Significant Vascular Stenosis Research Articles

Detection and Imaging of Active Substances in Early Atherosclerotic Lesions Using Fluorescent Probes.

Atherosclerosis (AS) is a vascular disease caused by chronic inflammation and lipids that is the main cause of myocardial infarction, stroke and other cardiovascular diseases. Atherosclerosis is often difficult to detect in its early stages due to the absence of clinically significant vascular stenosis. This is not conducive to early intervention or treatment of the disease. Over the past decade, researchers have developed various imaging methods for the detection and imaging of atherosclerosis. At the same time, more and more biomarkers are being found that can be used as targets for detecting atherosclerosis. Therefore, the development of a variety of imaging methods and a variety of targeted imaging probes is an important project to achieve early assessment and treatment of atherosclerosis. This paper provides a comprehensive review of the optical probes used to detect and target atherosclerosis imaging in recent years, and describes the current challenges and future development directions.

Status Epilepticus, Hemispheric Confusion, a CT Perfusion Pitfall in “Code Stroke” Patients: A Case Report

: CT perfusion (CTP) is an evolving protocol for stroke evaluation in many hospitals, but there are several pitfalls in CT perfusion. Herein I present a patient suspicious of brain infarction under “stroke code”. CT perfusion was initially visually interpreted and because of obvious asymmetry between the right and left cerebral hemispheres the interpretation was consistent with right cerebral ischemia. CT angiogram (CTA) did not demonstrate significant vascular stenosis. Subsequent electroencephalography (EEG) was consistent with status epilepticus from the left cerebral hemisphere. Since more and more CTPs are now performed in acute setting of code stroke more patients are being imaged with ongoing seizure with increased perfusion in epileptogenic brain parenchyma. This is different from the conventional concept of hypo perfusion of the involved brain in CTP performed in the “post-ictal” phase. The interpreting radiologist should be informed about the patient symptoms and should avoid solo visual assessment of CT perfusion in patients under the “stroke code”.

Small Tenuous Intracranial Arteries Can Well Tolerate the Deployment of 2 Stents in Y Configuration or an Overlapping Manner in Treating Intracranial Aneurysms

To investigate parent vessel response to deployment of 2 stents for treatment of cerebral aneurysms. Fifteen patients (11 women and 4 men; age range, 25-83 years) with 18 wide-necked intracranial aneurysms were treated with 2 stents with or without subsequent coiling. The vascular diameter was measured and compared within the native parent artery, and the single stent and double stent were measured and compared before and immediately after stenting and at angiographic follow-up. Thirty stents were deployed. Before stenting, the mean vessel diameter was 3.4 ± 0.21 mm at point A, 3.06 ± 0.18 mm at point B, 3.16 ± 0.21 mm at point C, 2.67 ± 0.27 mm at point D, and 2.56 ± 0.23 mm at point E. The deployment of 2 stents resulted in statistically significant increases in both the average vascular diameter and cross-sectional area at points C (3.51 ± 0.22 mm, P= 0.0006; and 9.76 ± 1.17 mm2, P= 0.001, respectively) and E (2.88 ± 0.32mm, P= 0.01; and 7.28 ± 1.46 mm2, P= 0.02, respectively) compared with prestenting. At angiographic follow-ups, compared with before stenting, significant increases were documented at point C (3.42 ± 0.22 mm and 9.42 ± 1.37 mm2, respectively) at first angiographic follow-up but at points A (3.62 ± 0.45 mm and 10.51 ± 2.37 mm2, respectively) and B (3.26 ± 0.24 mm and 8.47±1.26 mm2, respectively) at second angiographic follow-up. No significant vascular stenosis was demonstrated at the double-stent segment compared with the single-stent or native artery segments. The small tenuous cerebral arteries can well tolerate the deployment of 2 stents for the treatment of intracranial aneurysms.

