COR-KNOT

Description of Event or Problem

A ROUTINE LSI LITERATURE SEARCH IDENTIFIED A PREPUBLICATION MANUSCRIPT TITLED "LATE EMBOLIZATION OF A COR-KNOT FASTENER DEVICE RESULTING IN LEFT ANTERIOR DESCENDING ARTERY OCCLUSION." THE AUTHORS OF THIS PREPUBLICATION DOCUMENT REPORT THAT A 57-YEAR-OLD FEMALE PATIENT UNDERWENT A MINIMALLY INVASIVE MITRAL VALVE REPAIR PROCEDURE IN WHICH A COR-KNOT MINI® DEVICE WAS USED TO DEPLOY COR-KNOT® TITANIUM FASTENERS (REFERRED TO AS "FASTENERS" THROUGHOUT THIS DOCUMENT) FOR THE PURPOSE OF SECURING SUTURE HOLDING AN ANNULOPLASTY RING. THE SURGEONS WHO IMPLANTED THE ANNULOPLASTY RING NOTED: "WE DID NOT OBSERVE ANY DEVICE MALFUNCTION OR INAPPROPRIATE COR-KNOT PLACEMENT". THEY FURTHER REPORTED THAT "INTRAOPERATIVE AND POSTOPERATIVE ECHOCARDIOGRAPHY, THE LATTER PERFORMED ON POSTOPERATIVE DAY 7, DEMONSTRATED PRESERVED SYSTOLIC LV FUNCTION WITH NO REGIONAL WALL MOTION ABNORMALITIES AND NO RESIDUAL MR. THE POSTOPERATIVE COURSE WAS UNEVENTFUL, EXCEPT FOR A BRIEF EPISODE OF ATRIAL FIBRILLATION AND THE PATIENT WAS DISCHARGED HOME ON POSTOPERATIVE DAY 8." NOTE: THERE IS NO MENTION OF THE NUMBER OF FASTENERS OBSERVED ON THE PROSTHETIC ANNULOPLASTY RING IN THE POSTOPERATIVE DAY 7 ECHO. APPROXIMATELY 6 MONTHS AFTER THIS PATIENT'S INITIAL MITRAL VALVE REPAIR PROCEDURE, THE PATIENT WAS REPORTED TO PRESENT WITH: NEW-ONSET FATIGUE, EXERTIONAL DYSPNEA, THORACIC PAIN AND EPIGASTRIC DISCOMFORT. THE BLOOD TROPONIN LEVELS WERE NOT ELEVATED BUT TRANSTHORACIC ECHOCARDIOGRAPHY DEMONSTRATED MODERATELY REDUCED SYSTOLIC LV FUNCTION (40%) AND NEW REGIONAL WALL MOTION ABNORMALITIES WITH AKINESIA OF THE LV APEX. CARDIAC CATHETERIZATION DEMONSTRATED AN OCCLUSION OF THE LEFT ANTERIOR DESCENDING ARTERY, CAUSED BY FOREIGN METALLIC BODIES. NOTE: AN APPROXIMATELY 10 SECOND VIDEO AVAILABLE THROUGH THIS PREPUBLICATION DOCUMENT SHOWS THE LEFT ANTERIOR DESCENDING ARTERY WITH TWO INDWELLING FOREIGN OBJECTS, BUT IT DOES SHOW CONTRAST-ENHANCED BLOOD FLOW DISTAL TO THE FOREIGN BODIES AND FLOWING TOWARD AND AROUND THE APEX OF THE HEART. THE AUTHORS REPORT THAT THE ASSOCIATED MYOCARDIAL INFARCTION "WAS CONSIDERED REMOTE RATHER THAN ACUTE... PRECLUDING ANY REASONABLE OPTION FOR SUBSEQUENT REVASCULARIZATION." THE AUTHORS REPORT THAT 2 OF THE 11 FASTENERS SHOWN IN THE INTRAOPERATIVE MITRAL REPAIR ECHO WERE NOT SEEN ON THE ANNULOPLASTY RING IN THE APPROXIMATELY 6 MONTHS POSTOPERATIVE ECHO. NINE BUMPS, PRESUMABLY FASTENERS, WERE OBSERVED TO BE ON THE SUTURE HOLDING THE ANNULOPLASTY RING IN PLACE, AND THESE CRIMPED FASTENERS WERE REPORTED TO APPEAR STABLE. PRESERVED VALVE FUNCTION WITHOUT MITRAL REGURGITATION OR RING DEHISCENCE WAS OBSERVED. THE RISK OF FURTHER EMBOLIZATION WAS REPORTED TO BE CONSIDERED LOW, REPORTEDLY RULING OUT A NEED FOR REPEAT SURGERY. THE PATIENT WAS REPORTED TO REMAIN UNDER OBSERVATION.

