Vessel Angulation Research Articles

The effect of heart rate and vessel angulation on coronary artery stenosis evaluation from cardiac CT angiography

Introduction Cardiac CT angiography (CCTA) is considered a valuable tool for non-invasive assessment of coronary artery stenoses in patients with low to intermediate risk for coronary artery disease. Purpose To investigate the effect of heart rate and artery orientation on the accuracy of stenosis quantification from CCTA studies. Materials and methods A QRM CT cardiac phantom equipped with cardiac motion simulator was subjected to standard prospective and retrospective CCTA image acquisitions on a modern 128-slice CT scanner. CCTA image series were separately produced for three coronary artery phantoms representing stenosis of 25%, 50% and 75% with heart rate varying from 40 to 120 bpm (in 10 bpm steps) and vessel orientation varying from 0° to 40° (in 10° steps) with respect to z-axis. Stenoses were evaluated by an experienced radiologist using a dedicated cardiac CT software for coronary artery assessment and analysis. Results Stenosis quantification accuracy was found to be considerably deteriorated for increasing heart rate (p Conclusion High inaccuracies in coronary artery may occur for increased heart rate during the CCTA scan acquisition with the effect being more prominent for increased vessel angulations. To suppress stenosis evaluation inaccuracy below 15%, beam heart rate during the examination should be maintained

Glutamate excitotoxicity and oxidative stress induced by experimental thrombosis of retinal vessels

We studied the effect of thrombosis of retina vessels on the development of glutamate excitotoxicity in chinchilla rabbits. Thrombosis was induced by administration of Bengal rose dye at a dose of 40 mg/kg into the auricular vein of the animals followed by focal lighting with white light. Lighting was performed for 10 min on average at the temporal vascular arcade in the location of the angulation of vessels over the border of the disk of the optic nerve using a binocular ophtalmoscope and a condensing +14.0 D lens. We found that experimental thrombosis induced the accumulation of glutamate, aspartate, glycine, and GABA, as well as oxidative stress, which was associated with decreased activity of superoxide dismutase, glutathione peroxidase, and glutathione-S-transferase.

PC4. Comparative Geometric Analysis of Renal Artery Anatomy Before and After Fenestrated or Snorkel/Chimney EVAR

Values in mean 6 standard deviation. D, Change from pre-op to post-op; NS, no Positive end-stent angle indicates vessel angulation with respect to the stent end Significant changes from pre-op to post-op (P < .05). Significant difference between LRA and RRA (P < .05). underwent computed tomography angiography before and after F-EVAR (n 1⁄4 21) or Sn-EVAR (n 1⁄4 20), which involved a total of 74 renal artery stents. Renal artery geometry was quantified using three-dimensional modelbased centerline extraction. Stented length was computed from vessel origin to stent end. Branch angle was computed relative to orthogonal configuration with respect to the aorta at vessel origin. End-stent angle was computed relative to distal native renal artery. The radius of curvature was defined by the circumscribed circle at the highest curvature within the proximal portion from the origin to the stent end, and distal portion from the stent end to first renal artery bifurcation. Results: Stented renal artery length, branch angle, end-stent angle, and maximum change in radius of curvature from preoperative to postoperative are presented in the Table. Sn-renals had greater stented length compared with F-renals (P < .02). From preoperative to postoperative, origins of the Sn-renals angled increasingly downward (P < .002), whereas F-renals angled increasingly upward (P < .002). End-stent angle of SnRRA increased from preoperative to postoperative (P < .00001), and Sn-RRA exhibited a greater magnitude change in end-stent angle compared with Sn-LRA (P < .05) and F-RRA (P < .0005). Radius of curvature decreased in distal Sn-RRAs (P < .02). Acute renal failure occurred in 9.8% of patients, and none required dialysis. Renal stent patency was 98.6% at mean follow-up of 13.7 months. Five type IA endoleaks were identified, prompting one secondary procedure. One renal artery reintervention was performed due to an asymptomatic kinked left renal stent. Conclusions: Stented renal arteries were angled more inferiorly after Sn-EVAR and superiorly after F-EVAR due to stent configuration. Sn-EVAR induced significantly greater angle change at the stent end and curvature change distal to the stent compared to F-EVAR due to greater angle change of the Sn-renals, although no difference in patency was noted. Sn-RRA exhibited larger endstent angle change from preoperatively to postoperatively compared to the Sn-LRA, likely because the presence of the IVC on the right side restricts motion of the proximal RRA. The occurrence of the kinked left renal stent is consistent with the proximal right renal artery being more mechanically supported by the IVC. Additional

