Balloon-Expandable Transcatheter Mitral Valve Replacement Through Minimally Invasive Approach in Big MAC

Severe mitral annulus calcification (MAC) is associated with increased cardiovascular morbidity and mortality in patients undergoing mitral valve replacement. It poses a significant challenge for even the most experienced surgeons, and multiple techniques have been proposed to address this challenging problem. In high-risk patients, an alternative to conventional surgical techniques involves the placement of a balloon-expandable transcatheter valve either through a transapical, transseptal, or open surgical approach.

Hybrid mitral valve surgery has emerged as a treatment option for mitral valve disease in patients unsuitable for standard mitral valve surgery. This report describes a versatile approach to a very complex condition using SAPIEN 3 aortic valves with surrounding bovine pericardial patch placed in the mitral position inserted through a minimally invasive approach.

Introduction

Carpentier and Cols. have developed surgical techniques for patients with big MAC, (1) which affects between 8% and 15% of patients with mitral stenosis and increases with age, cardiovascular risk factors, and severe renal impairment. (2)

The first transcatheter mitral replacement (TCMR) in humans was reported in 2013 with the use of a transapical approach (3). Since then, different surgical approaches have aimed to decrease the rates of complications associated with severe MAC, such as cardiac rupture at the atrioventricular junction, injury to the circumflex artery, calcium embolism, and rupture of the left ventricular free wall. Additionally, surgeons have a further challenge: significant calcification makes debridement and placement of transannular sutures very difficult. Extensive removal of MAC usually requires repair with an atrial sliding plasty or pericardial patch reconstruction, with a subsequent high-risk mortality rate.

The goal of hybrid mitral procedures is to reduce complications and shorten the surgical duration. Patients previously considered nonsurgical candidates due to severe MAC and high surgical risk are now potential candidates for a hybrid procedure using this innovative surgical technique. 

Case Presentation

A 75-year-old woman with worsening dyspnea (NYHA III-IV), congestive heart failure, and very limited ambulatory capacity was assisted at the authors’ center.

The patient’s medical history included hyperlipidemia, hypertension, obesity (weight: 90 kg; height: 160 cm), coronary disease with stent placed in the right coronary artery one month before, and COPD. Echocardiography showed severe mitral valve stenosis (area: 1.2 cm2, and mean gradient: 7 mm Hg) and moderate mitral valve regurgitation with a severe mitral annular calcification (MAC). A CT scan confirmed echocardiographic findings. The coronary calcium score was 2,117 (Agatston score). In the cath lab, there were no additional findings except for the big MAC.

Surgical Technique

A right anterior minithoracotomy was performed in the 4th-5th intercostal space (ICS). Two accessory ports (5 mm) were used to insert the Chitwood aortic clamp (right 3rd ICS, midaxillary line) and video camera (right 4th ICS). A Mohr atrial retractor (Geister™), long-shafted instruments for mini-invasive surgery (Geister™) and long-shafted knotters were used. A Storz™ video camera with a mechanical arm was used. Long arterial and venous cannulas (Edwards™ or Medtronic™) for CPB management were inserted through a minimal incision (3-4 mm) in both femoral arteries and right femoral vein the position was guided and controlled by transesophageal echocardiography (TEE). A single dose of 2,000 ml Bretschneider™ cardioplegic solution was used. 

A valve analysis revealed a severe big MAC, with severe calcification of the anterior and posterior annulus and extended toward the subvalvular apparatus. Partial resection of anterior leaflet and subvalvular apparatus was performed to facilitate prosthetic anchoring. In addition, 13 pledgeted sutures were placed along the annulus, given the paramount importance of placing the highest possible number of annulus stitches. A balloon Balt 25x45mm (Crystal Balt®) was used to measure the annulus area. 

The percutaneous valve, Edwards SAPIEN 3 valve number 29 (Edwards Life-sciences, Irvine, California), was chosen and prepared with an improvised circumferential bovine pericardial patch. At a later stage, the patch was attached to the valve stent with a 5.0 polypropylene suture. The valve was crimped following standard techniques and then deployed with the standard balloon-expandable technique guide with direct-vision. Subsequently, sutures were passed through the pericardial patch to secure the valve and prevent paravalvular leak, using automated suture fastening system (COR-NOT® device). Lastly, the attachment of the pericardial patch within the atrium was performed with a circumferential running suture with a 5.0 polypropylene suture. Intraoperative transesophageal echocardiography off CPB revealed a mild perivalvular leak on P2-P3 position and no left ventricular tract obstruction.

Discussion

When compared to minimally invasive surgery (MICS), under certain circumstances hybrid surgery may have advantages. For instance, patients that have contraindications to transseptal approaches can undergo hybrid mitral surgery (4). Such contraindications may include calcification of the subvalvular apparatus, noncircumferential annular calcification, coronary artery disease, concomitant multivalvular disease, and/or left ventricular outflow tract obstruction (LVOTO). In such cases, a hybrid procedure may be a valid alternative.

Big MAC is considered a relative/absolute contraindication for minimally invasive approaches; however, when a sutureless valve is available, and in order to avoid decalcifying the annulus, the MICS approach could be feasible. Despite this, even surgeons with vast experience may find the level of difficulty for MAC to be noticeable. In order to tackle this issue, different approaches have been attempted, which include autologous or xenograft patch plasty, novel atrial sliding plasties, and anterior leaflet transposition, although these options may have downsides that entail risks (3). First of all, the aforementioned options can imply calcium embolization, atrioventricular dissociation, and circumflex artery injury (5). Furthermore, such approaches demand a considerable amount of time for myocardial ischemic and cardiopulmonary bypass. The use of a sutureless valve and automated sutures for the few annulus stitches can reduce operative times.

In this surgery, there were limited options. As a result of this, to minimize paravalvular leak and to prevent valve migration, the authors performed a direct-vision deployment of a Sapien 3 valve surrounded by an improvised bovine pericardial patch (6). Considering the above and the current knowledge, until specialized transcatheter mitral valve devices become available in their country, the approach used by their center could prove to be a valid option for surgeons and interventional cardiologists.

References 

1. Carpentier AF, Pellerin M, Fuzellier JF, Relland JY. Exntensive calcification of the mitral valve annulus: Pathology and surgical management. J Thorac Cardiovasc Surg. 1996:718-729.
2. Abramowitz Y, Jilaihawi H, Chakravarty T, Mack MJ, Makkar RR. Mitral annulus calcification J Am Coll Cardiol. 2015;66:1934-1941.
3. Marcus S, Mahadevan V, Deuse T. Hybrid open minimally invasive transcatheter mitral valve replacement. Ann Thorac Surg. 2018;106:e57-59.
4. Castillo JG, Tang GHL, Adams DH, El-Eshmawi A. Hybrid mitral valve replacement: a heart team approach to severe mitral annular calcification. J Am Coll Cardiol Case Rep. 2019;1:495–499. 
5. Fortunato G, Misfeld M, Battellini B, Garbade J, Borger MA, Kotowicz V. Situation awareness for circumflex artery injury during mitral valve surgery. Ann Thorac Surg. 2019;108:e329–332
6. Lee R, Fukuhara S, George I, Borger MA. Mitral valve replacement with a transcatheter valve in the setting of severe mitral annular calcification. J Thorac Cardiovasc Surg. 2016;151:e47–49.

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