The cool seal system: A practical solution to the shaft seal problem and heat related complications with implantable rotary blood pumps

Kenji Yamazaki, Toshio Mori, Jun Tomioka, Philip Litwak, James F. Antaki, Osamu Tagusari, Hitoshi Koyanagi, Bartley P. Griffith, Robert L. Kormos

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

A critical issue facing the development of an implantable, rotary blood pump is the maintenance of an effective seal at the rotating shaft. Mechanical seals are the most versatile type of seal in wide industrial applications. However, an a rotary blood pump, typical seal life is much shorter than required for chronic support. Seal failure is related to adhesion and aggregation of heat denatured blood proteins that diffuse into the lubricating film between seal faces. Among the blood proteins, fibrinogen plays an important role due to its strong propensity for adhesion and low transition temperature (approximately 50°C). Once exposed to temperature exceeding 50°C, fibrinogen molecules fuse together by multi-attachment between heat denatured D-domains. This quasi-polymerized fibrin increases the frictional heat, which proliferates the process into seal failure. If the temperature of the seal faces is maintained well below 50°C, a mechanical seal would not fail in blood. Based on this 'Cool-Seal' concept, we developed a miniature mechanical seal made of highly thermally conductive material (SiC), combined with a recirculating purge system. A large supply of purge fluid is recirculated behind the seal face to augment convective heat transfer to maintain the seal temperature below 40°C. It also cools all heat generating pump parts (motor coil, bearing, seal). The purge consumption has been optimized of virtually nil (<0.5 cc/day). An ultrafiltration unit integrated in the recirculating purge system continuously purifies and sterilizes the purge fluid for more than 5 months without filter change. The seal system has now been incorporated into our intraventricular axial flow blood pump (IVAP) and newly designed centrifugal pump. Ongoing in vivo evaluation of these system has demonstrated good seal integrity for more than 160 days. The Cool-Seal system can be applied to any type of rotary blood pump (axial, diagonal, centrifugal, etc.) and offers a practical solution to the shaft seal problem and heat related complications, which currently limit the use of implantable rotary blood pumps.

Original languageEnglish
JournalASAIO Journal
Volume43
Issue number5
Publication statusPublished - 1997 Sep
Externally publishedYes

Fingerprint

Shafts (machine components)
Seals
Blood
Hot Temperature
Pumps
Fibrinogen
Temperature
Blood Proteins
Transition Temperature
Ultrafiltration
Fibrin
Bearings (structural)
Adhesion
Proteins
Conductive materials
Fluids
Axial flow
Centrifugal pumps

ASJC Scopus subject areas

  • Biophysics
  • Bioengineering

Cite this

The cool seal system : A practical solution to the shaft seal problem and heat related complications with implantable rotary blood pumps. / Yamazaki, Kenji; Mori, Toshio; Tomioka, Jun; Litwak, Philip; Antaki, James F.; Tagusari, Osamu; Koyanagi, Hitoshi; Griffith, Bartley P.; Kormos, Robert L.

In: ASAIO Journal, Vol. 43, No. 5, 09.1997.

Research output: Contribution to journalArticle

Yamazaki, K, Mori, T, Tomioka, J, Litwak, P, Antaki, JF, Tagusari, O, Koyanagi, H, Griffith, BP & Kormos, RL 1997, 'The cool seal system: A practical solution to the shaft seal problem and heat related complications with implantable rotary blood pumps', ASAIO Journal, vol. 43, no. 5.
Yamazaki, Kenji ; Mori, Toshio ; Tomioka, Jun ; Litwak, Philip ; Antaki, James F. ; Tagusari, Osamu ; Koyanagi, Hitoshi ; Griffith, Bartley P. ; Kormos, Robert L. / The cool seal system : A practical solution to the shaft seal problem and heat related complications with implantable rotary blood pumps. In: ASAIO Journal. 1997 ; Vol. 43, No. 5.
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