Stent fracture in revascularization for symptomatic ostial vertebral artery stenosis

Using drug-coated balloons for symptomatic vertebral artery origin stenosis: A systematic review and meta-Analysis

BACKGROUND

Endovascular stenting has emerged as an effective treatment for patients with symptomatic vertebral artery origin stenosis (VAOS), but the incidence of severe restenosis is concerning. Angioplasty alone with a drug-coated balloon (DCB) is a potential treatment for VAOS. The purpose of this systematic review and meta-analysis was to assess the utility of DCB angioplasty for VAOS.

METHODS

A systematic search of the Medline (PubMed), Embase, CNKI, and Cochrane databases for studies on the treatment of VAOS by DCB angioplasty published in English and Chinese before June 15, 2022 was conducted. Data were extracted using standardized methods. The incidence rates of restenosis, technical success, and perioperative complication in the follow-up period were pooled using Freeman-Tukey double arcsine transformation with random or fixed-effect models. Tests for heterogeneity and publication bias were performed.

RESULTS

A total of seven studies containing 159 patients were included in this review and meta-analysis. The pre-treatment stenosis rate of the vertebral artery in the DCB group ranged from 70.0 % to 86.3 %, and the median follow-up time ranged from 6.0 to 14.1 months. The pooled restenosis incidence was 11.9 % (95 % CI: 3.4 %-23.4 %; I² = 59 %, p = 0.02) during the follow-up period. The pooled technical success rate was 96.6 % (95 % CI: 91.4 %-99.7 %; I² = 37 %, p = 0.14). The overall perioperative complication rate was 2.9 % (95 % CI: 0.3 %-6.9 %; I² = 0 %, p = 0.64). According to the funnel diagram and Egger's test, there was no evidence of publication bias.

CONCLUSION

It is suggested in this review and meta-analysis that angioplasty with DCB may be a potential treatment for VAOS. However, randomized studies including a large representative sample of VAOS patients are needed to validate our findings.

Comparison of Drug-Coated Balloons to Bare Metal Stents in the Treatment of Symptomatic Vertebral Artery-Origin Stenosis: A Prospective Randomized Trial

OBJECTIVE

We sought to compare the angiographic and clinical outcomes of drug-coated balloon (DCB) with distal embolic protection devices (EPDs) versus bare metal stent (BMS) without EPD in the treatment of symptomatic vertebral artery origin stenosis (VAOS).

METHODS

Between January 2017 and December 2018, a prospective randomized trial was conducted involving 95 patients with symptomatic VAOS randomly assigned to treatment with DCB + EPD (n = 49) or BMS without EPD (n = 46). Target vessel restenosis (RS) >50% detected by computed tomography angiography was the primary endpoint. Technical success, clinical success, and signal intensity abnormalities on diffusion-weighted imaging within 3 days after operation were compared.

RESULTS

The 30-day technical success rate was 93.9% for DCB group versus 95.7% for the BMS group (P = 0.094). Diffusion-weighted imaging within 3 days postoperative showed asymptomatic embolization in 2 (4.1%) patients in the DCB group and 9 (19.6%) patients in the BMS group (P = 0.004). At a mean 16-month follow-up, the clinical success rate was 89.8% for the DCB group versus 91.3% (42/46) for the BMS group (P = 0.125). The RS was seen in 5/49 (10.2%) in the DCB group and 6/46 (13.0%) in the BMS group (P = 0.082). Target vessel revascularization was performed in 4 (8.7%) BMS group versus 3 (6.1%) in the DCB group (P = 0.091).

CONCLUSIONS

DCB with EPD in the treatment of symptomatic VAOS is technically feasible and safe and significantly reduced thromboembolic events on imaging when compared with BMS without EPD. There was no significant difference between the 2 groups in the rate of RS during 12 months after surgery.