Characteristic anatomical conformation of the vertebral artery causing vascular compression against the root exit zone of the facial nerve in patients with hemifacial spasm.

Hemifacial spasm (HFS) is caused by tortuous offending vessels near the facial nerve root exit zone. However, the definitive mechanism of offending vessel formation remains unclear. We hypothesized that vascular angulation and tortuosity, probably caused by uneven vertebral artery blood flow, result in vascular compression of the facial nerve root exit zone. The authors observed two anatomical characteristics of the vertebrobasilar arterial system in 120 subjects in the surgical group and 188 controls. The presence of the dominant vertebral artery (DVA) and laterality of the vertebrobasilar junction (VBJ) were observed. We also analyzed the morphological characteristics of the surgical group showing the presence of DVA. The morphological characteristics were classified into three types: type I had the VBJ and DVA on the same side, type II had the VBJ within 2 mm of the midline, and type III had the VBJ opposite the DVA. The DVA was more prevalent in the surgical group than in the control group (71 % versus 54 %, P < 0.05). The surgical group patients with HFS on the left were more likely to have a DVA on the left (P < 0.05) and with HFS on the right were more likely to have a DVA on the right (P < 0.01) compared with controls. The direction of the VBJ was more common on the same side as the DVA, which corresponds with the laterality of the HFS. In the surgical group with the DVA and HFS on the same side, type I was predominant, but in the surgical group with a contralateral DVA and HFS, type III was predominant. The presence of a DVA and shifting of the VBJ on the same side plays a role in the angulation and tortuosity of vessels in the perivertebrobasilar junction, resulting in neurovascular compression of the facial nerve root exit zone and thereby causing HFS.

Modificações na angulação coronária após implante de suporte vascular bioabsorvível e de stents de cromo-cobalto e aço inoxidável

INTRODUÇÃO: A conformabilidade do stent, definida como a adaptação da prótese à forma natural do vaso, é a principal responsável pelas alterações geométricas produzidas após o implante do dispositivo, sendo influenciada pelo material e pelo desenho do stent. Ela pode ser aferida medindo-se as modificações da curvatura e a angulação do segmento tratado após o implante do stent. O objetivo deste estudo foi comparar as mudanças na angulação coronária após implante do suporte vascular bioabsorvível (SVB) e das plataformas metálicas de cromo-cobalto e aço inoxidável, utilizadas em stents farmacológicos de segunda geração. MÉTODOS: Foram incluídos, nesta análise retrospectiva, 50 pacientes com lesões únicas, de novo, em coronárias nativas, com diâmetro entre 2,5 e 3,5 mm e extensão de até 23 mm. Vinte e cinco pacientes foram tratados com SVB e 25 pacientes com plataformas metálicas de cromo-cobalto (n = 12) ou de aço inoxidável (n = 13). A angulação foi medida usando um software de angiografia coronária quantitativa dedicado. RESULTADOS: A angulação do vaso modificou-se significativamente após o implante dos dispositivos. No grupo submetido ao implante de plataformas metálicas, houve maior modificação do ângulo coronário quando comparado ao tratado com SVB (41,6% vs. 14,9%; P < 0,01). Quando observado o comportamento do SVB e das diferentes plataformas metálicas, a alteração do ângulo coronário foi maior para as plataformas de aço inoxidável, seguida das plataformas de cromo-cobalto e os SVB (53,7% vs. 28,5% vs. 14,9%; P < 0,01). CONCLUSÕES: Nesta avaliação preliminar, o SVB produziu uma menor mudança da angulação coronária. O impacto clínico deste achado necessita ser investigado prospectivamente em uma coorte maior e mais complexa.

