Descriptions listed below provide an overview of the clinical observations and/or analysis findings associated with each pulse generator confirmed malfunction pattern listed in this report.

All of the patterns listed are thoroughly investigated and analyzed. As part of Boston Scientific's process of continuous improvement, when possible, changes have been or will be implemented in response to identified malfunction patterns. "Improvements implemented" may include product design changes in existing or subsequent generations, manufacturing process modifications, software updates, educational communications, labeling changes, etc. Improvement implementation may vary by geography due to various factors, including regulatory review timing, and may not completely mitigate or eliminate the potential for additional malfunctions.

1. Subpectoral implant 2009— Noise, oversensing, inappropriate shocks, pacing inhibition, high impedance when implanted subpectorally. Weakened bond between header and titanium case. Improvement implemented.
2. Shortened replacement window— Accelerated battery depletion may reduce time between elective replacement (ERI) and end of life (EOL) indicators to less than three months. Device replacement indicators continue to function normally. Degradation of low-voltage capacitor. Improvement implemented.
3. Low-voltage capacitor— Premature battery depletion, no output, no interrogation. Failed low-voltage capacitor. Improvement implemented.
4. Premature battery depletion— Premature battery depletion, significantly shortened longevity and duration between elective replacement (ERI) and end of life (EOL) indicators. Gradual, premature battery depletion most common; in rare instances, rapid depletion occurred with no therapy available. Failed low-voltage capacitor. Improvement implemented.
5. Subpectoral implant— Beeping tones and programmer warning screen upon interrogation, loss of telemetry communications, loss of pacing (intermittent or permanent) and/or loss of shock therapy. Repetitive mechanical stress-induced component damage, only when implanted subpectorally with the serial number facing the ribs. Improvement implemented.
6. Hermetic sealing component - Second Population— Premature battery depletion resulting in loss of telemetry and/or loss of pacing output without warning, appearance of a reset warning message upon interrogation, inappropriate early display of replacement indicators, inappropriate accelerometer function resulting in sustained pacing at the programmed maximum sensor rate, or lack of appropriate accelerometer rate response during activity. Gradual degradation of hermetic sealing component with higher than normal moisture content in pacemaker case late in device service life. Improvement implemented.
7. Crystal timing component - Failure Mode 1— Intermittent or permanent loss of pacing output without warning, intermittent or permanent loss of telemetry, reversion to VVI mode or appearance of a reset warning message upon interrogation. Foreign material within a crystal timing component. Improvement implemented.
8. Crystal timing component - Failure Mode 2— At implant procedure or during pre-implant testing: Intermittent or permanent loss of pacing output without warning, intermittent or permanent loss of telemetry, reversion to VVI mode, or appearance of a reset warning message upon interrogation. Microscopic particle within a crystal timing component. Three failures have been reported following confirmation of successful implantation. No currently distributed devices are subject to this peri-implant failure mode. Improvement implemented.
9. Hermetic sealing component - Original Population— Premature battery depletion resulting in loss of telemetry and/or loss of pacing output without warning, appearance of a reset warning message upon interrogation, inappropriate early display of replacement indicators, inappropriate accelerometer function resulting in sustained pacing at the programmed maximum sensor rate or lack of appropriate accelerometer rate response during activity. Gradual degradation of hermetic sealing component with higher than normal moisture content in pacemaker case late in device service life. Improvement implemented.
10. Magnetic switch— Inhibition of tachyarrhythmia therapy (with no impact on bradycardia pacing) and affecting battery longevity. Magnetic switch stuck in closed position. Improvement implemented.
11. Shorting under header— Permanent loss of shock and pacing therapy. Deterioration of wire insulator (in conjunction with other factors), electric short. Improvement implemented.
12. Shorting in header (pre-April 2002 PRIZM 2 DR)— Permanent loss of shock and pacing therapy. Deterioration of wire insulator (in conjunction with other factors), electrical short. Improvement implemented.
13. Functional latching— Limited therapy availability. Functional "latching." Original June 17 advisory recommendations revised because new information indicated programming Atrial Tachy Episode Data Storage to 0% caused latching in subset of devices with previously stored atrial episode data. Reference July 22, 2005 advisory for more details. New software is now available worldwide to prevent functional latching. Improvement implemented.
14. Safety Mode— Switch to Safety Mode due to rare interaction between device and specific memory component; beeping tones emitted to alert patient. Affected devices still provide full output shock delivery in Safety Mode. Improvement implemented.
15. Integrated circuit chips— Loss of pacing, premature replacement indicators, backup mode operation, disruption of diagnostic measurements. High current drain resulting from a short circuit between two integrated circuit chips. Improvement implemented.
16. Extended charge time post-mid-life— Extended charge time post-mid-life resulting in decreased longevity, shortened ERI to EOL or no time stamp, due to increased battery impedance. Improvement implemented.
