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….?