incorporating a pressure sensor-transmitter (rf) complex on transseptal cannula for use with...
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Incorporating a Pressure Sensor-Transmitter(RF) Complex on Transseptal Cannula for
use with TandemHeart™ PTVA System
Team Members: Mihoko Hashimoto Lauren Kokai
Nitin NarayanaKatie O’Callaghan
Project Advisors: David H.J. Wang, Ph.D. Douglas E. Smith, Ph.D.
Dennis KopilecMarlin H. Mickle, Ph.D.
December 5, 2003
University of PittsburghSenior Design – BioE 1160
Overview
TandemHeartTM - A centrifugal pump that allows for fast deployment of oxygenated blood from the Left Atrium (LA) to the femoral artery and thus bypassing the Left Ventricle (LV).
• Advantages: Reduced workload on LV, possible healing of LV, helps maintain blood circulation and organ perfusion during heart surgery, bridge to transplant.
• Audience: Cardiologists and Cardiac Surgeons (maintaining blood flow), patients suffering from myocardial infarction or acute carditis, patients with deteriorating LV functionality waiting for a transplant, patients recuperating from heart surgery (increase speed of LV healing).
OverviewProblem:
Unmonitored changes in LA pressure (below a certain pressure threshold) may pose a threat to the patient due to a potential “suck down” of tissue (overdrainage of LA). Cause tissue damage and reduce blood flow.
Solution:
Real time pressure readings in the LA can possibly prevent the tissue “suck down”.
• Incorporate a pressure sensor into the tip of the Transseptal Cannula along with the use of RF-technology for signal transmission.
• Effectively determine an appropriate pump speed depending on patient’s conditions without further invasive processes.
Project GoalsThe ultimate goal of this project is to enable real-time
measurements of Left Atrial Pressure (LAP) with TandemHeart use, by placing a barometric absolute pressure (BAP) sensor chip (Kavlico sCAP1) at the tip of the cannula.
+ Incorporation of RF transmitter complex to transmit the real-time measurements without need for wiring.
+ Determine durability of the device after coating using simulated conditions.
High Level Timing Goals
1) Analysis of pressure sensor properties & manufacturing limitations
2) Development of sensor-signal transmitter (RF?) complex
3) Establish that device meets PDS under simulated clinical use conditions
4) Verify accurate signal transmission in intended clinical environment
Future Project Opportunities
Successful completion of this project could be used for future development of a safety pump speed adjust feature in the pump controller.By developing an algorithm to respond to low LAP conditions, the
controller on the TandemHeartTM will be able to auto-adjust (a vital safety feature) by decreasing pump speeds.
The sensor-RF transmitter complex could also be applied for countless other internal biomedical devices!!
Features & Benefits
Pressure sensor
provide potential for accurate real-time monitoring of LAP to prevent “suck down” of LA
allow for more accurate/sensitive pump speed for individual patient’s condition
(less need for highly trained system operator)
RF transmitter
no need for wiring
Group Object Tree
Pressure Sensor on Transseptal Cannula for TandemHeartTM PTVA System
CostW=0.2
Application BenefitsW=0.15
FeasibilityW=0.65
Testing equipment
provided by CAIW=0.6
Pressure sensor paid for by CAIW=0.4
Prevent sucking down
of atriumW=0.7
Pump speed can be altered
for changing patient conditions
W=0.3
Existence ofsmall
electrical components W=0.40
Sensor attachment
and coating is feasibleW=0.25
RF technologyexpertise provided
by Dr. MickleW=0.35
W= 0.2275W= 0.105 W= 0.045 W= 0.26W= 0.08W= 0.12 W= 0.1625
Design Sketch
Pressure Sensor
1.5mm
1.2mm
Receiver
RF Transmitter
Design Alternatives
• Pressure sensor: other manufacturers
• Various sensor placements• Single sensor
• Inside lumen / exterior
• Various RF transmitter placements• Further away from cannula tip
• Integrated on microchip
• Potential need for extra transmitter outside body
• Potential need to include amplification of signal in order to transmit through the chest wall
• Pressure signal output via wire (instead of RF transmitter)
Group Function-Means Tree
Improved safety and efficiency of TandemHeartTM PTVA System
Incorporating a pressure sensor – RF transmitter complex on the cannula tip
Measurementof LAP
RF transmitter complex for signal
transmission
Small pressure sensorOptimal
placement(s) of pressure sensor(s)
Electrical coupling of pressure sensor & RF transmitter
Power in to pressure sensor
Accuracy Accuracy
Between sensor& RF transmitter
Between RF transmitter & receiver
Tolerance
Durability underhigh pressure
Wide rangeof temperatures
(+ manufacturing)
Within range:5-10mmHg
Within extendedlow range
MechanismMechanism
Competitive Analysis
Integrated pressure sensing capabilities don’t yet exist!