Endovascular treatment of patient with multiple extracranial large vessel stenosis and coexistent unruptured wide-neck intracranial aneurysm using a WEB device and Szabo-technique

The coexistence of severe extracranial large vessel stenosis and unruptured intracranial aneurysms is not rare. There are different treatment approaches for these conditions, such as initial treatment of the aneurysm before revascularization of the stenosis; single-stage endovascular treatment of both lesions; stenosis eliminating followed by treatment of the aneurysm, or without treating the aneurysm. But, taking into account the risk of aneurysm rupture on the one hand and the risk of ischemic stroke on the other, it is sometimes difficult to choose the right management strategy. Despite this fact, there are still no guidelines or consensus on the management of these coexistent lesions. The article describes a clinical case of endovascular treatment of multiple extracranial stenosis and coexistent unruptured wide-neck aneurysm of the middle cerebral artery. The endovascular treatment of the carotid stenosis and aneurysm using a woven endobridge device was performed in one session; endovascular treatment of vertebral artery stenosis with Szabo technique was performed in another session.

Endovascular treatment of the vertebral artery origin stenosis by using the closed-cell, self-expandable Carotid Wallstent

BACKGROUND

Endovascular treatment has been considered a good alternative to surgery for symptomatic vertebral artery origin stenosis (VAOS) due to the high risk of morbidity associated with surgery. The purpose of this study was to evaluate the feasibility and efficacy of insertion of the closed-cell, self-expandable Carotid Wallstent for the treatment of VAOS.

METHODS

The records of 72 patients with VAOS refractory to adequate medication who were treated by endovascular treatment with the Carotid Wallstent from December 2006 to November 2018 were retrospectively evaluated.

RESULTS

Of the 72 patients, 43 presented with transient ischemic attacks. Forty-seven patients (65.3%) manifested other brachiocephalic stenoses; of these, 40 patients had occlusion, hypoplasia, or stenosis of the contralateral vertebral artery. Overall technical success (defined as 20% or less residual stenosis) was 100%. Procedure-related complications (n = 8, 11.1%) included sudden asystole (n = 1), acute in-stent thrombosis (n = 3), minor stroke (n = 3), and stent shortening (n = 1). All complications were resolved without permanent neurological deficit. Angiographic follow-up (mean, 13.0 months) was achieved in 49 patients and revealed in-stent restenosis in 1 patient (2.0%) and stent malposition by shortening in 2 patients (4.1%). Follow-up records were available in 57 patients (mean 15.6 months). Three of the 57 patients (n = 3, 5.3%) had recurrent symptoms of vertebrobasilar ischemia and none was retreated.

CONCLUSIONS

Endovascular treatment of symptomatic VAOS using the closed-cell, self-expandable Carotid Wallstent is technically feasible and effective in alleviating patient symptoms and for improving vertebrobasilar blood flow.

The presence of long and heavily calcified lesions predisposes for fracture in patients undergoing stenting of the first part of the subclavian artery

OBJECTIVE

To determine the prevalence and risk factors of subclavian artery stent fractures and to investigate their impact on in-stent restenosis development.

METHODS

One hundred eight patients (65 females; median age, 58.3 years [interquartile range, 53.4-65.5 years]) with steno-occlusive disease of the first part of the subclavian artery who underwent stenting (N = 108 stents; balloon-expandable, 83.3%; self-expandable, 16.7%) between 2005 and 2015 and returned for a fluoroscopic examination of the implanted stents in 2017 were included in our study. Fractures were type I (single strut fracture), type II (multiple strut fractures without deformation), type III (multiple strut fractures with deformation), type IV (multiple strut fractures with acquired transection but without gap), or type V (multiple strut fractures with acquired transection with gap in the stent body). Stent patency was monitored by duplex ultrasound imaging. The Mann-Whitney U and Fisher's exact tests; Kaplan-Meier, receiver operating characteristic, and logistic regression analyses; as well as a log-rank test were used as statistical methods.

