EPS320 Cardiac Stimulator Service Manual ver 1.4

EPS320 Service Manual

CONTENTS 1

INTRODUCTION 1.1 PURPOSE 1.2 SCOPE 1.3 RELATED DOCUMENTS 1.4 DEFINITIONS, ACRONYMS, AND ABBREVIATIONS

2

DOCUMENT OVERVIEW 2.1 DOCUMENT CONTENTS 2.2 SOFTWARE LICENSE AND W ARRANTY 2.3 SERVICE POLICY

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SAFETY, WARNINGS AND PRECAUTIONS BRIEF DEVICE DESCRIPTION Intended Use Description of system Accompanying Documentation W ARNINGS AND PRECAUTIONS General Warnings Warnings Specific to the EPS320 Stimulator Warnings Related to the use of EPS320 Stimulator with RF Ablation Equipment General Precautions in Handling the EPS320 Stimulator ADVERSE EVENTS Observed Adverse Events POTENTIAL ADVERSE EVENTS

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OVERVIEW OF STIMULATOR SYSTEM 4.1 GENERAL 4.2 HARDWARE OVERVIEW

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4 4 4 4 4 6 6 6 7 8 8 8 8 8 10 10 11 11 12 13 13 14 17 17 17

PRINCIPLES OF OPERATION

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5.1 BACKGROUND INFORMATION 5.2 SYSTEM FUNCTIONAL DESCRIPTION

19 20

6

DEVICE SPECIFICATION ERROR! BOOKMARK NOT DEFINED.

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DESCRIPTION OF SYSTEM COMPONENTS 7.1 SYSTEM CONFIGURATION OPTIONS 7.2 POWER REQUIREMENTS 7.3 SYSTEM INTERCONNECTION 7.4 ECG SENSING OPTIONS 7.5 THE EPS320 STIMULUS GENERATION UNIT (SGU) OVERVIEW 7.6 SGU HARDWARE-PATIENT INTERFACE SPECIFICATION 7.7 PATIENT INTERFACE OUTPUTS 7.8 CONNECTOR PIN OUTS 7.9 GU CIRCUIT DESCRIPTIONS 7.10 SGU MAIN AND FRONT PCB FUNCTIONAL DESCRIPTION 7.11 STIMULATOR PHYSICAL LAYOUT

23 23 25 25 27 29 29 31 32 33 33 35

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ESP320 SYSTEM TROUBLESHOOTING

36

9

PACING AND SENSING TROUBLESHOOTING

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9.1 PACING 9.2 ECG SENSING AND QRS SYNCHRONIZATION 10 SGU TROUBLESHOOTING 10.1EQUIPMENT REQUIRED 10.2GENERAL 10.3TROUBLESHOOTING OBJECTIVES 2

38 39 40 40 40 40

10.4SGU PROBLEMS 11 COMPUTER SETUP & TROUBLESHOOTING

40 44

11.1COMPUTER HARDWARE SETUP 11.2CMOS SETUP 11.3PC OPERATING SYSTEM 11.4SOFTWARE INSTALLATION

44 44 44 45

12 SOFTWARE TROUBLESHOOTING

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12.1SOFTWARE ERROR MESSAGES 12.2ERRORS RECORDED IN STIM.LOG 12.3HARDWARE-RELATED W ARNING MESSAGES ON THE COMPUTER DISPLAY

47 48 49

13 SUB-ASSEMBLY REPLACEMENT

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14 TESTING AND RE-INSTALLATION OF REPAIRED EPS320 SYSTEM

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15 EPS320 SPARE PARTS LIST ERROR! BOOKMARK NOT DEFINED. 16 SERVICE RECORD

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FIGURES Figure 1 EPS Stimulator System... 18 Figure 2 EPS320 Stimulator main components... 20 Figure 3 Typical EPS320 installation, with the Bard Duo EP Recording System. ... 26 Figure 4 External ECG sensing schematic... 28 Figure 5 Simpler set up for Catheter-tip ECG sensing... 28 Figure 6 Auxillary Interface ... 32 Figure 7 Patient Connector... 32 Figure 8 Emergency Pace Connector ... 32 Figure 9 EPS320 System Schematic Layout... 33 Figure 10 SGU off PCB component connections... 34 Figure 11 SGU Subsystem Physical Components Layout ... 35

TABLES Table 1 Suggested connections for external ECG sensing. ... 27 Table 2 Accessing the catheter-tip ECG sensing ... 28 Table 3 Intracardiac ECG Input Specifications ... 29 Table 4 High Level ECG Input Specifications... 30 Table 5 Sync In Specifications... 30 Table 6 Intracardiac ECG Input Specifications ... 30 Table 7 Intracardiac Pace Output Specifications... 31 Table 8 Sync Out Specifications ... 31 Table 9 Emergency Pace Output Specifications... 31 Table 10 Tabulated SGU Error messages ... 41 Table 11 SGU Error Code Number interpretation... 42 Table 12 Table of File-related errors, recorded in the 'stim.log'... 48 Table 13 Table of warning and advisory messages... 49 Table 14 EPS320 Spare parts list ... 53 Table 15 EPS320 Test jig Spare parts list... 54

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EPS320 Service Manual

1 INTRODUCTION

1.1 Purpose This document is intended to enable the servicing of the EPS320 Cardiac Stimulator system by Micropace service staff and by Distributor Service Department technicians suitable trained by Micropace.

