冠状动脉内弹力膜缺损与内膜增厚的关系

目的：研究冠状动脉（冠脉）内弹力膜缺损与内膜增厚及动脉粥样硬化发生发展的关系。方法：应用图像分析仪对北京地区１０２例意外死亡年轻人（１５～３９岁）冠脉近侧端进行了形态定量及统计学处理。结果：在同体三支冠脉的比较中内弹力膜缺损程度以左前降支居首位，其次为右冠脉和左旋支。男重于女。内弹力膜缺损程度与内膜增厚呈正相关（ｒ＝０．８７，Ｐ＜０．０１）。紧接内膜增厚高峰之后的年龄组第二弹力膜检出率最高，此后十年间内膜亦无明显进一步增厚。随年龄增长第二弹力膜检出率降低，内膜增厚程度加重。结论：内弹力膜缺损的量与内膜增厚的程度及速度关系密切；第二弹力膜的形成对减慢内膜增厚速度有重要意义。     

The Effect of Intracoronary β-Radiation on Neointimal Formation and Vascular Remodeling in Balloon-Injured Porcine Coronary Arteries: Effect of Dose Rate

Background: Neointimal formation and vascular remodeling are major mechanisms contributing to coronary restenosis after percutaneous transluminal coronary angioplasty. Intracoronary γ- and β-radiation have been shown to inhibit neointimal formation in balloon-injured porcine coronary arteries. However, the effects of Intracoronary radiation (ICR) dose and dose rate on vascular remodeling versus inhibition of neointimal formation have not been evaluated. Methods and Results: Forty-one Hanford Miniature swine were subjected to oversized balloon injury in the left anterior descending and right coronary artery. A spiral centering catheter with perfusion capabilities was placed in the injured segment for circumferentially uniform radiation dose delivery to the vessel wall. Each artery was randomly afterloaded with a dummy wire or an active wire with the ³²P source encapsulated in either a short (3 mm) or long (27 mm) segment at the distal end of the wire. The 3-mm source wire was used to deliver 650, 1,300, and 1,900 cGy while the 27-mm source wire was used to deliver 1,200 and 3,500 cGy of β-radiation to the adventitia (～ 0.5 mm into the vessel wall). The dose rate for ICR varied from 2.5 to 140 cGylsec, depending on the mCi strength of the ³²P source at the time of endovascular radiation. One month later, repeat coronary angiography and intravascular ultrasound (IVUS) to measure the external elastic lamina (EEL) area were done. The animals were sacrificed and the coronary vasculature was perfusion fixed. Morphometric, quantitative coronary angiographic, and IVUS analyses were carried out in a blinded fashion. A significant reduction in percent area stenosis (PAS) and neointimal area (NA) was observed on morphometry in coronary arteries treated with 3,500 cGy of β-radiation. The PAS and NA was 44%± 13% and 0.96 ± 0.25 mm² in the control groups versus 19%± 14% and 0.30 ± 0.23 mm² in the 3,500-cGy group (P < 0.02). There was no significant difference on morphometry between the control and the other four β-radiationtreated groups. There was no significant improvement in the change in minimum lumen diameter (ΔMLD) between the control and the five radiation-treated groups. Further analysis of angiographic data revealed that the apparent lack of beneficial effect on angiography was due to significant reductions in lumen diameter in the subgroups of arteries subjected to ICR at a dose rate > 50 cGylsec with the 3-mm source wire only. The ΔMLD was -1.39 ± 0.49, –1.79 ± 0.64, and -1.79 ± 0.39 mm in the 650-, 1,300-, and 1,900-cGy groups treated with a dose rate > 50 cGylsec versus -0.56 ± 0.95 in control (P < 0.05). This reduction in lumen diameter on angiography was associated with a significant reduction in vessel (EEL) area especially in the groups treated with the 3 mm source at a dose rate > 50 cGylsec. The EEL area was 8.8 ± 1.7, 9.9 ± 1.7, and 8.9 ± 0.6 mm² in the 650, 1,300, and 1,900 cGy groups treated at a dose rate > 50 cGylsec compared to 11.7 ± 1.6 mm² in control arteries (P < 0.001). Conclusions: Endovascular β-radiation at high doses (3,500 cGy to adventitia) and dose rate < 50 cGylsec inhibits restenosis after balloon injury in the porcine model of coronary restenosis. This dose and dose rate is associated with a neutral effect on vascular remodeling. While lower doses of ICR did not worsen the PAS, a reduction in MLD and EEL area were observed. However, this adverse effect on angiographic restenosis and vascular remodeling appears to be largely limited to the subgroups treated at dose rates > 50 cGylsec.     