Dynamic CT angiography for the diagnosis of patients with thoracic outlet syndrome: Correlation with patient symptoms

IntroductionVasculo-nervous structures serving the upper limbs may be compressed as they pass through three areas: the inter-scalene triangle (IST), the costo-clavicular space (CCS) and the retropectoralis minor space (RMS). The diagnosis of thoracic outlet syndrome (TOS) is essentially clinical, but requires imaging to specify the site of compression, its grade and the existence of predisposing anatomical factors, in order to guide the treatment and eliminate the main differential diagnoses. Material and methodsImages from 141 patients who underwent dynamic CT angiography of the thoracic outlets from June 2008 to January 2015 were analyzed retrospectively. Patients had unilateral or bilateral vascular, neurological, mixed or atypical symptoms. We studied the degree of stenosis of the subclavian artery with the following grading system: 1 (0-<25%), 2 (25-<50%), 3 (50-<75%), 4 (75-100%). The site of stenosis and the presence of underlying anatomical predisposing factors were also taken in account. ResultsA total of 221 thoracic outlets were analyzed. Symptoms were neurological, mixed, vascular and atypical in 30%, 28%, 13% and 12%, respectively. Among patients with bilateral acquisitions, 38 outlets were asymptomatic; 40% of symptomatic outlets and only 5% of asymptomatic ones had grade 3 or 4 stenosis. 63% of the stenosis were in the CCS and 37% in the IST; 21% had a predisposing anatomical factor most often a costo-clavicular anomaly, associated with significant stenosis in 50% of cases. ConclusionVascular stenosis of more than 50% on dynamic CT angiography is strongly associated with TOS. Predisposing factors were present in 21% of cases, causing significant vascular stenosis in half, underscoring the need for functional evaluation.

Coronary Artery Disease in Patients with Critical Limb Ischemia Undergoing Major Amputation or Not.

Background:Due to the increase of elderly and diabetes patients, surgeons encounter patients requiring treatment of critical limb ischemia (CLI) in the presence of systemic arteriosclerotic diseases. In this study, we retrospectively investigated the prevalence of coronary artery disease (CAD) in patients with CLI who underwent major (above-the-ankle) amputation or nonmajor amputation (below-the-ankle amputation or debridement of wound).Methods:We retrospectively investigated 129 consecutive patients surgically managed for CLI in our institution between January 2013 and December 2015. The prevalence of CAD was defined as a cardiac treatment history or significant vascular stenosis (stenosis of > 75%). The outcomes were compared between patients who underwent major amputation (n = 36) and nonmajor amputation (n = 93). Additionally, archived record of 566 patients treated nonsurgically by percutaneous transluminal angioplasty in our institution was investigated to evaluate patients with milder peripheral artery disease.Results:CAD was present in 83 patients (69%), including 82% of patients who underwent major amputation and 63% of nonmajor amputation group. The prevalence of CAD was significantly higher in the major amputation group (P = 0.042). Ejection fraction was not significantly different (P > 0.05). Among the 566 CLI patients treated by only percutaneous transluminal angioplasty, 227 (40%) had CAD, which was a significantly lower prevalence than those surgically treated (P < 0.001).Conclusions:The presence of CAD is more frequent in CLI patients who require extended surgical management of the limb than in those who do not. Evaluation of CAD and careful perioperative management are important for patients with CLI patients.

Combining Coronary with Carotid and Cerebrovascular Angiography Using Prospective ECG Gating and Iterative Reconstruction with 256-slice CT.

To investigate the image quality and radiation dose of combined coronary and carotid/cerebrovascular angiography with ECG gating and iterative reconstruction using 256-slice CT compared with the findings with the two examinations performed separately. One hundred sixty-five consecutive patients underwent a single-injection single-pass combination of coronary and carotid/cerebrovascular CT angiography (group A), coronary CT angiography alone (group B), or carotid/cerebrovascular CT angiography alone (group C). We assessed the image quality of the combined and separate examinations and calculated the respective effective radiation doses. We evaluated the differences in the proportions of image quality grade between the combination and single-examination groups. Diagnostic performance of the combined scanning for detecting significant vascular stenosis has been compared with reference digital subtraction angiography (DSA) in the patient subgroup of group A. There was no significant difference in age, body mass index (BMI), or gender distribution among the 3 groups (all P>0.05). But there was significant difference in scan length, DLP, and effective dose among the 3 groups (all P<0.05). There were no significant differences in the effective radiation dose of coronary scanning between groups A and B (P>0.05), while the effective radiation dose of carotid/cerebrovascular scanning in group A was significantly lower than that in group C (P<0.05), and the total effective radiation dose in group A were relatively low (2.21±1.38mSv). The differences of the proportion of carotid/cerebrovascular image quality grades between groups A and C were not significant (P>0.05). In a subgroup of group A of 30 patients with DSA, combined computed tomographic angiography successfully detected 56 coronary stenosis on per-segment basis, and 62 stenosis on carotid and cerebral artery. The sensitivity, specificity, positive and negative predictive value (NPV) of coronary stenosis were 91.80%, 95.60%, 87.50% and 97.21%, respectively. The sensitivity, specificity, positive and NPV of carotid/cerebrovascular stenosis were 93.55%, 94.68%, 92.06% and 95.70%, respectively. Combination of coronary and carotid/cerebrovascular angiography with 256-slice CT scanner with prospective ECG gating and iterative reconstruction produces diagnostic-quality images of the coronary, carotid, and cerebrovascular systems in a single examination, using less contrast medium and a lower radiation dose than when the two examinations are performed separately. This novel technique has high accuracy in detecting significant stenosis in one image setting.