1.2 Scope This manual covers the covers the servicing by sub-assembly replacement only of all EPS320 components including the SGU, PC and software and connecting cables. Issues of device interaction between the EPS320 and connected equipment are also covered. Outside of the scope of this document are the repair of the accessory computer, computer display, power supplies and component level repair of the EPS320 printed circuit boards.

1.3 Related documents Inputs: TestJigManual.doc EPS320-SGUAcceptanceProtocol.doc

q q

Outputs: q Nil

1.4 Definitions, Acronyms, and Abbreviations The following abbreviations are applicable to this document. SYMBOL SGU: ECG: IECG: RF: JP: TP: EMC

EMI PC POST Moniputer LED µP

4

EXPLANATION Stimulus Generator Unit Electrocardiogram Intracardiac Electrocardiogram Radio Frequency Header or a connector Test point Electromagnetic compatibility. This will refer to emissions of electromagnetic waves and the effect of these on the environment. It also refers to the effects of electromagnetic waves on the equipment Electromagnetic Interference Personal computer, IBM compatible Power On Self Test Refers to a combined computer monitor/CPU Light emitting diodes and seven segment displays when referring to display information Microprocessor, in this manual refers specifically to the PIC16C77 microcontroller, by Microchip

Stimulus Generator Box controls and terms: SGU or Stim Box Backup mode PC mode Standby mode 'Pace Output' socket 'Emergency Output' socket Switches: 'Power' switch 'Backup Enable' switch 'Pace On/Off' switch

= Stimulus Generator Unit = 'Backup Manual Pace Control' mode, whereby SGU operates independently of the PC as a simple pacemaker = 'PC Pace Control' mode, whereby SGU opertation is controlled by the Custom PC Software = Low power SGU operational mode; Mains Power flashes Green colour = 'Pace Output' green coloured socket on SGU front membrane = 'Emergency Fixed Pace Output' red coloured socket on SGU front membrane providing backup pacing at 100bpm independent of SGU or PC Software. = SGU Power On/Off switch located at rear of SGU = Blue membrane push button switch on front of SGU; invokes alternatively Backup mode and Standby mode = Red membrane push button switch on front of SGU; starts & stops pacing in the Backup mode

Numeric Indicators on SGU front panel 'Pace Interval' display = Backup Manual Pace Mode Pacing interval display, adjustable by adjacent up and down push button keys 'Current' display = Backup Manual Pace Mode Pacing current display, adjustable by adjacent up and down push button keys LED Indicators on SGU front panel 'Mains Power' = Constant Green: Mains power connected and SGU Power switch On and unit in Backup or PC Control mode; flashing Green: Mains power connected and SGU Power switched On and in unit in Standby state; Orange: Mains power connected and SGU Power switch Off. Backup battery trickle charges with any flashing or steady Green 'Battery Power' = SGU power switch On but unit disconnected from mains power and using battery power 'Battery Low' = SGU internal backup 12V battery near depletion 'Atrium Pace' LED = Stimulus issued on Atrial channel 'Ventricle Pace' LED = Stimulus issued on Ventricular channel 'Atrium Check Lead' LED = High impedance (>4Kohm) detected on channel 'Ventricle Check Lead' LED = High impedance (>4Kohm) detected on channel 'QRS' LED = QRS complex (peak) detected on programmed ECG input channel. Inactive when Software QRS detection selected in software. 'Emergency Pace V' LED = Stimulus issued on Emergency Pace channel;

'Emergency Battery OK' LED = Emergency Pace is engaged and 9V Lithium Battery has adequate charge

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EPS320 Service Manual

2 DOCUMENT OVERVIEW 2.1 Document Contents This document aims to provide the service technician with the resources to troubleshoot, repair, obtain further help and and report on problems associated with the EPS320 Cardiac Stimulator installation. For technicians not familiar with electrophysiology, the section Background Information within the Principles of Operation chapter gives an overview of the topic. This manual contains the following: (i) (ii) (iii) (iv) (v) (vi) (vii) (viii) (ix) (x)

Safety, Warning and Precautions Overview of the Stimulator System Description of the principle of operations Device Specification Device Installation Requirements Descriptions of the system components and interconnections Troubleshooting guide Testing and Re-installing Repair Available spare parts list Reporting Forms

2.2 Software License And Warranty Refer to user instruction manual for the terms of software license and warranty.

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2.3 Service Policy Micropace recommends servicing of the EPS320 by the various stakeholders according to the following schema: Site User / Hospital biomedical Engineering

Distributor Service Dept.

Micropace Service Dept.

Recommended scope of repair / Service 1. Replacement of apparently faulty accessories, such as power supplies, signal cables, isolation transformer, LCD Display Screen. 2. Replacement of fuses in Isolation transformer with Micropace supplied fused only. 3. Replacement of batteries internal to the SGU, namely the 12V lead acid backup battery (MP3109) and the 9V Lithium PP3 format battery (MP3110), when SGU POST indicates faulty battery. Use Micropace supplied batteries only. 4. Upgrade of product firmware by replacement of EEPROM/ Microcontroller on SGU main PCB. 5. Upgrade of product software by installation of software from FDD or by replacement of Compact Flash Memory Card in PC. 1. As above, plus: 2. Repair of faulty PC by a Micropace-approved and identified Computer service center and subsequent reloading of software. 1. Repair of SGU internal subassemblies including PCB’s, PCB header cables and connectors or chassis components by replacement. 2. Calibration of SGU current delivery system. As above, plus Repair of cables and connector subassemblies or their replacement. Repair of PCB’s through through-hole or SMT component replacement or PCB repair.