Intracoronary Irradiation with 186/188Rhenium Following Balloon Overstretch Injury Reduces Neointima But Does Not Impair Vasoreactivity of Porcine Coronary Arteries

Objective: The purpose of this study was to assess the effect of ^186/188rhenium (^186/188Re) on the neointimal proliferation and on the vasomotion of irradiated porcine coronary arteries following balloon injury. Background: Intracoronary radiation (IR) at doses of 10–25 Gy reduces intimal hyperplasia in animal models and lowers restenosis in clinical trials. The response of coronary arteries to acetylcholine (ACh) has been used to examine endothelial function, but this has not been reported in porcine coronary arteries subjected to overstretch balloon injury (BI) and subsequent IR. Methods: Vasomotor response was studied at baseline and at 2 weeks in 20 swine. Baseline vasomotor study without BI was carried out in six animals (12 arteries; Group I, no injury, no radiation). Subsequently the left anterior descending (LAD) and the left circumflex (LCX) arteries of 11 animals were subjected to BI. Eight of these animals (15 arteries) were subjected to IR with ^186/188Re in the LAD and LCX arteries in doses of 15 Gy followed by vasomotor studies at 2 weeks (Group II, BI, radiation). Three animals, (six arteries) of the BI group were not subjected to IR and their vasomotor functions assessed two weeks later (Group HI, BI, no radiation). Endothelium dependent vasomotion was assessed by Doppler flow wire and by quantitative coronary angiography (QCA) following selective infusion of serial doses of ACh proximal to the injured and irradiated segments. Nitroglycerin (200 μg) was injected intracoronary to detect endothelium independent vasodilatation. Histomorphometry and QCA analysis was performed to confirm the effect of IR on intimal area (IA), and IA corrected for fracture length (IA/FL). Results: Responses to ACh infusion and coronary flow reserve were similar at baseline before injury and at 2 weeks following injury with and without radiation. The irradiated vessels demonstrated normal vasodilatation responses to nitroglycerin. The irradiated vessels showed a marked reduction in IA and IA/FL. Conclusion: The vasoreactivity of irradiated coronary arteries is preserved at doses that inhibit neointima formation in the porcine model.     

Local Intracoronary Fibrinolysis in Acute Myocardial Infarction of Ectatic Coronary Arteries in the Post-Abciximab Era

Percutaneous intervention in the context of coronary artery ectasia (CAE) is penalized with no-reflow phenomenon. The glycoprotein-IIb/IIIa-inhibitor abciximab was the most accepted method for pharmacology thrombus resolution in this scenario, nevertheless, this agent was recently withdrawn. We describe 5 patients treated with local intracoronary fibrinolysis administrated through predesigned catheters in the setting of AMI and CAE.     

Acute Stent Thrombosis in the Setting of Cocaine Abuse Following Percutaneous Coronary Intervention

The treatment of acute coronary syndrome (ACS) in patients with documented cocaine abuse has always presented significant challenges. Issues related to medication compliance, the potential risks of beta adrenergic blockade, and possible continued cocaine abuse postmyocardial infarction necessitate a unique, individualized approach to these patients. Recent data in the era of extensive percutaneous coronary interventions (PCI) and intracoronary stent (ICS) implantation have raised questions regarding the safety of ICS in patients who may revert to cocaine abuse postacute coronary syndrome as a result of the potentially higher risk of stent thrombosis in these patients. While the precise reason as to why cocaine use may increase the risk of stent thrombosis is not fully understood, it is likely the result of a confluence of factors, including coronary vessel vasoconstriction, impaired vascular compliance, as well as the platelet-activating effect of cocaine. We present the case a 46-year-old male with a history of cocaine abuse who presented with an acute stent thrombosis 2 days post-PCI likely as a result of cocaine abuse on the day of discharge following initial stent implantation for a non-ST-elevation myocardial infarction (NSTEMI). We also review the literature regarding the safety of PCI in cocaine abusers.     