17. Longevity labeling— Battery longevity inconsistent with longevity labeling. Device battery status indicators are accurate and no loss of therapy has been reported.
18. Solder bond— Loss of device output, loss of sensing. Separation of component solder from substrate. Improvement implemented.
19. Longevity Remaining error— When near ERT, Longevity Remaining Estimate is incorrect when amplitude is reprogrammed to a higher value. Gas gauge display is not affected.
20. Parameter errors— During RF interrogation, parameter errors occur, requiring manual parameter correction. Corruption in telemetry logic. Improvement implemented.
21. Firmware error— Device beeping unaffected by magnet application, missing EGMs, loss of telemetry, loss of tachy therapy. Multiple resets due to firmware error. Improvement implemented.
22. Integrated circuit— Power on Reset state, loss of telemetry, safety mode operation or loss of output. Failed digital integrated circuit.
23. Capacitor— Premature battery depletion, inability to interrogate. Damage to low-voltage capacitor.
24. Setscrew thread depth— No pacing or pauses in pacing, intermittent or lack of setscrew contact with lead. Incorrect setscrew thread depth. Improvement implemented.
25. Pacing wire weld— Loss of telemetry, loss of pacing. Weld failure between header and internal circuitry.
26. Reconfirmation after charge— Tachy therapy delayed. Redetection and therapy occur after lack of reconfirmation after initial charge. Timing conflict involving specific features. Improvement implemented.
27. Capacitor— No telemetry, no pacing, premature battery depletion. Gradual, premature battery depletion most common; in rare instances, rapid depletion occurred with no therapy available. Failed low-voltage capacitor.
28. Header— Loosened header at pulse generator replacement or lead revision due to process variability. Improvement implemented.
29. Hybrid circuit— Fault codes or loss of output. Failed solder joints on device hybrid circuit. Improvement implemented.
30. Short circuit— Permanent loss of shock and pacing therapy. Deterioration of wire insulator (in conjunction with other factors), electrical short. Improvement implemented.
31. Feedthrough wires— High impedance and/or loss of pacing therapy. Broken wire connecting header to internal circuitry. Improvement implemented.
32. Short circuit— Permanent loss of shock and pacing therapy, electrical short. Insulation degradation due to incorrect wire routing. Improvement implemented.
33. Battery depletion— Premature battery depletion. Failed battery.
34. Power on reset— Power on Reset state for which tachy and brady therapy are available at preset parameters.
35. Battery depletion— Premature battery depletion.
36. High current drain— Loss of pacing, premature replacement indicators, backup mode operation, disruption of diagnostic measurements. High current drain resulting from a short circuit between two integrated circuit chips. Improvement implemented.
37. Capacitor array— Loss of device output, loss of capture, inability to accurately measure charge times causing elective replacement indicator declaration. Damage to capacitor array. Improvement implemented.
38. Integrated circuit— No telemetry, premature battery depletion. Integrated circuit issue within high-voltage transistor.
39. Impedance measurements— High impedance value (generally >3000 ohms) recorded and displayed as weekly average impedance. Low daily impedance recordings cause error in calculating weekly average impedance due to memory storage limitations. Device fully capable of therapy delivery as programmed. Improvement implemented.
40. Shortened ERI to EOL— Time from ERI to EOL less than expected. Increased battery impedance near EOL.
41. Battery depletion— Premature battery depletion and loss of capture.
42. Memory error— Pacing not as expected. Memory map error. Improvement implemented.
43. Seal plug— Non-cardiac signals on electrograms leading to inhibition of pacing and/or inappropriate shock delivery. Damaged seal plug. Improvement implemented.
44. Oscillator circuit— Beeping and/or display of Fault Code during interrogation shortly after implant. Oscillator circuit operates at higher frequency due to increase in temperature. Improvement implemented.
45. Sensing— Undersensing of cardiac signals.
46. Magnet response— No magnet response. Particulate material in component. Improvement implemented.
47. Header— High impedance, compromised header bonding identified during lead revision procedures. Insufficient medical adhesive bonding between header and case. Improvement implemented.
48. Overestimation of battery status— Improvement in battery status between follow-up visits and/or overestimation of remaining longevity. Very specific conditions involving the use of an atrial tachycardia response feature. Software upgrade distributed late November 2003 eliminated the possibility of battery status overestimation. Improvement implemented.
49. Impedance— Atrial and/or ventricular pacing impedances >2500 ohms in unipolar and bipolar modes.
50. Telemetry or atrial noise— Noise during telemetry and/or atrial sensing. Inappropriate contact between telemetry coil and device case. Improvement implemented.
51. Diagnostic data error— No ventricular sense (VS) markers displayed on real-time EGMs when hysteresis is on. Improvement implemented.
