Incorporating a Pressure Sensor-Transmitter (RF) Complex on Transseptal Cannula for use with TandemHeart™ PTVA System Team Members: Mihoko Hashimoto Lauren Kokai Nitin Narayana Katie O’Callaghan Project Advisors: David H.J. Wang, Ph.D. Douglas E. Smith, Ph.D. Dennis Kopilec Marlin H. Mickle, Ph.D. December 5, 2003 University of Pittsburgh Senior Design – BioE 1160

Overview TandemHeart TM - 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).

Overview Problem: 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 Goals The 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 TandemHeart TM 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 W= W= 0.105W= 0.045W= 0.26 W= 0.08 W= 0.12 W=

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 TandemHeart TM PTVA System Incorporating a pressure sensor – RF transmitter complex on the cannula tip Measurement of LAP Small pressure sensor Accuracy Within range: 5-10mmHg Within extended low range Tolerance Durability under high pressure Wide range of temperatures (+ manufacturing) Optimal placement(s) of pressure sensor(s) RF transmitter complex for signal transmission Electrical coupling of pressure sensor & RF transmitter Accuracy Between sensor & RF transmitter Between RF transmitter & receiver Mechanism Power in to pressure sensor Mechanism

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 tip  no need for separate LAP line  safety feature to prevent LA “suck down”  real-time monitoring of patient LAP RF pressure signal transmission  no wires for signal output  future 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%)

Current Status Tasks 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….?