64-Slice MDCT Angiography of Upper Extremity in Assessment of Native Hemodialysis Access

To compare multidetector row computed tomographic (MDCT) angiography with conventional digital subtraction angiography (DSA) in the evaluation of vascular access stenoses in hemodialysis patients. Twenty-one consecutive patients were imaged with MDCT angiography and subsequent DSA. The superficial vein of leg was used as the route for intravenous administration. The vascular stenosis was assessed in not significant (<50% stenosis), moderate stenosis (50%-74% stenosis), severe stenosis (75%-99%), and total occlusion (100%). The accuracy, sensitivity, specificity, positive, and negative predictive values were calculated for significant vascular stenosis using DSA as the standard reference. The sensitivity and specificity of MDCT angiography for the detection of significant hemodialysis vascular access were 100% (95% CI, 89.3%-100%) and 94.8% (95% CI, 89.1%-97.6%), respectively. The positive and negative predictive values were 84.2% (95% CI, 68.1%-93.4%) and 100% (95% CI, 95.8%-100%), respectively. The accuracy of MDCT angiography for detection of significant stenoses was 95.9% (95% CI, 91.4%-97.0%). MDCT angiography provides excellent correlation in vascular stenosis as compared with DSA in hemodialysis access. Complete assessment of entire vascular segments could be performing with MDCT angiography in planning before endovascular intervention or surgical correction.

Time to Symptomatic Vascular Stenosis at Different Locations in Patients with Arteriovenous Grafts

Most arteriovenous grafts fail due to irreversible thrombosis, superimposed on hemodynamically significant vascular stenosis. Previous studies observed the highest frequency of stenosis at the venous anastomosis, without addressing the timing of stenosis. The present study quantified time to symptomatic stenosis at different vascular locations, and related it to permanent graft failure. A prospective computerized vascular access database was queried retrospectively to identify 309 hemodialysis patients receiving new upper extremity grafts during a 4-year period at a large dialysis center. For each vascular site we calculated the time to symptomatic stenosis using survival techniques. The cumulative likelihood of symptomatic stenosis at 2 years was 67% for venous anastomotic stenosis, 19% for intra-graft stenosis, 16% for venous outlet stenosis, 13% for central vein stenosis, and 5% for arterial anastomotic stenosis. The cumulative risk of graft failure at 2 years was 40%. Stenosis at the venous anastomosis was twice as likely as cumulative graft failure (hazard ratio [HR] 1.95; 95% confidence interval [CI], 1.65-2.52, p < 0.001). In contrast, intra-graft stenosis was half as likely as cumulative graft failure (HR 0.45; 95% CI, 0.36-0.61, p < 0.001). Central vein stenosis was more likely in patients with a previous ipsilateral catheter compared with those without one (HR 2.40; 95% CI, 1.39-5.58, p = 0.004). Symptomatic stenosis occurs much earlier at the venous anastomosis compared with other vascular sites. Moreover, preexisting ipsilateral internal jugular dialysis catheters more than double the risk of central vein stenosis.

