Description of Event or Problem · 1
IT WAS REPORTED THAT A VNS THERAPY PHYSICIAN HAD BEEN UNABLE TO INTERROGATE A PT'S DEMIPULSE GENERATOR AND THAT THE PT'S BEHAVIOR HAD BECOME INCREASINGLY WORSE IN ADDITION TO AN INCREASE IN NIGHT TIME SEIZURES, THOUGH NOT A SIGNIFICANT INCREASE, WITHIN THE LAST MONTH. THE PT'S MOTHER INDICATED THAT THE PT CRIED 75% OF THE DAY AND THAT SHE WAS CONCERNED THAT VNS WAS CAUSING THE PT IRRITATION OR PAIN UPON STIMULATION. EVENTUALLY, THE PT'S DEVICE WAS ABLE TO BE INTERROGATED AND THE DEVICE REPORTEDLY INDICATED THAT IT WAS AT EOS AND THE PT'S PHYSICIAN INDICATED THAT THE PT'S SEIZURE INCREASE WAS LIKELY RELATED TO THIS DEVICE CONDITION. THE PT UNDERWENT GENERATOR REVISION SURGERY AND THE EXPLANTED DEMIPULSE GENERATOR WAS RETURNED FOR ANALYSIS. DURING AN EXTERNAL VISUAL ANALYSIS OF THE DEVICE NO ANOMALIES WERE IDENTIFIED (I.E. SHARP EDGES, HEADER DELAMINATION, OPEN POCKETS, DECOMPOSITION, CORROSION OR VOIDS). UPON OPENING THE GENERATOR CASE, A VISUAL ANALYSIS IDENTIFIED THE PRESENCE OF SURFACE CONTAMINATION AND FOREIGN MATTER ON THE INSIDE OF THE CAN WELD AREA, THE BATTERY CASE, THE RETAINER, AND THE PC-BOARD. EXAMINATION ALSO SHOWED THAT IN SOME AREAS THE FOREIGN MATTER WAS BRIDGING TRACES AND OTHER COMPONENTS. THE FOREIGN MATTER WAS SUBJECTED TO SEM/EDX FOR ANALYSIS. ANALYSIS INDICATED THAT THE MATTER WAS COMPRISED MAINLY OF TIN, LEAD AND SODIUM, CHLORINE (SODIUM CHLORIDE). OTHER TRACE ELEMENTS WERE ALSO NOTED. THE PRESENCE OF SODIUM AND CHLORINE ON THE PC-BOARD COULD POTENTIALLY CAUSE THE CORROSION THAT WAS OBSERVED. ADDITIONALLY, NO LEAKAGE WAS IDENTIFIED AT THE GENERATOR'S BATTERY TERMINALS. THE SOURCE OF THE ELEMENTS COULD NOT BE DETERMINED. THE BATTERY VOLTAGE MEASURED 15.2 MV, INDICATING THAT THE BATTERY WAS DEPLETED. NO FURTHER ELECTRICAL TESTING COULD BE PERFORMED DUE TO THE PRESENCE OF DAMAGE TO THE PC-BOARD FROM THE FOREIGN MATTER. THE GENERATOR DEVICE HISTORY RECORD (DHR) WAS REVIEWED; ALL LINE ITEMS WERE VERIFIED TO HAVE BEEN SIGNED OFF, ALL ELECTRICAL TESTS/VISUAL INSPECTIONS WERE PASSED AND THERE WERE NO UNRESOLVED NON-CONFORMANCES PRIOR TO DEVICE SHIPMENT. AS THE CORROSION OF THE GENERATOR WAS CONTAINED WITHIN THE GENERATOR'S CANISTER, THERE WAS NO LIKELY INTERACTION WITH THE PT'S EXTRACELLULAR ENVIRONMENT. IN THE WORST CASE SCENARIO, THE GENERATOR WILL NO LONGER FUNCTION PROPERLY OR NOT BE ABLE TO DELIVER THE INTENDED AMOUNT OF THERAPY. IT APPEARS THAT THE BATTERY WAS PREMATURELY DEPLETED. THE PREMATURE DEPLETION IS RELATED TO THE REMNANTS OF FOREIGN MATTER/CORROSION THAT WERE OBSERVED ON THE PC-BOARD, MOST LIKELY DUE TO PRESENCE OF SODIUM, CHLORINE (SODIUM CHLORIDE) ON PC BOARD. GOOD FAITH ATTEMPTS TO OBTAIN PROGRAMMING/DEVICE DIAGNOSTIC HISTORY HAVE BEEN UNSUCCESSFUL TO DATE.