RESULTS

The median follow-up was 73.8 months (interquartile range, 35.6-104.2 months). Thirty-eight fractures (35.2%) were detected; fractures were type I in 13, type II in 12, type III in 6, type IV in 4, and type V in 3 cases. Multivariable logistic regression analysis revealed the presence of long (≥20 mm) lesions (odds ratio, 3.3; 95% confidence interval, 1.3-8.4; P = .012) and heavy calcification (odds ratio, 4.7; 95% confidence interval, 1.7-12.7; P = .002) to be significant independent predictors of stent fracture. The primary patency rates were significantly worse (P = .035) in patients with stent fracture compared with those without stent fracture.

CONCLUSIONS

Stent fractures frequently occur. Patients with long and/or heavily calcified lesions require closer follow-up.

Incidence and Predictors of the In-stent Restenosis after Vertebral Artery Ostium Stenting

BACKGROUND

The incidence and predictors for in-stent restenosis (ISR) was not fully explored. We aim to investigate the incidence and predictors of ISR after stenting at the origin of vertebral artery.

MATERIALS AND METHODS

Two hundred and six patients with 229 stents implantation between July 1, 2005 and July 31, 2015 were included in the study. All patients underwent conventional clinical and angiographic (digital subtraction angiography) follow-up at around 6 months post procedure. ISR was defined as greater than 50% stenosis within or immediately (within 5 mm) adjacent to the stent. Multivariate Cox regression analyses were utilized to investigate the predictors for ISR.

RESULTS

The ISR was found in 30 patients (30/206, 14.6%) with 31 lesions (31/229, 13.5%) with the mean follow-up duration of 11.1-month (range: 3 - 92 months). Stent diameter (hazard ratio 0.504, 95% confidence interval 0.294 - 0.864) was an independent predictor for ISR.

CONCLUSION

ISR rate after Vertebral artery ostium stent placement is acceptable, which was conversely associated with the stent diameter.

Dynamic Respiratory Tortuosity of the Vertebral Artery Ostium

PURPOSE

To determine the prevalence of dynamic respiratory tortuosity (DRT) of the vertebral artery ostium (VAO) as well as to evaluate its correlation with in-stent restenosis (ISR) and stent fracture.

METHODS

From March 2012 to June 2015, 178 consecutive patients (mean age 65.2±5.8 years; 124 men) with symptoms of atherosclerotic vertebrobasilar ischemia underwent angiography prior to stent implantation in the vertebral, subclavian, and/or carotid arteries. In this cohort, 54 patients (mean age 67.3±5.3 years; 40 men) had VAO stent implantation. Angiography of the vertebral artery was recorded in 2 phases with breath-hold: deep inspiration (DIP) and deep expiration (DEP). Obvious VAO tortuosity was defined as any VAO angle ≤120° in DIP. Obvious VAO-DRT was defined as any VAO angle increasing ≥60° from DIP to DEP. Computed tomography angiography (CTA) or digital subtraction angiography was used in follow-up to detect ISR and stent fracture.

RESULTS

Of the 178 patients in this study, 21 (11.8%) had obvious VAO tortuosity and 8 (4.5%) had obvious VAO-DRT. Two of the 21 patients with obvious VAO tortuosity also had obvious VAO-DRT. Three of the 54 VAO stent patients had VAO-DRT. There were no correlations between VAO-DRT and age, sex, risk factors, body mass index, chronic obstructive pulmonary disease, asthma, or obvious VAO tortuosity (p>0.05). Over a mean follow-up of 28±10 months, there were 4 (7.4%) asymptomatic VAO ISR cases. Two (3.7%) were occlusions at 6 and 12 months, respectively; both were associated with stent fracture in patients with obvious VAO-DRT before stenting. Both stents fractured at the tortuous VAO region. VAO-DRT was correlated with stent fracture (Spearman ρ=0.81, p<0.01) and ISR (Spearman ρ=0.55, p<0.01).