Opposing Responses of the Calcium Channel Blocker Nicardipine to Vascular Stiffness in the Elastic and Muscular Arteries in Rabbits

Aim: The cardio-ankle vascular index (CAVI) consists of intrinsic and functional arterial stiffness mainly regulated by vasoactive compounds. A new stiffness index of the aorta (aBeta) and iliac-femoral arteries (ifBeta) was determined by applying the CAVI theory to the whole aorta and iliac-femoral arteries. We investigated the changes in aBeta and ifBeta in response to decreased blood pressure (BP) induced by the Ca ^2＋ channel blocker nicardipine to elucidate the involvement of Ca ^2＋ in aBeta and ifBeta. Methods: Pressure waves at the origin of the aorta (oA), distal end of the abdominal aorta (dA), and left femoral artery (fA) as well as flow waves at the oA were simultaneously recorded before and after the infusion of nicardipine (50 µg/kg/min) for 2 min in 12 male rabbits under pentobarbital anesthesia. Beta was calculated using the following formula: Beta=2ρ / PP×ln (SBP / DBP)×PWV ² , where ρ, SBP, DBP, and PP denote blood density and systolic, diastolic, and pulse pressures, respectively. aBeta, ifBeta, and aortic-iliac-femoral Beta (aifBeta) were calculated using aPWV, ifPWV, and aifPWV, respectively. Results: SBP, mean arterial pressure (MAP), DBP, and total peripheral vascular resistance significantly decreased during the administration of nicardipine, whereas cardiac output significantly increased. aBeta and ifBeta significantly increased and decreased, respectively, whereas aifBeta did not change despite the decrease in BP. ifBeta and aBeta positively and negatively correlated with BP, respectively, whereas aifBeta did not correlate with SBP. Conclusions: There were contradictory arterial responses to nicardipine between the elastic and muscular arteries. Unknown vasoconstriction mechanisms that are not involved in Ca ^2＋ influx may function in the aorta in response to decreased BP.     

Anatomic Correlates of Mitral Systolic Anterior Motion in Transposition of the Great Arteries Following Atrial Switch Operation

Introduction: We sought to investigate whether the development of sub-pulmonic systolic anterior motion (SAM) may be inherent to the anatomy of the the mitral valve (MV) or affected by external factors, such as a dilated right ventricle or chest abnormalities in d-looped transposition of the great arteries post atrial switch operation (d-TGA/AtS). Methods: Analysis was performed of clinical and cardiac imaging studies acquired on 19 adult patients with d-TGA/AtS (age 42 ± 6 years old, 56% male) between 2015–2019. Echocardiography data included mitral apparatus anatomy, and CT/MRI data included biventricular dimensions, function, and Haller index (HI) for pectus deformity. Results: Patients with leaflet SAM (n = 6) compared to patients without SAM (n = 13) had higher MV protrusion height (2.3 ± 0.5 vs. 1.5 ± 0.4 cm, p ≤ 0.01) and longer anterior MV leaflet length (3.1 ± 0.4 cm vs. 2.6 ± 0.3 cm p ≤ 0.05), when compared to those without. CT/MRI showed higher sub-pulmonic left ventricular ejection fraction (LVEF) in the SAM group (71% ± 8% vs. 54% ± 7%, respectively). RV size and function, significant chest deformity (HI > 3.5), presence of a ventricular lead pacemaker, and septal thickness did not play a role in development of SAM. Conclusions: An elongated mitral apparatus is associated with the development of SAM, and the development of left ventricular outflow tract obstruction (LVOTO), in d-TGA/AtS. LV hyperkinesia is associated with SAM. Systemic RV dimensions, septal thickness, and degree of chest deformity did not differ significantly between subjects with SAM and those without.     