Verification of repair 1. System functions OK.

2. System functions; only supplied fuses used. 3. POST passes OK; only supplied batteries used.

4. POST passes OK 5. POST passes OK and software launches OK. As above Software tests own checksum and essential PC resources. Verification with te.exe test jig/test software.

As above. Acceptance testing at Micropace. Performance of the full EPS320-SGUAcceptanceProtocol.doc

There are no user serviceable parts inside the Stimulus Generation Box. It is recommended that hospital service personnel contact the distributor with details of any faults prior to attempted repairs to obtain recommendations for repair procedures. It is also recommended that on-site repair be limited to repair of any off-PCB faults and visual inspection of PCB. Apparently faulty PCB's should be tested by replacement of either the main PC board or display PC board; defective PC boards should be returned to the manufacturer for repair.

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EPS320 Service Manual

3 SAFETY, WARNINGS AND PRECAUTIONS Brief Device Description Intended Use The Micropace EPS320 Cardiac Stimulator is used to stimulate the heart via intracardiac electrodes during electrophysiological cardiac studies. The stimulator system is a diagnostic tool intended for provocative electrical stimulation of the heart for the purpose of measurement of cardiac conduction properties and induction and diagnosis of arrhythmias. Note that the system is not a life support device and is not intended to qualify as a life support device in respect to its functionality, construction or reliability.

Description of system The EPS320 Cardiac Stimulator by Micropace Pty Ltd. is a diagnostic external programmable cardiac stimulator. The Stimulator consists of a self-contained two channel microcontroller-based Stimulus Generator Unit independently capable of generating simple regular pacing pulses, but under normal use externally interactively programmable by the user for complex pacing patterns via a serial data link, using a custom software program implemented on a standard personal computer. The two stimulation channels are independent isolated constant current pulse generators capable of generating 0.5 to 10ms pulses at 0.1 to 25mA with a maximum output voltage of 27V. The stimulus output may be used to stimulate the human heart during electrophysiological studies via any third party legally marketed transvenous intracardiac pacing catheters directly or via any third party legally marketed EP recording equipment intended to switch pacing pulses of above description without distortion to selected specific catheters and electrodes. The Stimulus Generator Unit is mains-powered via a DC power supply and has an internal tricklecharged backup battery in case of power failure. Its outputs are defibrillator and RF energy protected and it features external ECG input ports as well as catheter-tip ECG sensing for triggering of pacing events and three trigger output channels for synchronization with other equipment. The system is powered from the mains via a medical grade isolation transformer. The EPS320 software allows interactive programming of all aspects of the pacing stimulus: the current amplitude, pulse width, delivery to channel 1 or 2 or both, and all stimulus parameters including drive train number, timing and up to 6 extra-stimuli. The stimulator has an intuitive user interface, with all commonly used stimulus and pacing protocol parameters located on fixed menus on the one screen instantly adjustable via hotkeys including during actual pacing. All standard EP stimulation protocols are available pre-programmed but may be reconfigured and automated according to user requirements.

Accompanying Documentation A reference package, comprising of a manual and a leaflet, is provided with the EPS 320 Cardiac Stimulator. Included in the package are: q User Instruction Manual q Accessories Unit Contents and Instructions for Use Leaflet It is strongly recommended that the Operator reads the User Instruction Manual document in its entirety and is familiar with its contents before using the Stimulator on patients. One further document is available on request, contact your distributor for copies of this document: Software Reference Manual This Service Manual applies to PC Software ver. 3.19.59 and SGU Firmware ver. 4.68. q

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Compatible Equipment The EPS320 Stimulator’s primary function is the generation of constant current predominantly rectangular stimulation pulses with amplitudes of 0.1 to 25mA, duration of 0.5 to 10ms and with a maximum voltage of +/- 27V. Third party switching equipment with the following special characteristics must be used to carry the stimulus pulses to the intracardiac electrodes without significant distortion: q q q q

Series resistance: < 100 Ohms at up to +/- 25mA Shunt resistance: > 100,000 Ohms at up to +/- 27V Frequency bandwidth: DC to 300 Hz Interference RF energy sources: < 350Vpp at 400 kHz to 600 kHz, or 150W into a 300 Ohm load

Higher series resistance reduces maximal attainable pulse current amplitude; lower shunt resistance reduces delivered current in all ranges; reduced frequency bandwidth may alter efficacy of stimulation at any current level and higher RF energy exposure may activate over-voltage safety elements, reducing RF energy delivery and overheating within the EPS320 system’s Stimulus Connection Box. Subject to these requirements, the EPS320 Stimulator is intended for use with the following equipment; the user should contact Micropace Pty Ltd for compatibility information prior to use of other equipment: Diagnostic pacing electrode catheters q Currently available legally marketed electrophysiological diagnostic electrode catheters, including those manufactured by CR Bard, Cordis Biosense Webster, Daig, Medtronic and EPT. Ablation electrode catheters q The EPS320 is tested for use with a number of legally marketed RF ablation catheters. Contact Micropace Pty Ltd for further information (Refer also to “Warnings and Precautions” section below). EP Recording equipment Computerised EP Recording systems manufactured by Bard Electrophysiology (LabSystemTM TM Duo ) and GE/Prucka (CardioLab 4000) have been tested for use with the EPS320 Stimulator.

q

RF Ablation Equipment q RF ablation equipment manufactured by EPT (EPT1000XP) and Medtronic (Atakar RF Generator) have been tested for use with the EPS320 Stimulator.