CONCLUSION

VAO-DRT could be a risk factor for stent fracture and restenosis after VAO stent implantation. Angiography in both inspiration and expiration phases, especially the latter, should be considered before VAO stenting. Using a shorter stent to avoid crossing the tortuosity could reduce the occurrence of fracture.

Comparison of self-expanding stents with distal embolic protection to balloon-expandable stents without a protection device in the treatment of symptomatic vertebral artery origin stenosis: a prospective randomized trial

PURPOSE

To compare the angiographic and clinical outcomes of self-expanding stents (SES) with distal embolic protection devices (EPD) vs balloon-expandable stents (BES) without EPD in the treatment of symptomatic atherosclerotic vertebral artery ostial stenosis (VAOS).

METHODS

Between July 2011 and March 2013, a prospective randomized trial was conducted involving 127 patients (mean age 67.3±10.2 years; 94 men) with symptomatic VAOS randomly assigned to treatment with SES + EPD (Precise RX or RX Acculink stent + Spider FX EPD; n=61) or BES (Palmaz Blue or Resolute RX; n=66) without EPD. In-stent restenosis (ISR) >50% detected by duplex ultrasound was the primary endpoint. Technical success, clinical success, complications within 30 days, and signal intensity abnormalities on diffusion weighted imaging (DWI) after stenting were compared.

RESULTS

The 30-day technical success rate was 95.5% (63/66) for SES+EPD vs 100% (70/70) for BES without EPD (p=0.072). DWI at 24 hours poststenting showed 2 hyperintense lesions in 2 (3.3%) SES + EPD cases and 15 hyperintense lesions in 13 (18.6%) BES patients (p<0.01). At a mean 18-month follow-up, the clinical success rate was 93.9% (62/66) for the SES + EPD group vs 85.7% (60/70) for the BES group (p=0.115). The ISR was seen in 16/70 (22.9%) arteries in the BES group and 2/66 (3.1%) arteries in SES + EPD group (p<0.01). Target vessel revascularization was performed in 7 (10.0%) BES arteries vs none in the SES + EPD group (p<0.01).

CONCLUSION

SES with EPD in the treatment of symptomatic VAOS is technically feasible and safe, with low rates of ISR and significantly reduced thromboembolic events on imaging when compared to BES without EPD.

Stent fracture and occlusion after treatment of symptomatic vertebral artery ostium stenosis with a self-expanding device. A case report

Endovascular stenting with a balloon expandable device is currently the preferred treatment modality for symptomatic proximal vertebral artery stenosis, but high rates of in-stent restenosis remain a major problem, for which stent fracture might be a contributing factor. Limited reports showed that placement of self-expanding stents in the proximal vertebral artery might reduce restenosis; no stent fracture has been reported to date. We describe here a new case of fracture and occlusion of a self-expanding stent after endovascular treatment of symptomatic vertebral artery ostium stenosis.

Treatment of proximal vertebral artery disease

Vertebral arterial disease (VAD) is a less commonly recognized and treated source of cerebrovascular ischemia compared with carotid artery disease. Patients are often referred for treatment after they have developed symptoms in the form of transient ischemic attacks or had a posterior hemispheric stroke. Traditional treatment of VAD has been surgical. More recently, endovascular treatment of VAD has been utilized. We performed a retrospective review of our institutional experience in treating VAD from 2001 to 2010. For treatment of proximal VAD, perioperative morbidity is lower for the endovascular group than for the surgical group, but six-week mortality was higher for the endovascular group. Complete resolution of symptoms occurred more frequently with surgery than with endovascular therapy. Therefore surgical reconstruction appears to be preferable to angioplasty and stenting for treatment of proximal vertebral artery occlusive disease.

Percutaneous transluminal angioplasty and stenting in patients with proximal vertebral artery stenosis

BACKGROUND

Atherosclerotic occlusive disease of the proximal vertebral artery is an important cause of cerebrovascular ischemic events with a significant associated morbidity and mortality. Endovascular treatment has emerged as a promising tool of the therapeutic armamentarium, along with medical therapy and surgical reconstruction. Our objective was to systemically review the pertinent evidence on the endovascular management of proximal vertebral artery disease and perform an analysis of the published outcomes.

