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Case Report
Hammock mitral valve: A rare cause of congenital mitral regurgitation e A case report Gopalan Nair Rajesh a,*, Kalathingathodika Sajeer b, Anishkumar Nair c, Chakanalil Govindan Sajeev d, Mangalath Narayanan Krishnan e a
Additional Professor, Department of Cardiology, Government Medical College, Kozhikode, Kerala 673008, India Senior Resident, Department of Cardiology, Government Medical College, Kozhikode, Kerala, India c Senior Resident, Department of Cardiology, Government Medical College, Kozhikode, Kerala, India d Professor, Department of Cardiology, Government Medical College, Kozhikode, Kerala, India e Professor and Head, Department of Cardiology, Government Medical College, Kozhikode, Kerala, India b
article info
abstract
Article history:
Hammock valve, also known as anomalous mitral arcade is a rare mechanism for
Received 20 November 2013
congenital mitral insufficiency. We report a case of a two-week-old neonate who presented
Accepted 23 March 2014
with features of heart failure and an apical systolic murmur. Echocardiogram showed
Available online 16 April 2014
severe mitral regurgitation and abnormal mitral valve with direct attachment of mitral leaflets to papillary muscle without intervening chordae tendinae, typical of hammock
Keywords:
valve. Heart failure was controlled with ionotrpes and diuretics. The literature on the
Congenital
hammock mitral valve is reviewed.
Mitral valve
Copyright ª 2014, Cardiological Society of India. All rights reserved.
Mitral regurgitation Hammock valve
1.
Introduction
Congenital mitral regurgitation due to hammock mitral valve is very rare, and to date, only 13 cases of this anomaly have been reported, most of which were detected before 3 years of age.1 It is a congenital malformation of the mitral tensor apparatus characterized by enlarged papillary muscles connected to mitral leaflets by a typical fibrous tissue bridge which creates a fibrous continuity between valvular and subvalvular apparatus.
2.
Case report
A 2-week-old newborn was referred to our institution for evaluation of respiratory distress. Examination revealed subcostal and intercostal retraction, cardiomegaly with left ventricular type of apex beat and prominent systolic murmur at apex. Oxygen saturation was 94% on room air and there was mild hepatomegaly. Chest X-ray showed pulmonary congestion and electrocardiogram showed biventricular dominance with right axis deviation. Transthoracic echo evaluation
* Corresponding author. Tel.: þ91 9447290609. E-mail address:
[email protected] (G.N. Rajesh). http://dx.doi.org/10.1016/j.ihj.2014.03.008 0019-4832/Copyright ª 2014, Cardiological Society of India. All rights reserved.
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Fig. 1 e A: Transthoracic echocardiogram e parasternal long axis view: showing direct attachment of mitral leaflets to papillary muscle without chordae tendinae B: Transthoracic echocardiogram e apical four chamber view showing direct attachment of mitral leaflets to papillary muscle without chordae. C: transthoracic echocardiogram depicting colour Doppler flow (arrow) suggestive of significant mitral regurgitation. PM e papillary muscle, AML e anterior mitral leaflet, PML e posterior mitral leaflet, RA e right atrium, RV e right ventricle, LA e left atria, LV e left ventricle, Ao e aorta. showed abnormal mitral valve with direct attachment of mitral leaflets to papillary muscle without intervening chordae tendinae. Colour Doppler echo evaluation showed severe mitral regurgitation (Fig. 1AeC Movie 1, 2). Heart failure was managed with inotropes and diuretics. Supplementary video related to this article can be found at http://dx.doi.org/10.1016/j.ihj.2014.03.008
3.
Discussion
Anomalous mitral arcade or hammock mitral valve is a rare congenital malformation of the mitral valve and of its tensor apparatus that was first described in 1967 by Layman Edwards.2 The term hammock mitral valve was first coined by in 1976 by Carpentier, because of the unique appearance of mitral valve apparatus from its left atrial aspect as viewed during cardiac surgery.3 This anomaly is characterized by enlarged and elongated papillary muscles connected to each other and to the free edge of the anterior mitral leaflet by a bridge of fibrous tissue. The absence of chordae tendinae between the fibrous bridge and anterior leaflet results in a fibrous continuity that interferes with the valvular motion and prevents normal apposition of leaflets. It is suggested that this malformation is the result of an arrest in the developmental stage before attenuation and lengthening of the collagenized chordae tendineae. The features of anomalous mitral valve arcade are (1) A near normal mitral valve orifice; (2) short, thick, and poorly differentiated chordae tendinae with direct attachment of the papillary muscles to the anterior mitral leaflet; (3) narrow interchordal spaces and (4) relatively well developed chordae attached to the posterior papillary muscle. The papillary muscles which are large and elongated are connected to each other and to the free edge of the anterior mitral leaflet by a bridge of fibrous tissue. The natural history of the malformation is characterized by progressive worsening of valvular regurgitation, stenosis or both.4 Pulmonary vascular resistance changes throughout the gestation and after birth. In neonate, rise in pulmonary venous pressure is preceded by greater increase in pulmonary arterial pressure. This results in increase of calculated resistance across pulmonary vascular bed. Thus post capillary pulmonary hypertension as consequence of severe mitral regurgitation due to hammock mitral valve may increase
pulmonary vascular resistance.5 In cases of mitral regurgitation presenting with heart failure, changes in left atrial pressure which occurs independent of alteration in pulmonary vascular resistance, should also be considered. The majority of the reported cases are in the paediatric age group and there are only a few reports of anomalous mitral arcade in adults.6 A patient who reaches adulthood usually undergoes mitral valve repair or replacement. In Hammock mitral valve, repair can be performed using annuloplasty, commissurotomy, modified GerbodeeHetzer plication plasty, modified PanetheHetzer posterior annulus shortening techniques and papillary muscle splitting according to the presenting morphology.7,8 The clinical course varies depending on the severity of mitral stenosis and regurgitation.
Conflicts of interest All authors have none to declare.
references
1. Federici D, Palmerini E, Lisi M, Centola L, Chiavarelli M, Mondillo S. Congenital mitral disease: anomalous mitral arcade in a young man. Ann Thorac Surg. 2010;89:629e631. 2. Layman TE, Edwards JE. Anomalous mitral arcade: a type of congenital mitral insufficiency. Circulation. 1967;35:389e395. 3. Carpentier A, Brizard CP. Congenital malformations of the mitral valve. In: Stark J, Leval M, Tsang V, eds. Surgery for Congenital Heart Defects. London: Wiley; 2006:573e590. 4. Castaneda AR, Anderson RC, Edwards JE. Congenital mitral stenosis resulting from anomalous arcade and obstructing papillary muscles: report of correction by use of ball valve prosthesis. Am J Cardiol. 1969;24:237e240. 5. wheeler Derek S, Vong Hector R, Shanley Thomas P. Pediatric critical care medicine: basic sciences and clinical evidence. Spinger. 2007:571. 6. Peretz JA, Herzberg AJ, Reimer KA, Bashore TM. Congenital mitral insufficiency secondary to anomalous mitral arcade in an adult. Am Heart J. 1987;114:894e895. 7. Delmo Walter EM, Komoda T, Siniawski H, Hetzer R. Repair strategies in hammock and parachute mitral valves in infants and children. Thorac cardiovasc Surg. 2012;60:37. 8. Hetzer Roland, Delmo Walter Eva Maria. No ring at all in mitral valve repair: indications, techniques and long-term outcome. Eur J Cardiothorac Surg. 2014, 30. PubMed PMID: 23818567.