Transradial interventions with the GuideLiner catheter: Role of proximal vessel angulation

Transradial coronary intervention (TRI) is increasingly common, but anatomic variations and lack of guide catheter support may increase the complexity of TRI. The GuideLiner catheter (Vascular Solutions, Minneapolis,MN) is a guide catheter extension developed to provide increased guide catheter support. We hypothesized that TRI cases requiring GuideLiner support would have a greater proximal vessel angle and increased lesion angle tortuosity. This was a retrospective study reviewing 146 TRI cases performed at a single institution between August 2010 and June 2012. 22 cases (15%) required use of the GuideLiner support catheter. Procedural and angiographic characteristics of all cases were analyzed. Multivariable analysis and receiver operator curves (ROC) were used to analyze predictors of GuideLiner use. The indications for TRI were similar between both groups. Subjects who required use of the GuideLiner support catheter at the time of TRI were significantly older (69±12years vs. 62±13years, p=0.03). The proximal vessel angle was significantly greater in the cases requiring GuideLiner support (74°±35° vs. 37°±23°, p<0.001). Lesion angle in the Guideliner group was also significantly greater (48°±32° vs. 28°±25°, p<0.001). On multivariable analysis, proximal vessel angle independently predicted the need for GuideLiner support (AOR 1.4 per 10°, p<0.001). A 45° proximal vessel angle predicted the need for GuideLiner use with a sensitivity of 73% and specificity of 74% (c-statistic 0.79). None of the Guideliner TRI cases required conversion to femoral access. TRIs requiring GuideLiner catheter support had significantly increased lesion complexity and vessel tortuosity. Proximal vessel angulation is significantly associated with the need for GuideLiner use during transradial intervention. Use of the Guideliner facilitated successful completion of PCI despite the use of a wide variety of guiding catheters in this series.

Predicting the Risk for Acute Type B Aortic Dissection in Hypertensive Patients Using Anatomic Variables

This study sought to identify possible anatomic predictors of acute type B aortic dissection (AAD) in hypertensive patients using multidetector computed tomography angiography (CTA). Although hypertension remains one of the most significant risk factors for AAD development, it is unlikely to be the only risk factor for AAD. Few studies have assessed anatomical predictors of AAD development. CTA of normotensive patients without AAD (group 1, n = 35), hypertensive patients without AAD (group 2, n = 37), and hypertensive patients with AAD (group 3, n = 37) were compared. The length, diameter, volume, and tortuosity of the aorta as well as arch vessel angulation were measured for each patient and normalized to group 1 averages. Stepwise logistic regression identified significant anatomical associations; the model was validated based on 1,000 bootstrapped samples. The demographics of the groups were similar. The length of the proximal and entire aorta, the diameters in the proximal ascending aorta and aortic arch, and the aortic volumes were all greater (p < 0.0001, p = 0.0064 for ascending aortic diameter) in group 3 than in groups 1 and 2, as was entire aortic tortuosity (p < 0.0001). An AAD risk model was developed based on aortic arch diameter, length from the aortic root to the iliac bifurcation, and angulation of the brachiocephalic artery origin from the aorta. The bootstrap estimate of the area under the receiver operating curve was 0.974. Enlargement of the ascending aorta and aortic arch and increased aortic tortuosity reflect an aortopathy which enhances the probability of AAD. A model based on 3 anatomical variables demonstrates significant associations with AAD: it may allow identification by aortic imaging of the hypertensive patient most at risk, and permit implementation of aggressive medical management and consideration of pre-emptive surgery to prevent dissection.