More coronary artery stenosis, more cerebral artery stenosis? A simultaneous angiographic study discloses their strong correlation

Cerebral artery stenosis (CAS) has the same pathogenesis as coronary artery disease (CAD), but the coexistence of these two diseases has been rarely reported. To detect coexistent CAS in CAD patients, we conducted a study of simultaneous coronary and cerebral angiography. Of the 663 consecutive newly diagnosed CAD patients who had not yet been explored to have CAS, 80 were admitted to undergo angiography of bilateral carotid and vertebral system during the same procedure. We defined significant vascular stenosis, either located intracranially or extracranially, as the lesions of diameter stenosis more than 50%. Association between carotid or vertebral stenosis and their potential risk factors were also analyzed. Of our patients, 18 (22.5%) had significant extracranial vascular stenosis, 14 (17.5%) suffered from intracranial stenosis, and 20 (25%) had both. Only 28 patients (35%) had no significant intracranial or extracranial stenosis. None of the demographic parameters as hypertension or diabetes showed significant differences between the cerebral patent group and the CAS group, except for the number of coronary stenotic vessels (1.71 +/- 0.81 versus 2.69 +/- 0.64, P < 0.001). The number of coronary stenotic vessels is correlated well to the number of cerebral stenotic lesions (r = 0.562, P < 0.001). Besides, 8 of the cerebral stenotic patients and 2 of the cerebral patent patients had ischemic stroke previously. We conclude the CAS is coexistent in more than half of the CAD patients in this study. Our study also implies a proportional increase in the severity of CAS to CAD severity.

Acute and Chronic Effects of Extensive Radiofrequency Lesions in the Canine Caval Veins: Implications for Ablation of Atrial Arrhythmias

Although radiofrequency (RF) ablation within the caval veins has been increasingly used to treat a variety of atrial tachyarrhythmias, the consequences of RF ablation in the caval veins are unknown. We explored the acute and chronic angiographic and pathological effects of extensive RF ablation in the caval veins. Under fluoroscopy guidance, conventional (4 mm tip, 60 degrees C, 60 seconds) RF applications (n = 6-7) were delivered in each vena cava (from +/-2 cm into the vein to the veno-atrial junction) of 15 dogs (10 +/- 3 kg). Animals were killed 1 hour and 5 weeks after ablation for histological analysis. Angiography was performed before ablation (acute dogs only) and at sacrifice to assess the degree of vascular stenosis. In acute dogs (n = 5), luminal narrowing was noted in 10/10 (100%) targeted veins (mild in two; moderate in three and severe in five, including two total occlusions). In the six chronic animals that completed the protocol (four died during follow-up), stenosis was also observed in 12/12 (100%) ablated veins (mild in six; moderate in four and severe in two). Of these, one superior vena cava was suboccluded with development of extensive collateral circulation. Histologically, acute lesions displayed typical transmural coagulative necrosis, whereas chronic lesions revealed intimal proliferation, necrotic muscle replaced with collagen, endovascular contraction, and disruption and thickening of the internal elastic lamina. In this model, extensive RF ablation in the caval veins may result in significant vascular stenosis. These findings may have implications for catheter ablation of arrhythmias originating within the caval veins.

Kardiovaskuläre MR-Ganzkörperbildgebung bei Patienten mit symptomatischer Atherosklerose der peripheren Gefäße

To examine patients with peripheral-arterial-occlusive-disease (PAOD) for systemic effects associated with atherosclerosis using a comprehensive state-of-the-art whole-body MR examination protocol. The protocol comprises the assessment of the complete arterial vasculature (except coronary arteries), the brain, and the heart. Multi-station whole-body 3D MR angiography was performed in sixty consecutive patients with clinical suspicion for PAOD at 1.5 T (Magnetom Avanto, Siemens, Erlangen, Germany). Functional and delayed enhancement cardiac images were acquired, as well as FLAIR images of the brain and TOF angiography of intracranial vessels. MR and DSA images were assessed by independent observers for atherosclerotic manifestations and other pathology. Sensitivity and specificity for the detection of vascular pathology was calculated for MR data using conventional DSA of the symptomatic region as standard-of-reference. Sensitivity and specificity for the detection of significant vascular stenosis (> 70 % luminal narrowing) was 94 % and 96 % (PPV 87 %, NPV 98 %). Significant microangiopathic tissue alterations (n = 7) and/or cerebral infarction (n = 18) were diagnosed in 23/60 patients. Thirty-eight of 60 patients presented with systolic left ventricular wall motion abnormalities. In 24 patients subendocardial or transmural delayed enhancement was detected in corresponding regions, indicating prior myocardial infarction. For patients with PAOD and suspected systemic atherosclerotic disease a comprehensive diagnosis of accompanying cardiovascular pathology and therefore staging of systemic atherosclerotic disease is feasible within one MR examination.

