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Division of Cardiac Surgery, Department of Surgery and Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
Division of Cardiac Surgery, Department of Surgery and Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
Division of Cardiac Surgery, Department of Surgery and Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
Division of Cardiac Surgery, Department of Surgery and Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
Division of Cardiac Surgery, Department of Surgery and Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
Division of Cardiac Surgery, Department of Surgery and Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
Address correspondence to Dr Melnitchouk, Division of Cardiac Surgery, Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114
Division of Cardiac Surgery, Department of Surgery and Corrigan Minehan Heart Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
Mitral annular calcification (MAC) in mitral valve surgery constitutes a major challenge. Debridement with patch reconstruction of the mitral annulus facilitates valve repair or replacement, however, there is a perception that this procedure may elevate operative risk. This study sought to review a single-center experience with mitral annular debridement and patch reconstruction in patients with MAC.
Methods
Data were collected on patients operated on from January 2017 to December 2020 in the setting of significant MAC. Patients underwent a systematic approach to MAC excision, involving complete removal of the entire calcium bar. This was followed by patch reconstruction of the debridement area before either valve repair or replacement.
Results
The investigators identified 38 patients (24 female, 12 male) whose median age was 72 years (interquartile range, 62-80 years). There were 14 mitral valve repairs and 24 replacements. Twenty-five patients underwent a concomitant cardiac procedure. Seven cases were redo sternotomies. There were 2 (5%) 30-day mortalities. Median length of intensive care unit stay was 2.4 days, and median hospital stay was 8.5 days. One patient required postoperative extracorporeal support. There were 4 late deaths. Actuarial survival at 1 and 2 years was 89% and 82%, respectively. No patient has required reoperation for valvular dysfunction.
Conclusions
A systematic approach to MAC debridement, involving excision of the entire calcium bar and annular reconstruction, can be used in patients undergoing either isolated or combined complex mitral valve surgery. This strategy can be performed with a low risk of perioperative mortality despite relatively longer operative times.
In Short
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A systematic approach to mitral annular calcification debridement, involving excision and annular reconstruction, can be used in mitral valve surgery with a low rate of mortality.
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The technique is efficacious when performed systematically, with attention to tissue handling, myocardial protection, hemostasis, and perioperative hemodynamic management.
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Until transcatheter devices evolve to become more widely applicable to these patients, the surgical management of mitral annular calcification must remain well within surgeons’ armamentarium.
Mitral annular calcification (MAC) presents a major challenge during mitral valve surgery. Its presence makes valve implantation problematic.
Attempting to place valve sutures through calcium is often not possible, whereas placing deeper bites behind the calcium risks injury to structures in the atrioventricular groove. Excision and debridement of the MAC with patch repair, followed by valve replacement or repair, are often touted as the optimal approach to these situations.
However, this operation is perceived to be a high-risk procedure given the potentially longer cross-clamp time and the inherent risk of atrioventricular groove injury.
We thus sought to review the experience of our center (Massachusetts General Hospital, Harvard Medical School, Boston, MA) with MAC, whereby an aggressive approach to excision, patch repair, and valve replacement or repair has been adopted, to determine the efficacy and safety of this approach in these high-risk patients.
Patients and Methods
Patient Selection
We identified patients with significant MAC who were undergoing mitral valve surgery as either an isolated operation or a combined procedure between January 2017 and December 2020. To minimize the heterogeneity of surgical technique, we included data on procedures performed by 1 surgeon (S.M.). Institutional Review Board approval was obtained.
Baseline demographic, investigative, and operative data were drawn from a combination of our divisional cardiac surgery database and chart review. All patients underwent preoperative transthoracic echocardiography (TTE). Patients with significant MAC visualized on TTE underwent computed tomographic scans of the chest.
Surgical Technique
A systematic approach to excision and debridement was performed. First, the base of the posterior leaflet of the mitral valve was incised and detached from the MAC (Figure 1A ). Next, using blend-cut electrocautery, the calcium bar was meticulously excised in its entirety, if necessary up to the left and right fibrous trigones (Figure 1B). Here, care was taken to dissect in the plane behind the calcium to permit a clean excision while at the same time avoiding injury to atrioventricular groove structures. Use of electrocautery on “cut” is important to mitigate thermic spread to the myocardium and leave a clean debridement area.