52. Integrated circuit— Lack of ventricular markers and reversion to Safety Mode, due to IC fault. Improvement implemented.
53. Resistor— Various fault codes upon interrogation. Damaged resistor. Improvement implemented
54. Battery weld— No pacing output and/or inability to interrogate. Battery weld. Improvement implemented.
55. Battery depletion— Premature battery depletion.
56. Reset during charge— Power on reset state during therapeutic shock charging attempt due to firmware issue. Improvement implemented.
57. Memory error— Device resets (including pacing at reset parameters) and inability to interrogate. Errors in device memory.
58. Transformer— Charge time fault code and/or end of life (EOL) indicator displayed, loss of shock therapy. Damaged transformer. Improvement implemented.
59. Adhesive consistency— Non-cardiac signals on electrograms leading to inhibition of pacing and/or inappropriate shock delivery. Bubbles or voids in adhesive. Improvement implemented.
60. Rate fault declaration— Inappropriate pacing due to timing interaction when autocapture is programmed on. Improvement implemented.
61. Capacitor— Premature battery depletion, no telemetry. Damage to capacitor. Improvement implemented.
62. Circuit connection— Loss of telemetry, no magnet tones, loss of pacing, loss of shock therapy. Damaged internal circuit connection. Improvement implemented.
63. Telemetry coil— No pacing output and/or an inability to interrogate. Short circuit between pulse generator feedthrough wires and telemetry coil. Improvement implemented.
64. Memory address— Inability to interrogate. Memory address error. Improvement implemented.
65. Capacitor— Premature battery depletion, significantly shortened ERI to EOL time. Gradual, premature battery depletion most common; in rare instances, rapid depletion occurred with no therapy available. Failed low-voltage capacitor. Improvement implemented.
66. Device tones— Inappropriately sustained device tone. Magnet removal or initialization of programming event during specific timing window. Device fully capable of therapy delivery as programmed. Improvement implemented.
67. Setscrew block— No pacing or pauses in pacing, intermittent or lack of setscrew contact with lead. Incorrect setscrew block. Improvement implemented.
68. Battery depletion— Premature, gradual depletion of battery; in rare instances, rapid depletion with no therapy available.
69. Feedthrough filter capacitor— Inability to interrogate device following shock delivery. High voltage build up between feedthrough leads on capacitor surface. Improvement implemented.
70. Battery depletion— Loss of therapy, inability to interrogate, no magnet response, premature battery depletion.
71. Internal device connection— Intermittent or no telemetry. Telemetry coil connection. Improvement implemented.
72. Memory location— Inappropriate early display of elective replacement indicator (ERI). Incorrect data within a specific memory location.
73. Solder bond— Inability to interrogate, no magnet response, no pacing output. Broken solder bond between wire mounting surface and internal circuitry. Improvement implemented.
74. Memory location— Inability to perform diagnostic testing, loss of shock therapy. Incorrect data within a specific memory location. Improvement implemented.
75. Stored EGMs— Inability to view stored EGMs. Incorrect EGM index location.
76. Memory location— Loss of pacing and/or shock therapy, premature battery depletion, inability to perform diagnostic testing, loss of telemetry, and/or incorrect diagnostic information. Incorrect data within a specific memory location.
77. Mid-life display of replacement indicators— Extended charge time resulting in early occurrence of ERI or EOL, or shortened ERI to EOL time. Please reference the ERI Charge Time Limit Extended During Mid-Life Product Update for more details. Improvement implemented.
78. High-voltage capacitor— In most cases, temporary long capform charge time; in some cases delayed therapy or loss of tachy therapy. Extended charge time could prompt EOL declaration. High-voltage capacitor issue.
79. Battery post— Inability to interrogate, no pacing output. Bent battery post. Improvement implemented.
80. Sensing— Oversensing and/or delivery of inappropriate shocks. Physiologic and/or mechanical signals. Improvement implemented.
81. Early ERI declaration— Early appearance of ERI. Increased battery impedance prompts ERI declaration. End of life indicators operate as designed.
82. Software download— Safety Mode operation at predetermined brady and tachy parameters. Incomplete software download. Restoration tool available. Improvement implemented.
83. A/D module— Inability to obtain telemetry, reversion to Safety Mode, device beeping. Failure within Analog to Digital (A/D) module.
84. Integrated circuit— Premature battery depletion, loss of pacing output, inability to interrogate, loss of sensing, high-rate pacing, loss of shock therapy. Damage to integrated circuit. Improvement implemented.
85. Battery depletion— Premature battery depletion due to current drain.
86. Early ERI declaration— Early appearance of elective replacement indicator (ERI). Increased battery impedance extends charge time and prompts ERI declaration. Therapy availability unaffected, end of life indicators operate as designed. Longevity estimation relabeled. Improvement implemented. Please reference the ICD Longevity Product Update for more details.