Improvements of surgical techniques in a rat model of an orthotopic single lung transplant

BackgroundRats are widely used in modeling orthotopic lung transplantation. Recently the introduction of the cuff technique has greatly facilitated the anastomosing procedure used during the transplant. However, the procedure is still associated with several drawbacks including twisting of blood vessels, tissue injury and the extensive time required for the procedure. This study was performed to optimize the model of rat lung transplantation (LT) with the cuff technique.MethodsA total of 42 adult Lewis rats received orthotopic LT with our newly modified procedures. The modified procedures were based on the traditional procedure and incorporated improvements involving orotracheal intubation; a cuff without a tail; conservative dissection in the hilum; preservation of the left lung during anastomosis; successive anatomizing of the bronchus, the pulmonary vein, and the pulmonary artery; and one operator.ResultsTransplants were performed in 42 rats with a successful rate of 95.23% (40/42). The mean duration for the complete procedure was 82.93 ± 14.56 minutes. All anastomoses were completed in one attempt without vessel laceration, twisting or angulation. In our study, two animals died within three days and one animal died ten days after the operation. All grafts were well inflated with robust blood perfusion and functioned normally as demonstrated by blood gas analysis.ConclusionsWe have developed a modified orthotopic LT technique that can be easily performed while overcoming major drawbacks. The modified technique has many advantages, such as easy graft implanting, shortened operation time, fewer complications and high reproducibility.

Changes in Coronary Angulation After Bioresorbable Vascular Scaffold and Cobalt-Chromium and Stainless Steel Stent Implantation

ABSTRACT Background The conformability of the stent, defined as the adaptation of the prosthesis to the natural shape of the vessel, is the major cause of geometrical changes after stenting and is influenced by the stent material and design. It may be assessed by measuring changes in the curvature and the angulation of the treated segment after stent implantation. The objective of this study was to compare changes in coronary angulation after implantation of the bioresorbable vascular scaffold (BVS) and cobalt-chromium and stainless steel metal platforms used in second-generation drug-eluting stents. Methods In this retrospective analysis, 50 patients with single de novo lesions in native coronary arteries and diameter between 2.5 and 3.5 mm and length up to 23 mm were included. Twenty-five patients were treated with BVS and 25 patients were treated with cobalt-chromium (n = 12) or stainless steel (n = 13) platforms. Angulation was measured using a dedicated quantitative angiography analysis software. Results Vessel angulation significantly changed after device implantation. In the group submitted to the implantation of metal platforms there was greater coronary angulation change when compared to the group treated with BVS (41.6% vs. 14.9%; P Conclusions In this preliminary assessment, the BVS produced a smaller coronary angulation change. The clinical impact of this finding must be prospectively investigated in a larger and more complex cohort.

A prospective multicenter registry of laser therapy for degenerated saphenous vein graft stenosis: the COronary graft Results following Atherectomy with Laser (CORAL) trial

The primary aim of this study was to prospectively evaluate the safety and efficacy of Excimer laser atherectomy as a primary treatment strategy in consecutively eligible patients presenting for percutaneous coronary intervention (PCI) of degenerated saphenous vein graft (SVG) lesions using a multicenter registry. Prior single-center experience suggested that laser atherectomy may decrease acute procedural complications during treatment of degenerated SVGs, including lesions not amenable to distal protection devices (DPDs). The COronary graft Results following Atherectomy with Laser investigators enrolled 98 patients at 18 centers between June 23, 2003, and October 4, 2004, with greater than 50% stenosis of an SVG who presented for PCI due to angina pectoris or objective evidence of myocardial ischemia in a concordant myocardial distribution. Laser atherectomy was planned. Patients were excluded if the operator planned to utilize a DPD. Inclusion and exclusion criteria were aligned to those in the Saphenous vein graft Angioplasty Free of Emboli Randomized (SAFER) trial. The primary end point [30-day major adverse cardiac events (MACE)] occurred in 18/98 (18.4%) patients driven primarily by non-q-wave myocardial infarction. Major procedural complications included no reflow (n=5) and major dissection (n=1). No perforations occurred. Univariate predictors of 30-day MACE included lesion length, vessel angulation, plaque burden, SVG degeneracy score, number of laser pulses used, and larger-sized laser catheters. This study demonstrated that Excimer laser atherectomy of diseased SVGs is feasible with results comparable to the 30-day MACE in the control population from the SAFER trial. Whether the addition of laser to embolic protection devices is of any clinical utility remains to be tested in future studies.

