CASE DESCRIPTION
A 60-year-old woman with a history of ischemic cardiomyopathy presented to the hospital with chest pain and dyspnea. Her preoperative workup included coronary angiography, demonstrating multiple blockages, and a transthoracic echocardiogram, which showed a dilated left ventricle with an ejection fraction of 20% and a severe, centrally directed jet of mitral regurgitation (MR). Given these findings, she was enrolled in an ongoing trial of mitral valve (MV) repair versus replacement for patients with ischemic MR. The patient was then taken to the operating room for coronary artery bypass graft and MV surgery. She consented to have the following case details and images published.
After uneventful induction of anesthesia, a transesophageal echocardiogram (TEE) was performed. It confirmed a moderately dilated left ventricle with an ejection fraction of 25%. The centrally directed jet of MR was moderate in severity, likely decreased because of the effects of anesthesia, with a vena contracta of 0.4 cm. Both anterior and posterior leaflets appeared tethered, confirming the preoperative diagnosis of ischemic MR. Upon close examination of the midesophageal transgastric basal view, however, a small gap was noted in the posterior mitral leaflet (Fig. 1) (see Supplemental Digital Content 1, Video 1, https://links.lww.com/AA/A189; see Appendix for video legends). No other congenital anomalies were visualized.
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Figure 1: Transgastric basal short-axis view during mid-diastole with arrow pointing toward the cleft in the posterior leaflet. The posteromedial (PM) and anterolateral (AL) commissures have been identified.
Given the rarity of isolated MV posterior leaflet clefts, and the fact that structural leaflet pathology was an exclusion criterion for the study, 3-dimensional (3D) TEE was used to better define the lesion. The cleft was confirmed using the left atrial view (surgeon's view) on 3D examination (Fig. 2) (see Supplemental Digital Content 2, Video 2, https://links.lww.com/AA/A190; see Appendix for video legends). It originated in the P2 region, almost dividing the posterior leaflet in half. The patient was excluded from the study and underwent 4-vessel coronary artery bypass graft and MV repair. Primary repair of the valve was accomplished using a single suture to close the cleft with an annuloplasty ring for support. Only trace residual MR was noted on TEE after chest closure. The patient recovered from the operation uneventfully and was discharged home on postoperative day 7.
Figure 2: Three-dimensional (3D) transesophageal echocardiographic view from the left atrium (LA), also known as the “surgeon's view,” during mid-diastole with arrow pointing toward cleft in the region of P2. A red “X” denotes a normal slit forming the P3 scallop (see text for details).
DISCUSSION
A cleft MV almost always refers to a fissure in the anterior leaflet and is usually seen in conjunction with a primum atrial septal defect. These 2 findings are typically diagnosed in the pediatric population as part of an incomplete or transitional atrioventricular canal defect, the details of which have been discussed in a previous Echo Rounds.1 A cleft posterior MV leaflet, however, does not appear to be associated with septal defects and is not usually seen in children.2
Even in adults, a cleft posterior mitral leaflet is an extremely rare finding, with an incidence of only about 0.1% in the echocardiographic population.3 Myxomatous changes of the leaflets can be seen with posterior clefts, and an association with Marfan syndrome has been suggested.4 Additional associated anomalies with the MV apparatus, such as malrotation of the papillary muscles, have also been reported.5 Overall, however, little is known about cleft posterior leaflet MVs.
In the largest published series of 22 patients, Wyss et al.3 reported posterior clefts to occur most frequently in the P2 region, as seen in our patient. In the same series, the cleft resulted in severe MR in 50% of the patients, with the MR being only trivial in several individuals.3 Relating these findings to our patient, it is difficult to say how much the cleft contributed to the overall MR severity and it may have been only an incidental finding.
Clefts in the MV can be visualized using 2D TEE. Midesophageal 4-chamber, 2-chamber, and long-axis views may demonstrate a defect in 1 of the leaflets. Applying color flow Doppler to these views typically shows a central, broad-based jet of MR, which may originate from >1 opening. The transgastric basal short-axis view is also beneficial for diagnosing cleft MVs. As demonstrated in Figure 1, this gives the echocardiographer an en face view of both leaflets in their entirety, clearly demonstrating the abnormal fissure. One must be careful in interpreting leaflet gaps in this view, however. There is often some echo dropout because of annular calcification and the imaging plane can cut through the leaflets obliquely, creating the impression of a fissure that is not actually present.