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EPS320 Service Manual

Warnings and Precautions General Warnings Warning: Stimulator must be used only under supervision by a cardiologist. q The Micropace EPS320 Cardiac Stimulator is used in procedures, during which

intentional or unintentional induction of potentially dangerous cardiac arrhythmias is likely to occur. The Stimulator must only be used by appropriately qualified and experienced personnel, in appropriate facilities and in conjunction with adequate safety equipment. q Specifically, the EPS320 Stimulator System may be used on humans only by or under

the direct supervision at all times by a physician familiar with the operation of this Stimulator. Warning: Installation only by qualified personnel. q Only qualified personnel, such as representatives of Micropace, its authorized

distributor or hospital-appointed biomedical engineers with guidance from Micropace, may carry out installation or modifications of the EPS320 Stimulator and its connection to other equipment. Incorrect installation may create electrocution hazards or impair performance of the Stimulator. Warning: The Stimulator must only use isolated mains power supply. q To avoid electrocution hazards, the EPS320 Stimulus Generator Unit power supply,

computer power supply, and monitor power lead must all be connected to a mains isolation transformer and never directly to a mains power outlet, (i.e. wall outlet). q To avoid electrocution hazards, do not plug cables or leads directly into mains power

outlet. Warning: Connect Stimulator system only to legally marketed, mains-isolated electrical equipment q To avoid electrocution hazards and system malfunction, the Stimulator outputs, RS232

communication port, Auxiliary port and ECG and Sync ports may be connected to other equipment provided the other equipment is also isolated from the mains power supply, and complies with IEC601-1, IEC601-2 and IEC601-1-1 standards and is legally marketed in the country of use and CE marked for installations in the EU countries. Warning: Use Stimulator only in ventilated areas and away from flammable gasses. q To avoid risk of explosion, the Stimulator should only be used in a ventilated area, as

gasses may be released during charging of backup battery, and should not be used in rooms with flammable anesthesia.

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Warnings Specific to the EPS320 Stimulator Warning: Stimulator is not a life support device and may fail to pace – To avoid injury to patient from bradycardia, use only with immediately available backup temporary external pacemaker. q The EPS320 Stimulator System is a diagnostic tool for provocative electrophysiological

testing of the human heart. The Stimulator System is not intended, designed or fit for the purpose of life support. Two levels of backup pacing are provided in case of failure of normal functioning of the Stimulator and are for use in non-life-threatening bradycardia or until temporary external pacing is established in case of life-threatening bradycardia or asystole. q A backup temporary external pacemaker must be immediately available for use in case of occurrence of life-threatening bradycardia and should preferably be connected directly to an intracardiac electrical catheter located in a ventricle, bypassing any switching apparatus in case of failure or inappropriate settings of such switching apparatus. Warning: Stimulator may not always function as expected – To avoid injury to patient from arrhythmias, monitor function of Stimulator and patient’s vital signs continuously while Stimulator is connected. q The EPS320 Stimulator software is warranted to operate substantially according to

specification however it is not guaranteed to do so at all times, in all possible circumstances and in an uninterrupted manner, nor to be error-free. The Stimulator could potentially fail to stimulate or unintentionally stimulate the patient; to avoid injury to the patient, the Stimulator and the patient must be observed for abnormal function of Stimulator at all times while the Stimulator is connected to the patient. q In case of recurrent or persistent unexplained life-threatening ventricular tachycardia or

ventricular fibrillation occurring despite cardioversion/defibrillation during the use of the Stimulator, disconnect the patient from the Stimulator and any attached third party switching equipment in case of occult malfunction in any of the equipment is causing microelectrocution or DC current stimulation and repeat cardioversion/defibrillation. It is recommended to disconnect patient at the intra-cardiac electrode catheter connectors; the Stimulator itself may be disconnected instantly by unplugging the green Pace Output plug on the front panel. Warning: Measurements by stimulator are for information only. q Measurements displayed by stimulator, including the Impedance measurement and SNRT

measurement are for facilitation of use of stimulator. The user should use third party legally marketed measurement devices independent of the Stimulator to measure these parameters for the purpose of clinical diagnoses.

Warnings Related to the use of EPS320 Stimulator with RF Ablation Equipment Warning: Use Stimulator only with Stimulus Connection Box (Micropace Parts MP3014 or MP3065) q Use only supplied Stimulus Connection Box (Micropace Parts MP3014) or alternative

optional In-line RF Filter (MP3065) components to connect Stimulator output to patient circuits. These components contain RF suppression filters to prevent large RF energies from RF Ablation equipment not equipped with RF filters from reaching the Stimulator output circuits. Use of other, including custom made connectors may bypass RF filtering and potentially lead to repeated alarms and shutdowns of the Stimulator and possible induction of unintended life-threatening arrhythmias during delivery of RF ablation energy. Warning: Do not stimulate via ablation electrode during delivery of RF Ablation energy. q To avoid possibility of unintended arrhythmia induction, do not stimulate myocardium via

the ablation electrode during application of RF energy. Efficacy and potential for adverse effects of stimulation of heated myocardium in the process of ablation have not been established.

