## 1 Introduction  
According to the WHO, cardiovascular diseases are the leading causes of death globally, estimated to claim 17.9 million lives each year [1]. Furthermore, heart failures caused by a reduced or impaired blood pumping function of the heart, affect 64.3 million patients annually [2]; this includes pediatric patients [3] and is associated with high morbidity and mortality. Unfortunately, despite ongoing developments in cardiac surgery, it is also estimated that more than 40% of patients diagnosed with heart failure will die within five years [4; 5; 6]. The same applies to pharmacological treatment, which can only slow down the process. The standard and best solution for patients with advanced heart failure is heart transplantation [7]. Transplantation is not always possible due to the shortage of donors [8], long waiting lists [9], high costs [10], problems with organ rejection, and high mortality [11]. Left ventricular assist devices (LVADs) are typically used as a bridge to heart transplant [12], as a bridge to recovery, or as destination therapy [13]. The former is used when medical treatment (conservative treatment) or surgery (e.g., heart transplantation) are no longer options, or are simply unsuccessful at preventing further deterioration. A bridge to recovery is cardiac support intended for use while the heart recovers, at a time when it is too weak. Finally, destination therapy is for patients who do not qualify for a heart transplant. This also means that destination therapy provides permanent cardiac support. Moreover, LVADs are used for both short-term therapy and destination therapy, and they are considered an effective therapeutic approach as a bridge to heart transplantation [14]. LVADs in the form of mechanical pumps consist of several components, including inflow and outflow cannulae, the pump itself, a battery pack, and a controller. Some of these components are implantable. The most important component is the mechanical pump, which replaces or supports the action of the failing heart and is controlled by a controller. The most commonly implantable parts are cannulae, the shape of which is also subject to optimization [15]. The most well-known and popular intra-aortic pumps include Imppella(r), POLVAD [16], Levitronix CentriMag(tm), TandemHeart(tm), HeartMate(tm), HeartWare(tm), MicroMed DeBakey [17], and EXCOR(tm) Berlin Heart. Moreover, the intra-aortic balloon pumps and VA ECMO (veno-arterial extracorporeal membrane oxygenation) [18; 19] can also be added to the above. However, it is important to be aware of the potential complications associated with the use of certain devices, which may include bleeding, requiring transfusion, infection, hemolysis, and limb ischemia [20]. The second major limitation is that the aforementioned devices are mostly designed for temporary support during hospitalization. The exceptions may, however, be HeartMate(tm) and HeartWare(tm), only if continuous monitoring is possible. Total artificial hearts and ventricular assist devices have been developed for decades [21]. While the former aim to completely replace the function of the heart, the latter merely assist the function of the failing heart by supporting it. The first generation of pumps were pulsatile flow pumps, which were the dominant solution until 2009 [22]. Interestingly, pulsatile flow pumps mimic the cyclic action of the heart using artificial heart valves, which consequently contributes to their large size and weight. The noise generated by this type of equipment was also not insignificant. Since 2010, the next generation of pumps, namely continuous flow pumps, has been in widespread and almost exclusive use [23; 24]. The biggest advantages of continuous flow pumps include their smaller size and reduced noise generation. Another significant advantage is their portability, allowing patients greater freedom of movement. Continuous flow pumps are further categorized into axial and centrifugal pumps.