The Internal Viscosity of the Human Erythrocyte May Determine Its Lifespan in Vivo

Young red cells obtained by high-speed centrifugation of a normal blood sample had an MCHC of 31.7 g/dl which corresponds to an internal viscocity of about 9 cP. Old red cells from the same blood sample had an average MCHC of 37.5 g/dl which is equivalent to a mean internal viscosity of about 54 cP. This increased internal viscocity of old cells must result in a prolonged transit time through the narrow channels of the splenic microvasculature and consequently an increased probability of contact with a phagocytic macrophage. This probability of contact increases as the internal viscosity of the cell is further increased and may represent one of the major factors associated with the detection and subsequent elimination of senescent cells by the spleen.     

A One-dimensional Model of Blood Flow in Arteries with Friction and Convection Based on the Womersley Velocity Profile

In this paper, we present a one-dimensional model for blood flow in arteries, without assuming an a priori shape for the velocity profile across an artery (Azer, Ph.D. thesis, Courant Institute, New York University, 2006). We combine the one-dimensional equations for conservation of mass and momentum with the Womersley model for the velocity profile in an iterative way. The pressure gradient of the one-dimensional model drives the Womersley equations, and the velocity profiles calculated then feed back into both the friction and nonlinear parts of the one-dimensional model. Besides enabling us to evaluate the friction correctly and also to use the velocity profile to correct the nonlinear terms, having the velocity profile available as output should be useful in a variety of applications. We present flow simulations using both structured trees and pure resistance models for the small arteries, and compare the resulting flow and pressure waves under various friction models. Moreover, we show how to couple the one-dimensional equations with the Taylor diffusion limit (Azer, Int J Heat Mass Transfer 2005;48:2735–40; Taylor, Proc R Soc Lond Ser A 1953;219:186–203) of the convection-diffusion equations to drive the concentration of a solute along an artery in time.     

Effectiveness of the Cough Reflex in Patients with Aspiration Following Radiation for Head and Neck Cancer

The effectiveness of the cough reflex in patients who aspirated following radiation for head and neck cancer was evaluated in 89 patients (49 chemoradiation, 33 postoperative radiation, and 7 radiation alone). All patients had modified barium swallow because of dysphagia. The cough reflex was graded as present and effective, ineffective, intermittently effective, or absent. All patients were cancer-free at the time of the swallowing study. The cough reflex was present and effective in 46 patients (52%), ineffective in 17 patients (19%), and absent in 26 patients (29%) on initial investigation. Among the 43 patients who had ineffective or absent cough reflex, their treatment was chemoradiation (26), postoperative radiation (13), and radiation alone (4). In 30 patients who had sequential modified barium swallow, the cough reflex was constantly effective, ineffective, or intermittently effective in 12 (40%), 13 (43%), and 5 (17%) patients, respectively. The cough reflex was frequently ineffective or absent in patients who aspirated following radiation for head and neck cancer. Cough may also be intermittently ineffective to protect the airways following radiation.     

Study of the Magnetized Hybrid Nanofluid Flow through a Flat Elastic Surface with Applications in Solar Energy

The main theme of the present study is to analyze numerically the effects of the magnetic field on the hybrid nanofluid flow over a flat elastic surface. The effects of the thermal and velocity slips are also analyzed in view of the hybrid nanofluid flow. It is considered a combination of titanium oxide (TiO₂) and copper oxide (CuO) nanoparticles that are suspended in the incompressible and electrically conducting fluid (water). The behavior of the Brownian motion of the nanoparticles and the thermophoretic forces are contemplated in the physical and mathematical formulations. Moreover, the impact of the Joule heating and viscous dissipation are also discussed using the energy equation. The mathematical modeling is simulated with the help of similarity variables. The resulting equations are solved using the Keller–Box method with a combination of finite difference schemes (FDSs). Hybrid nanofluids provide significant advantages over the usual heat transfer fluids. Therefore, the use of nanofluids is beneficial to improve the thermophysical properties of the working fluid. All of the results are discussed for the various physical parameters involved in governing the flow. From the graphical results, it is found that the hybrid nanoparticles improve the concentration, temperature, and velocity profiles, as well as the thickness of the relevant boundary layer. The conjunction of a magnetic field and the velocity slip, strongly opposes the fluid motion. The boundary layer thickness and concentration profile are significantly reduced with the higher levels of the Schmidt number.     

