Published by Elsevier on behalf of the American College of Cardiology Foundation. This is an open access article under the
CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
CASE
HISTORY OF PRESENTATION. A 38-year-old asymp-tomatic white male consulted for a routine checkupwith his general practitioner who noticed a 3/6 pro-tomesosystolic heart murmur at the left lower sternalborder. The rest of the physical examination wasnormal. The patient was referred to the authors’
EARNING OBJECTIVES
Transthoracic echocardiography is the ex-amination of choice in the presence of a newor loud ($3/6) systolic heart murmur.Parachute mitral valve is a rare congenitalanomaly, usually diagnosed in childhood,which is defined as the attachment of allmitral chordae tendinae to 1 papillary mus-cle, which typically leads to mitral stenosisand is often associated with left ventricularoutflow obstructions.A multidisciplinary team approach should beencouraged in associated congenital cardiacanomalies, in which no specific recommen-dations apply.
N 2666-0849
m the aService of Cardiology, Geneva University Hospitals, Geneva, Swi
spitals, Geneva, Switzerland; and the cService of Cardiovascular Surgery,
e authors have reported that they have no relationships relevant to the c
ormed consent was obtained for this case.
nuscript received September 17, 2019; revised manuscript received Nove
outpatient clinic for a transthoracic echocardiogram,which showed an abnormal mitral valve with likely 1single posteromedial papillary muscle but withoutsignificant valve dysfunction. Attached to theanterior mitral leaflet was a supplementary mobilestructure protruding into the left ventricularoutflow tract (LVOT), causing an obstruction. Theseverity of LVOT obstruction was difficult to assess,but a peak velocity of almost 4 m/s (maximalgradient, 47 mm Hg) was measured using a Pedofftransducer in nonstandard right parasternal views(Figure 1, Video 1).
DIFFERENTIAL DIAGNOSIS. The supplementaryecho structure inserted to the anterior mitral leafletcould correspond to a vegetation or to a primary orsecondary cardiac tumor. However, in the absence ofsymptoms or signs and of any mitral valve dysfunc-tion, the first differential diagnosis was a congenitalabnormal mitral valve, likely a parachute mitral valve(PMV), associated with supernumerary tissue causingLVOT obstruction.
INVESTIGATIONS. Transesophageal echocardiogra-phy visualized a parachute-like structure attached tothe anterior mitral leaflet and protruding through theaortic valve. In short-axis views, the obstruction was
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tzerland; bDivision of Radiology, Geneva University
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well characterized in the LVOT with bloodonly flowing around the parachute-likestructure, which seemed impermeable(Figure 2, Videos 2 and 3). Cardiac resonancemagnetic imaging did not reveal any othercongenital defects but confirmed the PMVwith all chordae attached to the poster-omedial papillary muscle. A very smallanterolateral papillary muscle was detectedwithout any attachment to it. The parachute-like membrane was better characterized as a
E 1 Transthoracic Echocardiography
cessory mitral valve tissue (AMVT) protruding through the aortic v
leaflet (AML), parasternal short-axis view. (C) Single posteromed
in the left ventricular outflow tract measured by continuous wa
deo 1.
membranous accessory mitral valve tissue (AMVT)with insertions on both the anterior mitral leaflet andthe posteromedial papillary muscle (Figure 3, Video4). Maximal cycle ergometer exercise testingshowed only a mild reduction of exercise capacity,corresponding to 8.5 metabolic equivalent of task(78% of predicted value) with a normal heart rate buta blunted blood pressure response with a peak valueof 170/75 mm Hg. Finally, exercise echocardiographyrevealed a significant increase of LVOT obstructionwith a peak measurable gradient of 60 mm Hg.
alve, parasternal long-axis view. (B) AMVT attached to the anterior
ial papillary muscle (PM), parasternal short-axis view. (D) High ve-
ve Doppler (Pedoff transducer), nonstandard right parasternal view.
(A) AVMT membrane protruding through the AV and attached to the AML, mid-esophageal long-axis view. (B) AVMT membrane protruding
between opened AL, mid-esophageal short-axis view. (C) Anterograde aortic flow around the AVMT membrane on color Doppler,
mid-esophageal long-axis view. (D) Anterograde aortic flow around AVMT membrane on color Doppler, mid-esophageal short-axis view. See
Videos 2 and 3. AL ¼ aortal valve leaflets; AV ¼ aortic valve; other abbreviations as in Figure 1.
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MANAGEMENT. This case was discussed in a multi-disciplinary meeting with congenital heart diseasespecialists and congenital cardiac surgeons. Those infavor of an intervention pointed out the presence ofsignificant LVOT obstruction that could eventuallybecome symptomatic or even cause sudden death andthe possible thromboembolic risk related to thepresence of a significant amount of AMVT. Those notin favor of an intervention noted the absence ofsymptoms and the risk of destabilizing the geometryof the mitral valve by excising AMVT, which could
require mitral valve repair or even replacement. Thepatient was informed of the risk-benefit balance andfinally opted for surgery. Open heart surgery withsubtotal resection of the parachute-like membranethrough aortotomy was performed (Figure 4). Greatcare was taken to avoid injury of primary chordaeand subsequent destabilization of the mitral valve.A small part of the AMVT was left in place becauseit was too close to the anterior mitral leaflet toallow resection without risking significant valveinsufficiency.
