Transcript Advances in LVAD Design

Advances in LVAD Design
Improving Reliability and Minimizing Risk of Stroke & Thrombosis
Steve Reichenbach, PhD
Senior Director, Technology Development
Thoratec Corporation
J100-1111
Key Objectives In LVAD Design—Implications For
HeartMate II®
 Maximize reliability
 Minimize stroke complications and thrombus
formation
 Minimize infection risk
 Reduce device size
 Reduce anticoagulation requirements
 Enable return to highly active lifestyle
HeartMate II LVAS
6,000 Implants Worldwide
HeartMate II—Designed For Extended Reliability
 Elegant design and configuration
 Precision engineering
 Design targeting more than 10 years of support
 30 years of clinical experience reflected in the
design
 More than 6,000 HeartMate II patients
implanted worldwide
 Longest ongoing patient supported more than 6
years and 60 patients more than 4 years
HeartMate II—Designed For Extended Reliability
 Redundant circuitry of the
percutaneous lead and system
controller provides backup if there is a
problem with the primary source
 Lithium-ion batteries provide a full work
day of support (10–14 hours) on a
single charge and are designed to last
up to 3 years before replacement
 Reliability of percutaneous lead design
continuously refined through extensive
clinical trial data and feedback over
thousands of implants
HeartMate II—Designed For Highly Washed Flow Path And
Low Rates Of Stroke & Pump Thrombosis
Rotor speed typically set
between 8,000 and 10,000 RPM
and capable of pumping up to 10
liters of blood per minute.
A single moving part combined
with open flow paths help to
optimize the blood flow.
Flow dynamics designed to
maximize washing and minimize
the risk of thrombus stasis
formation and stroke.
Flow design maintains integrity
of blood cells.
HeartMate II—Designed For Low Rates Of Stroke And
Pump Thrombosis Over Extended Periods
Blood-immersed ruby bearings
designed for ultra long-life—
analysis of explanted pumps
indicates an excess of 17 years
with an average expected life of
60 years.*
No bearing failures in the 6,000
worldwide patient experience.
High-precision bearing / cup
design enables plasma to serve
as lubricant while dissipating
heat, avoiding damage to red
blood cells and preventing
thrombus formation.
*Reichenbach SH. Negligible bearing wear in explanted HeartMate II LVADs following
clinical support for up to 4 years. Paper presented at: Annual Meeting of the International
Society for Rotary Blood Pumps 2010; October 14–16, 2010; Berlin, Germany.
Benefits Of Textured Surfaces
Most LVADs have been designed with
smooth interior surfaces in an effort to
minimize sites for thrombus nucleation yet
the frequency of thromboembolic
complications associated with LVADs has
been reported to be as high as 29%.
Thoratec began evaluating textured surfaces
for LVAD applications more than 3 decades
ago and refined its application over that
period.
Textured surfaces in select areas of the
device encourage a dense, adherent
pseudo-neointima, thereby eliminating the
direct interface between prosthetic material
and blood elements, reducing the risk of
thromboembolic complications.
Textured Surfaces
Rose EA, Lewis HR, Oz MC, et al. Artificial circulatory support
with textured interior surfaces: a counterintuitive approach to
minimizing thromboembolism. Circulation. 1994;90:87-91.
Zapanta CM, Griffith JW, Hess GD, et al. Microtextured
materials for circulatory support devices: preliminary studies.
ASAIO J. 2006;52(1):17-23.
HeartMate II—Designed For Low Rates Of Stroke And
Pump Thrombosis Over Extended Periods
HeartMate II uses customized texturing that has been refined and proven
throughout decades of clinical experience.
Rose et al. found that despite the low levels in
anticoagulation (including patients with no
anticoagulation regimen), only 3.5% of patients
had thromboembolic complications with the
first-generation HeartMate that incorporated
Thoratec’s customized texturing process.
