COR-KNOT

Additional Manufacturer Narrative

COR-KNOT® TITANIUM FASTENERS ARE USED TO SECURE SUTURE IN GENERAL AND CARDIOVASCULAR SURGICAL APPLICATIONS. IN PRACTICE, THE USER 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® DEVICE. THE USER THEN PULLS THE SNARE TO DRAW SUTURE ENDS THROUGH THE TITANIUM FASTENER LOADED IN THE COR-KNOT® DEVICE. THE SNARE IS SET ASIDE, AND THE USER GENTLY SLIDES THE DISTAL TIP OF THE LOADED COR-KNOT® 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 A LEVER ON THE COR-KNOT® DEVICE TO CRIMP THE TITANIUM FASTENER ONTO THE SUTURE AND TRIM THE SUTURE TAILS. THE CRIMPED COR-KNOT® FASTENER SECURES THE SUTURE. THERE IS NO REPORT THAT THE COR-KNOT® DEVICE DID NOT PERFORM ITS INTENDED FUNCTION OF SECURING SUTURE WITHIN THE CRIMPED TITANIUM FASTENERS. REFERENCING THE ISHIGAKI PAPER, THE CAPTION FOR THE IMAGE SHARED IN FIG. 1 OF THE ATTACHED IMAGE PDF FILE STATES, "THE TIPS OF THE TWO COR-KNOTS (BLACK ARROWHEAD) ARE ATTACHED TO THE AORTIC ROOT WALL BELOW THE OSTIUM OF THE RIGHT CORONARY ARTERY". IN OTHER WORDS, THE TITANIUM FASTENERS WERE OBSERVED TO BE DIRECTLY IN CONTACT WITH THE AORTIC ROOT WALL. AS POINTED OUT IN THE COR-KNOT® INSTRUCTIONS FOR USE, EACH COR-KNOT® TITANIUM FASTENER AND ITS SUTURE TAILS SHOULD BE VISUALLY INSPECTED. SURGEONS ARE WARNED THAT "DIRECT CONTACT BETWEEN SENSITIVE TISSUE STRUCTURES (E.G., PULSATILE ARTERIES, CARDIAC VALVE LEAFLETS, VALVE CHORDAE, ETC.) AND FOREIGN MATERIALS CAN LEAD TO TISSUE INJURY OR DAMAGE, SUCH AS TISSUE EROSION. ALWAYS ORIENT COR-KNOT® FASTENERS AND REMNANT SUTURE TAILS TO AVOID DIRECT CONTACT BETWEEN DELICATE TISSUE OR PROSTHETIC STRUCTURES." AS WITH ANY DEVICE, THERE IS THE POTENTIAL TO INJURE TISSUE IF THE DEVICE IS BROUGHT INTO CONTACT WITH SENSITIVE TISSUE. THE COR-KNOT® DEVICE LABELING CLEARLY WARNS AGAINST DIRECT CONTACT BETWEEN THE TITANIUM FASTENERS AND SENSITIVE TISSUE STRUCTURE LIKE THE AORTIC WALL. HOWEVER, THE ISHIGAKI PAPER SHOWS THAT THE TITANIUM FASTENERS WERE PLACED IN A LOCATION WHICH DIRECTLY CONTACTS THE AORTIC WALL, AND AS A RESULT, THIS CONTACT APPEARS TO HAVE INJURED THE WALL. THIS IS A CLEAR USE ERROR THAT SHOULD NOT HAVE OCCURRED. WE DO NOT BELIEVE THAT IT IS NECESSARY TO ADD ANY FURTHER PRECAUTIONS. THE CURRENT PRECAUTIONS ARE VERY CLEAR AND ON-POINT FOR THE SITUATION REPORTED IN THE ISHIGAKI PAPER. THE AORTIC WALL PERFORATION REPORTED IN THE ISHIGAKI PAPER IS AN EXCEEDINGLY RARE EVENT THAT IS NOT THE RESULT OF A TECHNOLOGY OR DEVICE FAILURE. RATHER, IT IS LIKELY THE RESULT OF A SUBOPTIMAL USER TECHNIQUE IN DIRECT CONTRAINDICATION TO THE COR-KNOT® INSTRUCTIONS. MORE THAN 18,281,506 COR-KNOT® TITANIUM FASTENERS HAVE BEEN USED WORLDWIDE IN 1,129,603 CARDIAC SURGICAL CASES SINCE 2011. IN THAT TIME, THERE HAVE BEEN TWO REPORTS OF AORTIC WALL INJURY (THIS INCLUDES THE CURRENT REPORT AND A SEPARATELY REPORTED INJURY TO THE SINUS OF VALSALVA). THEREFORE, THE OCCURRENCE RATE OF COR-KNOT® PATIENTS WITH AN AORTIC WALL PERFORATION IS 0.00018% (= 2 ÷ 1,129,603) FOR CARDIAC SURGICAL CASES. AS AN ADDITIONAL