Abstract
The COR-KNOT suture fastening device has dramatically improved the efficiency of valve suture fixation. Despite its relative ease of use, there are important considerations in deployment to limit the risk of prosthetic valve injury. Herein, we report a case of iatrogenic aortic bioprosthetic insufficiency caused by poorly positioned COR-KNOTs and outline technical strategies to ensure success.
Keywords: Valve replacement, COR-KNOT, Sutures, Aortic valve, Case report
Case report
The COR-KNOT (LSI Solutions, Victor, NY, USA) is an automated suture fastening system that, with a squeeze of the device, crimps a metal fastener to secure and then trim sutures. It is designed to expedite suture fixation of valves and reduce operative time, particularly in minimally invasive surgery where the limited working space can make knot-tying challenging. The ease of this device, however, cannot be taken for granted. If the metal fasteners are improperly oriented, they may damage valve leaflets. Herein, we report a case of re-operative aortic valve replacement due to severe aortic insufficiency from multiple presumed COR-KNOT-induced leaflet injuries.
The patient was a 64-year-old with hypertension, hyperlipidemia, type 2 diabetes (hemoglobin A1c 7.1%), heart failure with reduced ejection fraction (ejection fraction 40%), coronary artery disease (multiple angioplasties without stenting), and bicuspid aortic stenosis who underwent a prior tissue aortic valve replacement (27-mm Carpentier-Edwards) and ascending aortic replacement (30-mm graft) at an outside hospital in 2018. Though asymptomatic on follow-up, echocardiography revealed severe eccentric aortic insufficiency, paravalvular leak (PVL), a left ventricular end-diastolic diameter of 5.8 cm, and an ejection fraction of 32%. Cardiac catheterization also showed a mid-left anterior descending coronary lesion. Therefore, re-operative aortic valve replacement and coronary artery bypass grafting were planned.
He underwent an uneventful re-operative sternotomy and left internal mammary artery (LIMA) harvest. The heart was dissected out and central cannulation was performed. A retrograde cardioplegia cannula was inserted into the coronary sinus and, upon aortic cross-clamping, retrograde cardioplegia was given and a left ventricular vent was inserted into the superior pulmonary vein. The aorta was opened and ostial cardioplegia was given down the right and left coronary ostia.
The LIMA was grafted to the left anterior descending artery, and attention returned to the aortic valve. Upon inspection, there appeared to be 3 distinct holes—1 in the center of the right sinus leaflet and 2 in the non-coronary sinus leaflet (Fig. 1). Immediately adjacent to each of these holes was a COR-KNOT that was inwardly bent, such that when the leaflets extended to the open position, those corresponding COR-KNOTs were located exactly adjacent to the holes (Supplementary Video 1). We surmised that the inward orientation of these core-knots caused friction-induced holes to form on the non-calcified leaflets. The site of PVL was also identified at the level of the left coronary ostia.
Fig. 1.
Intraoperative pictures showing COR-KNOT-induced leaflet perforations. (A) Perforation of the right leaflet. Arrow marks COR-KNOT. (B) Two perforations in the non-coronary leaflet. (C) Explanted valve demonstrating perforations (circled). R, right sinus; L, left sinus; N, non- coronary sinus.
The valve and pledgets were explanted and a 29-mm Inspiris valve (Edwards Lifesciences, Irvine, CA, USA) was seated and secured with COR-KNOTs, remaining vigilant to ensure that their orientation was perpendicular to the annulus. The aorta was closed in 2 layers. After confirmation of good valvular function with absence of PVL, the patient was weaned from cardiopulmonary bypass, hemostasis was achieved, and the patient was closed and transported to the intensive care unit in stable condition.
The patient provided written informed consent for publication of the case details and clinical images.
Discussion
The COR-KNOT device has revolutionized efficiency in cardiac surgery. Valves can be seated more quickly, reducing the cross-clamp time, and perhaps more securely in minimally invasive surgery where knot tying in deep holes can be cumbersome [1].
Several case studies have reported late-stage leaflet perforation resulting in severe aortic insufficiency with the COR-KNOT device [2-4]. In all these reports, there appeared to be a medially directed COR-KNOT, which, through presumed constant abrasion on the leaflet, led to eventual perforation.
We have used the COR-KNOT in thousands of valve operations, including both rigid and flexible mitral annuloplasty rings, without any reports of leaflet perforation. We believe that this complication can be prevented by meticulous attention to several steps when firing the device. Specifically, the 3 most important tenets are: (1) Ensuring that the device is secured on the outer ring of the valve. The Inspiris valve, for example, has an inner ring that supports the valve leaflets, and an outer ring for the aortic sewing cuff. (2) Holding the device perpendicular to the annulus, and remaining conscientious to never cant the device inwards, which would result in a medially directed fastener. (3) Holding tension on the sutures and the thumb plate of the device for 3 seconds before firing the device. This ensures the fastener has adequate time to seat and properly engage at the base of the outer sewing ring and prevents a loose COR-KNOT from interacting with a leaflet.
Finally, in the current case, the originally implanted valve appeared undersized, which resulted in a more intra-annular position (and may have contributed to PVL as well). With an undersized valve, the COR-KNOT may also tend to face inwards. We believe that by following these 3 steps, the issue of COR-KNOT-induced leaflet perforation can all but be eliminated.
Supplementary materials
Supplementary materials can be found via https://doi.org/10.5090/jcs.23.076. Supplementary Video 1. Intraoperative inspection of damaged prosthesis leaflets.
Funding Statement
Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Article information
Author contributions
Conceptualization: all authors. Project administration: all authors. Writing–original draft: MS. Final approval of the manuscript: all authors.
Conflict of interest
No potential conflict of interest relevant to this article was reported.
References
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