosis area around the stent. Treatment time and stent temperature were optimized in further tests. CONCLUSION: Selective noninvasive energy transfer to coronary stainless steel stents by inductive heating is possible within a wide range of power. By thermal conduction, vital cells close to the stent struts can be affected. The frequency of 200 kHz turned out to be favorable. There is still room for further optimization of energy dosage with regard to material and stent design, to induce controlled cell death. The method has potential to serve as an alternative approach for prevention of instent restenosis.     

Is there improvement of "vascular depression" after carotid artery stent placement?

PURPOSE: To prospectively evaluate if high-grade (> or = 80% luminal narrowing) internal carotid artery stenosis is associated with depressive symptoms and if carotid artery stent placement (CAS) potentially improves depressive symptoms. MATERIALS AND METHODS: The study was approved by the local ethics committee, and informed consent was obtained from all subjects. One hundred forty-three patients (91 men, 52 women; interquartile range, 63-76 years) undergoing CAS because of asymptomatic high-grade (> or = 80% luminal narrowing) carotid artery stenosis and 102 control subjects (64 men, 38 women; interquartile range, 63-73 years) with advanced peripheral artery disease and without carotid artery stenosis undergoing lower-limb percutaneous transluminal angioplasty were included. Substantial depressive symptoms (defined as a Beck Depression Inventory score of 10 or higher) were recorded at baseline and at 4 weeks (follow-up) after the percutaneous procedures. The chi2 test, Mann-Whitney U test, McNemar test, Wilcoxon rank sum test, and two-group t test were used to check for statistical significance. RESULTS: A significantly higher prevalence of depressive symptoms was found in patients with carotid artery stenosis than in control subjects with peripheral artery disease at baseline (33.6% vs 16.7%, P = .003). At follow-up, a significant reduction of depressive symptoms was found in patients who underwent CAS (33.6% vs 9.8%, P < .001). The frequency of depressive symptoms remained unaffected in control subjects (16.7% vs 13.0%, P = .1). CONCLUSION: High-grade carotid artery stenosis is associated with depressive symptoms in patients with atherosclerosis. CAS seems to exert beneficial effects on the course of depressive symptoms in these patients.     

Coronary–subclavian steal syndrome: treatment with percutaneous transluminal angioplasty and stent placement

The aim of this study was to assess the efficacy of percutaneous transluminal angioplasty (PTA) and stenting in the management of the coronary-subclavian steal syndrome (CSSS). A 56-year-old man presented with CSSS due to occlusion of the left subclavian artery. He was treated with PTA and placement of two stents in the left subclavian artery. Systolic blood pressure became equal in both arms and dizziness disappeared. There were no complications. Percutaneous transluminal angioplasty and stenting can effectively and safely manage CSSS. Received: 6 May 1998; Revision received: 22 July 1998; Accepted: 12 August 1998     

Strecker stent migration to the pulmonary artery: long-term result of a “wait-and-see attitude”

Accidental dislodgement of an endoprosthesis into the right cavities or the pulmonary artery is a rarely described complication of percutaneous venous stenting. In such cases the migrated stent needs to be promptly extracted by percutaneous techniques in order to avoid any major complication. We report the first case of a delayed Strecker stent migration from the left inominate vein into the right pulmonary artery, successfully managed with anticoagulant therapy and a “wait-and-see” attitude. The advanced stage-disease (metastatic cancer patient) and the large-caliber stent in a disease-free pulmonary artery led us to adopt this unorthodox attitude, as compared with the current clinical practice. Received: 26 May 2000 Revised: 11 August 2000 Accepted: 11 August 2000     

Angiographic CT: in vitro comparison of different carotid artery stents—does stent orientation matter?

Introduction

Our aim was to evaluate the in vitro visualization of different carotid artery stents on angiographic CT (ACT). Of particular interest was the influence of stent orientation to the angiography system by measurement of artificial lumen narrowing (ALN) caused by the stent material within the stented vessel segment to determine whether ACT can be used to detect restenosis within the stent.

Methods

ACT appearances of 17 carotid artery stents of different designs and sizes (4.0 to 11.0 mm) were investigated in vitro. Stents were placed in different orientations to the angiography system. Standard algorithm image reconstruction and stent-optimized algorithm image reconstruction was performed. For each stent, ALN was calculated.

Results

With standard algorithm image reconstruction, ALN ranged from 19.0 to 43.6 %. With stent-optimized algorithm image reconstruction, ALN was significantly lower and ranged from 8.2 to 18.7 %. Stent struts could be visualized in all stents. Differences in ALN between the different stent orientations to the angiography system were not significant.