Despite using multiple views with 2D TEE, it can be difficult to detect cleft leaflets and it has been suggested that 3D imaging can improve their visualization.6 As shown in Figure 2, viewing the MV in 3D provides a clearer picture of the entire valve and makes it easier to obtain a true en face view. A caveat with this improved visualization, however, is that structures not always seen on 2D can become readily apparent, requiring the echocardiographer to identify them as normal. For example, the smaller crevice seen in Figure 2, identified by an “X,” is a posteromedial slit that helps form the P2/P3 scallops of the posterior leaflet. Surgeons can distinguish this from an abnormal cleft by its chordal attachments.7 Less has been written about this distinction in the echocardiography literature, but a proposed definition is that a cleft completely splits the leaflet to the annulus and causes some degree of regurgitation.3
In conclusion, we have presented a rare case of an isolated posterior leaflet cleft MV. Thanks to a thorough TEE examination and the fortunate addition of 3D imaging, this uncommon pathology was easily diagnosed.
REFERENCES
1. Joffe DC, Oxorn DC. Transitional atrioventricular canal. Anesth Analg 2009;109:358–60
2. Banerjee A, Kohl T, Sliverman NH. Echocardiographic evaluation of congenital mitral valve anomalies in children. Am J Cardiol 1996;77:164–9
3. Wyss CA, Enseleit F, Van der Loo B, Grunenfelder J, Oechslin EN, Jenni R. Isolated cleft in the posterior mitral valve leaflet: a congenital form of mitral regurgitation. Clin Cardiol 2009;32:553–60
4. Izgi C, Feray H, Saltan Y, Kahraman R. Isolated cleft of the posterior mitral valve leaflet in a patient with Marfan syndrome. Int J Cardiol. 2009 . [Epub ahead of print] doi: 10.1016/j.ijcard.2008.12.167
5. Kent SM, Markwood TT, Vernalis MN, Tighe JF. Cleft posterior mitral valve leaflet associated with counterclockwise papillary muscle malrotation. J Am Soc Echocardiogr 2001; 14:303–4
6. Nomoto K, Hollinger I, DiLuozzo, Fischer GW. Recognition of a cleft mitral valve utilizing real-time three-dimensional transesophageal echocardiography. Eur J Echocardiogr 2009; 10:367–9
7. Victor S, Nayak VM. Definition and function of commissures, slits, and scallops of the mitral valve: analysis of 100 hearts. Asia Pacific J Thorac Cardiovasc Surg 1994;3:10–6
APPENDIX: VIDEO LEGENDS
Video 1: The first part of the video is a transgastric (TG) mid-papillary short-axis (SAX) view demonstrating poor ventricular function. This is followed by color-compare midesophageal (ME) long-axis (LAX) and 2-chamber (2C) views showing a central jet of moderate mitral regurgitation and some leaflet tethering. The final clip of the video shows a transgastric basal short axis, with an arrow pointing toward the cleft in the posterior leaflet. AV = aortic valve.
Video 2: This 3-dimensional (3D) transesophageal echocardiographic image is oriented with the anterior mitral leaflet at the top of the screen and the posterior leaflet on the bottom, as seen by the surgeon after left atriotomy. The arrow points toward the cleft in the P2 region. LA = left atrium.
Clinician's Key Teaching Points By Martin M. Stechert, MD, Kent H. Rehfeldt, MD, and Martin J. London, MD
- Mitral valve (MV) clefts usually involve the anterior leaflet and occur in conjunction with atrioventricular canal defects. Clefts affecting the posterior mitral leaflet are a rare finding that may be seen in isolation, or associated with myxomatous valve changes, accessory or malpositioned papillary muscles, or possibly Marfan syndrome.
- Visualization of the MV clefts uses standard 2-dimensional (2D)–transesophageal echocardiogram (TEE) views, including midesophageal 4-chamber, 2-chamber, and long-axis views. In addition, the transgastric basal short-axis view provides an en face view of the valve and may assist in localization of the defect. Color and spectral Doppler examinations are mandatory to assess jet direction and overall severity of mitral regurgitation, which may range from trivial to severe.
- In this case, a cleft posterior leaflet was noted during the 2D TEE assessment of ischemic mitral regurgitation. The use of 3D TEE imaging afforded additional en face views from a left atrial perspective that provided enhanced visualization of the cleft along with a small slit or crevice located between the middle and medial posterior scallops, which is a normal finding.
- MV clefts have been defined as splits in the leaflet from free edge to annulus that result in some degree of regurgitation. Three-dimensional TEE may be superior to 2D TEE for diagnosis of specific mitral leaflet pathology, such as clefts, although additional training is necessary to effectively acquire, manipulate, and accurately interpret MV 3D datasets.
