Feasibility of concomitant exclusion of left atrial appendage during novel transapical off-pump beating heart mitral valve repair

This series retrospectively reviewed the first seven patients who underwent mitral valve repair with NeoChord DS 1000 Artificial Chordae Delivery System (NeoChord, Inc., St. Louis Park, MN) with concomitant LAA closure with AtriClip (AtriCure, Mason, OH, USA). The study was approved on 18/7/2018 by the local ethics committee (No. UW 18-337), and written consent for the combined procedure was obtained from all patients.

Patient selection

All the patients referred for mitral valve surgery were screened according to their clinical and echocardiogram data. Patients who were potential candidates for off-pump beating heart mitral valve repair underwent a preoperative TEE to assess their suitability for NeoChord repair. All the patients had a guideline-based indication for surgical correction of mitral regurgitation (MR) [8].

The morphology of the mitral valve was assessed by TEE prior to surgery, according to the methodology reported previously [9]. The length of the leaflets and the annulus diameter were measured in two (2D) and three dimensional (3D) views of the prolapsing segments. According to the mitral valve morphology, anatomical types were defined as previously described: ‘Type A’, isolated central posterior leaflet prolapse/flail; ‘Type B’, posterior multisegment prolapse/flail and ‘Type C’, anterior, bileaflet or paracommissural disease with or without leaflet and annular calcifications [10].

Apart from the area of prolapse, the leaflet-to-annulus ratio or index (LTI) was used to predict procedural success. LTI is defined as the ratio between the sum of anterior and posterior leaflet lengths over antero-posterior length, and if greater than 1.2, the coaptation is expected to be adequate after correction of the prolapse by the NeoChord repair [11].

Even though the selection criteria for NeoChord repair were mainly based on the presence of favourable anatomy, it was reserved for older and higher-risk patients due to the lack of long-term results.

Patients were excluded from the study if they had previously undergone mitral valve surgery or any other cardiac procedures within the previous three months, were in an emergency situation or failed to provide informed consent.

After the patient agreed to the NeoChord procedure, those diagnosed with paroxysmal AF or persistent AF were offered the option of concomitant LAA closure. During the discussion, they were informed that the concomitant procedure would only be carried out if the intra-operative TEE revealed no left atrial clot, an exclusion criterion for the LAA closure procedure.

Operative technique

The NeoChord repair was performed as described previously [12,13,14]. Briefly, the patient was put under general anaesthesia and intubated with a single-lumen endotracheal tube without lung isolation and monitored as usual. A perfusionist with a primed cardiopulmonary circuit was on standby in the operating room. Before draping, hand-held transthoracic echocardiography was used to determine the location of the apex, and a 3 to 5 cm left thoracotomy incision was made. The pericardium was then opened, and a soft tissue retractor was inserted directly into the pericardium as a wound retractor, eliminating the need for rib-spreading. The apical entry site was identified by digital palpation and TEE, posterior and lateral to the true apex (Fig. 1). Heparin was given to achieve an activated clotting time of 250 s. Two ‘U’ purse-string sutures with 2/0 Prolene (Ethicon, Somerville, NJ, USA) pledgets were applied at the entry site. The NeoChord DS 1000 system was prepared and introduced into the left ventricular cavity of the beating heart. Under real-time 2D/3D TEE guidance, jaws of the NeoChord system were opened, the prolapsing leaflet segment was grasped, and Gore-Tex CV-4 neochordae (Gore-Tex; W.L. Gore & Associates Inc., Flagstaff, AZ, USA) were implanted on it. The procedure was repeated until a sufficient number of neochordae had been implanted to support the prolapsing segment. We aimed to achieve ‘over-correction’; usually, a trivial to mild residual posterior directing MR would be left. Procedural success was defined as less than moderate MR at the end of the procedure.

Fig. 1figure 1

NeoChord procedure. A TEE finger test. X-plane image of left ventricle showing finger probing (red arrows) postero-lateral to the true apex; B purse-string sutures at the entry site; C blue arrow showing completed NeoChord procedure with 3 fixed artificial chordae at the entry site. Red arrow showing camera port inserted at 3rd intercostal space, anterior axillary line; D TEE X-plane assessment of mitral valve showing no prolapse and residual mitral regurgitation

The LAA was managed once the NeoChord procedure was completed and the apical entrance site was closed. A 5 mm port was inserted in the 3rd intercostal space near the anterior axillary line (Fig. 2) directly through the chest wall and pericardium during temporary respiratory apnea of about 5 s. The superior margin of LAA was identified using a 30-degree endoscope passed through this port. The AtriClip device was inserted through the pre-existing left thoracotomy wound (Fig. 3). The base of LAA was visualized and measured using an AtriClip sizer to select the appropriate device length (35, 40, 45 or 50 mm). The AtriClip Pro 1 clip was utilized in the first two cases, while the rest of the patients received the AtriClip Pro 2 clip. By adjusting the device knobs and utilizing minimally invasive instruments, the clip was put near the base of LAA. After the clip was temporarily clamped, TEE and endoscopic assessment were used to confirm its proper placement, which was defined by previous reports as a residual stump of less than 10 mm and the absence of flow between the left atrium and the LAA with color Doppler [4]. If not, the clip was opened and repositioned. Once the satisfactory position was achieved, the clip was released. The deploying system was withdrawn, and the minithoracotomy was closed in a routine fashion.

Fig. 2figure 2

Setup of left atrial appendage closure. A Atricure Pro 2 clip-direction adjusted according to the LAA before insertion; B the clip inserted through the thoracotomy wound (red arrow) used for the NeoChord procedure; C the camera port used for chest tube insertion after the procedure

Fig. 3figure 3

AtriClip closure of the left atrial appendage. A Sizing of LAA; B application of LAA clip; C AtriClip deployed; D TEE assessment of the LAA: blue arrows—TEE X-plane images of LAA before closure, orange arrows-TEE X-plane images showing closed LAA and red bracket-assessment of the residual stump length

All patients were monitored in the intensive care unit on the first post-operative day. They were discharged after the removal of the chest tube and echocardiogram.

At 6 months, 1-year, and 2-year post-procedure, all patients had routine clinical follow-ups, and echocardiography was performed to assess the mitral valve. TEE assessment of the LAA status was usually not done until three months after the surgery. However, due to COVID-19, it was further delayed for some patients.

Statistical analysis

Demographic categorical variables were expressed as percentages, while quantitative variables were expressed as the median and interquartile range (IQR) or mean ± SD (minimum and maximum). SPSS statistical software was used for this purpose (IBM SPSS Statistics, version 24.0. Armonk, NY, USA).

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