Aorto-Mitral Curtain Reconstruction with Multiple Bovine Pericardial Patches: A Case of Multiple Valve Infective Endocarditis

Invasive infective endocarditis (IE) with abscess formation involving the intervalvular fibrous body (IFB) between the aortic and mitral valves or aorto-mitral curtain (AMC) can make surgical repair and reconstruction a particularly complex and high-risk surgical procedure. Tirone David initially described the reestablishment of the “neo-aortomitral curtain” continuity through the use of bovine pericardial or Dacron fabric patchesthat can range from a ”Hemi-Commando procedure,” which allows for sparing of the anterior mitral leaflet (AML) free edge, to a much more extensive “Commando” or “UFO” procedure, as described by the Cleveland Clinic and Leipzig group, respectively (1,2). The Commando procedure is associated with high, early, and late mortality rates because of the invasiveness of the surgery and critical status of the patients that require it. Therefore, where there is sparing of the free edge of the anterior mitral leaflet in cases of invasive IE with AMC destruction, “neo-aortomitral continuity” can successfully be restored using a patch repair approach to AMC reconstruction without the need for double-valve replacement (3,4). 

Clinical Vignette 

The patient was a fifty-two-year-old female with invasive multiple valve native infective endocarditis with an aortic root abscess who successfully underwent pericardial patch reconstruction of neo-aortomitral continuity and aortic valve replacement with mitral and tricuspid valve repair. She was initially presented to another institution with right knee septic arthritis and severe community-acquired pneumonia on the background of a routine dental extraction two weeks prior. She was delirious and clinically septicemic on arrival and was admitted for further management with broad-spectrum intravenous antibiotics.  

The streptococcus pneumoniae was isolated on knee joint aspirate and blood cultures. Following surgical washout of the affected knee joint, the patient clinically deteriorated because of worsening sepsis and respiratory failure, thus requiring transfer to intensive care for further management following intubation and commencement of noradrenaline infusion. A new systolic murmur was noted with first-degree heart block on electrocardiogram, raising suspicion for infective endocarditis. An initial transthoracic echocardiogram demonstrated severe aortic regurgitation with large aortic root abscess and destruction of aorto-mitral continuity. Because of the patient’s severe heart failure and active ongoing sepsis, the patient was transferred to our institution where further evaluation with transoesophageal echocardiogram confirmed the above findings, along with multiple fistulous connections and perforations from the abscess cavity.  

At surgery, extensive debridement of all infected valve and myocardial tissue necessitated reconstruction of the aorto-mitral curtain, anterior mitral leaflet, left ventricular outflow tract (LVOT), ventricular septal defect (VSD) and tricuspid septal leaflet with multiple bovine pericardial patches, along with aortic valve replacement. 

Following completion of antibiotic treatment and rehabilitation, the patient made a full recovery with normal biventricular systolic function at follow-up echocardiogram. 

Surgical Technique 

Following median sternotomy, cardiopulmonary bypass (CPB) was initiated and nasopharynx temperature was lowered to 34°C. Antegrade and retrograde cardioplegia was then used for myocardial protection. 

The right atrium was opened parallel to the right atrioventricular groove. The mitral valve was exposed by opening the interatrial septum through the fossa ovalis and extending the incision upward in the left atrial roof. Adequate exposure of the aortic valve was achieved via standard oblique aortotomy, which was further extended into the non-coronary aortic sinus. 

This revealed a tricuspid aortic valve with severe regurgitation because of destroyed leaflets from large vegetations. All infected and abnormal aortic valve tissue was excised to expose a deep-seated root abscess cavity located underneath the left coronary cusp, which was circumferentially extending toward the membranous septum and extending downward toward the left ventricular base. The absess reached the papillary muscle, causing a fistulous connection and ventricular septal defect (VSD) between the left ventricle and right atrium just above the commissure of the septal and anterior leaflets of tricuspid valve. Also, the septal leaflet of the tricuspid valve was inflamed. The tissues were very fragile and pus was oozing from the cavity during debridement. The abscess also extended to the level of the aortomitral curtain, resulting in a fistulous connection between the left ventricular outflow tract (LVOT) and left atrium. The posterior mitral leaflet had flail P2 segment from ruptured head of papillary muscle. 

