title: Effects of mechanical valve orifice direction on the flow pattern in a ventricular assist device.
abstract: We have been developing a pneumatic ventricular assist device (PVAD) system consisting of a diaphragm-type blood pump. The objective of the present study was to evaluate the flow pattern inside the PVAD, which may greatly affect thrombus formation, with respect to the inflow valve-mount orientation. To analyze the change of flow behavior caused by the orifice direction (OD) of the valve, the flow pattern in this pump was visualized. Particle image velocimetry was used as a measurement technique to visualize the flow dynamics. A monoleaflet mechanical valve was mounted in the inlet and outlet ports of the PVAD, which was connected to a mock circulatory loop tester. The OD of the inlet valve was set at six different angles (OD = 0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees, and 270 degrees, where the OD opening toward the diaphragm was defined as 0 degrees ) and the pump rate was fixed at 80 bpm to create a 5.0 l/min flow rate. The main circular flow in the blood pump was affected by the OD of the inlet valve. The observed regional flow velocity was relatively low in the area between the inlet and outlet port roots, and was lowest at an OD of 90 degrees. In contrast, the regional flow velocity in this area was highest at an OD of 135 degrees. The OD is an important factor in optimizing the flow condition in our PVAD in terms of preventing flow stagnation, and the best flow behavior was realized at an OD of 135 degrees.
authors.affiliation: Department of Artificial Organs, the Advanced Medical Engineering Center, National Cardiovascular Center Research Institute, 5-7-1 Fujishiro-dai, Suita, Osaka, 565-8565, Japan. akagawa@ri.ncvc.go.jp
authors.forename: Eiki
authors.initials: E
authors.lastname: Akagawa
authors.forename: Hwansung
authors.initials: H
authors.lastname: Lee
authors.forename: Eisuke
authors.initials: E
authors.lastname: Tatsumi
authors.forename: Akihiko
authors.initials: A
authors.lastname: Homma
authors.forename: Tomonori
authors.initials: T
authors.lastname: Tsukiya
authors.forename: Nobumasa
authors.initials: N
authors.lastname: Katagiri
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Kakuta
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Nishinaka
authors.forename: Toshihide
authors.initials: T
authors.lastname: Mizuno
authors.forename: Kei
authors.initials: K
authors.lastname: Ota
authors.forename: Rei
authors.initials: R
authors.lastname: Kansaku
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Taenaka
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology*; D006353:Heart-Assist Devices; D018056:Hemorheology / Q000295:instrumentation; D006801:Humans; D011474:Prosthesis Design; D013927:Thrombosis / Q000503:physiopathology*