Mechanical circulatory support systems: evolution, the systems and outlook

Abstract

The joint efforts in the fields of surgery, medicine and biomedical engineering, sponsored by both the government and the industry, have led to the development of mechanical support devices that can provide reliable circulatory support, which can temporarily support a patient's circulation until either the heart recovers or until a new heart can be transplanted or permanently replace a failed heart. Their development has been driven by the shortage of donor organs. Various systems have eventually evolved for short or long-term support of patients suffering from cardiogenic and/or advanced heart failure (HF).Over time, several have been withdrawn from the market due to high rate of thromboembolism and pumprelated complications, but many others remained with modern principles of circulatory support proved to be durable and reliable. Hopefully, the ever-evolving technology will yield several devices aimed at their miniaturization, with an energy supply without risk of infection, a system which is simple to implant and to exchange, minimalization of thrombus formation by optimal interior pump design, new antithrombotic medications and a system with demand-based pump activity. It is important to remember that such devices are only implanted to keep a patient alive or in an immediate life-threatening stage. In such circumstances, attribution of aforementioned difficulties to pump limitations or to advanced disease states remains difficult.In the coming years, ventricular assist devices (VADs) could be the most common surgical preference for treating severe HF.

Left ventricular assist device placement in the setting of congenital VSD

“…ME, mid esophageal; RV, right ventricle; VSD, ventricular septal defect may lead to elevated right ventricular pressure after LVAD implantation. 14,15 These shifted pressure differentials can become problematic in the setting of pre-existing atrial or VSDs. Consequently, substantial increases in right-to-left-shunting may occur, causing severe hypoxemia.…”

Don't pig(!) the wrong heart!

“…It is up to the immunologists to judge whether such patients would as well be complex immunologic candidates for inducing tolerance for cross‐species transplants. Total artificial hearts offer already a solid alternative for highly sensitized patients 6 …”

“…Total artificial hearts offer already a solid alternative for highly sensitized patients. 6 Particular attention has been directed to patients with complex congenital heart disease. 14 It is unclear why these patients should be better candidates for xenotransplantation than for human donor organs.…”

“…Recent studies have demonstrated survival rates after left ventricular assist device (LVAD) implantation identical to heart transplantation. Two‐year survival ranges at over 80% 6,7 . There is little doubt that heart transplantation has an enormous advantage when it comes to long‐term survival, but implantable LVADs have made quite some progress in this regard lately 8 .…”

“…Twoyear survival ranges at over 80%. 6,7 There is little doubt that heart transplantation has an enormous advantage when it comes to longterm survival, but implantable LVADs have made quite some progress in this regard lately. 8 A therapy that offers 3-6 months of survival cannot compete with mechanical support today.…”