Additional Manufacturer Narrative

SINCE WE ARE UNABLE TO PASTE PHOTOGRAPHS INTO THIS FORM, WE ARE ALSO ATTACHING A SEPARATE PDF DOCUMENT WITH THIS REPORT WHICH INCLUDES THE FIGURES TO WHICH WE REFER IN THIS DOCUMENT. PLEASE SEE THE ATTACHED SEPARATE PDF FILES TITLED "INCIDENT REPORT IMAGES FOR MEDWATCH TO VIEW ANY ASSOCIATED FIGURES. THE VIDEO REFERENCED IN THIS PAPER, WHICH SHOWS CONTRAST-AIDED ANGIOGRAPHY OF THE LEFT CORONARY ARTERIAL DISTRIBUTION, CAN BE OBTAINED VIA THE PUBLISHER'S WEBSITE (DOI.ORG/10.1093/EJCTS/EZAF466). AGAIN, NOTE THAT IN THIS VIDEO THE CONTRAST-ENHANCED BLOOD FLOWS BEYOND THE LEFT ANTERIOR DESCENDING ARTERY "OCCLUSION." COR-KNOT® TITANIUM FASTENERS ARE USED TO SECURE SUTURE IN GENERAL AND CARDIOVASCULAR SURGICAL APPLICATIONS. IN PRACTICE, A LOADER LOADS A COR-KNOT® QUICK LOAD® UNIT, COMPRISING A HOLLOW COR-KNOT® TITANIUM FASTENER AND A WIRE SNARE, INTO THE DISTAL TIP OF A COR-KNOT MINI® DEVICE. THE LOADER IS CLEARLY INSTRUCTED IN THE INSTRUCTIONS FOR USE (IFU) TO INSPECT THE DEVICE TO ENSURE THAT THE FASTENER IS WELL LOADED AND FULLY SEATED (IFU P. 2). (FOR REFERENCE, THE FULL COR-KNOT MINI® IFU IS INCLUDED AS AN ATTACHMENT WITH THIS MEDWATCH SUBMISSION.) TO DEPLOY A FASTENER TO SECURE SUTURE, THE USER PULLS THE SNARE TO THREAD SUTURE ENDS THROUGH THE FASTENER LOADED IN THE COR-KNOT MINI® DEVICE. THE SNARE IS THEN SET ASIDE. THE USER IS ALSO INSTRUCTED TO INSPECT THE DEVICE TO ENSURE THE FASTENER IS FULLY SEATED IN THE DEVICE TIP AFTER SUTURE HAS BEEN THREADED THROUGH THE FASTENER (IFU P. 3). NEXT, THE USER GENTLY SLIDES THE DISTAL TIP OF THE LOADED COR-KNOT MINI® DEVICE OVER THE SUTURE DOWN TO A TARGETED SITE. THE USER ORIENTS THE DEVICE APPROPRIATELY AND TENSIONS THE SUTURE AS DESIRED. THE USER THEN SQUEEZES THE COR-KNOT MINI® DEVICE LEVER TO CRIMP THE FASTENER ONTO THE SUTURE. WHILE HOLDING THE LEVER SQUEEZED, THE USER APPLIES TENSION TO THE ENDS OF THE SUTURE TO TRIM THE SUTURE TAILS. THE LEVER IS RELEASED AND THE DEVICE REMOVED, LEAVING IN PLACE A CRIMPED FASTENER THAT SECURES THE SUTURE. THE IFU FURTHER INSTRUCTS THAT THE USER IS REQUIRED TO CONFIRM PROPER POSITION OF THE CRIMPED FASTENER AND TO INSPECT THE FASTENER TO ENSURE THAT