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EPS320 Service Manual

General Precautions in Handling the EPS320 Stimulator Caution: Installation, Transport and Storage. q To ensure reliable operation of the Stimulator, install away from dust, excessive heat or

humidity, direct sunlight and splashing liquids and in a well-ventilated place. q To ensure that operator may see important error messages displayed during operation,

install the Stimulus Generator Unit with the front panel visible to the operator. q To avoid damage to the Stimulator, avoid exposure to chemical gases, excessive vibration,

impact, temperatures above 60 ºC or ambient air pressures less than 500 hPa during transport and handling. q To ensure that backup battery remains fully charged, store Stimulator between uses with

the Stimulus Generator Unit connected to isolated mains power supply, switched on at the rear panel switch (Mains Power green Led should blink) and in the Standby Mode . Caution: Precautions prior to use. q Ensure that all cables are free from defects, are properly installed and secured. q Ensure isolation of the mains power supply to the Stimulator and that no newly attached

equipment is compromising the electrical safety of the installation. q If the stimulator has been unused or may have been disconnected from mains power

supply for more than 1 month, charge backup battery by leaving connected to the mains supply in standby mode overnight and check that Emergency Backup Fixed Pacing and the stimulator functions correctly. q Do not use the Stimulator if any component appears damaged, computer appears to start

up abnormally, or error messages appear on the computer screen or Stimulator front panel. If in doubt, contact the Distributor or Micropace directly. q Ensure that the Operator is trained thoroughly on how to switch the Stimulator to Backup

Manual mode and Emergency Fixed Rate Pacing modes, and knows how to bypass any third party switching apparatus to maintain pacing capability in case of failure of that apparatus. q To prevent EPS320 software malfunction, do not attempt to install drivers, utilities or

software into the EPS320 PC other than that supplied by Micropace. The EPS320 software will not execute if Terminate and Stay Resident (TSR) programs are detected by the software. Caution: Precautions during use. q Observe the Stimulator and patient at all times for abnormal function and rectify any

problem promptly or disconnect the patient from the Stimulator (by unplugging the green Pace Output plug on the front panel). q Do not use the Stimulator and disconnect it from the patient if it repeatedly switches to

Backup Manual mode or repeatedly displays error messages on the front panel. Contact your Micropace Distributor. q Use of excessive stimulation currents increases potential for induction of fibrillation, which

may be harmful to the patient and may be prognostically non-specific in ventricular stimulation studies. q To ensure reliable pacing capture, the user must establish pacing current thresholds for

electrode catheters, including RF ablation catheters, prior to diagnostic stimulation studies and set pacing current accordingly. Pacing thresholds, impedance and sensing characteristics may differ amongst various diagnostic and RF Ablation electrode catheters due to differing electrode geometries and associated electrical pathways. q To reduce chance of accidentally inducing ventricular fibrillation, ensure reliable ECG

sensing and use Synch-to-QRS function to avoid stimulating in the vulnerable diastolic period where appropriate. Caution: The Stimulus Generator Unit should be charging its backup battery while not in use.

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q The EPS320 Stimulator should be connected to external power; its Power switched on at

the rear panel switch and in the Standby Mode while not in use to ensure that backup battery remains fully charged. q The Stimulator should be maintained according to “Maintenance” section of this manual.

Adverse Events Observed Adverse Events The EPS320 produces standard cardiac stimulation outputs similar to other existing programmable cardiac stimulators in use for the past 30 years. The standard pulse output characteristics are well defined in standard Electrophysiology texts and the application, safety and clinical efficacy of this group of devices is well established in the medical field (2,3). and in one recent review by McLaughlin et al (4). Report of adverse events related to EPS320 arises from the following clinical experience with the product subject to product vigilance (device exposure estimated by adopting an estimate of 14 patients per stimulator per month of use, each patient exposed for an estimated mean time of 2.5 hours) Clinical use of the device in its evolving form since January 1998, evaluated in October 1999 by a survey of 6 clinicians using 6 Stimulators with an accrued clinical experience with the product on more than 1600 patients q A prospective field trial of safety and efficacy of the EPS320 performed in May to July 1999

concurrently at 4 hospitals in Sydney, involving 6 Stimulators / cardiologist users and a total of 23 patients. q Clinical use of the EPS320 in Australia and Southeast Asia from July 1999 to October

2001, involving 22 Stimulators and an estimated 7400 patients. q Clinical use of the EPS320 in EC countries from January 2001 to October 2001, consisting

of 17 Stimulators accumulating clinical exposure to an estimated 2400 patients. The EPS320 Stimulator has thus been used on an estimated total of 10,000 patients, approximately half using the current firmware version, leading to an estimated device exposure of 25,000 hours. No deaths or injuries related to the use of the EPS320 Stimulator have been reported during the device exposure. Two adverse events were reported, both due to device interaction with an RF Ablation Generator. They were non-sustained Ventricular arrhythmias arising when operators simultaneously paced and delivered RF ablation energy through the same ablation electrode; the EPS320 Stimulator detected the interaction and shut down in both cases. Device interaction has been eliminated in the field by the issue of a Safety Alert warning against this application and the addition of RF filters to Stimulator’s Stimulus Connection Box to isolate Stimulator from RF signals.