Hygrothermal Performance of Salt (NaCl) for Internal Surface Applications in the Building Envelope

Salt (NaCl), as a by-product from the potash and desalination industry, can be the solution to the scarcity of building materials and might replace more energy-consuming materials. However, salt carries the risk of deliquescence in humid environments. This study conducted fundamental research on the hygrothermal performance of salt for internal surface applications in the building envelope in six different climate conditions. In addition, salt’s performance was also compared with that of gypsum in similar applications. The simulation models (using WUFI^®Pro, WUFI^®Plus) and in situ measurements were applied to investigate the hygrothermal consequences of the incorporation of salt on the thermal envelope, indoor environment, and energy consumption. Our studies revealed that salt provided the best hygrothermal responses without Heating, Ventilation, and Air Conditioning (HVAC) in very hot-dry and the worst in very hot-humid climates. With an energy-efficient thermal envelope and HVAC, salt can also find an indoor application in temperate, continental, and subpolar climates. In comparison to gypsum, salt has a slightly higher energy demand (heating, cooling, and dehumidification) due to its higher thermal conductivity and moisture resistance. This study fills the knowledge gap on salt’s hygrothermal performance and shows the potential in its utilization.     

Atrial Baffle Problems Following the Mustard Operation in Children and Young Adults with Dextro‐Transposition of the Great Arteries: The Need for Improved Clinical Detection in the Current Era

Objective. Intraatrial Mustard baffle repair of dextro‐transposition of the great arteries (d‐TGA) is vulnerable to complications, typically obstruction and leaks. Because patients often require pacemakers or intracardiac electrophysiology studies (EPS)/ablation for arrhythmias, narrowed or obstructed baffles restrict cardiac access hindering intracardiac procedures. Current guidelines recommend clinical as well as comprehensive transthoracic echocardiographic/Doppler (TTE) studies to identify baffle problems. This study reviews the effectiveness of these guidelines in detection of baffle issues pre‐EPS catheterization and need for ancillary vascular interventions. Design. Data from all patients with repaired d‐TGA referred for hemodynamic catheterization or EPS between 1995 and 2009 at our institution were reviewed, including symptoms and TTE findings. Obstruction was defined as either a disturbed color Doppler flow or mean velocity >1 m/s above the mitral valve or directly measured pressure gradient >4 mm Hg or more than 50% baffle diameter narrowing by venography. Results. Of 59 patients (34 pacemaker, 9 ablation, 16 routine hemodynamic) ages 8–39 years (mean 22.8), only three (5%) had symptoms of obstruction. However, baffle complications were found in 33 patients (56%), some with more than one problem: superior vena cava (SVC) obstruction in 32, inferior VC in two and leak in four. Baffle stenting was required in 24 patients and leak closure in two. Precatheterization TTE was available in 51 patients and showed 34% sensitivity, 61% specificity, 63% negative predictive value, and only 37% positive predictive value in recognizing baffle complications when compared with the actual catheterization findings. Conclusion. This study reports that baffle complications in patients with d‐TGA following Mustard operation are more common than previously reported. However, comprehensive TTE and clinical symptoms are not effective enough to recognize these complications. Suspicion of and better noninvasive imaging prior to catheterization is required.     

