Starck Christoph T, Becker Jakob, Fuhrer Roland, Sündermann Simon, Stark Jan Wendelin, Falk Volkmar
Clinic of Cardiac and Vascular Surgery, University Hospital Zurich, Zurich, Switzerland.
Interact Cardiovasc Thorac Surg. 2014 Jan;18(1):13-6. doi: 10.1093/icvts/ivt416. Epub 2013 Sep 22.
Based on a ferromagnetic silicone cuff for extra-aortic counterpulsation, a new assist device concept was developed. The driving force is generated by an external magnetic field, which leads to contraction of a soft magnetic cuff. The force generation capacity of the device was tested in a silicone aorta model.
Magnetic elastomers can be constructed through dispersion of micro- or nanoparticles in polymer matrices and were designed to act as soft actuators. Two magnetically active silicone cuffs were produced with a nanomagnet loading of 250 wt% (Cuff 1) and a micromagnet loading of 67 wt% (Cuff 2). The magnetic cuffs were applied on a silicone aorta model and contracted against hydrostatic pressure.
A full contraction of Cuff 1 was possible against a maximal hydrostatic pressure of 30 cmH₂O (22 mmHg) at a magnetic flux density of 0.4 T (Tesla) and 65 cmH₂O (48 mmHg) at a magnetic flux density of 1.2 T. A 50% contraction of Cuff 2 was possible against a maximal hydrostatic pressure of 80 cmH₂O (59 mmHg) at a magnet-cuff-distance (MCD) of 0 cm. At MCDs of 1 and 2 cm a 50% contraction was possible against 33 cmH₂O (24 mmHg) and 10 cmH₂O (7 mmHg), respectively.
Combining the advantages of magnetic elastomers with the principle of extra-aortic counterpulsation in a new assist device concept avoids the need for anticoagulation (no contact with bloodstream). With regard to the magnetic principle of action, no intra- to extracorporeal connection is needed. More experimental work is needed to further increase the force generated by the silicone cuff and to transfer the device concept into an in vivo setting.
基于一种用于主动脉外反搏的铁磁硅橡胶袖带，开发了一种新的辅助装置概念。驱动力由外部磁场产生，该磁场导致软磁袖带收缩。在硅橡胶主动脉模型中测试了该装置的力产生能力。
磁性弹性体可通过将微米或纳米颗粒分散在聚合物基质中构建，并设计用作软致动器。制备了两个具有250 wt%纳米磁体负载量的磁性活性硅橡胶袖带（袖带1）和67 wt%微磁体负载量的磁性活性硅橡胶袖带（袖带2）。将磁性袖带应用于硅橡胶主动脉模型，并抵抗静水压力进行收缩。
在磁通密度为0.4 T（特斯拉）时，袖带1能够在最大静水压力30 cmH₂O（22 mmHg）下完全收缩，在磁通密度为1.2 T时，能在65 cmH₂O（48 mmHg）下完全收缩。在磁体与袖带距离（MCD）为0 cm时，袖带2能够在最大静水压力80 cmH₂O（59 mmHg）下实现50%收缩。在MCD为1 cm和2 cm时，分别能在33 cmH₂O（24 mmHg）和10 cmH₂O（7 mmHg）下实现50%收缩。
在一种新的辅助装置概念中，将磁性弹性体的优点与主动脉外反搏原理相结合，避免了抗凝的需要（不与血流接触）。就磁作用原理而言，无需体内到体外的连接。需要更多的实验工作来进一步增加硅橡胶袖带产生的力，并将该装置概念转化为体内应用。
