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Cardiovascular Anesthesiology: Echo Rounds

An Unusual Cause of Mitral Regurgitation

The Intraoperative Diagnosis of an Aberrant Mitral Valve Chord

Warrick, Adrienne B. MD; Leff, Jonathan D. MD

Author Information
doi: 10.1213/ANE.0000000000000635

An 82-year-old female presented with a 3-week history of shortness of breath and new-onset atrial fibrillation. Her comorbidities were significant for hypertension and severe chronic obstructive pulmonary disease. After hospital admission, she became hemodynamically unstable, and multiple-lead ST segment elevations were noted on her electrocardiogram. The patient was tracheally intubated and taken for cardiac catheterization, which revealed severe 3-vessel coronary disease. Transthoracic echocardiography showed moderate mitral regurgitation (MR) and a left ventricular ejection fraction of 40%. The condition of the patient continued to deteriorate, requiring vasoactive medications and insertion of an intra-aortic balloon pump. She was brought to the operating room for emergent coronary revascularization and mitral valve (MV) repair versus replacement. Intraoperative transesophageal echocardiogram (TEE) examination was significant for biatrial enlargement, thickened MV leaflets with bileaflet restriction, calcified and thickened subvalvular apparatus, lack of MV leaflet coaptation, and global left ventricular hypokinesis. A mobile structure on the tip of the anterior MV leaflet (AMVL) was also observed, which was suspicious for a vegetation or thrombus (Supplemental Digital Content 1, video, http://links.lww.com/AA/B66). The MR jet was centrally directed and occurred along the coaptation line (Supplemental Digital Content 2, video, http://links.lww.com/AA/B67). The MR mechanism can be described as functional, type IIIa, with restrictive motion in both systole and diastole. The morphology of the valve showed anterior and posterior leaflet thickening, tethered mitral leaflets, and MV annulus dilation. Three-dimensional imaging of the valve revealed a thin, elongated connective structure on the atrial side of the AMVL that limited MV motion (Supplemental Digital Content 3, video, http://links.lww.com/AA/B68). Further examination using multiplanar reconstructive software of the 3D images revealed an aberrant attachment between the tip of the AMVL at the A2 scallop that extended into the left atrium (Fig. 1). Surgical exposure was consistent with TEE findings and revealed a fibrinous band connecting the anterolateral portion of the left atrium to the tip of the A1-A2 segment of the AMVL (Fig. 2). This fibrinous band attached to the AMVL resulted in restrictive motion of the A2 tip of the leaflet throughout the cardiac cycle. Given the degenerative disease of the MV and the age of the patient, she received an MV replacement in lieu of MV repair. The patient underwent 3-vessel coronary artery bypass grafting and MV replacement with a 29-mm Biologic Magna Ease bioprosthetic valve. Her postoperative course was complicated by cardiogenic shock, respiratory failure requiring tracheostomy, and acute kidney injury. The patient did recover and was discharged to a skilled nursing facility after a 7-week hospitalization.

Figure 1
Figure 1:
Multiplanar reconstruction of 3D acquired images illustrating the anomalous chord and its attachment nearest to the tip of the A2 segment of the mitral valve leaflet. The red arrows denote the aberrant chord. The reconstructed planes are represented by the colors green (top left pane), red (top right pane), and blue (bottom left pane). The top left pane is a long-axis view, the top right pane is a coronal view, and the bottom left pane is a transverse plane showing the base of the mitral valve. The anterior and posterior mitral valve leaflets are labeled “A” and “P” in the top left pane. The bottom right pane represents the “3D zoom” image of the mitral valve oriented to the surgeon’s view. LA = left atrium; LV = left ventricle.
Figure 2
Figure 2:
Intraoperative images of the aberrant chord in situ (left) and the anterior mitral valve leaflet along with the aberrant chord after surgical resection (right). The atrial attachment is seen in the lateral part of the in situ photo corresponding to the lateral and anterior portion of the left atrium. The in situ picture on the left represents the surgeon’s view of the mitral valve. After the valve was resected, it appeared that the valvular attachment site corresponded to the left atrial side of the A1-A2 tip of the anterior mitral leaflet (pictured on the right).