Atherosclerotic Disease: Whole-Body Cardiovascular Imaging with MR System with 32 Receiver Channels and Total-Body Surface Coil Technology—Initial Clinical Results

In this prospective study, the feasibility of a comprehensive cardiovascular imaging protocol with a dedicated whole-body 1.5-T magnetic resonance (MR) imager with 32 receiver channels in 34 patients with peripheral arterial occlusive disease was evaluated. Informed consent and institutional review board approval were obtained. Three-dimensional MR angiographic data sets were acquired with adapted injection protocol. Cardiac functional imaging and delayed-enhancement imaging were performed, as were fluid-attenuated inversion-recovery imaging of the brain and time-of-flight MR angiography of the intracranial blood vessels. Sensitivity and specificity for depiction of significant vascular stenosis (> 70%) were 96%, with conventional digital subtraction angiography as the standard. Substantial microangiopathic tissue alterations (n = 4) and/or cerebral infarction (n = 4) were diagnosed in seven patients. In seven patients, subendocardial or transmural delayed enhancement was detected in corresponding regions, indicating prior myocardial infarction. Previously unknown findings diagnosed with MR imaging required midterm follow-up or therapy in 24 patients, whereas change of therapy or immediate treatment was necessary in three. For patients suspected of having systemic atherosclerotic disease, comprehensive risk assessment is feasible within 30 minutes.

Vascular complications after living related liver transplantation: evaluation with gadolinium-enhanced three-dimensional MR angiography.

The purpose of this study was to evaluate the efficacy of gadolinium-enhanced three-dimensional (3D) MR angiography for detection of vascular complications in patients who have undergone living related liver transplantation. Seventy-six patients who underwent living related liver transplantation were evaluated with gadolinium-enhanced 3D MR angiography. All MR angiograms were assessed for patency of the hepatic artery and the portal vein using a four-point scale (grades I-IV). The results were correlated with conventional angiography (n = 23) and clinical follow-up with Doppler sonography (n = 53) for more than 6 months. Seventy-three of 76 MR angiography procedures were technically adequate. When grades III (focal narrowing [> 50%] at the anastomotic site) and IV (abrupt cutoff at the anastomotic site with nonvisualization of the right [or left] hepatic artery distal to the anastomosis) were regarded as the diagnostic criteria for hepatic artery stenosis, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MR angiography were 100%, 74%, 29%, 100%, and 77%, respectively. In the portal vein, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MR angiography were 100%, 84%, 35%, 100%, and 85%, respectively, when grades III (narrowing [> 50%] without poststenotic dilatation) and IV (narrowing [> 50%] with poststenotic dilatation) were defined as criteria for portal vein stenosis. MR angiography was sensitive but not specific in the detection of significant vascular stenosis after living related liver transplantation. However, normal MR angiography findings reliably exclude the possibility of significant stenosis.

Dobutamine-atropine stress myocardial perfusion SPECT imaging in the diagnosis of graft stenosis after coronary artery bypass grafting

