Viscoelastic properties of the autologous bypass grafts: A comparative study among the small saphenous vein and internal thoracic artery

Internal thoracic artery (ITA) and small saphenous vein (SSV) are two viable conduits for coronary artery bypass grafts. The aim of this study was to investigate the viscoelastic behavior of the small saphenous vein and internal thoracic artery under compressive and tensile loadings at body temperature. The dynamic mechanical analysis was used to measure the viscoelastic properties of the ITA and SSV at both the desired temperature and load frequency range. Storage modulus, loss modulus as well as phase angle of both the blood vessels were measured at the temperature of 37 ± 1 °C and under a sinusoidal load with the frequency range of 1–2 Hz. The mean storage and loss modulus of the SSV were both higher than that of the ITA. Furthermore, the SSV showed a higher stiffness and internal friction compared to those values under the tensile load. While ITA was stiffer under the tensile load, no considerable difference was observed among the compressive and tensile loss modulus. A more intense viscous behavior was observed under the radial direction. The results also revealed that the SSV has much higher stiffness whereas less viscous behavior compared to the ITA, especially in the radial direction. The results may have implications not only for understanding of the viscoelastic time-dependent mechanical behavior of the ITA and SSV but also for tissue engineering applications to make scaffolds according to the real time-dependent viscoelastic mechanical properties of these arteries and veins.     

Acute aortic syndromes: aortic dissections,penetrating aortic ulcers and intramural aortic hematomas

Acute aortic syndromes, including dissections, intramural hematomas and penetrating aortic ulcers, are a catastrophic clinical entity that are relatively uncommon. A high index of clinical suspicion along with proper imaging modalities are critical in making a prompt and accurate diagnosis for immediate management and to improve survival of the patient.     

Reducing delirium and cognitive dysfunction after off-pump coronary bypass: A randomized trial

BackgroundNeuropsychiatric complications of surgical coronary revascularization are inconspicuous but frequent and clinically relevant. So far, attempts to reduce their occurrence, such as the introduction of off-pump coronary artery bypass (OPCAB) grafting method, have not brought the desired results. The aim of this trial was to determine whether using any of the 2 selected modifications of OPCAB could decrease the incidence of these undesired sequelae.MethodsIn this single-center, assessor- and patient-blinded, superiority, randomized controlled trial, 192 patients scheduled for elective isolated OPCAB were randomized to 3 parallel arms. The control arm underwent “conventional” OPCAB with vein grafts. The first study arm underwent anaortic OPCAB (ANA) with total arterial revascularization. The second study arm underwent OPCAB with vein grafts using carbon dioxide surgical field flooding (CO₂FF). Outcomes included the incidence of postoperative delirium (PD) and early postoperative cognitive dysfunction (ePOCD).ResultsThe incidence of PD was 35.9% in the control (OPCAB) arm, 32.8% in the CO₂FF arm, and 12.5% in the ANA arm (χ² [2, N = 191] = 10.17; P = .006). Post hoc tests revealed that the incidence of PD in the ANA arm differed from that in the OPCAB arm (odds ratio [OR], 0.26; 95% confidence interval [CI], 0.09-0.68; P = .002). The incidence of ePOCD was 34.4% in the OPCAB arm, 28.1% in the CO₂FF arm, and 9.5% in the ANA arm (χ² [2, N = 191] = 11.58; P = .003). Post hoc tests revealed that the incidence of ePOCD differed between the ANA and OPCAB arms (OR, 0.20; 95% CI, 0.06-0.58; P < .001).ConclusionsPerforming ANA significantly decreases the incidence of PD and ePOCD compared with “conventional” OPCAB with vein grafts, whereas CO₂FF is inconsequential in this regard. These results, which probably reflect decreased delivery of embolic load to the brain in ANA, may have practical applicability in daily practice to improve clinical outcomes.     

支架结合弹簧圈治疗破裂椎动脉夹层动脉瘤

目的评估支架结合弹簧圈技术治疗破裂椎动脉夹层动脉瘤（VADA）的可行性、有效性和安全性。方法回顾性分析57例破裂VADA的临床资料,均使用支架结合弹簧圈技术治疗,按使用支架数量分为单支架组（n=32）和多支架组（n=25）,比较两组间即刻和随访的影像学结果及临床结果。结果治疗即刻VADA完全栓塞、近全栓塞和部分栓塞,单支架组分别为4例（12.5%）、7例（21.9%）、21例（65.6%）,多支架组分别为13例（52%）、7例（28%）、5例（20%）。影像学随访12~78个月,单支架组30例,其中VADA完全栓塞19例（63.3%）,显影11例;多支架组24例,其中VADA完全栓塞23例（95.8%）、显影1例。术后即刻与随访期VADA完全栓塞率,多支架组显著高于单支架组（P〈0.05）。死亡3例。改良mRS评分在两组间差异无统计学意义（P〉0.05）。结论长期随访结果显示,支架辅助栓塞治疗破裂椎动脉夹层动脉瘤在技术上是安全有效的,多支架结合弹簧圈栓塞可有效提高即刻及远期的完全栓塞率,降低术后复发及再出血风险。     

Influence of trial design,heterogeneity and regulatory environment on the results of clinical trials: An appraisal in the context of recent trials on acute stroke intervention

The outcome of randomized controlled trials can vary depending on the eligibility criteria of the patients entering into the trial, as well as the heterogeneity of the eligible population and/or the interventions. If the subject population and/or interventions are heterogeneous, the final outcome of the trial depends on the degree of concordance of effects of the subgroups of interventions on the subgroups of the subject population. The considerations that go into the calculation of sample size and determination of the study stopping rules also would affect the nature of the outcome of the study. In this paper we try to examine these phenomena with respect to the recent trials on endovascular therapy in acute ischemic stroke.