The study concluded that this specific
application of sintered titanium surfaces can be
used for prolonged periods with limited TE
complications despite minimal anticoagulation.
Due to the benefits observed with the use of
textured surfaces in the first-generation
HeartMate, they have been incorporated into
the HeartMate II design.
HeartMate II Inflow Conduit
Rose EA, Lewis HR, Oz MC, et al. Artificial circulatory support
with textured interior surfaces: a counterintuitive approach to
minimizing thromboembolism. Circulation. 1994;90:87-91.
HeartMate II—Designed For Low Rates Of Stroke &
Pump Thrombosis Over Extended Periods
Flex section consists of a knitted polyester graft
that is reinforced and covered with a silicone
sleeve.
Inflow Conduit
Flexibility allows for relative movement between
the native left ventricle and the LVAD:
Flex Section
 Maintains an open flow path
 Accommodates reverse remodeling of the heart over
time while maintaining cannula position inside left
ventricle
 Prevents misalignment against ventricular wall
 Helps avoid “suckdown” events
Suction detection algorithm:
 Detects suction events and automatically adjusts
pump speed
 Intended to prevent suckdown events which
subsequently might cause ventricular arrhythmias,
flow interruption, or damage to the left ventricle
Low Rates of Stroke and Pump Thrombosis With
The HeartMate II
Boyle AJ, Russell SD, Teuteberg JJ, et al. Low thromboembolism and pump thrombosis
with the HeartMate II left ventricular assist device: analysis of outpatient anticoagulation.
J Heart Lung Transplant. 2009;28:881-7.
Low Rates Of Stroke & Pump Thrombosis With The
HeartMate II
In 331 patients
discharged on support:
HeartMate II Bridge-to-Transplantation
Clinical Trial Experience
 2.4% had ischemic stroke
 0.9% had pump
thrombosis
 2.1% suffered from
hemorrhagic stroke
This study also concluded that the INR range should target between
1.5 to 2.5 to minimize the risk of hemorrhagic events.
Boyle AJ, Russell SD, Teuteberg JJ, et al. Low thromboembolism and pump thrombosis
with the HeartMate II left ventricular assist device: analysis of outpatient anticoagulation.
J Heart Lung Transplant. 2009;28:881-7.
Low Rates Of Stroke & Pump Thrombosis With The
HeartMate II
 No pump replacements through
the first 6 months of HeartMate II
support
 Low ischemic and hemorrhagic
stroke rates
HeartMate II Bridge-to-Transplantation
Commercial Study Experience
HeartMate II Left Ventricular Assist System [instructions for use] #105747.
Pleasanton, Calif. Thoratec Corp; October, 2010.
HeartMate II—Proven Technology
HeartMate II provides efficacy and reliability through
simplicity of design with a single moving part, open
blood flow paths, durable bearings and compliant
inflow conduit to accommodate reverse remodeling
of the heart.
HeartMate II has the lowest published rates of stroke
and pump thrombosis of any continuous-flow LVAD.*
HeartMate II has the lowest published
anticoagulation regimen for continuous-flow
LVAD therapy.*
HeartMate II offers excellent reliability, proven in
more than 6,000 implanted patients worldwide.
* Based on published data from multicenter experience and
separate studies, which may involve different patient populations
and other variables. Please refer to the HeartMate II Instructions
for Use about indications, contraindications, adverse events,
warnings, and precautions (http://www.thoratec.com/medicalprofessionals/resource-library/ifus-manuals/heartmate-lllvad.aspx#levelFour).
Boyle AJ, Russell SD, Teuteberg JJ, et al. Low thromboembolism and pump thrombosis with
the HeartMate II left ventricular assist device: analysis of outpatient anticoagulation. J Heart
Lung Transplant. 2009;28:881-7.
Slaughter MS, Pagani FD, Rogers JG, et al. Clinical management of continuous-flow left
ventricular assist devices in advanced heart failure. J Heart Lung Transplant. 2010;29:S1-39.