Objective. To assess the accuracy of dobutamine stress myocardial perfusion single photon emission computed tomographic imaging (SPECT) for the diagnosis of vascular stenosis after coronary artery bypass grafting (CABG). Background. Exercise thallium scintigraphy is a clinically useful method for the diagnosis of graft stenosis after CABG. Although dobutamine perfusion scintigraphy is an alternative method for the evaluation of patients with limited exercise capacity, its value in the diagnosis of vascular stenosis after CABG has not been studied. Methods. Dobutamine (up to 40 μg/kg/min)-atropine (up to 1 mg) stress test in conjunction with myocardial perfusion SPECT imaging ( 201Tl or 99m technetium sestamibi [MIBI]) was performed in 71 patients (mean age 58 ± 9 years, 57 men) with limited exercise capacity referred for evaluation of myocardial ischemia 3.7 ± 3.5 years after CABG. Significant vascular stenosis was defined as ≥50% luminal diameter stenosis of a graft or a native nongrafted coronary artery and was predicted on the basis of reversible perfusion abnormalities. Results. Significant vascular stenosis was detected in 52 patients. Sensitivity, specificity, and accuracy of reversible perfusion defects at dobutamine SPECT for the overall diagnosis of vascular stenosis were 81%, confidence interval (CI) 72 to 90, 79%, CI 69 to 88, and 80%, CI 71 to 90, respectively. Significant vascular stenosis was detected in 73 arterial regions. Sensitivity, specificity, and accuracy of dobutamine SPECT for the diagnosis of regional vascular stenosis were 66%, CI 58 to 74, 83%, CI 76 to 89, and 74%, CI 67 to 81, respectively. Patients with multivessel stenosis had a higher number of ischemic segments (1.6 ± 1.3 vs 1 ± 1, P < .05) and ischemic perfusion score (3.2 ± 2.7 vs 2.2 ± 2.3, P < .05) than patients with single-vessel stenosis, respectively. Significant graft stenosis was detected in 67 graft regions. Sensitivity, specificity, and accuracy of dobutamine SPECT for the diagnosis of regional graft stenosis were 64%, CI 56 to 73, 85%, CI 78 to 91, and 74%, CI 66 to 82, respectively. Conclusion. Dobutamine stress myocardial perfusion SPECT imaging is a useful method for the diagnosis of significant vascular stenosis after CABG in patients with limited exercise capacity. (J Nucl Cardiol 1998;5:491–497)

Relationship of vascular thrombosis and inflammatory leukocyte infiltration to neointimal growth following porcine coronary artery stent placement

Background: Superficial and intramural thrombosis are reproducible histopathological features of the porcine coronary oversized stent injury model. Fibrin and its degradation products are chemotactic for mononuclear leukocytes, and promote the proliferation and migration of vascular smooth muscle cells (VSMC) in vitro. The goal of this study was to quantitate the serial histomorphologic evolution of thrombosis, leukocyte infiltration, VSMC proliferation and collagen accumulation following porcine coronary artery stent placement in a porcine model. Methods: Twenty-four normocholesterolemic swine underwent oversized balloon (3.5 – 4.0 mm) coronary angioplasty and tantalum metal stent placement. Twenty-six different arterial sites were injured, followed by serial sacrifice at day 4 ( n = 6), 8 ( n = 6), 14 ( n = 6), and 28 ( n = 6). Quantitative analysis of the neointima was performed using a high resolution video-microscopy interface and a validated histomorphometric software program. Alpha actin-positive VSMC density (per 10 4 μ 2 neointimal area) and collagen-specific picro-sirius red fluorescence (percent of neointima) were quantitated at sites adjacent to and distant from coronary artery stent placement. Results: The percent of total neointimal area occupied by resolving thrombus material was greater at days 4–8 compared to 14–28 days (59–63% vs. 1–2%; P = 0.001). Mononuclear leukocytes were also significantly increased at days 4 and 8 (92 ± 1 and 70 ± 8%) compared to days 14–28 (both 3 ± 3%; P = 0.001), as a percentage of the total neointimal cellularity. Total neointimal cell density did not change (20 ± 10, 12 ± 6, 23 ± 7 and 20 ± 3 cells/10 4 μ 2; P-value, NS), despite progressive cross-sectional vascular area stenosis reduction from 7 ± 3% at day 4 to 72 ± 14% at day 28 ( P = 0.001). Percent neointimal fibrinoid thrombus content and mononuclear leukocyte cellularity were correlated in this model ( R = 0.81; P < 0.001). Peri-stent neointimal collagen staining exceeded that at vascular sites distant from porcine coronary stent placement by 14 days (29 ± 6 vs. 15 ± 3%), and remained greater at 28 days (35 ± 11 vs. 16 ± 12%) (both P < 0.05). Conclusions: Quantitative serial histomorphometry of porcine coronary vascular stent delivery sites demonstrates early (4–8 day) neointimal mononuclear leukocyte infiltration which is histomorphologically and temporally related to intramural fibrinoid thrombosis. Significant vascular stenosis and collagen deposition occurs by 14–28 days at these vascular injury sites. These data suggest a local interaction between thrombotic and inflammatory elements in porcine coronary neointima following oversized stent injury.