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EPS320 Service Manual

Potential Adverse Events Following is a list of potential adverse events which could be directly associated with diagnostic cardiac stimulation using the EPS320 during electrophysiological studies (in alphabetical order): Bradycardia or asystole q

Should a patient develop bradycardia or asystole during the use of the Stimulator, failure to promptly backup pace the patient may lead to hypotensive injury within seconds to minutes. Such arrhythmia may typically occur (i) in patients with atrioventricular conduction defects, (ii) during placement of intra-cardiac electrode catheters, (iii) after cardioversion/defibrillation or (iv) during RF ablation.

q

The Stimulator may fail to normally deliver stimuli due to (i) power failure or power interruption, (ii) failure of PC, (iii) loss of communication between PC and Stimulus Generator Unit (SGU), e.g. due to lead disconnection or (iv) failure of SGU itself due to spontaneous fault or damage from external events such as defibrillation of RF ablation energies.

q

To avoid patient injury, the user may use the battery powered Backup Manual Pace mode in case of power failure, failure of PC or the communication link, and the Emergency Fixed Pacing mode in case of failure of normal operation of the SGU. The EPS320 Stimulator is not a life-support device; these functions are for use in non-lifethreatening bradycardia or until external temporary pacing is established in case of asystole. Refer to “The EPS320 Stimulus Generator Unit” section below for instructions on the use of these features.

DC voltages greater than 5000V or RF voltages greater than 350V pp applied to Stimulator outputs may cause circuit failure; the Stimulator issues a range of alarms in case of failure of output circuits – see Section “Hardware Error Messages on the Stimulus Generator Unit.” Explosion or fire q

q

Explosion could arise from accumulation and ignition of explosive gasses vented from charging of the backup battery within the Stimulator. Use Stimulator only in well ventilated areas.

q

Explosion could also arise from electrical sparks within the Stimulator igniting explosive anaesthetic gasses in the operating room. Do not use Stimulator in the presence of volatile anaesthetic gasses.

Continuous RF voltages greater than 350V pp applied to Stimulator outputs in contravention of labeling may cause overheating of the Stimulus Connection Box and possibly cause a fire hazard. Similar hazards would probably be present in other equipment with over-voltage protection. Special care will be required should RF generators capable of delivering such voltages (corresponding to in excess of 150W into 300 Ohm load) become available. Myocardial injury q

q

Excessive current flows through intra-cardiac electrodes, such as due to failure of Stimulator output circuit causing excessive stimulation currents and inadvertent shunting of defibrillation or RF ablation energies through a malfunctioning Stimulator or equipment attached to its outputs could theoretically cause localized myocardial damage at the pacing electrode.

In order to minimize risk of myocardial injury, connect EPS320 Stimulator stimulation outputs only to legally marketed medical equipment compliant with IEC60601-1 and IEC60601-1-1, and if error messages appear on the SGU, consult the section “Hardware Error Messages on the Stimulus Generator Unit.” prior to using the Stimulator again. Operator electrocution q

q

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The EPS320 Stimulator auxiliary signal input/output ports and RS232 communications port are optically isolated from patient circuits, but connect directly to Stimulator signal ground plane, in accordance with IEC60601-1. Connection of these ports to equipment

without appropriate mains isolation or protective grounding may cause electrocution of the operator by mains-derived AC current in case of malfunction in the connected equipment. q

In order to minimize risk of electrocution to the operator, connect EPS320 Stimulator input/output ports only to legally marketed medical equipment, isolated from mains power and compliant with IEC60601-1 and IEC60601-1-1.

