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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 allegation that the cor-knot® device did not perform its intended function of securing suture within the crimped titanium fastener.It is our understanding that neither the original cor-knot mini® device, the explanted titanium fasteners, nor the explanted valve are available for evaluation.It is also our understanding that intraoperative photos of the original prosthetic valve before it was explanted are unavailable.Despite the lack of access to devices for evaluation, we believe that some of the suture tails extending from the original titanium fasteners and the titanium fasteners were installed in an improper orientation, which allowed the suture tails extending from the titanium fasteners and possibly the fasteners themselves to come into contact with the delicate leaflets of the prosthetic valve when the leaflets opened during use.This repeated contact was likely the cause of the leaflet perforation.The leaflet perforation reported by the university of vermont medical center 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 our instructions and training, as well as the techniques supported by the vast related surgical literature.In our instructions for use, users of the cor-knot® devices and fasteners are directed to inspect the cor-knot® fastener and suture tails to ensure they are orientated away from delicate tissue and prosthetic structures.As previously noted above, the instructions for use also warn 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." (b)(4).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 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 fasteners are employed, relative to the use of hand-tying.(b)(4).Furthermore, several of the 13 reported cases of leaflet perforation have been written up in the medical literature, and the overwhelming conclusions are that these rare instances of leaflet perforation are associated with suboptimal technique.For example: valvular regurgitation after implantation of prostheses secured with cor-knot automated fasteners, brescia aa, bolling sf, patel hj.{ann thorac surg.June 2017;103(6):e491-e492.Available online 26 november 2016}: "valvular regurgitation is a recognized complication of aortic and mitral valve procedures.The primary mechanism of recurrent aortic insufficiency after aortic valve replacement is paravalvular leak, whereas transvalvular leak occurs less commonly.Recurrent mitral regurgitation (mr) is an important indication for a redo mitral valve operation"."the cor-knot (lsi solutions, victor, ny) automated fastener has been increasingly used for aortic and mitral valve operations.This device has been shown to be a safe, viable alternative to knot-pusher instruments and manual knot tying, with one series of minimally invasive mitral repairs showing significant time saved in cardioplegic arrest and cardiopulmonary bypass with its use" "in the 2 patients described in this case report, the leaflet defects appeared to be directly caused by continuous trauma from leaflet motion against suboptimally placed cor-knot fasteners." "the first patient described in this report" {re-do avr / mitral & tricuspid repair} "particularly suggests that this complication can arise from intraannular orientation of an aortic valve and use of the cor-knot device, particularly if the placed fastener is oriented toward the centerline of flow." "we have used this device liberally at our institution, but choose to place aortic valves in a supraannular position and have not seen this complication." "the second patient described here {re-do mitral repair, tricuspid annuloplasty dehiscence repair, asd closure} demonstrates that even mitral valve repair with the cor-knot can result in leaflet damage from the fasteners, particularly if care is not taken to orient the fasteners toward the outer edge of the annuloplasty ring and not obliquely towards the posterior leaflet." leaflet perforation by cor-knot automated fasteners: more usual than you think, to the editor:, biefer hrc, weber a, maisano f, benussi s.{ann thorac surg.February 2018;105(2):664-665.Available online 20 january 2018}."at our institution, the use of the cor-knot is standard in minimally invasive mitral valve reconstruction for more than 2 years now, in over 120 patients.Although it is uncommon, we have also observed at least 2 patients in whom a perforation of the anterior leaflet by cor-knots led to moderate to severe mitral valve insufficiency[?] since the occurrence of these adverse events, we have changed our practice regarding the use of cor-knots.First, we ensure a proper atrial orientation of the cor-knots, and thus away from the leaflets, during deployment.Second, the use of cor-knots is exclusively for rigid mitral rings.After applying these changes, we have not seen any more adverse events." reply to the editor:, brescia aa, bolling sf, patel hj.{ann thorac surg.February 2018;105(2):665.Available online 20 january 2018}."we regularly use flexible, semirigid, and rigid incomplete and complete rings during our mitral operations, and we do not believe that the choice of ring should affect the propensity for cor-knot fasteners to result in perforation.We have not observed a single case of this rare adverse event of leaflet perforation over hundreds of minimally invasive and redo mitral and tricuspid annuloplasty operations.We believe that a wide variety of rings can be used with the cor-knot device and that the key to avoiding this adverse event remains devoting special consideration to needle angles and angulating the fasteners optimally.This rare adverse event is not a surgical device difficulty but rather a surgical technique problem." cor-knot perforation of aortic valve leaflet, to the editor:, baciewicz fa.{ann thorac surg.September 2018;106(3):936-937.Available online 12 may 2018} "i have used cor-knot on both aortic and mitral valve replacements performed via a median sternotomy technique for the last 4 years." with one "patient who developed moderate aortic insufficiency" requiring a "re-do procedure.The leaflet perforation was felt to be secondary to a medially directed cor-knot.Since this single experience with the aortic valve, i have been careful to have the cor-knot deployment device oriented with the fastener away from the prosthesis.I have not seen another occurrence since being meticulous with cor-knot device orientation." "this letter is to alert the readership to the need for meticulous technique in using this device, particularly in a narrow aortic root with small prosthesis size." reply to the editor:, brescia aa, bolling sf, patel hj.{ann thorac surg.September 2018;106(3):937.Available online 12 may 2018}."we agree with dr baciewicz that surgical technique remains paramount to successful use of cor-knot fasteners, regardless of the type of utilized valve prosthesis or annuloplasty ring.As suggested in our initial article and in our reply to our colleagues from zurich, special attention to needle angles, optimal angulation of cor-knot fasteners away from the centerline of flow, and supraannular rather than intraannular positioning of the aortic prosthesis remain important in avoiding aortic valve leaflet perforation.We continue to use the cor-knot device in most of our valve procedures and, as with dr baciewicz, believe that this complication remains exceedingly rare but requires thoughtful consideration of surgical technique." cor-knot perforation of aortic valve leaflet, to the editor, balan r, mogilansky c, larsen al, massoudy p.{interact cardiovasc thorac surg.July 2017;25:153-154.Available online 31 march 2017}."we report the case of severe aortic regurgitation 8 months after implantation of a 25-mm sutureless pericardial aortic valve prosthesis." "on examination of the explanted valve prosthesis, a perforation was observed in one of the leaflets.The leaflet perforation was in alignment with one of the knots produced by the automatic knot fastener.Obviously, the leaflet had hit the knot repeatedly which had caused the perforation.Leaflet perforation has been reported in the context of suture tails after manual tying.Thus, the orientation of the {titanium} knot must certainly not be towards a neighbouring leaflet." the instructions for use provided with the cor-knot® devices and fasteners clearly instruct the user to ensure the titanium fasteners are not oriented towards sensitive tissue structures such as leaflets.Leaflet perforation has an extremely low occurrence rate in cardiac surgical cases where cor-knot® fasteners are used.The substantive relevant literature from high-impact journals shows that the medical community recognizes that surgeons should be paying attention to fastener orientation relative to sensitive tissue structures and confirms that this is a rare event.We are grateful that this patient's reoperation appears highly successful.Bioprosthetic leaflet erosion from moving leaflets contacting suture tails is a known complication in valve replacement surgery.The extremely rare leaflet 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.
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