THE FASTENER IS CRIMPED PROPERLY (IFU P. 3). THE AUTHORS HAVE NOT ALLEGED THAT THE COR-KNOT MINI® DEVICE DID NOT PERFORM ITS INTENDED FUNCTION OF SECURING SUTURE WITHIN THE CRIMPED FASTENERS. THE AUTHORS SPECIFICALLY STATE THAT "WE DID NOT OBSERVE ANY DEVICE MALFUNCTION OR INAPPROPRIATE COR-KNOT PLACEMENT". FIG. 1 INCLUDES THE INTRAOPERATIVE ECHO IMAGE (FIG. 1A) AND APPROXIMATELY 6 MONTHS POSTOPERATIVE ECHO IMAGE (FIG. 1B) INCLUDED BY THE AUTHORS. NOTE THAT THESE IMAGES HAVE BEEN ROTATED AND CROPPED FOR EASE OF COMPARISON. [PLACEHOLDER FOR FIGS. 1A AND 1B - ECHO IMAGES SHOWING THE PATIENT'S MITRAL ANNULOPLASTY RING INTRAOPERATIVELY (A) AND AT APPROXIMATELY 6 MONTHS POSTOPERATIVELY (B)]. AS SHOWN IN FIG. 1A, AN INTRAOPERATIVE ECHO IMAGE SHOWS 11 LOCATIONS (EACH ASSIGNED A SEQUENTIAL NUMBER, 1-11, THE LABELS OF WHICH SOMEWHAT OBSCURE THE UNDERLYING IMAGE) THAT ARE REPORTED TO CORRESPOND WITH FASTENERS ARRAYED AROUND AN ANNULOPLASTY RING DURING THE SURGICAL PROCEDURE. THERE WAS NO MENTION IN THE PREPUBLICATION DOCUMENT REGARDING WHICH NUMBERS REPRESENT THE FIRST OR THE LAST FASTENERS PLACED; THE ORDER OF FASTENER PLACEMENT WAS ALSO NOT PROVIDED. AS SHOWN IN FIG. 1B, AN APPROXIMATELY 6 MONTHS POSTOPERATIVE ECHO IMAGE SHOWS 9 LOCATIONS THAT ARE REPORTED TO CORRESPOND WITH FASTENERS ARRAYED AROUND THE SAME ANNULOPLASTY RING. IN FIG. 1B, THERE APPEARS TO BE A LACK OF A FASTENER AND ITS CORRESPONDING LABEL IN POSITIONS PREVIOUSLY NUMBERED 4 AND 11 WHEN COMPARED TO THE FIG. 1A INTRAOPERATIVE ECHO IMAGE. NOTE: TWO COR-KNOT MINI® DEVICES ARE PROVIDED IN EACH KIT, ALLOWING THE SURGEON TO ALTERNATE DEVICES DURING SUTURE SECURING. WHILE ONE DEVICE IS BEING USED BY THE SURGEON TO PLACE A FASTENER, THE OTHER DEVICE IS TYPICALLY BEING LOADED BY THE SCRUB STAFF. IN THIS CASE, IF THE TYPICAL PROCEDURE FOR LOADING AND FIRING WAS PERFORMED, THE FASTENERS LABELED 4 AND 11 IN FIG. 1 WOULD EACH HAVE BEEN DEPLOYED BY A DIFFERENT DEVICE. AS SHOWN IN FIG. 2, THE PAPER FURTHER PROVIDES IMAGES THAT ARE DESCRIBED AS SHOWING TWO METALLIC BODIES VISIBLE IN THE CORONARY ARTERY. [PLACEHOLDER FOR FIG. 2 - IMAGES DESCRIBED AS "TWO METALLIC BODIES... IN THE CORONARY ARTERY"] FROM THESE IMAGES, IT