Ventricular tachycardia or fibrillation q

The EPS320 Stimulator may be used to intentionally induce ventricular or atrial arrhythmias including ventricular tachycardia and fibrillation. Causes of inadvertent induction of such arrhythmias includes operator error, Stimulator malfunction and device interactions: (i) Myocardial stimulation with DC current. Myocardial stimulation with DC current is likely to cause arrhythmias, including intractable ventricular fibrillation (if operator is unaware of the fault and does not remove the source from the patient, ventricular fibrillation may repeatedly recur after defibrillation, possibly leading to patient death). DC current flow in the stimulation circuit loop, may potentially be caused by Stimulator output circuit failure, failure in other third party equipment inserted in the stimulation circuit loop or device interaction between interconnected equipment. Should the EPS320 detect such a condition a DC-ERROR alarm is issued, (_,d,c,_,E,r,r )displayed on SGU front panel and DC-ERROR alarm message on the computer), followed by a safe state shut down of the Stimulator. Refer to section “Hardware Error Messages on the Stimulus Generator Unit” below for instructions in this case. Regardless of Stimulator alarm state, recurrent unexplained ventricular fibrillation should prompt user to immediately disconnect the patient from the stimulation circuit, preferably at the intracardiac electrode catheter connectors. (ii) Intended cardiac stimulation in the vulnerable diastolic cardiac period User should ensure that ECG sensing by the Stimulator is reliable and always use the Synch-to-QRS function to avoid stimulating in the vulnerable diastolic period, where appropriate. External amplified ECG signal is the recommended source of ECG, however, where external ECG source is not available or unreliable, the EPS320 may be configured to sense intra-cardiac ECG from either of the stimulation output channels. (iii) Inappropriately rapid cardiac stimulation Cardiac stimulation at rapid intervals, typically less than 300 ms, may cause undesirable arrhythmias including ventricular fibrillation. Inadvertent rapid stimulation, may occur either through user error, inappropriate Stimulator software safety parameter configuration or Stimulator hardware or software malfunction. The Stimulator’s SGU monitors for unprogrammed rapid stimulation and if detected, issues a Rate Error alarm, followed by a shut down safety state. Monitor the Stimulator function, patient’s ECG and observe the patient continuously for unexpected behaviour whenever patient is connected to the Stimulator; disconnect the patient from the Stimulator and do not use if abnormal stimulation is observed. (iv) Unprogrammed isolated stimulation pulses Unintended cardiac stimulation with isolated stimulation pulses may cause undesirable arrhythmias including ventricular fibrillation. Isolated stimulation pulses may potentially occur due to Stimulator hardware or software malfunction. The Stimulator’s SGU monitor detects unprogrammed stimulus pulses occurring within 300 ms of another stimulus pulse and issues a Rate Error alarm, followed by a shut down safety state. Monitor the Stimulator function, patient’s ECG and observe the patient continuously for unexpected behaviour whenever patient is connected to the Stimulator; disconnect the patient from the Stimulator and do not use if abnormal stimulation is observed. (v) Mains derived AC current microshock 15

EPS320 Service Manual

Mains derived AC leakage currents to ground may cause patient microshock leading to arrhythmias, including intractable ventricular fibrillation. AC leakage currents may potentially arise from a malfunction in the EPS320 Stimulator or connected third party equipment if the mains power supply is not isolated in all interconnected equipment. Ensure that the EPS320 Stimulator system, including the PC and all connected third party equipment is connected only to isolated mains power supply.

Adverse events which may be directly associated with diagnostic cardiac stimulation during electrophysiological studies (in alphabetical order): q q q

Arrhythmias Death Temporary chest pain

Adverse events may occur arising from use of third party equipment attached to the EPS320 Stimulator during EP studies. Refer to User Instructions for such third party equipment for warnings, precautions and lists of adverse events.

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4 OVERVIEW OF STIMULATOR SYSTEM 4.1 General The Micropace EPS320 is a programmable external cardiac pacemaker used in electrophysiological studies. The device features two independent fully programmable and isolated constant current stimulator channels used to pace the heart temporarily via transvenous intracardiac electrodes. The EPS320 system consists of a manufactured instrument case containing the Stimulus Generator Unit (SGU) connected to and controlled by a Personal Computer (PC) via a serial RS232 interface. A Stimulus Box connected to the SGU output is used to interface the stimulus output to third party transvenous pacing electrodes and to filter out any unwanted electrical interference. The transvenous electrodes are not part of the EPS320; they are a disposable medical product. Normal operation of the EPS320 SGU is under control of software running on the attached PC which sends specific real-time commands to generate pacing pulses and control the associated functions (see the software description for more details). In case of software or communication failure, the SGU can operate independently in the Manual Backup mode, capable of providing constant pacing at a rate and pulse current displayed on and programmable from the SGU's front panel. A secondary backup facility is available, the Emergency Fixed Backup mode, which is a completely separate analogue circuit pacemaker, powered by a ultra-long life battery, capable of providing a fixed pacing train at 500 ms, 5mA and 2ms pulse width. The two isolated outputs will deliver pulse widths from 0.5ms to 10ms, adjusted in 1ms steps. The current amplitude can be adjusted from 0.1mA to 25mA in steps of 0.1mA. The maximum available output voltage is 26V, so the maximum output pulse current will be less than 25mA for load impedance greater than 1kΩ.

4.2 Hardware Overview The EPS320 stimulator system: • • • • • • •

A computer with power supply (CPU and separate Display as shown or all-in-one PC) Stimulus Generator Unit (SGU) Mains Isolation Transformer 15VDC power supply unit Patient Connection Box Auxiliary cables for connection to an EPS recording system Various power cables as shown