POINT OF REFERENCE, ONE POSSIBLE COMPLICATION FROM CARDIAC VALVE REPLACEMENT SURGERY IS PARAVALVULAR LEAKING (PVL) CAUSED BY INSUFFICIENTLY TENSIONED HAND-TIED SUTURE KNOTS, WHICH ALLOW BLOOD TO PASS BETWEEN THE SEWING CUFF OF A PROSTHETIC VALVE AND THE NATIVE TISSUE WHERE THE PROSTHETIC VALVE IS SEATED. THE SURGICAL LITERATURE REPORTS THAT PVL OCCURS IN APPROXIMATELY 2-5% OF SURGICAL AORTIC VALVE REPLACEMENT (SAVR) CASES USING HAND-TIED KNOTS, AND WHEN IT OCCURS, A REDO OPERATION IS TYPICALLY NECESSARY. THIS >2% REDO RATE FOR PVL IS CONSIDERED ACCEPTABLE BY SURGEONS BECAUSE THE BENEFITS OF THE PROSTHETIC CARDIAC VALVE THAT IS REPLACING A DISEASED VALVE FAR OUTWEIGH THE RISK OF PVL. USE OF COR-KNOT® TITANIUM FASTENERS TO SECURE SUTURE INSTEAD OF HAND-TIED KNOTS ALSO ENABLES THE IMPLANTATION OF REPLACEMENT CARDIAC VALVES BUT BENEFICIALLY HAS BEEN SHOWN TO HAVE AN 82% REDUCTION IN RELATIVE RISK FOR PVL COMPARED TO HAND-TIED KNOTS, WHILE ALSO ENABLING LESS INVASIVE PROCEDURES. IN A PUBLICATION FROM LANKENAU MEDICAL CENTER IN PHILADELPHIA, "INCIDENCE, NATURAL HISTORY, AND FACTORS ASSOCIATED WITH PARAVALVULAR LEAK FOLLOWING SURGICAL AORTIC VALVE REPLACEMENT," THE AUTHORS ADDRESS THE RESULTS OF USING TITANIUM FASTENERS VS. HAND-TYING FOR SECURING AORTIC VALVES IN MINIMALLY INVASIVE AND OPEN SAVR DURING A 7 YEAR PERIOD. THEIR ANALYSIS DEMONSTRATES A REDUCED TREND OF LEAKAGE OVER TIME WHEN TITANIUM FASTENERS ARE EMPLOYED, RELATIVE TO THE USE OF HAND-TYING. (SEE FIG. 2 OF THE ATTACHED IMAGE PDF FILE). [PLACEHOLDER FOR FIG. 2 - COMPARISON OF CUMULATIVE INCIDENCES OF PVL BETWEEN COR-KNOT® AND HAND-TIED KNOTS. THE (B)(4) RATE OF PATIENTS EXPERIENCING AORTIC WALL PERFORATION ASSOCIATED WITH CARDIAC SURGICAL CASES PERFORMED WITH COR-KNOT® TITANIUM FASTENERS IS OVER 11,200 TIMES LESS LIKELY THAN THE ACCEPTED PVL RATE ASSOCIATED WITH THE USE OF HAND-TIED SUTURES. THEREFORE, THE RISK OF AORTIC WALL PERFORATION OCCURRING THROUGH THE INAPPROPRIATE USE OF THIS TECHNOLOGY IS ORDERS OF MAGNITUDES LESS THAN THE BENEFITS COR-KNOT® OFFERS PATIENTS AND SURGEONS. OUR DEVICE INSTRUCTIONS APPROPRIATELY ALERT SURGEONS THAT DIRECT CONTACT BETWEEN SENSITIVE TISSUE STRUCTURES AND FOREIGN MATERIALS CAN LEAD TO TISSUE INJURY OR DAMAGE, SUCH AS TISSUE EROSION. INCLUDING THE REPORTED EVENT, THERE HAVE BEEN ONLY TWO REPORTS OF AORTIC WALL PERFORATION COINCIDING WITH A SURGICAL CASE WHERE COR-KNOT® DEVICES WERE USED, OUT OF 1,129,603 CASES WORLDWIDE. THEREFORE, AS NOTED ABOVE, THE RATE OF OCCURRENCE PER PATIENT FOR AORTIC WALL PERFORATION ASSOCIATED WITH COR-KNOT® FASTENERS IS AN EXTREMELY RARE (B)(4)%. IMPORTANTLY, THE PATIENT WAS REPORTED TO HAVE RECOVERED UNEVENTFULLY. WE ARE GRATEFUL THAT THIS PATIENT'S OPERATION APPEARS TO HAVE BEEN HIGHLY SUCCESSFUL. THIS EXTREMELY RARE AORTIC WALL PERFORATION EXPERIENCED IN THIS UNFORTUNATE SITUATION IS ATTRIBUTABLE TO THE SURGICAL TECHNIQUE. THIS IS NOT A PRODUCT DESIGN OR MANUFACTURING FAILURE. CLOSER ADHERENCE TO THE INSTRUCTIONS FOR USE (IFU) MAY HAVE PREVENTED THIS AVOIDABLE OUTCOME.