Risk of target lesion failure in relationship to vessel angiographic geometry and stent conformability using the second generation of drug-eluting stents

Vessel angulation and large changes in vessel geometry after stent implantation have been associated with an increased risk of target lesion failure (TLF) using bare-metal stents. Second-generation drug-eluting stents (DES)offer superior conformability and inhibition of neointima. The aim of the study is to investigate the relationship between pre and post-implant vessel geometry and the occurrence of TLF at 1 year after treatment with second-generation DES; and to compare the conformability of Resolute and Xience stents. The RESOLUTE All-Comers trial randomized 2292 patients (3366 lesions) to Resolute zotarolimus-DES (Medtronic CardioVascular) or Xience everolimus-DES (Abbott Vascular). At 1 year, 176 lesions (121 patients)presented with TLF; a composite of cardiac death, acute myocardial infarction (AMI) and target lesion revascularization (TLR). Lesions with TLF were matched with 176 lesions (168 patients) without TLF adjusting for clinical and procedural characteristics. The number of bends, vessel curvature and angulation were assessed with quantitative coronary angiography pre and post-implantation. The absolute difference post minus pre-implantation was used as a surrogate of stent conformability. At pre-implantation, lesions without and with TLF had similar numbers of bends/lesion (1.81 vs 1.74; P = .35), vessel curvature (0.295 cm(-1) vs 0.363 cm(-1); P = .13) and vessel angulation (46.3° vs 43.5°; P = .80), respectively. Lesions without and with TLR also had similar numbers of bends/lesion (1.39 vs 1.39; P = .83), vessel curvature (0.368 cm(-1) vs 0.325 cm(-1); P = .33) and angulation (40.2° vs 37.2°; P = .19). Lesions without and with in-hospital AMI also presented with similar number of bends/lesion (1.69 vs 1.81; P = .48), vessel curvature (0.349 cm(-1) vs 0.345 cm(-1); P = .91) and vessel angulation (43.53° vs 48.45°; P = .38). The absolute difference post- - pre-implantation was similar in lesions without and with TLF, TLR and In-hospital AMI. The absolute difference post- - pre-implantation was similar with both Resolute and Xience in vessel curvature (-0.046 cm(-1) vs -0.047 cm(-1); P = .66) and was smaller in number of bends/lesion (-0.08 vs -0.16; P = .13) and in vessel angulation (-6.0° vs -10.1°; P = .03) with the Resolute. Bended, curved, and angulated lesions and changes in the number of bends/lesion, vessel curvature, and angulation from pre to post-implantation have no relation with TLF and TLR at 1 year and have no relation with In-hospital AMI using second-generation of DES. Resolute appears to be more conformable than Xience.

The role of vascular calcification in inducing fatigue and fracture of coronary stents

Traditional approaches for in-vitro pulsatile and fatigue testing of endovascular stents do not take into consideration the pathologies of the stented vessel and their associated biomechanical effects. One important pathology is calcification, which may be capable of inducing changes in the vessel wall leading to inhomogeneous distribution of stresses combined with wall motion during the cardiac cycle. These local property changes in the region adjacent to stents could directly influence in-vivo stent performance. Seven cases containing a total of 18 stents were obtained from autopsy. Radiographs were evaluated and vessels were sectioned for histology and stent topographical analysis. Stents were retrieved by chemical removal of surrounding tissue and surfaces were evaluated using 3D digital optical and scanning electron microscopy for biomechanical abrasion and fracture features. Pathologic complications such as restenosis and thrombus formation were assessed from histological sections. Direct evidence of fracture was found in 6 of the 7 cases (in 12 out of 18 stents; 9 drug eluting and 3 bare metal). The degree of stent alterations was variable, where separation of segments due to fracture occurred mostly in drug-eluting stents. All fracture surfaces were representative of a high cycle fatigue mechanism. These fractures occurred in complex lesions involving the presence of diffuse calcification alone, or in combination with vessel angulations and multiple overlapping stents. Morphologic analysis of tissue at or near some fracture sites showed evidence of thrombus formation and/or neointimal tissue growth.