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EPS320 Service Manual

Figure 1 EPS Stimulator System

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5 PRINCIPLES OF OPERATION 5.1 Background Information The EPS 320 cardiac stimulator is a 2 channel constant current stimulator designed for delivery of complex sequence of cardiac pacing stimuli for the purpose of clinical electrophysiological testing of the human heart. Pacing stimuli are delivered to the heart by a third party transvenous pacing electrode. The stimulator is a class 2B medical device according to MDD classification and class III medical device according to FDA classification. The stimulus parameters and timing sequences are programmed by the operator on the computer which issues commands to the microprocessor controlled Stimulus Generation Unit at the appropriate time. Stimulus protocols include simple constant rate stimulation, decremental stimulation with ever decreasing inter-stimulus interval, single extra stimulus consisting of a drive train of eight (8) constant interval stimuli followed by one (1) extra stimulus with progressively decreasing coupling interval. More than one (1) extra stimuli may be called upon to be delivered with or without synchronization with the cardiac intrinsic rhythm. In the VT induction protocol up to six (6) independently timed extra stimuli are given at close coupling intervals to determine if the heart can be provoked into abnormal ventricular arrhythmias. Potentially dangerous rhythms are routinely induced in patients during these studies and external DC cardioversion or defibrillation is frequently performed. Despite the frequent such rhythms and the frequent severe ill health of patients undergoing the test, electrophysiological studies performed by trained personnel are remarkably safe with expected death rates of approximately one (1) in 5000 studies. What is an Electrophysiological Study? Electrophysiological studies are diagnostic tests performed to investigate patients with complaints of palpitations, fainting or resuscitated from sudden death. The information obtained from these studies aids in clinical decisions regarding therapy, which may include drug, radio-frequency ablation or implantation of an implantable defibrillator. What is a Pacing Stimulus? The heart may be electrically stimulated to contract by an electrical pulse if the current-duration product exceeds the pacing threshold for that part. Pacing threshold may vary due to presence of heart disease, drug therapy and depend heavily on the site of the stimulation within the heart. Stimuli less than 0.03ms and less than 0.1mA generally do not produce cardiac depolarization (myocardial capture). The usual pacing pulse parameters in the EPS laboratory are 2ms in duration and applied from a constant current source at 0.1-5.0mA. Normal satisfactory pacing threshold is less than 1.0mA for the ventricle and less than 1.5mA for the atrium. Current amplitudes of up to 20mA may be required for patients with severe heart disease or in emergency situations. Pacing impedance varies from 300-100 Ω and thus the constant current source must be able to supply up to 20 volts to deliver 20mA into 1kΩ resistance. The EPS 320 delivers up to 25mA. Certain specialized applications such as transoesophageal stimulation require wider pulse width. Cardiac capture depends on pulse strength-duration product and thus is not sensitive to the shape of the waveform, which should be approximately square with little effect from ringing, damping or noise. Whereas chronic pacing arguably benefits from a biphasic pacing pulse, the application of a small reverse polarity between pacing spikes prevent myocardial polarization, this is not an issue in short term pacing involved in EPS studies and thus the pulse may be entirely positive. The pacing electrode tip should be negative with respect to the reference electrode. Pacing during EPS studies is usually bipolar. The current amplitude has modest accuracy requirements - stimulation is usually performed in steps of 0.1mA up to 1mA, steps of 0.2mA up to 5mA and in 1mA steps up to 25mA.

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EPS320 Service Manual

Stimulation rates are typically 230ms to 700ms but may on occasion be as rapid as 100ms. Pacing duration is typically from 1 second up to 1 minute. Extra stimulus coupling intervals vary typically from 300 to 100ms but may be as short as 50ms.

5.2 System Functional Description The EPS320 Stimulator is made up of two main components described below and illustrated in Figure 2: 1. Desktop IBM compatible Computer (PC): This computer executes a DOS program with a windows-like graphical user interface using the keyboard as the only user input. The software generates each stimulus by sending a serial command to the Stimulus Generation Unit to initiate a stimulus pulse. Stimulus parameters may be altered any time between stimuli by other specific serial commands. Since the PC software programs each stimulus one at a time, its parameters and its timing may be altered by the user at any time prior to the actual occurrence of the stimulus pulse, affording the user the desired control over stimulation at all times, as one would have with most hardware stimulators.

Monitor

Stimulus Output: Atrium & Ventricle Channels

COM1

EPS320 STIMULUS GENERATOR UNIT (SGU)

Computer

Emergency Pace Output

Auxiliary Port ECG1 In ECG1 In

15 VDC

Sync1 Out

Power Supply 110-240VAC-15V

Front Panel Display/ Keys

Figure 2 EPS320 Stimulator main components 2. Stimulus Generation Unit (SGU): The Stimulus Generation Unit contains a PIC16C77 µP and two optically isolated digitally programmable constant current generators. Channel 0 is labeled and intended for pacing the atrium and Channel 1 the ventricle, although they are electrically identically. The µP firmware normally operates in one of two user modes: (i)

(ii) (iii)

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In the Manual Backup mode, the Stimulus Generation Unit operates independently of the PC, and is capable of generating regular pacing stimuli (always 2ms wide pulses into both channels) at amplitudes and intervals adjustable by buttons And displayed by 7-segment LED displays on the front panel. This mode is intended for backup use only in the rare instance of the failure of the PC or its software at a time when the patient urgently requires pacing. In the PC Control mode, the Stimulus Generation Unit communicates with the PC via a 19,200-baud asynchronous serial link. Transmission takes place in three 8 bit word st nd rd 'command strings', the 1 word the ‘frame’, 2 word ‘command’ and 3 word ‘data’. The PC transmits to the Stimulus Generation Unit a watchdog command string every 47ms and at other times any command strings produced by software logic or operator actions. The Stimulus Generation Unit transmits to the PC a command string every 2ms with every second transmission containing either an embedded 8 bit ECG data or status report word. The Stimulus Generation Unit returns four words containing measured stimulus data after executing each stimulus command from the PC. In case of communications failure, the PC computer is able to reset the Stimulus Generation Unit microprocessor by raising the DTR line in the RS232 port, which is wired to the microprocessor master reset.