Existing Designs (circulatory support):
• Centrifugal flow pumps:
• Thoratec, Arrow, MicroMedical, MedQuest, Kriton Medical, Terumo…
• Other forms of circulatory assistance:
• IABP (Intra-Aortic Balloon Pump)
Competitive Analysis
Strengths of our Design:• Incorporated LAP-sensor on
cannula tipno need for separate LAP
linesafety feature to prevent
LA “suck down”real-time monitoring of
patient LAP• RF pressure signal
transmissionno wires for signal outputfuture integration of auto
safety adjust in controller
Weaknesses of our Design:• More complicated (more
potential failure modes)• Higher production cost
Technology
• Using new technology:
• MEMS pressure sensor chip
• RF data transmission (of pressure signal)
• Engineering Models:
• SolidWorks: design modifications
• Simulated pressure/flow loop systems
Team / Resources
Advisors:• Drs. David Wang & Doug Smith, Dennis Kopilec
(CardiacAssist, Inc.) Medical device design, cannula design, clinical
knowledge
• Dr. Marlin Mickle
(Dept. of Electrical Engineering, Univ. of Pittsburgh) RF technology
Locations:• Lab space for testing of design: CardiacAssist, Univ.
of Pittsburgh• Swanson Center: design and RF systems
Team / Resources
Equipment:• Pump system supplies and testing equipment:
CardiacAssist, Inc.
• Pressure sensor: Kavlico, Inc.
• RF transmitter: not yet identified
Manufacturing: to be determined by CardiacAssist, Inc.
Projected Task Schedule
Personal Responsibilities
Project Criteria: Milestone 1 (30%) Milestone 2 (30%)
Milestone 3 (10%) Milestone 4 (10%)
Milestone 5 (5%) Milestone 6 (7.5%)
Milestone 7 (7.5%)
1 (1/31/04) 2 (1/31/04) 3 (2/20/04) 4 (3/5/04) 5 (3/26/04) 6 (4/8/04) 7 (4/9/04)
Mihoko Hashimoto
Research Adhesive/ Document
Design
Lauren Kokai
Nitin NarayanaDetermine
OR Compatibility
Katie O'CallaghanDevelop Mock
Loop
Evaluate Accuracy of
Signal Transmission
Test Complex Durability &
Analyze Bio-compatibility
Determine Feasibility of Incorporated
Sensor Device For Left Atrial Pressure
Measurement with THTC
MILESTONEGROUP MEMBER
Analyze PS: Meet Stated
Product Specs
Develop Sensor
Complex with Accurate
Signal Transfer
Research Adhesive/ Placement
Testing
Determine Sensor Accuracy
Range/Quick Response
(Simulated Use Conditions)
Characterize Sensor Response
to Simulated Suction Conditions
Research Range of Human
Chest Wall Thickness
Current StatusTasks completed as of 12/5/2003
• Group meeting with CardiacAssist
-Determined scope of project and documented specific deliverables CAI requires from students at conclusion of project
*Determined Product Design Specifications
-Communicated project schedule and goals through Gantt chart, Function Means Tree, Object Tree
• Group meeting with U of P advisor Marlin H. Mickle, Ph.D
-Students presented summary of project goals and relevant design information, discussed student needs for assistance and obtained background info on RF technology and circuit integration components, as well as anticipated difficulties
• Order placement for Kavlico sCAP 1 BAP sensor chips (5)
Acknowledgements
CardiacAssist• Drs. Doug Smith & David Wang, Dennis Kopilec
• Project funding
• Provision of pump system supplies & testing equipment
• Lab space
• Great project opportunity!!
Dr. Mickle• RF technology expertise & project guidance re: electrical aspects
• Lab space
MG• Project development guidance
• FDA background info (ad nauseum)
• Moral support!
Questions….?