Coronary Stent Fracture

Coronary stent fracture is a relatively uncommon and rare complication of stent implantation. The reported incidence of stent fracture among drug-eluting stents ranges from 1% to 8%. Since 2003, when the use of drug-eluding stents was approved by the FDA for the treatment of coronary atherosclerosis, a number of retrospective and prospective studies and case reports have been published. We reviewed these publications to determine the incidence, predictors, clinical implications, and different management strategies for drug-eluding stent fracture in the coronary arteries. A review of the literature showed that the risk for stent fracture was higher with right coronary artery location, increased vessel tortuosity and angulation prior to stenting, use of overlapping stents, and use of longer stents. A higher risk of bare metal stent fracture was reported in saphenous vein bypass grafts. The authors also report in this issue in the Department “Case Study” a symptomatic fracture of a sirolimus-eluding Cypher® stent in the mid-left anterior descending artery.

Calibration‐free device sizing using an inverse geometry x‐ray system

Quantitative coronary angiography (QCA) can be used to support device size selection for cardiovascular interventions. The accuracy of QCA measurements using conventional x-ray fluoroscopy depends on proper calibration using a reference object and avoiding vessel foreshortening. The authors have developed a novel interventional device sizing method using the inverse geometry scanning-beam digital x-ray (SBDX) fluoroscopy system. The proposed method can measure the diameter and length of vessel segments without imaging a reference object and when vessels appear foreshortened. SBDX creates multiple tomosynthetic x-ray images corresponding to planes through the patient volume. The structures that lie in the plane are in focus and the features above and below the plane are blurred. Three-dimensional localization of the vessel edges was performed by examining the degree of blurring at each image plane. A 3D vessel centerline was created and used to determine vessel magnification and angulation relative to the image planes. Diameter measurements were performed using a model-based method and length measurements were calculated from the 3D centerline. Phantom validation was performed by measuring the diameter and length of vessel segments with nominal diameters ranging from 0.5 to 2.8 mm and nominal lengths of 42 mm. The phantoms were imaged at a range of positions between the source and the detector (+/- 16 cm relative to isocenter) and with a range of foreshortening angles (0 degrees-75 degrees). Changes in vessel phantom position created magnifications ranging from 87% to 118% relative to isocenter magnification. Average diameter errors were less than 0.15 mm. Average length measurements were within 1% (0.3 mm) of the true length. No trends were observed between measurement accuracy and magnification. Changes in vessel phantom orientation resulted in decreased apparent length down to 28% of the original nonforeshortened length. Average diameter errors were less than 0.25 mm across all vessel angulations; errors were less than 0.1 mm for smaller diameter vessels and low to moderate vessel angles. Diameter errors increased with true diameter and vessel angle relative to the image plane. Average length measurement errors were also within 1% (0.3 mm) for each angulation. Tomosynthetic imaging with SBDX can accurately measure dimensions of vessels in various magnifications and angulations without calibration. This method may be more accurate and convenient than conventional QCA techniques.

Flat panel digital detector cinefluoroscopy late following SES or BMS implantation for detection of coronary stent fracture in asymptomatic patients

BackgroundCoronary stent fracture (SF), is rare and confined mainly in patients treated with sirolimus eluting stents (SES). The role of flat panel digital detector (FPDD) fluoroscopy in detecting SF has not been investigated. MethodsAssessment with FPDD fluoroscopy of asymptomatic patients, with 200 SES (Cypher, Cordis, J&J, Miami, Florida, US), and 200 bare metal stents (BMS), at 45.5±15.7 and 38.4±3.9months post-stenting respectively. SF was defined as discontinuity of stent struts on fluoroscopy. Coronary angiography was reserved for patients with documented SF. ResultsEffective radiation dose was 0.26±0.14mSv. SF was depicted in 6 (3%) SES, and 1 BMS (0.5%). Stent length was an independent predictor of SF (OR 1.19, 95% CI 1.03–1.4, p=0.024). RCA location and vessel angulation were marginally significant (OR 7.7, 95% CI 0.8–74.2, p=0.077 and OR 5.1, 95% CI 0.8–34, p=0.089). Significant angiographic restenosis was detected in 4 SES (66.6%), and 1 BMS (0.5%). Re-intervention was needed in 3 (42.8%) cases, (2 SES and 1 BMS). ConclusionDetection of SF with FPDD cinefluoroscopy late following coronary stenting is feasible, involves low radiation and is confined mainly to SES compared to BMS. Application of cinefluoroscopy as part of a routine stent surveillance programme in asymptomatic patients may be more appropriate in “high risk” settings (SES, long stents and adverse angiographic characteristics). The role of invasive imaging and subsequent management of such patients need further studying.