METHODS

A systematic review of the literature identified all studies reporting percutaneous transluminal angioplasty or stenting, or both, for proximal vertebral artery stenosis. Web-based search engines were searched using the Medical Subject Headings terms "vertebral artery," "angioplasty," and "stents" in all possible combinations. Studies comprising a series of at least five patients were considered for analysis. Periprocedural transient ischemic attack and stroke and death from any cause ≤30 days of treatment were defined as the primary outcome end points.

RESULTS

One randomized controlled trial comparing angioplasty and stenting of the proximal vertebral artery and medical therapy was identified. No comparative studies of endovascular treatment and open surgical repair were found. Forty-two selected studies reported endovascular treatment (angioplasty or stenting, or both) of 1117 vertebral arteries in 1099 patients. The weighted mean technical success rate was 97% (range, 36%-100%). Periprocedural transient ischemic attack occurred in 17 patients (1.5%). The combined stroke and death rate was 1.1%. Recurrent symptoms of vertebrobasilar insufficiency developed in 65 of 967 patients (8%) within a reported follow-up of 6 to 54 months. Restenosis developed in 183 of 789 patients (23%) who underwent follow-up imaging (range, 0%-58%). Reintervention for recurrent disease during follow-up occurred in 86 patients (9%; range, 0%-35%).

CONCLUSIONS

There is limited comparative evidence on the efficacy of medical, surgical, and endovascular treatment of proximal vertebral artery disease. Percutaneous transluminal angioplasty and stenting has low periprocedural neurologic adverse events and mortality.

Stent placement for atherosclerotic stenosis of the vertebral artery ostium: angiographic and clinical outcomes in 117 consecutive patients

BACKGROUND

Although it is thought to be a safe treatment option, the main concerns related to treating vertebral artery ostium (VAO) stenosis with stents have been the rate of restenosis and the uncertain long-term results.

OBJECTIVE

To evaluate the angiographic and clinical results of stent placement for atherosclerotic stenosis of the VAO.

METHODS

One hundred seventeen consecutive patients with atherosclerotic VAO stenosis were treated with stent placement over a period of 12 years. All patients were retrospectively analyzed through the use of a prospectively collected database. The indication criteria for this treatment protocol were symptomatic severe VAO stenoses (> 60%) and asymptomatic severe VAO stenoses (> 60%) with incidentally detected infarction in the posterior circulation. The target diameter of stent dilatation from 1997 to 2000 was the normal vessel diameter just distal to the lesion. Moderate overdilation in the proximal portion of the stents has been performed since 2001.

RESULTS

Successful dilatation was obtained in 116 of 117 cases. Transient neurological complications developed in 2 patients; however, no patients experienced any permanent neurological complications. One hundred four patients underwent follow-up angiography at 6 months after stenting. The restenosis rate at the 6-month follow-up was 9.6% (10 of 104). Until 2000, the restenosis rate after stenting was 13.3%. Since 2001, the restenosis rate has decreased to 4.5%. The median clinical follow-up period was 48 months. The annual rate of strokes in the posterior circulation was 0.95%.

CONCLUSION

Stent placement for atherosclerotic VAO stenosis is considered to be a feasible and safe treatment and may be effective for stroke prevention. The moderate overdilation of stents may be an effective modality for the prevention of restenosis.

Influence of vessel size and tortuosity on in-stent restenosis after stent implantation in the vertebral artery ostium

PURPOSE

Percutaneous transluminal angioplasty and stenting is emerging as an alternative for treating atherosclerotic stenosis in the vertebral artery ostium. However, in-stent restenosis (ISR) still remains a critical issue to be addressed. Little is known about the relationship between anatomic characteristics of the artery and ISR after stent implantation. In this study, we have evaluated influential factors for ISR in a cohort of the patients with stenting in the vertebral artery ostium.