An aberrant MV chord resulting in MV regurgitation is an uncommon finding, with only a few cases reported.1,2 Although this anomalous structure does not account for all of this patient’s valvular pathology, it did contribute to the severity of the MR encountered in the operating room. We reasoned that with the onset of ischemia and additional annular dilation, the aberrant attachment retracted the anterior mitral leaflet toward the left atrium during systole and prevented appropriate coaptation. The MV is a complex structure, with normal chordae attachments along the ventricular surface of the valve and insertion in the papillary muscles. The chordae tendineae are classified based on their insertion site along the ventricular surface of the MV and consist of primary, secondary, and tertiary chordae. Primary and secondary chords attach proximally at the papillary muscles. The distal primary chordal attachment is at the tip or free edge of the MV and precludes the leaflet from ascending above the annular plane, thus preventing MV flail and subsequent regurgitation. Secondary chords attach just within the free margin or body of the MV leaflet on the ventricular side of the MV. Tertiary chords arise from the free wall of the left ventricle and attach only to the basal zone of the posterior leaflet. In our case, the aberrant structure resembled a primary chord with attachment at the leaflet tip but differed in that it did not originate from a papillary muscle. The patient’s aberrant chord retracted the leaflet tip of the AMVL, prevented coaptation, and restricted its movement in both systole and diastole. Other case reports described similar findings and note the absence of “normal” anatomic primary chordae when surgically inspected. In addition, the repair of this valve is possible and has been described by removing the aberrant chordae and constructing neochordae to support the A2 segment of the AMVL.2 This technique, along with a stabilizing annuloplasty ring, is a viable way to surgically address the abnormality.

Regarding the etiology of this discovered structure, a review of the literature revealed case reports of similar anomalous structures causing MR in a usually younger adult patient population or as a cause of MR in the pediatric population.3 These aberrant or anomalous mitral chords (as they are described) are congenital in nature. The differential diagnosis of a left atrial-sided MV attachment or structure includes anomalous chords, endocarditis, rheumatic disease process, intracardiac tumor, and cor triatriatum. Intracardiac tumors as well as endocarditis vegetations exhibit independent and random movement with regard to the cardiac cycle on echocardiography. Cor triatriatum sinister describes the division of the left atrium by a fibromuscular septum, which is most consistently diagnosed with echocardiography. TEE is the gold standard for diagnosing cor triatriatum, for which careful examination of the left atrium, the membrane within the left atrium, and pulmonary venous connections is performed.4 The addition of color flow Doppler is used to properly identify obstruction of flow. Patients affected with chronic rheumatic heart disease undergo deforming fibrosis of the affected valve, causing leaflet thickening, calcification and retraction, periannular calcification, leaflet fusion, chordal thickening, and papillary inflammation. Although most case reports describe younger patients with an aberrant mitral chord, we surmise that the delayed discovery of this structure was secondary to annular dilation after an ischemic event. Other anomalous chords and structures include false tendons, moderator bands, and abnormal chords within the right ventricle that cause tricuspid valve regurgitation by tethering the tricuspid valve with their attachment.5 Abnormal findings that involve the subvalvular apparatus of the MV include anomalous or aberrant papillary muscles. These are papillary muscles that most commonly insert into the AMVL or ventricular septum. Abnormal papillary muscle insertion into the AMVL is seen in approximately 15% of patients who undergo valve replacement for hypertrophic obstructive cardiomyopathy. It is important to appreciate that these aberrant papillary muscles contribute to the degree of left ventricular outflow tract obstruction by a different mechanism than the typical dynamic obstruction attributable to systolic anterior motion of the MV.6

Echocardiographic evaluation of the MV should be aimed at identifying the presence of regurgitation or stenosis and the morphologic features of the valve. This can be achieved with the use of both 2D and 3D modalities. In this case, after a complete examination of the MV in 2D revealed a severely dilated mitral annulus and severe central MR, 3D TEE was used to enhance visualization of the mitral anatomy. This unusual case of an aberrant MV chord highlights the need to perform a complete TEE evaluation of the MV in all cases, as well as a rare cause of an aberrant chord contributing to a patient’s MR.