Multi-Layer Technique (MLT) with Porcine Collagenated Cortical Bone Lamina for Bone Regeneration Procedures and Immediate Post-Extraction Implantation in the Esthetic Area: A Retrospective Case Series with a Mean Follow-Up of 5 Years

Background: Augmentation of the edentulous atrophic anterior region is a challenging situation. The purpose of this article was to evaluate the effectiveness of a collagenated cortical bone lamina of porcine origin for horizontal ridge augmentation in patients with inadequate alveolar ridge width undergoing immediate post-extraction implantation in the anterior sites, and to report on implant survival rates/complications. Materials and methods: The cases were extracted electronically from a large database according to these specific inclusion criteria: patients with inadequate alveolar ridge width in the anterior maxilla or mandible, who underwent immediate post-extraction implant placement and simultaneous alveolar bone reconstruction using xenogeneic cortical bone lamina. An additional layer of palatal connective tissue graft was inserted between lamina and the vestibular mucosa, for improving soft tissue healing. A collagenated bone substitute was additionally placed in the gap between the lamina and implant surface in all patients. The main outcomes were implant survival and complications. Results: Forty-nine patients with 65 implants were included. Patients’ mean age at the time of implant surgery was 60.0 ± 13.6 years. The mean follow-up was 60.5 ± 26.6 months after implant placement. The implant survival was 100%. Four postoperative complications occurred in four patients. No specific factor was found to be associated with complication occurrence. Conclusion: The use of collagenated cortical bone lamina can be considered as a successful option for alveolar reconstruction in immediate post-extraction implant insertion procedures in anterior regions with inadequate alveolar ridge width.     

Real Time Intraprocedural Ultrasound Measurements of the Radial and Ulnar Arteries in 565 Consecutive Patients Undergoing Cardiac Catheterization and/or Percutaneous Coronary Intervention via the Wrist: Understanding Anatomy and Anomalies May Improve Access Success

Objectives

Ultrasound evaluation of both the radial artery (RA) and ulnar artery (UA) in patients undergoing cardiac catheterization/percutaneous coronary intervention.

Background

Arterial access from the wrist is almost exclusively obtained from the RA. Crossover to secondary femoral arterial access was observed in up to 7.6% in randomized multicenter trials utilizing palpation guided RA access.

Methods

Intraprocedural ultrasound evaluation of the RA and UA was performed in a consecutive series of patients. A difference of ≥20% in diameter was defined as significant. In the case of a dual artery, measurements of the dual arteries and the proximal confluens were obtained.

Results

A total of 566 RA/UA measurements were analysed (patients: n = 565, female: n = 201 [35.5%], mean age: 66.5 years). Overall, the RA measured 3.03 ± 0.57 mm and the UA 2.70 ± 0.57 mm (P < 0.01). The RA was larger in 210 (37.1%) and the UA in 37 (6.5%) measurements. A dual RA was present in 25 (4.4%) measurements. The mean diameters of the smaller and larger of the dual RAs were 1.82 ± 0.37 and 2.59 ± 0.36 mm (P < 0.01). The corresponding proximal confluens measured 3.10 ± 0.40 mm. No dual UA was observed.

Conclusion

In 10.9 % of patients, a larger UA or a dual RA with a more accessible confluens was observed. This information can only be obtained using ultrasound and may improve arterial access from the wrist if the larger UA or RA confluens is accessed instead of blind palpation guided RA access.

     

Relationship between the Surface Roughness of Material and Bone Cement: An Increased “Polished” Stem May Result in the Excessive Taper-Slip

Although some reports suggest that taper-slip cemented stems may be associated with a higher periprosthetic femoral fractures rate than composite-beam cemented stems, few studies have focused on the biomaterial effect of the polished material on the stem–cement interface. The purpose of this study was to investigate the relationship between surface roughness of materials and bone cement. Four types of metal discs—cobalt-chromium-molybdenum alloy (CoCr), stainless steel alloy 316 (SUS), and two titanium alloys (Ti-6Al-4V and Ti-15Mo-5Zr-3Al)—were prepared. Five discs of each material were produced with varying degrees of surface roughness. In order to evaluate surface wettability, the contact angle was measured using the sessile drop method. A pin was made using two bone cements and the frictional coefficient was assessed with a pin-on-disc test. The contact angle of each metal increased with decreasing surface roughness and the surface wettability of metal decreased with higher degrees of polishing. With a surface roughness of Ra = 0.06 μm and moderate viscosity bone cement, the frictional coefficient was significantly lower in CoCr than in SUS (p = 0.0073). In CoCr, the low adhesion effect with low frictional coefficient may result in excessive taper-slip, especially with the use of moderate viscosity bone cement.