METHODS

Sixty-one patients with 63 symptomatic lesions in vertebral artery ostium treated with stenting were enrolled onto this study. An average of 12.5 months' clinical and angiographic follow-up results were analyzed retrospectively. The possible influential factors for ISR, including conventional risk factors of cerebrovascular diseases and morphological characteristics of target lesions, were evaluated by univariate and multivariate regression analysis.

RESULTS

Technical success was achieved in all 63 interventional procedures. Stenosis was reduced from (mean±standard deviation) 75.5±12% before to 1±3.6% after the procedure. During the mean 12.5-month angiographic follow-up, ISR was detected in 17 treated vessels (27.0%), with 2 treated arteries (3.2%) resulting in occlusion, and a stent fracture in 1 case (1.6%). Multivariate Cox regression analysis showed that the tortuosity of V1 (hazard ratio 3.54, P=0.01) and smaller diameter of the stent (hazard ratio 3.8, P=0.04) were independent predictors of ISR.

CONCLUSIONS

Angioplasty and stenting for symptomatic stenosis in the vertebral artery ostium stenosis seem to be feasible and effective. Tortuosity and smaller diameter may affect ISR after stent implantation.

Clinical relevance and treatment of carotid stent fractures

OBJECTIVE

To review all published reports and investigate the clinical relevance and need for treatment of carotid stent fractures.

METHODS

Electronic and hand-searching of the published literature and the Manufacturer and User Facility Device Experience (MAUDE) database.

RESULTS

Thirteen articles were published. There are 10 case reports and 3 clinical studies. There are 26 reports of fractured stents in the MAUDE database. Fifty-five cases of carotid stent fractures are reported in total. A total of 201 carotid stents were examined in the 3 studies, and the incidence of fractures was 8.9% (18/201). Fractured stents were 22 Xact, 20 Acculink, 6 Precise, 2 Exponent, 1 Nexstent, 1 Genesis, 1 Symbiot, and 2 nonspecified nitinol self-expandable stents. Twenty-seven of the treated carotid lesions were atherosclerotic, 3 restenoses after carotid endarterectomy, 2 postradiational, 1 pseudoaneurysm, and 22 lesions of unknown pathology. Calcification was reported in 15 of the 27 atherosclerotic lesions (55.5%). Time from implantation to fracture ranged from 0 days (fracture during implantation) to 37 months. In 55% of the cases, stent fracture was associated with restenosis. Six patients presented with symptoms. Treatment was reported for 32 patients: 14 patients underwent de novo stent placement, 2 balloon angioplasty, 2 carotid endarterectomy, 2 bypass graft (1 vein, 1 polytetrafluoroethylene), 1 anticoagulation, and 11 patients were followed up.

CONCLUSION

Carotid stent fractures are mainly reported in self-expandable nitinol stents. Plaque calcification may be a risk factor for stent fractures. No difference was observed between open and closed-cell design. Stent fractures were often associated with restenosis and usually were asymptomatic. The actual incidence, clinical relevance, and optimal treatment remain to be clarified from larger prospective studies designed to investigate the issue.

Use of self-expanding stents for the treatment of vertebral artery ostial stenosis: a single center experience

Objective

To evaluate our early experience using self-expanding stents to treat atherosclerotic vertebral artery ostial stenosis (VAOS), with respect to technical feasibility and clinical and imaging follow-up results.

Materials and Methods

A total of 20 lesions in 20 patients underwent stenting of the VAOS using a self-expanding stent (Precise RX; Cordis Neurovascular, Miami Lakes, FL). Two patients were asymptomatic. We analyzed the technical success rate, causes of technical failure, occurrence of any vascular or neurological event, and the occurrence of any neurological abnormality or in-stent restenosis (ISR) seen on follow-up. The imaging follow-up was performed with Doppler ultrasound (DUS) as a primary screening modality.