AMVT attached to both the AML and the posteromedial PM on a long-axis view, cine
cardiac MRI images. See Video 4. LA ¼ left atrium; LV ¼ left ventricle; MRI ¼ magnetic
resonance imaging; other abbreviations as in Figure 1.
FIGURE 4 Surgica
TABLE 1 Evolution of Exercise Capacity Before and 6 Months
After Surgery*
Before Surgery6 Months
After Surgery
Power output (W) 161 238
Metabolic equivalent of task 8.5 10
Percentage of predicted value* 78 114
*The percentage of predicted value presented in the table are derived fromequations of: Hansen JE, Sue DY, Wasserman K. Predicted values for clinical ex-ercise testing. Am Rev Respir Dis 1984;129:S49–55.
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DISCUSSION
PMV is a rare congenital anomaly defined as theattachment of all mitral chordae tendinae toone papillary muscle. Its origin seems to be an
l View of the Accessory Mitral Valve Tissue
abnormal division of the predecessor of the papillarymuscle between the 5th and 19th weeks of gestation,forcing them to condense into a single muscle. Thechordae tendinae in PMV are often underdevelopedand hence short and thick, leading to decreasedmobility of the valve leaflets causing mitral stenosis.Mitral regurgitation is also often present due to aprolapsing mechanism. True PMV is distinguishedfrom parachute-like mitral valve, defined as 2 asym-metrical papillary muscles with most of the chordaeattached to 1 of them, the small anterolateral papil-lary muscle is located higher in the left ventricularwall (1). Most cases of PMV are associated with othercongenital heart disorders. Shone et al. (2) described aclassical association of 4 obstructive malformationsknown as Shone’s complex and consisting of PMVwith a supravalvular ring of the left atrium, subaorticstenosis, and coarctation of the aorta. Most patientsare symptomatic during childhood, and asymptom-atic PMV in adults is a rare condition. Hakim et al. (3)reported 10 cases of isolated PMV discovered inadults, only 1 of whom was asymptomatic at the timeof diagnosis.
Evidence is scarce about the management ofasymptomatic subaortic obstructions in publishedstudies (4). Most often it is caused by a membraneattached to the aortic valve, causing valvulardysfunction. In the present case, subaortic obstruc-tion was caused by this large AMVT prolapsing intothe LVOT. AMVT is a rare condition, with an inci-dence of 1/26,000 persons according to Prifti et al. (5),and none of the reported cases were similar to thepresent case (6,7).
FOLLOW-UP. Perioperative outcome showed suc-cessful relief of the obstruction by the AMVT and mildmitral regurgitation. Postoperative course was un-eventful with the exception of a readmission 2 weeksafter discharge for pericarditis, successfully treatedby using nonsteroidal anti-inflammatory drugs. Thepatient participated in a cardiac rehabilitation pro-gram and showed significant improvement of exer-cise capacity (Table 1). He remained totally
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asymptomatic without exercise intolerance andtransthoracic echocardiography at 6 months did notshow any progression of mitral regurgitation.
CONCLUSIONS
This paper describes the case of an incidentallydiagnosed PMV that was unusually associated with a
large parachute-like membranous AMVT causing sig-nificant LVOT obstruction and that was successfullyresected by open heart surgery.
ADDRESS FOR CORRESPONDENCE: Dr. PhilippeMeyer, Cardiology Service, Geneva University Hospi-tals, Rue Gabrielle Perret-Gentil 4, 1205 Geneva,Switzerland. E-mail: [email protected].
RE F E RENCE S
1. Oosthoek PW, Wenink AC, Wisse LJ, Gitten-berger-de Groot AC. Development of the papillarymuscles of the mitral valve: morphogeneticbackground of parachute-like asymmetric mitralvalves and other mitral valve anomalies. J ThoracCardiovasc Surg 1998;116:36–46.
2. Shone JD, Sellers RD, Anderson RC, Adams P Jr.,Lillehei CW, Edwards JE. The developmentalcomplex of “parachute mitral valve,” supravalvularring of left atrium, subaortic stenosis, and coarc-tation of aorta. Am J Cardiol 1963;11:714–25.
3. Hakim FA, Kendall CB, Alharthi M, Mancina JC,Tajik JA, Mookadam F. Parachute mitral valve inadults-a systematic overview. Echocardiography2010;27:581–6.
4. Stout KK, Daniels CJ, Aboulhosn JA, et al. 2018AHA/ACC guideline for the management of adultswith congenital heart disease: a report of theAmerican College of Cardiology/American HeartAssociation task force on clinical practice guide-lines. J Am Coll Cardiol 2019;73:e81–192.
5. Prifti E, Bonacchi M, Bartolozzi F, Frati G,Leacche M, Vanini V. Postoperative outcome inpatients with accessory mitral valve tissue. MedSci Monit 2003;9:RA126–33.
6. Li Y, Hu Y, Wang J, Liu L. A rare case ofaccessory mitral valve tissue causing left ventric-ular outflow tract obstruction associated withparachute mitral valve, ventricular septal defect,bicuspid aortic valve, unruptured aneurysm of
aortic sinus: a case report. Eur Heart J Case Rep2018;2:yty082.
7. Nikolic A, Joksimovic Z, Jovovic L. Exuberantaccessory mitral valve tissue with possible trueparachute mitral valve: a case report. J Med CaseRep 2012;6:292.
KEY WORDS congenital heart disease,echocardiography, mitral valve, MRsequences
APPENDIX For supplemental videos,please see the online version of this paper.