Carotid artery stent fracture identification and clinical relevance

This study was conducted to identify the prevalence, risk factors, and clinical relevance of carotid artery stent fracture. Commercially available carotid stents were implanted in this prospective, observational study that began in January 2004. Indications included asymptomatic patients (stenosis >80%), symptomatic patients (stenosis >60%), and ulcerated lesions (>50%). Stent integrity was assessed with plain radiography at 12 months. Data were analyzed in April 2009 on a series of 341 consecutive patients treated with carotid artery stenting with at least 12 months follow-up. Stent fracture prevalence was 3.4% at 12 months (95% confidence interval, 1.7%-6.1%). The median clinical follow-up was 30 months (range, 12-64 months) for 323 eligible patients. Treatment included 23.6% of symptomatic patients. According to univariate analysis, calcification type III increased the odds of stent fracture by more than 4.5 times (odds ratio [OR], 4.74; P = .006) and angulation >45 degrees increased the odds of stent fracture by 6.5 times (OR, 6.51; P = .008). Carotid stent cell type, stent length, and stent over-sizing were not correlated with stent fracture incidence. Stent fracture was not associated with stroke (0%), transient ischemic attack (0%), or death (0%). Restenosis was significantly associated with stent fracture (P < .001). Multivariate analysis evidenced that type III calcification (OR, 3.90; P = .029) and angulation >45 degrees (OR, 4.69; P = .026) were important risk factors for carotid stent fracture. Carotid stent fracture is a rare complication after CAS and is associated with vessel angulation, calcification, and restenosis. In this series, fracture identification was independent of stroke, transient ischemic attack, and mortality.

Impact of Dynamic Computed Tomographic Angiography on Endograft Sizing for Endovascular Aneurysm Repair

To quantify dynamic changes in aortoiliac dimensions using dynamic electrocardiographically (ECG)-gated computed tomographic angiography (CTA) and to investigate any potential impact on preoperative endograft sizing in relation to observer variability. Dynamic ECG-gated CTA was performed in 18 patients with abdominal aortic aneurysms. Postprocessing resulted in 11 datasets per patient: 1 static CTA and 10 dynamic CTA series. Vessel diameter, length, and angulation were measured for all phases of the cardiac cycle. The differences between diastolic and systolic aneurysm dimensions were analyzed for significance using paired t tests. To assess intraobserver variability, 20 randomly selected datasets were analyzed twice. Intraobserver repeatability coefficients (RC) were calculated using Bland-Altman analysis. Mean aortic diameter at the proximal neck was 21.4+/-3.0 mm at diastole and 23.2+/-2.9 mm at systole, a mean increase of 1.8+/-0.4 mm (8.5%, p<0.01). The RC for the aortic diameter at the level of the proximal aneurysm neck was 1.9 mm (8.9%). At the distal sealing zones, the mean increase in diameter was 1.7+/-0.3 mm (14.1%, p<0.01) for the right and 1.8+/-0.5 mm (14.2%, p<0.01) for the left common iliac artery (CIA). At both distal sealing zones, the mean increase in CIA diameter exceeded the RC (10.0% for the right CIA and 12.6% for the left CIA). The observed changes in aneurysm dimension during the cardiac cycle are small and in the range of intraobserver variability, so dynamic changes in proximal aneurysm neck diameter and aneurysm length likely have little impact on preoperative endograft selection. However, changes in diameter at the distal sealing zones may be relevant to sizing, so distal oversizing of up to 20% should be considered to prevent distal type I endoleak.