Results

One instance of technical failure was caused by failure of the guidewire passage. The stent diameter was 5 mm, and post-stenting balloon dilatations were necessary in all cases. Stent misplacement requiring placement of an additional stent occurred in four cases. Following a 14.8 month average clinical follow-up time, two patients showed anterior circulation ischemia, which was not attributed to the VAOS we treated. Following a 13.7 month average DUS follow-up, five patients showed a mild degree of diffuse or focal intimal thickening in the stent lumen; however, none of the stenosis showed luminal loss of more than 50% and no stent fracture was noted.

Conclusion

The use of self-expanding stents for treating VAOS was technically feasible and helped to improve artery patency during our limited follow-up interval.

Treatment of stenoses of vertebral artery origin using short drug-eluting coronary stents: improved follow-up results

BACKGROUND AND PURPOSE

Recent studies on stent placement of significant stenoses at the origin of the vertebral artery reported excellent immediate results. Long-term outcomes, however, were disappointing due to high restenosis rates and stent breakage. In the present study, we evaluated the application of a short drug-eluting balloon-expandable coronary stent for the endovascular treatment of these frequent lesions.

MATERIALS AND METHODS

In a period of 23 months, 48 patients (12 women, 36 men) with a mean age of 68 years (range, 46-82 years) harboring 52 significant ostial vertebral artery stenoses underwent treatment with short (8 mm) balloon-expandable paclitaxel-eluting coronary stents. Stents were deployed as closely as possible so that the proximal end was just at the origin of the vertebral artery, with high inflation pressure applied. Patients were under continuous medication with acetylsalicylic acid and clopidogrel before and after the treatment. Follow-up clinical assessment and angiography were performed in all patients.

RESULTS

Periprocedural complications were not encountered. Stenosis severity was reduced from 62 +/- 2% (mean +/- standard error of the mean) preprocedurally to 15 +/- 2% postprocedurally. Follow-up angiography at 7.7 +/- 0.6 months revealed a mean stenosis degree of 24 +/- 3%. None of the patients developed posterior circulation symptoms related to the treated segment during the follow-up period. Recurrent stenosis (>50%) at follow-up was found in 6 (12%) lesions.

CONCLUSIONS

Stent placement of significant ostial vertebral artery stenosis by using short drug-eluting stents is safe and yields good midterm patency rates and excellent protection from posterior circulation ischemia.

In situ fracture of stents implanted for relief of pulmonary arterial stenosis in patients with congenitally malformed hearts

BACKGROUND

One of the most common uses of stents in patients with congenitally malformed hearts is treatment of pulmonary arterial stenosis. Although there are reports of fractured pulmonary arterial stents, little is known about the risk factors for, and implications of, such fractures.

METHODS

We reviewed angiograms to identify fractures in stents previously inserted to relieve stenoses in pulmonary arteries from 1990 through 2001 in patients who also underwent follow-up catheterization at least 3 years after placement of the stent. We undertook matched cohort analysis, matching a ratio of 2 fractured to 1 unfractured stent.

RESULTS

Overall, 166 stents meeting the criterions of our study had been placed in 120 patients. We identified fractures in 35 stents (21%) in 29 patients. All fractured stents were in the central pulmonary arteries, 24 (69%) in the central part of the right pulmonary artery, and all were complete axial fractures, or complex fractures along at least 2 planes. Stent-related factors associated with increased risk of fracture identified by multivariable logistic regression included placement in close apposition to the ascending aorta (p = 0.001), and a larger expanded diameter (p = 0.002). There was obstruction across 28 of 35 fractured stents, which was severe in 11. We re-stented 21 of the fractured stents, and recurrent fracture was later diagnosed in 3 of these. A fragment of the fractured stent embolized distally in 2 patients, without clinically important effects.

CONCLUSIONS

In situ fracture of pulmonary arterial stents is relatively common, and in most cases is related to compression by the aorta. There is usually recurrent obstruction across the fractured stent, but fractured stents rarely embolize, and are not associated with other significant complications.