IS DIFFICULT TO DEFINITIVELY IDENTIFY WHAT THE HIGHLIGHTED FOREIGN BODIES ARE. HOWEVER, IF THE METALLIC BODIES ARE FASTENERS, THEIR APPEARANCE IS MORE CONSISTENT WITH UNCRIMPED FASTENERS THAN CRIMPED FASTENERS. IF THESE ARE FASTENERS AND THEY ARE UNCRIMPED, THIS MAY INDICATE THAT THESE 2 FASTENERS WERE NOT APPROPRIATELY LOADED INTO THEIR RESPECTIVE COR-KNOT MINI® DEVICES AT THE TIME THE DEVICE LEVER WAS SQUEEZED AND THEREFORE THE DEVICES WERE UNABLE TO SECURE THE SUTURE BY CRIMPING THE FASTENER. WHEN A FASTENER IS PROPERLY LOADED IN THE COR-KNOT MINI® DEVICE, A SQUEEZE OF THE DEVICE LEVER WILL CAUSE A WEDGE WITHIN THE SHAFT TO DRIVE DOWN AND PRESS INWARD TOWARD THE PROPERLY LOADED FASTENER TO COMPRESS THE FASTENER INTO ITS APPROPRIATE SHAPE, THEREBY SECURING THE INDWELLING SUTURE. OF NOTE, WHILE THE COMPRESSION OF THE FASTENER IS NOT VISIBLE DURING CRIMPING, THE TRIMMING OF THE SUTURE TAILS IS CLEARLY SEEN AND FELT. THE SUTURE BLADE IS CONNECTED TO THE WEDGE, SO TRIMMING OF THE SUTURE (READILY OBSERVED REAL-TIME) AFFIRMS PROPER WEDGE TRAVEL FOR FASTENER CRIMPING (WHEN THE FASTENER IS PROPERLY LOADED). WHILE IT IS READILY OBVIOUS IF A FASTENER HAS THE CORRECT CRIMP SHAPE WHEN VIEWED BY DIRECT VISUAL INSPECTION USING COMMON OPERATIVE LOUPES AT TYPICAL 1.5-3.0X MAGNIFICATION, IT IS NOT POSSIBLE TO SEE THESE FINE FEATURE DETAILS IN ECHO IMAGES. FIG. 1A SHOWS 11 ECHOGENIC BUMPS THAT APPEAR TO BE CONSISTENT WITH FASTENERS AROUND AN ANNULOPLASTY RING. IF THE 2 FOREIGN BODIES HIGHLIGHTED IN FIG. 2 ARE FASTENERS AND THEY ARE UNCRIMPED, IT APPEARS MOST LIKELY THAT THE LOADER DID NOT PROPERLY LOAD THE FASTENERS AND BOTH THE LOADER AND THE USER DID NOT INSPECT THE DEVICES TO ENSURE THAT THE FASTENERS WERE APPROPRIATELY LOADED (CONTRARY TO THE INSTRUCTIONS IN THE DEVICE IFU) PRIOR TO USING THE DEVICES. IF THESE ARE FASTENERS, THEY APPEAR TO BE NOT FULLY CRIMPED, AND FASTENERS NOT CRIMPED APPROPRIATELY WILL NOT SECURE SUTURE. IF A PARTIALLY CRIMPED FASTENER WAS LEFT IN PLACE AROUND THE ANNULOPLASTY RING IN THIS PATIENT, THE USER DID NOT PROPERLY INSPECT ALL FASTENERS AFTER DEPLOYMENT TO DETECT THIS POTENTIAL ISSUE. IF FASTENER INSPECTION WAS NOT CARRIED OUT APPROPRIATELY TO