Conclusion

ACT evaluation of vessel patency after stent placement is possible but is impaired by ALN. Stent orientation of the stents to the angiography system did not significantly influence ALN. Stent-optimized algorithm image reconstruction decreases ALN but further research is required to define the visibility of in-stent stenosis depending on image reconstruction.     

Clinical safety of cardiac magnetic resonance imaging at 3 T early after stent placement for acute myocardial infarction

The purpose of this study was to prospectively evaluate the safety of cardiac magnetic resonance (CMR) imaging at 3 T performed early (less than 14 days) after bare metal or drug-eluting coronary stent implantation in patients with acute myocardial infarction (AMI). Seventy-two consecutive patients with AMI treated by percutaneous revascularisation with a stent underwent CMR examination with a median delay of 6 days. Patients were followed-up for major adverse cardiac events, during hospitalisation and at 6 months. After CMR imaging, no acute stent thrombosis, death or repeated AMI were recorded at 6-month follow-up. Two symptomatic in-stent restenoses and two silent in-stent restenoses were recorded, at a mean delay of 106 days. In our population, we found a target revascularisation rate of 5.6%. This is consistent with the 6-month event rates after coronary artery stent (CAS) placement for AMI, evaluated by several studies. This preliminary clinical study supports the safety of 3-T CMR imaging performed early after coronary stent placement.     

Angioplasty or stent placement in the proximal common iliac artery: is protection of the contralateral side necessary?

PURPOSE: To determine if protection of the contralateral common iliac artery is necessary when performing angioplasty or stent placement in a proximal common iliac artery. MATERIALS AND METHODS: A retrospective review of all patients undergoing endovascular treatment for unilateral common iliac artery stenosis or occlusion from 1979 to 2000 was performed. All angiograms were reviewed independently by three experienced vascular interventional radiologists who evaluated both common iliac arteries before and after angioplasty or stent placement. RESULTS: The medical records or angiograms of 514 patients were located. Of these, complete records and angiograms were found for 175 patients who underwent proximal (within 2 cm of its origin) common iliac artery angioplasty or stent placement without treatment or protection of the contralateral common iliac artery. Treatment of proximal common iliac stenosis in 160 patients resulted in luminal compromise of the contralateral common iliac in two patients (17% and 24% reduction in luminal diameter). No contralateral compromise was noted in 15 patients treated for iliac occlusion. CONCLUSION: The data reported herein suggest that protection of the contralateral common iliac artery during angioplasty or stent placement in a proximal common iliac artery is not mandatory.     

Mechanical properties of metallic stents: How do these properties influence the choice of stent for specific lesions?

Purpose: To assess selected balloon-expandable and self-expanding stents for radial force, flexibility, radio-opacity, and trackability, and to relate these physical characteristics to potential indications for placement. Methods: Force–strain curves were plotted for each stent and the force required to produce 50% luminal narrowing was recorded. The ability of the stent to show elastic recoil following deformation was also noted. Flexibility was measured by bending the stents against a force transducer and recording the force required per degree of flexion. Radio-opacity was measured by comparing each stent against a standard aluminum step wedge. Trackability was measured by testing the ability of the stent on its delivery system to track over angles of 90° and 60°. Results: The balloon-expandable stents showed greater radial strength and radio-opacity but, apart from the AVE Iliac Bridge stent, showed poorer flexibility and trackability. The self-expanding stents showed less radial force but were able to re-expand following deformity. They were generally more flexible and had better trackability but lower radio-opacity. Conclusion: There is no stent which exhibits all the ideal properties required and therefore the interventionist will need to keep a range of stents available if all lesions are to be addressed.     

Horizontal stent-assisted coil embolisation of wide-necked intracranial aneurysms with the Enterprise stent—a case series with early angiographic follow-up

Introduction  The purpose of the study is to describe our experience in eight cases of horizontal stenting across the circle of Willis in patients with terminal aneurysms. Methods  Eight patients were treated with horizontal stent placement and aneurysm coiling. All aneurysms had highly unfavourable dome to neck ratios. All patients were followed up with digital subtraction angiography at 3–12 months following treatment. Results  The Enterprise stent was successfully deployed horizontally in vessels of less than 2-mm diameter with no stent occlusion. Neurological complications occurred in one patient. Immediate and follow-up angiographic results were encouraging with six stable occlusions at 6 months. There was one asymptomatic case of in-stent stenosis and one case of late organised in-stent thrombus. Conclusions  Horizontal deployment of the Enterprise stent to assist coil embolisation of wide-necked terminal aneurysms is feasible. This device can be navigated via relatively small communicating arteries, in cases with favourable anatomy. Early angiographic results were favourable; however, longer-term follow-up will be required.