A stenotic vessel can be opened using net-shape tubes called "stents" leading to the restoration of the bloodstream.Compared to the commonly used stainless steel stent, self-expandable stents have some advantages. They do not suffer from the risks of damage to the vascular tissue due to the balloon expansion. Moreover, overexpansion for compensating the elastic recoil is not needed, and there is no constant force applied on the artery until the occlusion of the device by the artery stops. However, the stent cannot restore the original dimensions of the vessel in the case of calcified plaques. Self-expandable stents can be utilized for the treatment of atherosclerotic lesions in the carotid, coronary, and peripheral arteries. Shape memory alloys (SMAs), mainly NiTi (nitinol), are employed for self-expandable vascular stent applications. Nitinol is widely applied for medical devices and implants due to its excellent fatigue performance, mechanical properties, and biocompatibility, which make this alloy suitable for long-term installations. Other materials used for self-expandable cardiovascular stents are shape memory polymers (SMPs). Shape memory effect is triggered by the hydration of polymers or temperature change preventing the collapse of small blood vessels. This review has focused on the mechanisms and properties of SMAs and SMPs as promising materials for stent application.

Introduction: The aim of this study was to determine the effect of fresh frozen plasma (FFP) for priming of cardiopulmonary bypass (CPB) circuit on rotational thromboelastometry (ROTEM) and transfusion in pediatric cardiac surgery. Methods: Eighty patients younger than seven years old, were divided into case (FFP) (n=40) and control (n=40) groups. In the case group,10-20 mL/kg fresh frozen plasm was used for priming the CPB. The control group received 10-20 mL/kg of hydroxyethyl starch. ROTEM was done before surgical incision and after separation from CPB. The amount of transfusion (platelet and FFP) in the operating room and 24 hours after surgery were recorded. Results: Statistically significant difference was found between the case and control group in terms of changes in the Rotem parameters. The amount of transfusion of platelets in the operating room was significantly higher in the control group than in the case group. Conclusion: It seems that adding FFP to the prime solution is more effective in young patients and infants due to the higher susceptibility of the infant coagulation system to coagulation and hemorrhagic disorders in comparison with other patients.