The EVAHEART left ventricular assist system (LVAS) was designed for the long-term support of a patient with severe heart failure. It has an original water lubrication system for seal and bearing. Wear was considered one of its critical failure modes. A durability test focusing on wear was designed herein. We developed a mock loop, which generates a physiologic pulsatile flow and is sufficiently durable for a long-term test. The pulsatile load and the low fluid viscosity enable the creation of a severe condition for the mechanical seal. A total of 18 EVAHEART blood pumps completed 2 years of operation under the pulsatile condition without any failure. The EVAHEART blood pump had a greater than 90% reliability with a 88% confidence level. The test achieved an average of 8.6 years, which was longer than the longest clinical use in Japan. The test result showed that no catastrophic, critical, or minor failures of the blood pump or their symptoms were observed. The seal performance was maintained after the test. Moreover, the surface roughness did not change, which showed any burn or abnormal wear occurred. The original water lubrication system equipped in EVAHEART LVAS prevent severe wear on the seal and the bearing, and it can be used in the bridge to transplant and destination therapy.
From the *Sun Medical Technology Research Corp., Nagano, Japan; †Tohoku University Graduate School of Biomedical Engineering, Miyagi, Japan; and ‡Waseda University Center for Advanced Biomedical Sciences (TWIns), Tokyo, Japan.
Submitted for consideration August 2016; accepted for publication in revised form August 2017.
Disclosure: The authors have no conflicts of interest to report.
Correspondence: Tomoya Kitano, Tohoku University Graduate School of Biomedical Engineering, Miyagi, Japan.