IDENTIFY AND REMOVE ANY POTENTIALLY IMPROPERLY DEPLOYED FASTENERS, THE FASTENERS COULD THEN POTENTIALLY EMBOLIZE WHEN LEFT IN THE PATIENT. MORE THAN 19,529,000 COR-KNOT® TITANIUM FASTENERS HAVE BEEN USED IN CARDIAC SURGERY WORLDWIDE SINCE 2011. IN THAT TIME, THE EVENT REPORTED IN THIS PAPER IS THE FOURTH OF ONLY 4 REPORTED INSTANCES IN WHICH A COR-KNOT® TITANIUM FASTENER IS PURPORTED TO HAVE EMBOLIZED. IN EACH OF THESE PREVIOUSLY REPORTED INSTANCES, THERE WAS NO EVIDENCE THAT THE FASTENER FAILED TO PERFORM ITS FUNCTION TO SECURE SUTURE WHEN APPROPRIATELY CRIMPED ONTO THE SUTURE. EACH PREVIOUSLY REPORTED INSTANCE IS DETAILED BELOW IN THE TABLE OF FIG. 3 AND THE THREE CORRESPONDING NUMBERED PARAGRAPHS BELOW. [PLACEHOLDER FOR FIG. 3 - TABLE OF OTHER REPORTED INSTANCES OF PURPORTED TITANIUM FASTENER EMBOLIZATION.] 1. A PATIENT REACHED OUT TO LSI TO REPORT THAT A FASTENER WAS NOTED IN HIS HEAD CT AFTER A WORKUP FOR TRAUMA. THE FASTENER FROM THIS STUDY WAS CLEARLY UNCRIMPED. FORTUNATELY, THE PATIENT HAD NO RELATED SYMPTOMS. LSI'S CONCLUSION IS THAT SOMEHOW DURING HIS SURGERY, AN UNCRIMPED FASTENER WAS INAPPROPRIATELY LEFT IN HIS CIRCULATING BLOOD. 2. FOUND IN OUR SURVEILLANCE OF THE RELEVANT LITERATURE WAS A PUBLICATION NOTING A METALLIC APPEARING FOREIGN BODY IDENTIFIED DURING A HEAD CT. THIS FOREIGN BODY DID NOT LOOK LIKE A FASTENER. IN ADDITION, ALL OF THE FASTENERS PLACED IN THIS PATIENT'S PRIOR SURGERY APPROXIMATELY 5 YEARS BEFORE THEIR ACUTE EVENT WERE IDENTIFIED STILL IN PLACE ON THE MITRAL PROSTHESIS AFTER THE ONSET OF THIS EMBOLIC EVENT. LSI'S CONCLUSION IS THAT THIS DOES NOT APPEAR TO BE RELATED TO AN EMBOLIZED FASTENER. 3. FOUND IN OUR SURVEILLANCE OF THE RELEVANT LITERATURE WAS A PUBLICATION REGARDING THE RETRIEVAL OF A FASTENER STILL CONTAINING A SEGMENT OF A BROKEN SUTURE REMOVED ENDOVASCULARLY FROM A PATIENT. ABOUT A WEEK AFTER THE PATIENT UNDERWENT AN AVR USING FASTENERS, THE PATIENT PRESENTED WITH NEW-ONSET SUBTLE NEUROLOGIC FINDINGS. A SUCCESSFUL ENDOVASCULAR RETRIEVAL OF THE FASTENER SECURED TO A BROKEN SUTURE WAS ACCOMPLISHED. THE PATIENT HAD NO FURTHER KNOWN SEQUELAE AND REPORTEDLY UNDERWENT A COMPLETE RECOVERY. LSI'S CONCLUSION IS THAT THE BROKEN