Calcification of the mitral valve (MV) and its annulus is increasingly prevalent as the life expectancy of dialysis patients rises. Mitral valve replacement (MVR) surgery for mitral annular calcification (MAC) has been documented, with a range of emerging surgical techniques. In this report, we present a case of extremely severe MAC, in which MVR was successfully performed using a mechanical valve.

A 61-year-old man had been receiving hemodialysis for 20 years due to end-stage renal dysfunction secondary to nephrosclerosis. His primary medical history included Y-shaped vascular graft replacement surgery to address lower limb arteriosclerosis obliterans resulting from abdominal aortic occlusion. For the past 3 months, the patient had been experiencing exertional chest pain. Echocardiography revealed severe mitral stenosis and regurgitation around the entire mitral annulus, necessitating surgical intervention. Echocardiographic findings, as depicted in Fig. 1A and B, included a left ventricular end-diastolic/end-systolic diameter of 50/43 mm, a left atrial dimension of 44 mm, a left ventricular ejection fraction of 34%, an MV area of 1.19 cm2, a mean MV pressure gradient of 12 mm Hg, and a maximum MV velocity of 2.9 m/sec. Additionally, left ventriculography confirmed the severity of mitral regurgitation, which was graded according to the Sellers classification (Fig. 1C). Three-dimensional computed tomography demonstrated extensive calcification around the MV annulus and within the left ventricular myocardium (Fig. 2).

Figure 1. Preoperative echocardiography and left ventriculography. Mitral regurgitation is directed toward the anterior wall of the left atrium (LA) (A), along with a mosaic flow velocity in the mitral valve during diastole (B). A left ventriculogram reveals mitral regurgitation classified as grade III according to the Seller criteria (C). LV, left ventricular.

Figure 2. Preoperative 3-dimensional computed tomography. Computed tomography revealed severe circumferential calcification of the mitral valve annulus and extensive calcification of the left ventricular (LV) myocardium. (A) Anterior view. (B) Posterior view. AscAo, ascending aorta.

Surgery was performed via a median sternotomy, with access to the MV achieved through the left atrium (LA) on the right side. The MV leaflets exhibited mild calcification, while severe, connected calcifications extended from the mitral annulus through the chordae to the papillary muscle (Fig. 3A, Supplementary Video 1). The anterior and posterior leaflets were excised 2 mm from the annulus. Calcification at the posterior leaflet annulus was fragmented and removed using a Sonopet ultrasonic aspirator (Stryker, Kalamazoo, MI, USA), ensuring enough clearance for the prosthetic valve to pass through the annulus (Fig. 3B, Supplementary Video 1). Three mattress sutures with pledgets were placed on the posterior leaflet annulus using 2-0 Ethibond Excel suture, and 13 interrupted sutures without pledgets were placed on the annulus of the opposing leaflet. These sutures were then threaded through a 23-mm St. Jude Medical valve (St. Jude Medical Inc., St. Paul, MN, USA) and ligated to secure the MVR (Fig. 3C, Supplementary Video 1). The area of regurgitation around the valve identified during the testing phase was addressed by suturing the left atrial wall to the sewing cuff of the valve, effectively controlling the regurgitation. Additionally, the entrance to the left atrial appendage was sealed from within the LA.

Figure 3. Surgical findings (surgeon’s view). The mitral valve annulus, chordae tendineae, and calcified tissue of the papillary muscles (A) and (B) were excised, and mitral valve replacement was performed on the mitral valve annulus. (C) Regurgitation originating from the posterior leaflet annulus was managed by suturing the atrial wall to the prosthetic valve (white lines). (D) Postoperative echocardiography revealed minimal mitral regurgitation. Additionally, the mechanical valve demonstrated satisfactory movement. Written informed consent for the publication of this image was obtained from the patient. LV, left ventricular; LA, left atrium.

On the first postoperative day, the patient was successfully weaned from the ventilator and underwent continuous hemodiafiltration. On the fourth postoperative day, hemodialysis was administered, and the patient was discharged from the intensive care unit. Postoperative cardiac echocardiography revealed minimal mitral regurgitation (Fig. 3D). Atrial fibrillation persisted from postoperative day 5 to 12 but spontaneously converted to sinus rhythm. The patient’s steady advancement in rehabilitation therapy, coupled with stable hemodialysis, facilitated discharge on postoperative day 22.

The patient provided informed consent for the publication of the case report and accompanying images.

MVR associated with MAC presents serious challenges and is associated with a high risk of surgical complications. These complications include myocardial rupture, injury to the left circumflex coronary artery, residual perivalvular leak (PVL), thromboembolic events, and an early mortality rate ranging from 9% to 28% [1]. In patients on dialysis, the extent of calcification in the MV is typically very pronounced, necessitating careful consideration of surgical strategy.

For the surgical procedure, we utilized the Sonopet ultrasonic aspirator, a device well-established for decalcification around calcified areas [2]. We selected the St. Jude Medical artificial valve because its leaflets do not protrude into the ventricular side as much as those of other artificial valves, reducing the likelihood of interference with the calcified tissue [3]. Minimizing decalcification is crucial to prevent the risk of left ventricular rupture and postoperative complications [4]. However, it is necessary to remove enough MAC to allow the artificial valve to pass through the mitral annulus. Decalcification of the annulus was limited to the extent necessary for the insertion of the needle thread required to sew the prosthetic valve. We considered applying a pericardial patch to the calcified area of the annulus [5], but the extensive calcification of the entire annulus made it technically challenging to secure an insertion site for the needle thread to attach the patch. As the degree of calcification from the chordae tendineae to the papillary muscles resembled that of the annulus, it was not feasible to perform minimal annular decalcification and insert the needle thread from a deep position from the left ventricular side to the LA side, as previously reported [6]. We also considered suturing an artificial valve with the LA serving as the annulus, as in the chimney method [7-9]. However, this approach has been associated with substantial long-term PVL [10]. In our patient, we verified that the artificial valve could pass adequately through the original annulus. Consequently, we proceeded with this approach and were able to assess potential PVL using a regurgitation test, subsequently suppressing it by sewing the cuff of the valve onto the atrial wall. We believe this technique is beneficial; however, it is essential to avoid damaging the conduction system, aortic valve, or coronary artery, depending on the location of the leak. In conclusion, we successfully performed MVR with a mechanical valve in a high-risk case involving extensive MAC. Our approach involved using a valve that minimized PVL, thereby reducing the need for extensive decalcification.

Author contributions

YN analyzed and interpreted the patient data regarding cardiac disease and transplantation. YN also performed the histological examination of the heart and played a key role in the writing of the manuscript. All authors have read and approved the final manuscript.

Conflict of interest

No potential conflict of interest relevant to this article was reported.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Supplementary materials

Supplementary materials can be found via https://doi.org/10.5090/jcs.24.017. Supplementary Video 1. The surgical procedure involved decalcification, the placement of valve sutures, and the suturing of the left atrial wall to the sewing cuff of the valve.