Clinician’s Key Teaching Points

By Nikolaos J. Skubas, MD, and Martin J. London, MD

  • With ischemic mitral regurgitation (MR), the mitral annulus is dilated with restriction of normal systolic motion of the mitral leaflets attributable to tethering. Thus, the mitral leaflets coapt deeper in the left ventricle (LV) than normal with reduced surface area causing regurgitation. Transesophageal echocardiogram is used to examine the morphology of the mitral valve and estimate the severity and direction of the MR jet.
  • The normal tendinous chords extend between the papillary muscles and either the tip or body of the mitral leaflets (termed primary or secondary attachment) or the free LV wall (tertiary attachment). They may be confused with LV false tendons (which run between LV walls) or anomalous papillary muscles that insert directly into the anterior mitral leaflet or LV septum and may cause LV outflow obstruction.
  • In this case of an 82-year-old woman with severe 3-vessel coronary artery disease and moderate ischemic MR scheduled for coronary revascularization and possible mitral valve repair, intraoperative 2D and 3D transesophageal echocardiogram revealed an abnormal fibrinous chord between the tip of the anterior middle segment (A2) and the left atrial wall. Alongside the thickened and calcified mitral leaflets, this chord further exacerbated the restricted motion of the anterior mitral leaflet and worsened the preoperative MR. These findings prompted the surgeon to perform mitral valve replacement instead of repair.
  • In contrast to the normal insertion of mitral chords from within the LV, aberrant chords located inside the left atrium are rare congenital findings. They should be differentiated from cor triatriatum sinister, which is a membrane splitting the left atrium and obstructing blood flow, and endocarditis, or tumors, which present as masses with independent motion. More important, their effect on the motion of the mitral leaflets should be systematically evaluated using appropriate mitral valve imaging planes.

DISCLOSURES

Name: Adrienne B. Warrick, MD.

Contribution: This author helped prepare the manuscript.

Attestation: Adrienne B. Warrick approved the final manuscript.

Conflicts of Interest: This author has no conflicts of interest to declare.

Name: Jonathan D. Leff, MD.

Contribution: This author helped prepare the manuscript.

Attestation: Jonathan D. Leff approved the final manuscript and is the archival author.

Conflicts of Interest: Jonathan D. Leff serves on the international steering committee for HeartWeb. He has also served as a consultant for Casmed in the past.

This manuscript was handled by: Martin J. London, MD.

REFERENCES

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2. Sawa S, Kawasuji M, Matsunaga Y, Kawakami K, Tedoriya T, Iwa T. Mitral regurgitation due to anomalous attachment of chordae tendinae to the left atrial wall. Nihon Kyōbu Geka Gakkai. 1989;37:2053–6
3. Khan H, Chaubey S, Kenny C, MacCarthy P, Wendler O. A rare case of an aberrant anterior mitral valve chord resulting in severe mitral regurgitation. J Surg Case Rep 2011. 2011;1
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5. Kobza R, Kurz DJ, Oechslin EN, Prêtre R, Zuber M, Vogt P, Jenni R. Aberrant tendinous chords with tethering of the tricuspid leaflets: a congenital anomaly causing severe tricuspid regurgitation. Heart. 2004;90:319–23
6. Klues HG, Roberts WC, Maron BJ. Anomalous insertion of papillary muscle directly into anterior mitral leaflet in hypertrophic cardiomyopathy. Significance in producing left ventricular outflow obstruction. Circulation. 1991;84:1188–97
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