SUTURE THAT LED TO THIS EMBOLISM IS NOT RELATED TO A FASTENER BUT RATHER MORE LIKELY DUE TO THE WELL REPORTED AND RECOGNIZED OCCURRENCE OF SUTURE BREAKAGE DURING SURGERY, INCLUDING DURING AORTIC VALVE REPLACEMENT SURGERY. IN EACH OF THESE 3 PREVIOUSLY REPORTED INSTANCES, THERE WERE NO ALLEGATIONS, AND NO DATA OR ANALYSIS TO SUPPORT, THAT THE COR-KNOT ® DEVICE USED DID NOT PERFORM ITS INTENDED FUNCTION OF SECURING SUTURE WITHIN THE CRIMPED FASTENERS. IN THIS MOST RECENT REPORT, WE DO NOT KNOW THE ORDER IN WHICH THE 11 FASTENERS WERE INITIALLY PLACED. HOWEVER, IF ROUTINE TECHNIQUES WERE USED, THE FASTENERS LABELED 4 AND 11 FIG. 1A WOULD HAVE EACH BEEN DEPLOYED BY A DIFFERENT DEVICE. EACH OF THESE DEVICES WOULD LIKELY HAVE APPROPRIATELY CRIMPED FASTENERS BEFORE AND/OR AFTER PLACING FASTENERS THAT ARE ALLEGED TO HAVE EMBOLIZED TO A SINGLE CORONARY ARTERY. IF THIS REPORTED EMBOLIC EVENT WAS IN FACT ATTRIBUTABLE TO 2 FASTENERS PLACED BY 2 DIFFERENT DEVICES FAILING TO APPROPRIATELY SECURE SUTURE IN THIS PATIENT, THE LIKELIHOOD OF THIS EVENT IS SOMEWHERE ON THE ORDER OF (1 IN 19,529,000) X (1 IN 19,529,000). THIS WOULD BE AN EXCEPTIONALLY RARE OCCURRENCE. EVEN IF THE 3 PREVIOUSLY REPORTED PURPORTED EMBOLIC EVENTS WERE ATTRIBUTABLE TO A COR-KNOT® FAILURE, THE RATE WOULD BE ABOUT 5 IN 19,529,000 (0.000026%). HOWEVER, THERE IS NO CLAIM THAT THE DEVICES NOR THE FASTENER ITSELF MALFUNCTIONED IN ANY WAY. IF THE FOREIGN BODIES HIGHLIGHTED IN FIG. 2 ARE INDEED FASTENERS, THEY APPEAR TO BE UNCRIMPED OR NOT FULLY CRIMPED, WHICH WOULD BE THE RESULT OF A SERIES OF USE ERRORS (I.E., A TECHNIQUE ERROR RELATED TO LOADING AND A FAILURE TO INSPECT PROPERLY, CONTRARY TO THE INSTRUCTIONS IN THE IFU) AND NOT RELATED TO A TECHNOLOGY MALFUNCTION. THE HISTORY, LITERATURE, AND KNOWN CLINICAL SURVEILLANCE OF THE USE OF FASTENERS IN CARDIAC SURGICAL PROCEDURES SUPPORT THE USE OF THIS TECHNOLOGY WHEN DEPLOYED CONSISTENT WITH THE ROUTINE STANDARD OF CARE. WHILE WE ARE SADDENED TO LEARN OF THIS UNFORTUNATE PATIENT'S SUBOPTIMAL CLINICAL OUTCOME, WE BELIEVE THAT THERE IS NO KNOWN DATA TO SUPPORT A CLAIM THAT ANY OF THESE DEVICES OR FASTENERS EVER FAILED TO PROPERLY HOLD SUTURE WHEN PROPERLY CRIMPED.