Description of Event or Problem

NOTE: SINCE WE ARE UNABLE TO PASTE PHOTOGRAPHS OR CHARTS INTO THIS FORM, WE ARE ALSO ATTACHING A SEPARATE PDF DOCUMENT WITH THIS REPORT WHICH INCLUDES ANY FIGURES TO WHICH WE REFER IN THIS DOCUMENT. "INCIDENT REPORT IMAGES FOR MEDWATCH" TO VIEW THE ASSOCIATED FIGURES. ON 25 JUL 2025, DURING A ROUTINE POST MARKET SURVEILLANCE LITERATURE SEARCH, LSI IDENTIFIED AN ARTICLE ENTITLED, "COR-KNOT-INDUCED AORTIC ROOT INJURY DURING MINIMALLY INVASIVE AORTIC VALVE REPLACEMENT OF A BICUSPID AORTIC VALVE: A CASE REPORT", AUTHORED BY TAKAHIRO ISHIGAKI ET AL. FOR CONVENIENCE, WE WILL REFER TO THIS PAPER AS THE "ISHIGAKI PAPER". THE ISHIGAKI PAPER DOES NOT IDENTIFY A SPECIFIC DATE FOR THE REPORTED EVENT, HOWEVER, BASED ON THE AFFILIATIONS OF THE AUTHORS, WE BELIEVE THE EVENT TOOK PLACE IN JAPAN. THE PATIENT, A 72-YEAR-OLD MALE PRESENTED WITH EXERTIONAL DYSPNEA. HIS MEDICAL HISTORY IS REPORTED TO INCLUDE PLEURAL PLAQUES SECONDARY TO ASBESTOS EXPOSURE AND HYPERTENSION. TRANSTHORACIC ECHOCARDIOGRAPHY REVEALED A BICUSPID AORTIC VALVE WITH FUSION OF THE RIGHT AND NON-CORONARY CUSPS AND SEVERE AORTIC STENOSIS (VALVE AREA, 0.73 CM2; PEAK VELOCITY, 4.7 M/S; MEAN GRADIENT, 59 MMHG) WITHOUT AORTIC INSUFFICIENCY. THE LEFT VENTRICULAR FUNCTION WAS PRESERVED (LEFT VENTRICULAR EJECTION FRACTION, 67%), AND COMPUTED TOMOGRAPHY REVEALED A 31 MM × 25 MM AORTIC ANNULUS. THE AORTIC ROOT WAS DISTORTED (40 MM × 33 MM), AND THE SINOTUBULAR JUNCTION WAS 33 MM × 32 MM. THE PATIENT WAS REPORTED TO RECEIVE MINIMALLY INVASIVE AORTIC VALVE REPLACEMENT VIA RIGHT THORACOTOMY. CARDIOPULMONARY BYPASS WAS ESTABLISHED WITH FEMORAL ARTERY AND VENOUS CANNULATION. AFTER AORTIC CROSS-CLAMPING AND AORTOTOMY, THE CALCIFIED CUSPS WERE EXCISED, AND DECALCIFICATION OF THE ANNULUS WAS PERFORMED. A BIOPROSTHESIS WAS IMPLANTED IN THE SUPRA-ANNULAR POSITION USING A COR-KNOT® DEVICE. ALL OF THE COR-KNOT® TITANIUM FASTENERS WERE REPORTED AS IMPLANTED IN THE DIRECTION OF THE OUTSIDE OF THE PROSTHETIC VALVE. IT WAS FURTHER REPORTED THAT, AFTER AORTOTOMY CLOSURE AND AORTIC DE-CLAMPING, VIGOROUS BLEEDING FROM THE ANTERIOR ASPECT OF THE AORTIC ROOT WAS OBSERVED. THE PROCEDURE WAS CONVERTED TO A MEDIAN STERNOTOMY, RE-AORTIC CROSS-CLAMPING WAS PERFORMED, AND ACCESS TO THE AORTIC VALVE WAS REESTABLISHED. PUNCTATE INJURIES OF THE AORTIC ROOT WERE OBSERVED BELOW THE RIGHT CORONARY OSTIUM, CORRESPONDING TO THE LOCATION OF THE TITANIUM FASTENERS. FIG. 2 OF THE ISHIGAKI PAPER (SEE FIG. 1 OF THE ATTACHED IMAGE PDF FILE) IS DESCRIBED AS SHOWING THIS. [PLACEHOLDER FOR FIG. 1 - ISHIGAKI PAPER FIGURE 2. SEE ATTACHED IMAGE PDF FILE.] THE DEFECT IN THE AORTIC ROOT WALL WAS REPAIRED WITH AN AUTOLOGOUS PERICARDIAL PATCH. THE SAME BIOPROSTHETIC VALVE WAS IMPLANTED AGAIN AND HAND-TIED, AND THE AORTOTOMY WAS CLOSED. POSTOPERATIVE TRANSESOPHAGEAL ECHOCARDIOGRAPHY CONFIRMED THE ABSENCE OF AORTIC ROOT PSEUDOANEURYSMS AND PARAVALVULAR LEAKAGE. THE PATIENT WAS REPORTED TO RECOVER UNEVENTFULLY AND WAS DISCHARGED 20 DAYS POSTOPERATIVELY.