© 2004 by European Society of Cardiology
Copyright © 2003, The European Society of Cardiology
Functional ventricularisation of the left atrium—severe mitral valve prolapse paradoxically resulting in minimal regurgitation
aUniversity of Ottawa Heart Institute, Ottawa, Ontario, Canada K1Y 4W7
bDepartment of Cardiology, City Hospital, Dudley Road, Birmingham B18 7QH, UK
Received 28 January 2003; received in revised form 5 May 2003; accepted after revision 12 May 2003.
* Corresponding author. University of Ottawa Heart Institute, Room H145, 40 Ruskin Street, Ottawa, Ontario, Canada K1Y 4W7. Tel.: +1-613-761-4914; fax: +1-613-761-4407. elau{at}ottawaheart.ca
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Abstract |
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 Top Abstract 1. Introduction2. Case details3. DiscussionReferences |
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Mitral valve prolapse is a common condition often associated with mitral regurgitation. Intuitively, one would expect a positive correlation between the severity of mitral valve prolapse and the associated regurgitation. This assumption is overturned by an unusual case of functional ventricularisation of the left atrium due to severe mitral valve prolapse which paradoxically resulted in minimal regurgitation.
Keywords: mitral valve prolapse; mitral regurgitation; atrial ventricularisation
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1. Introduction |
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TopAbstract1. Introduction2. Case details3. DiscussionReferences |
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Mitral valve prolapse is a common condition often associated with mitral regurgitation. Intuitively, one would expect a positive correlation between the severity of mitral valve prolapse and the associated regurgitation. This assumption is overturned by an unusual case of functional ventricularisation of the left atrium due to severe mitral valve prolapse which paradoxically resulted in minimal regurgitation.
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2. Case details |
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TopAbstract1. Introduction2. Case details3. DiscussionReferences |
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A 44-year-old man known to have Marfan's syndrome since adolescence was entirely asymptomatic. The patient was tall and thin with arachnodactyly and marked pectus excavatum. Cardiological examination revealed a mid-systolic click and a soft 2/6 mid-systolic murmur but no signs of aortic regurgitation, cardiomegaly or heart failure.
The patient was assessed with echocardiography, both transthoracic and transoesophageal. In the parasternal long-axis view on transthoracic echocardiogram, the anterior mitral valve leaflet was grossly elongated and had an exaggerated range of movement (Fig. 1). During diastole, the anterior mitral valve leaflet abutted the interventricular septum and was 6.5 mm thick at its tip. During systole, the anterior mitral valve leaflet prolapsed into the left atrium, with its entire body displaced above the annular plane into the left atrial cavity and its tip apposed against the left atrial free wall above the annular attachment of the posterior leaflet. In contrast, the posterior mitral valve leaflet was recessive and stayed within the left ventricular cavity throughout the cardiac cycle. In the two-chamber view on transoesophageal echocardiogram, it could be seen that the prolapsed anterior mitral valve leaflet formed an effective seal with the left atrial free wall and no mitral regurgitation was demonstrated on colour flow mapping (Fig. 2). The left atrium was 2.49 cm in diameter. The left ventricle was 4.4 cm in diameter at the end of diastole and the ejection fraction was 75%. The aortic root was 2.52 cm in diameter at the annular level, 3.93 cm at the sinus level and 4.06 cm at the sino-tubular junction. The aortic valve was tricuspid, thin and mobile, and without any regurgitation on the basis of colour flow mapping. The right heart was non-dilated. The tricuspid valve was competent with no regurgitation.
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3. Discussion |
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TopAbstract1. Introduction2. Case details3. DiscussionReferences |
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The mitral valve is a complex three-dimensional object and assessing it for possible prolapse by echocardiography needs to be rigorous and meticulous.1 In the case presented, the mitral valve was morphologically abnormal—the anterior leaflet was excessively large with elongated chordae whereas the posterior leaflet was recessive. The mitral valve prolapse in this case was severe.2 During systole, the entire body of the anterior leaflet rose above the annular plane of the mitral valve into the left atrium, and its tip apposed the left atrial free wall to form a seal separating the upper half of the left atrium from the lower half, which became functionally incorporated into the left ventricle.
Mitral valve prolapse is well-known to cause mitral regurgitation, which is usually mild but can occasionally be severe.3 It can be difficult to grade the severity of mitral regurgitation by echocardiography, especially when the regurgitant jet is eccentric and adherent to the left atrial wall. Consequently, new methods for quantitative and semi-quantitative assessment of mitral regurgitation are still being developed.4 Nonetheless, it seems logical to expect a positive correlation between the severity of mitral valve prolapse and the resulting regurgitation. This case proves the prediction wrong. The incidental seal formed by the tip of the anterior mitral valve leaflet and the left atrial free wall provided an effective functional equivalent to the anatomical mitral valve in terms of separating the pulmonary venous return from the systemic cardiac output during systole and there was no significant mitral regurgitation.
The management of this patient poses an interesting clinical question. According to the current ACC/AHA guidelines for the management of valvular heart disease, there was no class I indication for surgical interventions on the patient's mitral valve at the time based on his clinical status and echocardiographic data, despite the severity of prolapse.5 The anterior mitral valve leaflet abutted the interventricular septum during diastole rather than systole and hence should not result in any left ventricular outflow tract obstruction. The aortic root was dilated at the sino-tubular junction and in due course might need elective replacement as prophylaxis against aortic dissection and progressive aortic regurgitation. In this case, the patient was conservatively managed with regular review and serial echocardiograms.
In conclusion, the presented case shows an example of functional ventricularisation of the left atrium due to severe mitral valve prolapse in Marfan's syndrome. The long-term natural history of this case should help guide the management of patients with similar conditions in the future.
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References |
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TopAbstract1. Introduction2. Case details3. DiscussionReferences |
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- Pellerin D., Brecker S., Veyrat C. Degenerative mitral valve disease with emphasis on mitral valve prolapse. Heart (2002) 88(Suppl_IV):iv20–iv28.
[Free Full Text] - Cohen I.S. Two-dimensional echocardiographic mitral valve prolapse: evidence for a relationship of echocardiographic morphology to clinical findings and to mitral annular size. Am Heart J (1987) 113:859–868.[CrossRef][Web of Science][Medline]
- Freed L.A., Levy D., Levine R.A., et al. Prevalence and clinical outcome of mitral-valve prolapse. N Engl J Med (1999) 341:1–7.
[Abstract/Free Full Text] - Pu M., Thomas J.D., Vandervoort P.M., Stewart W.J., Cosgrove D.M., Griffin B.P. Comparison of quantitative and semiquantitative methods for assessing mitral regurgitation by transesophageal echocardiography. Am J Cardiol (2001) 87:66–70.[CrossRef][Web of Science][Medline]
- Bonow R.O., Carabello B., de Leon A.C. Jr., et al. Guidelines for the management of patients with valvular heart disease: executive summary. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Patients with Valvular Heart Disease). Circulation (1998) 98:1949–1984.
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