Figure 1Technique for mitral annular calcification excision and annular reconstruction. (A) The base of the posterior leaflet of the mitral valve is incised and detached from the mitral annulus. (B) The calcium bar is excised. (C) A piece of pericardium is fashioned and used to patch the defect with continuous polypropylene (Prolene, Ethicon) suture. (D) The patch is reinforced on the left ventricular side with multiple pledgeted sutures. (E) Valve sutures are then placed. (F) A prosthetic mitral valve is then parachuted and secured in standard fashion.
The nerve hook was used to create initial traction in the rightmost end of the calcium bar. Once the latter was elevated from the myocardium, the plane could be easily developed between the calcium bar and the myocardium while progressing in a leftward direction toward the leftmost end of the calcium bar. Whenever encountered, deeper calcium protrusions into the left ventricular myocardium were amputated while leaving them embedded in the muscle. Two of the main goals of such a complete or nearly complete calcium bar excision are to create a smooth muscle edge and to facilitate patch suturing.
Once the calcium was excised down to left ventricular myocardium, a piece of autologous (or bovine) pericardium was fashioned and used to patch the defect with continuous polypropylene (Prolene, Ethicon) 4-0 suture (Figure 1C). In most cases, autologous pericardium (treated with 0.6% glutaraldehyde for 15 minutes) was used. The suture line was then reinforced on the left ventricular side with multiple interrupted horizontal mattress pledgeted sutures (Figure 1D).
Valve sutures were then placed using a noneverting technique to minimize the risk of atrioventricular groove disruption (Figure 1E). In most cases, the remnant posterior leaflet with its intact chordal apparatus was used for additional support, although in some cases, the remnant anterior leaflet with its preserved primary chords was used for this purpose. Where the patch is situated, the needle may either enter the posterior leaflet tissue and exit within the patch or enter the leaflet and exit on the left atrium. The latter is useful for sutures closer to the commissures and aortomitral curtain. A prosthetic mitral valve was then parachuted and secured in standard fashion (Figure 1F). In mitral valve repair cases, the atrial side of the patch was sutured to the annulus while leaving a free rim of folded patch. After placing annuloplasty sutures, the posterior leaflet was reattached to the free rim of the patch with a running 5-0 Prolene suture. A neochordal or resection repair was then performed in standard fashion followed by placement of an annuloplasty ring. After bypass, and in the early postoperative period, we maintained strict blood pressure control (systolic blood pressure <110 mm Hg) for the first 48 hours.
Results
We identified 38 patients who underwent mitral valve surgery in the setting of significant MAC. Patients’ clinical characteristics are presented in the Table. Images of excised MAC specimens are shown in Figure 2.
Figure 2Examples of excised specimens of mitral annular calcium.
Operative and early postoperative outcomes are summarized in the Table. There were 2 (5%) 30-day mortalities resulting from right ventricular failure and hepatic failure, respectively. Median follow-up was 1.2 years (interquartile range, 0.6-2.1 years). There were 4 late mortalities. One occurred at 148 days postoperatively as a result of malignant disease, and the other occurred at 224 days as a result of pneumonia. Two deaths, occurring at 1.9 and 2.8 years postoperatively, respectively, had unknown causes. Actuarial survival is presented in Figure 3. No patient has been found to have more than a trace paravalvular leak (PVL). One patient underwent reoperative mitral valve replacement for prosthetic mitral valve endocarditis.
TableClinical, Operative, and Postoperative Characteristics
Some surgeons advocate conservative debridement of calcium, followed by placing deep sutures through the calcium or behind it to avoid aggressive decalcification. This approach inherently increases the potential for PVLs because rigid, calcified annulus is unable to lie uniformly against the sewing ring. One can mitigate the risk of PVL by placing a felt gasket under the sewing ring of the mitral valve prosthesis. In severe cases of MAC, passage of needles through the calcium may be extremely difficult, whereas needle passage behind the calcium may lead to coronary injury.
