Acute Mitral Regurgitation Following Minimally Invasive Aortic Valve Replacement

Dear Editor, We report a case of iatrogenic, acute mitral regurgitation (MR) caused by leaflet perforation during minimally invasive aortic valve replacement (AVR) surgery. The case described highlights the importance of comprehensive transesophageal echocardiographic (TEE) examination while coming off from cardiopulmonary bypass (CPB). A 49-year-old patient with a thick, calcified, bicuspid aortic valve, severe aortic stenosis (aortic valve area: 0.56 cm2, mean pressure gradient: 47 mmHg), and mild aortic regurgitation was admitted for AVR. There was no other valvular or cardiac abnormality [Video 1]. After debridement of the calcium specks and excision of the native aortic valve, AVR (21-mm SJM, Masters Series, Abbott Cardiovascular, MN) was performed via J-shaped hemisternotomy. Left ventricular vent was placed through the right superior pulmonary vein. While weaning from CPB, a posteriorly directed jet of severe MR was noticed on intraoperative TEE. A perforation measuring 3 mm was seen in the anterior mitral leaflet (AML) on two-dimensional TEE [Figure 1a and b]. Its exact location, near the base of the A1 scallop of AML, was aided by three-dimensional TEE [Figure 1c and Video 2]. The TEE findings were conveyed to the operating team, and the decision to repair the mitral valve by full sternotomy and reinstitution of CPB was taken. The perforation in the AML was closed by direct suture, followed by smooth weaning from CPB with no MR on TEE evaluation [Figure 1d]. {"href":"Single Video Player","role":"media-player-id","content-type":"play-in-place","position":"float","orientation":"portrait","label":"Video 1.","caption":"","object-id":[{"pub-id-type":"doi","id":""},{"pub-id-type":"other","content-type":"media-stream-id","id":"1_0tjr0clf"},{"pub-id-type":"other","content-type":"media-source","id":"Kaltura"}]} Figure 1: Transesophageal echocardiography (TEE) showing leaflet perforation (arrow) causing severe mitral regurgitation in mid-esophageal four-chamber view (a) and mitral commissural view (b). Three-dimensional TEE en-face view of the mitral valve showing perforation (arrow, c). Post-bypass TEE image showing absence of mitral regurgitation (d) {"href":"Single Video Player","role":"media-player-id","content-type":"play-in-place","position":"float","orientation":"portrait","label":"Video 2.","caption":"","object-id":[{"pub-id-type":"doi","id":""},{"pub-id-type":"other","content-type":"media-stream-id","id":"1_eyxzlxez"},{"pub-id-type":"other","content-type":"media-source","id":"Kaltura"}]} The prevalence of new or worsened MR after surgical AVR reported by a systemic review is 8.4%.[1] Furthermore, 16% of new MR occur from an organic etiology, while 83% of cases have a functional etiology, with no mortality. Acute MR following AVR can result from perforation or tear caused by injury to the AML, injury to the subvalvular apparatus caused by left ventricular vent, peri-annular suture-induced AML restriction, papillary muscle dysfunction, systolic anterior motion of the mitral valve, or myocardial ischemia produced by inadequate myocardial protection. Perforation of the leaflet is the most common cause of acute MR in patients undergoing AVR. Similar findings of AML perforation causing acute MR following AVR have been reported by Van Dyck et al. and a few other authors.[2-4] Anatomically, the AML is in fibrous continuity with the aortic valve through the aortomitral curtain, with the potential of causing injury to one valve during surgery for the other. The specks of calcification found on the aortic valve may extend up to AML. The perforation can result from the avulsion of calcified specks on the AML while the heavily calcified native aortic valve is removed. Another mechanism could be an injury to the AML caused by forceps or needle while removing calcium from the aortic valve. Intraoperative TEE is helpful not only for the diagnosis of perforation but also for assessing the mechanism of MR, severity of MR, and localization of the site of perforation. Absence of TEE, in this case, could have resulted in a return to the operating room for reoperation or the need for another intervention (transcatheter or surgical) at a later stage. The risk of developing MR after minimally invasive AVR is higher due to suboptimal myocardial preservation caused by lack of retrograde cardioplegia delivery, inability to use topical hypothermia, inadequate de-airing of the left ventricle, and coronary air-embolism. Geometric changes in the mitral valve anatomy imposed by an aortic valve prosthesis can also cause worsening of MR.[5] Displacement of the anterior mitral annulus toward the aorta by the prosthetic aortic valve can lead to increased tethering forces to the AML, causing severe MR. There are no guidelines for percutaneous closure of AML perforation; however, it should be reserved for high-risk surgical patients.[6] In conclusion, the case described highlights the importance of intraoperative TEE for the evaluation of new-onset severe MR following minimally invasive AVR, mechanism of MR, and for guiding the management plan. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.