87. Fault codes— During programmer interactions, fault codes appear which are able to be cleared. In one case, a fault code occurred with two memory errors after multiple device resets.
88. Diagnostic data error— Potential inability to view daily measurements and/or inappropriate indication of BOL. Rate fault reset. Improvement implemented.
89. Setscrew— Inability to tighten or loosen setscrews during implant or replacement procedure due to process variability. Improvement implemented.
90. Charge time limit— Early appearance of elective replacement indicator (ERI). Incorrect extended charge time limit. Improvement implemented.
91. Seal plug— Lifted or missing seal plugs. Inadequate medical adhesive bond. Improvement implemented
92. Interrogation at EOL— No interrogation at end of life (EOL). Improvement implemented.
93. Underestimation of battery status— Underestimation of remaining longevity due to invalid charge time measurement. Improvement implemented.
94. Interrupted telemetry— Early appearance of Elective Replacement Time (ERT) indicator, unexpected impedance measurements (>2500 ohms). Interruption in telemetry sequence during software upgrade. Improvement implemented.
95. Pacing rate limit— Inability to interrogate. Inappropriate pacing due to feature interaction. Improvement implemented.
96. Logic errors— Unable to complete diagnostic, cap reform or daily shock lead measurement processes; loss of pacing output, loss of shock therapy. Logic errors when device is performing capacitor reforms or shock impedance measurements.
97. Reed switch— While implanted, continuous device tone or beeping occurs. During interrogation, magnet presence dialog box appears. Tachy therapy unavailable if the Enable Magnet Use feature is programmed ON. Reed switch stuck in closed position. Improvement implemented.
98. Cracked solder joint— Safety mode operation, beeping tones. Cracked solder joint.
99. Transformer— Inability to interrogate, end of life (EOL) indicator displayed, loss of pacing and shock therapy. Failed transformer. Improvement implemented.
100. Atrial pacing fault code— Fault code 08 declared, beeping tones due to software design. No effect on therapy availability. Improvement implemented.
101. Connector block— Connector block can be moved out of alignment or displaced from header. Prolonged implant procedure, high impedance, no pacing, no sensing. Improvement implemented.
102. Misaligned markers— Stored episode markers do not match recorded EGM. Software error when ventricular episode begins during ATR episode. New software was released in 2006 which prevents misaligned markers. Improvement implemented.
103. Seal plug— Non-cardiac signals on electrograms may result in loss of pacing or inappropriate shocks. Seal plug allows air in lead port to escape.
104. Difficulty securing lead— Noise, high impedance, inappropriate shocks or loss of therapy due to crossthreaded setscrews, intermittent or lack of contact between lead and header. Improvement implemented.
105. Low-voltage capacitor— Premature battery depletion, early appearance of elective replacement indicator (ERI). Failed low-voltage capacitor. Improvement implemented.
106. Safety Core-electrocautery— During electrocautery, device may enter Safety Core. Circuitry response to noise caused by electrocautery.
107. Resistor— Fault code upon interrogation, beeping tones or premature battery depletion. Resistor material oxidation. Improvement implemented.
108. High-voltage capacitor— Fault code upon interrogation, extended charge time. Damaged high voltage capacitor.
109. Magnet rate— During interrogation, magnet rate remains after removal of magnet. Reed switch stuck in closed position. Improvement implemented.
110. Battery status— Battery status readings below BOL at or soon after implant caused by exposure to below room temperatures before implant. Actual battery status and longevity are not affected. Improvement implemented.
111. Header contacts— Noise, oversensing, inappropriate shock, high pacing impedance, possible loss of pacing and sensing. Poor header connection with lead terminals due to contacts.
112. Safety Core-programming— Device enters Safety Core after three consecutive invalid programming attempts, due to firmware issue. Improvement implemented.
113. Low-voltage capacitors— Premature battery depletion, fault code during followup, device beeping. Capacitor failure.
114. Bent flex circuit— Charge time-out and/or EOL declaration, due to bent flex circuit. Improvement implemented.
115. Fault codes not displayed post-EOL— No fault code display after EOL declaration.
116. Capacitor— Premature battery depletion, loss of therapy, no telemetry. Damaged capacitor.
117. Accelerometer— Loss of telemetry, reversion to reset mode. Mechanical damage to accelerometer component.
118. Integrated circuit— Premature battery depletion, no telemetry, loss of pacing and defibrillation therapies. Integrated circuit failure.
119. Header— Noise, oversensing, inappropriate shocks, pacing inhibition, high impedance when implanted subcutaneously. Weakened bond between header and titanium case. Improvement Implemented.
120. Solder joint— Beeping tones and programmer warning screen upon interrogation, loss of telemetry communications. Cracked solder joint due to repetitive mechanical stress-induced component damage when implanted subpectorally with the serial number facing the ribs.