Other more conservative measures have also been described to avoid aggressive decalcification in MAC. Some surgeons have described placing valve sutures to the leaflet tissues to avoid calcium,
although this is offset by the likelihood of sacrificing valve size and creating prosthesis-patient mismatch. Leaflet tissue itself may indeed tear, resulting in PVLs. Nezic and colleagues
Mitral valve replacement with posterior transposition of the anterior mitral leaflet which covers and buttresses partially decalcified posterior mitral annular bed.
described a method of partially decalcifying the posterior annulus and then transposing the anterior leaflet to buttress the annulus posteriorly. Implantation of the mitral prosthesis in the atrium has also been described.
This technique avoids interfering with annular calcium, although the left atrium under the prosthesis becomes ventricularized, which may increase the risk of left atrial aneurysm formation or valve dehiscence. The use of a balloon-expanded transcatheter aortic valve prosthesis placed in the mitral position (valve-in-MAC) has become more popular in recent years, with encouraging early outcomes,
although the risk of PVL remains. We have found a limited role of mitral transcatheter edge-to-edge repair in these patients. Frequently, these valves already have a reduced valve area with limited posterior leaflet length and mobility, thus often making transcatheter edge-to-edge repair unfeasible.
Aggressive annular decalcification and patch reconstruction remain uncommonly performed. Saran and colleagues
reviewed 1710 patients undergoing mitral valve replacement over a 15-year period. MAC was encountered in 115 patients, only 2 of whom underwent calcium excision and patch reconstruction of the annulus. Tomšič and colleagues
reviewed 627 patients undergoing mitral valve surgery, of whom 75 had significant MAC. These investigators reserved patch reconstruction for cases where the MAC extended deep into the left ventricle.
Our approach is somewhat aggressive, whereby calcium is completely excised with electrocautery on “cut” and the defect, which is often large, extending significantly into the left ventricle, is then patched. We have used this approach even in complex cases involving reoperation or concomitant valve surgery and in older patients. Although the basic technique for our approach has been described before, we believe that it need not be perceived as a high-risk approach and that it can be efficacious when performed systematically, with meticulous attention to tissue handling, myocardial protection, hemostasis, and perioperative hemodynamic management. The risk of atrioventricular groove dissociation can be reduced through reinforcement of the suture line on the left ventricular side with a series of interrupted pledgeted sutures. Using chordal and posterior leaflet support in the area of reconstruction is also useful, as is avoiding oversizing of the valve prosthesis. Circumflex artery injury can be avoided by dissecting closely adjacent to the calcium. After debridement, the annular sutures are placed to the edge of the left atrial tissue, with care taken to avoid deep placement of those sutures below the anterolateral commissure (P1 area).
A greater rate of PVL is expected in patients whose MAC is handled conservatively, given the presence of a rigid annulus. In the series reported by Saran and colleagues,
of the 115 patients undergoing mitral valve replacement with MAC, most of whom having not had an aggressive annular debridement, 18 patients had mild and 3 moderate PVL after bypass. However, 11 of these patients were discharged with moderate or more PVL on the basis of TTE. One patient subsequently required redo mitral valve replacement for PVL, whereas 3 underwent transcatheter closure of the PVL.
In our albeit smaller series, we have had no instances of significant PVL, given the presence of a pliable neoannulus. This result is, of course, offset by the greater complexity and operative time for these cases. The question remains whether a more aggressive approach to MAC and the potential for reduced PVL indeed confer a prognostic benefit or whether the incremental benefit of reduced PVL lies beyond the life expectancy of many patients in this subgroup.
Limitations
Our study describes a single-center and single-surgeon experience, which limits its generalizability. However, we believe that the approach described here can be taught to junior surgeons and then reproduced relatively safely. It remains to be seen whether late complications such as pseudoaneurysm are more prevalent in these patients.
Conclusion
A systematic approach to MAC debridement, involving excision of the entire calcium bar and annular reconstruction, can be used in patients undergoing either isolated or combined complex mitral valve surgery. Even though it involves more complex surgery performed on patients with comorbidities, this strategy has a relatively low risk of perioperative mortality.
Funding Sources
The authors have no funding sources to disclose.
Disclosures
The authors have no conflicts of interest to disclose.
References
Carpentier A.F.
Pellerin M.
Fuzellier F.J.
Relland J.Y.
Extensive calcification of the mitral valve anulus: pathology and surgical management.
Mitral valve replacement with posterior transposition of the anterior mitral leaflet which covers and buttresses partially decalcified posterior mitral annular bed.
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