Creation of a Cleft in an Angiography Catheter to Facilitate Catheterization of Branches of the Aorta Arising at an Acute Angle

The authors report on the use of a catheter with a cleft for catheterization of a branch artery arising from the aorta with an acute angle. The cleft was created on either the right or cephalad portion at the tip of a seated 4-F shepherd hook catheter in the artery origin, depending on vessel angulation during chemoembolization procedures. This catheter was used in eight arteries-seven inferior phrenic arteries and one right subcostal artery-that could not be catheterized with a conventional coaxial technique. The microcatheter was successfully introduced into all eight vessels through the cleft without complications.

A randomised controlled study comparing conventional and magnetic guidewires in a two‐dimensional branching tortuous phantom simulating angulated coronary vessels

To directly compare the magnetic navigation system (MNS) guidewires with conventional guidewires in branching tortuous phantoms with operators of varying MNS and percutaneous coronary intervention experience. Vessel tortuosity, angulation, and side branches remain limiting factors in coronary interventions. The MNS addresses these limitations by precisely directing the tip of a magnetised guidewire in vivo aided by two permanent adjustable external magnets. Crossing and fluoroscopy times of six operators were evaluated in five tortuous Perspex(R) phantom vessels in three consecutive attempts. Standard guidewire (SG) usage was unrestricted. Two 2nd generation magnetic guidewires (MG) were used. Failure was noted if the cross was unsuccessful within 5 min. The magnetic navigation was vastly superior to SG techniques with increasingly tortuous phantoms. It dramatically decreased both the crossing and fluoroscopy times with maximal reduction from 201.7 +/- 111 to 36.4 +/- 13 sec, P < 0.001 and 204.7 +/- 24 to 47.2 +/- 19 sec, P < 0.001, respectively. The MNS had a 98.8% procedural success rate compared to 68% with SG techniques. Moreover it considerably limited the amount of wire usage from 5.5 to 1.3. Operators with prior MG experience performed significantly better than those without, except in the simplest phantom where the difference was nonsignificant (33.8 +/- 13 sec vs. 41.7 +/- 17 sec, P = 0.2). MNS significantly reduces both the crossing and fluoroscopy times in tortuous coronary phantom models achieving excellent success rates with dramatic reductions in guidewire usage. Operators with prior MNS experience had an advantage over the inexperienced.

Theoretical Analysis of Bifurcating Branch Vessel Geometry for Stents

Many different techniques for stenting bifurcation lesions are based on lesion locations, angiographic appearances, and types. Rigorous geometrical models have not been developed to give consistent descriptions. This study presents a rigorous geometrical analysis of vessel bifurcations to understand problems associated with tubular stents in order to help optimize stent placements. A 2-D bifurcating geometrical model of the side branch vessel (SB) angulations to the main vessel (MV) was analyzed and examined: (a) side branch exposed stent length (SBExpSt), (b) the side branch horizontal distance of the stent overhang (SBStOvH) into the MV, (c) side branch longitudinal axis of the ostial opening (SBLongOp), (d) the “saddle gap” at the ostium of branch to the wall of the MV. Formulas for SBExpStent, SBStOvH, SBLongOp, and saddle gap were derived. Results showed a curvilinear relation between the SBExpStent, the SBStOvH, and the SBLongOp to the SB angulations (θ). The relationship between saddle gap and the MV diameter also appears to be curvilinear. From the graphs, an acceptable ostial branch vessel stent coverage occurs between 70∘ and 90∘; for a 3 mm diameter SB at 70∘, the SBExpStent = 1.1 mm, SBStOvH = 1.03 mm, and SBLongOp = 3.05 mm were calculated. From the geometrical analysis, SB angulation should be considered before the stents are placed at bifurcating vessels, regardless of the different methods or types of vessels. Stent protrusion and/or incomplete coverage should be calculated at the bifurcating areas, especially at SB angulations < 70∘.