Following adequate debridement of all infected tissue and removal of all contaminated instruments from the operating field, reconstruction with multiple bovine pericardial patches was performed. 

The first pericardial patch was used to close defect in the anterior mitral leaflet with reconstruction of mitral valve annulus and aortomitral curtain. The detached head of the papillary muscle was then debrided and replaced with neo-chordae to flail P2 segment of posterior mitral leaflet. A second patch was used to repair the large VSD that was created following detachment of the septal tricuspid valve leaflets, underneath the membranous septum. A third patch was placed underneath the left coronary cusp and the non-coronary cusp to recreate the destroyed aorto-mitral curtain and membranous septum. An adequately sized aortic valve was replaced with a 21mm St Jude Medical Regent mechanical valve with a series of 2-0 pledgeted mattress sutures placed circumferentially around a healthy aortic annulus and reconstructed LVOT. 

The aortic cross clamp was removed after a total aortic cross clamp time of 226 minutes. The patient was successfully weaned from cardiopulmonary bypass with inotropic support following a total cardiopulmonary bypass time of 255 minutes. 

Comments 

Infective endocarditis is a life-threatening disease associated with a high mortality. Management of these patients continues to present a clinical and logistical challenge for the cardiac surgeon, particularly where there is involvement of the aortomitral curtain (AMC). Delaying surgery may permit a longer duration of antibiotic therapy or hemodynamic stabilization but increases the risk of disease progression with valve destruction, heart block, vegetation and abscess formation, destruction of intervalvular fibrous body, and septic embolic complications. Early decision-making has the potential to improve clinical outcomes. 

Involvement of the intervalvular fibrous body or aorto-mitral curtain is rare in patients with endocarditis and requires complex and invasive surgery to achieve adequate source control and successfully restore anatomical integrity of closely related aortic and mitral valves, along with the AMC. 

At its most extensive, surgical management can involve aortic and mitral valve replacement with reconstruction of the AMC and LVOT using autologous or allograft pericardium, as originally suggested by Tirone David in 1976 and named the “Commando” or “UFO” procedure by the Cleveland Clinic and Leipzig group, respectively (1,2). 

Where there is less extensive disease with sparing of the free edge of the anterior mitral leaflet, an intermediate procedure called the “Hemi-Commando” has been proposed where mitral repair can be achieved along with restoration of “neo-aortomitral continuity”, thereby avoiding the significant early and late mortality associated with double-valve surgery (3,4,5). 

Over the past few decades, it has become apparent that valve repair is preferable to valve replacement for most patients undergoing surgery. We managed to successfully recreate “neo-aortomitral continuity” with sparing of the free edge of anterior mitral leaflet along with VSD and tricuspid valve repair, along with aortic valve replacement (4). 

References

1. Vojacek J, Zacek P, Ondrasek J. Multiple valve endocarditis: a Hemi-Commando Procedure. Ann Cardiothorac Surg. 2019 Nov; 8(6): 705-707.
2. David, TE, Juo J, Armstrong S. Aortic and mitral valve replacement with reconstruction of the intervalvular fibrous body. J Thorac Cardiovasc Surg. 1997 Nov; 114(8): 766-772.
3. Giambuzzi I, Bonalumi G, Di Mauro M, Roberto M, Corona S, Alamanni F, et al. Surgical Aortic Mitral Curtain Replacement: Systematic Review and Metanalysis of Early and Long-Term Results. J Clin Med. 2021 Jul; 10(14): 3163.
4. Navia JL, Al-Ruzzeh S, Gordon S, Fraser T, Agüero O, Rodríguez L. The incorporated aortomitral homograft: A new surgical option for double valve endocarditis. J Thorac Cardiovasc Surg. 2010 Apr; 139(4):1077-81.
5. Davierwala, PM, Binner C, Subramanian S, Luehr M, Pfannmueller B, Etz C, et al. Double valve replacement and reconstruction of the intervalvular fibrous body in patients with active infective endocarditis. Eur J Cardiothorac Surg. 2014 Jan; 45(1):146-52.

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