Mitral Valve Prolapse Simulating Left Atrial Myxoma

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GRAPHIC TECHNIQUES IN CARDIOLOGY

Mitral Valve Prolapse Simulating Left Atrial Myxoma* Noninvasive Correlation with Angiographic Findings Artur DeSa'Neto, M.D.; Haim Zeev BartaU, M.D .; Kenneth B. Desser, M.D.; F.G.G.P.; and Alberlo Benchimol, M.D., F.G.G.P.

patterns of "pseudomyxoma.P We present herein the noninvasive and angiographic findings from a patient with mitral valve prolapse who had abnormal echoes superficially suggesting left atrial myxoma.

M-mode echocardiography represents the most widely employed noninvasive technique for the diagnosis of left atrial myxoma. A mass or cloud of echoes behind the anterior leaflet of the mitral valve in diastole which move into the left atrium during systole are well-recognized ultrasonic hallmarks of this entity. Of all potential diseases which might mimic left atrial myxoma on the M-mode echogram, mitral valve prolapse is most frequently encountered. Indeed, a mass of echoes behind the mitral valve during diastole has been described in patients with prolapse of the mitral valve.' It has furthermore been stated that the absence of intraatrial echoes in such patients should help to identify

A 14-year-old girl was discovered to have a cardiac murmur during her annual physical examination for school and was referred to the Institute for Cardiovascular Diseases at Good Samaritan Hospital, Phoenix, Ariz, for further evaluation. Pertinent findings on physical examination were as follows: There was mild pectus excavatum. The point of maximum cardiac impulse was localized in the flfth intercostal space at the left midclavicular line. On auscultation, there was a regular heart rate at 90 beats per minute, with normal first and second heart sounds. A loud third heart sound was audible at the apeL A midsystolic click was heard and recorded over the entire precordium. The click was followed by a grade-3/6 late systolic murmur which was best heard at the mitral and tricuspid areas and which radiated to the axilla (Fig 1).

°From the Institute for Cardiovascular Diseases, Good Samaritan Hospital Phoenix, Ariz. Supported in part by the E. Nichols and Kim Sigsworth Memorial Funds and by the Institute for Cardiovascular Diseases, Inc. Reprint requests: Dr. Benchimol. Good Samaritan HQ8J1ital, 1033 East McDoweU, Phoenix 85006 Hz

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1. Simultaneously recorded phonoeardiograms of mitral area (MA), tricuspid area (TA), pulmonic area (PA), and aortic area (AA); lead 2 (LU) of ECG; and external carotid pulse tracing (CT). A (left), Note mid5Ystolic click (C) and late systolic murmur (SM ). Third heart sound (3) is recorded best at mitral area. ON, Dicrotic notch; 1, first heart sound; and 2, second heart sound. B ( center), High-frequency phonocardiogram demonstrates midsystolic click (C) and late systolic murmur (SM). C ( right), Apexeardiogram (ACG) demonstrates midsystolic retraction and late systolic bulge (SB). FiCURE

CHEST, 78: I, JULY, 1980

MITRAL VALVE PROLAPSE 87

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FIGURE 2. M-mode echocardiograms. A (left), Recording at level of mitral valve demonstrates late systolic prolapse and mass (M) of echoes behind anterior mitral valve leaflet (AMY) during diastole. IVS, Interventricular sephun; and Lil, lead 2 of ECG. B (right), Recording at level of aortic valve (AV) and left atrium (LA) discloses mass (M) of echoes in atrium during systole. AO R, Aortic root. An M-mode echocardiogram revealed late systolic prolapse of the mitral valve, along with a mass of echoes behind the anterior mitral valvular leaflet during diastole. When the transducer was directed to the left atrial region, a mass of echoes was recorded during ventricular systole (Fig 2) . A real-time sector scan demonstrated marked prolapse of both anterior and posterior leaflets of the mitral valve and a mass of echoes which appeared at the mitral valve orifice in middiastole. Opacification of the left atrium via a pulmonary angiogram revealed no filling defect. Left ventriculograms in the right anterior oblique projection delineated n'iitral valve prolapse and a thickened redundant posterior mitral valve leaflet which appeared at the mitral valve orifice during middiastole (Fig 3 ). DISCUSSION

False-positive M-mode echocardiographic diagnoses of atrial myxoma have been described in subjects with mitral stenosis and a heavily calcified posterior leaflet," marked prolapse of the mitral valve, 1 nonbacterial thrombotic lesions of the mitral valve, and ruptured chordae tendineae." Mitral

valve prolapse is a relatively frequent finding on the echocardiograms of young women, and coincidental association with other cardiac disorders, such as atrial myxoma, has been anticipated. The phonocardiographic findings and pulse-wave abnormalities associated with left atrial myxomas have been reviewed in detail by Nasser et al.4 The combination of a widely split or prolonged first heart sound and diastolic "plop" of a tumor was considered a strongly suggestive finding. A prominent systolic notch on the apexcardiogram is a distinctive noninvasive concomitant of left atrial myxoma. Auscultatory findings and their graphic representation on the phonocardiogram, along with a midsystolic retraction on the apexcardiogram, were consistent with the diagnosis of mitral valve prolapse in the subject described herein; however, the M-mode echocardiographic findings suggested the presence of a left atrial mass. Midsystolic posterior buckling motion of the mitral valve has been noted

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FIGURE 3. Angiograms in right anterior oblique projection. A (left), Levophase opacification of left atrium (LA), left ventricle (LV), and aorta (AO) demonstrates mitral valve prolapse (P) . There is no filling defect within left atrium (LA). B (center), Left ventricular angiogram during middiastole shows thick redundant posterior mitral valve leaflet in region of mitral ring (M). C (right), Left ventriculogram discloses marked systolic prolapse of mitral valve and mitral insufficiency.

88 DISI'NETO ET AL

CHEST, 78: 1, JULY, 1980

on the echocardiogram of a patient with left atrial myxoma.II 'These tumors have been demonstrated to produce structural abnormalities of the mitral valve as a result of continuous friction by the mass uponits atrial surface.v" Indeed, ruptured chordae tendineae and mitral regurgitation can arise in such cases in the setting of a "wrecking-ball syndrome." The findings from angiograms and cross-sectional short-axis sector scans in the subject described herein provide a basis for the pattern of "pseudomyxoma" observed on the M-mode echocardiogram. The redundant mitral valve tissue produced masslike echoes beneath the anterior mitral valvular leaflet during diastole and similar echoes within the left atrium during systole. Implications provided by this report are clear. In the absence of classic auscultatory signs or clinical symptoms that are considered diagnostic of left atrial myxoma, echoes indicating a "mass" beneath the anterior mitral valve leaflet and within the left atrium should be viewed with caution in subjects with midsystolic clicks, late systolic murmurs, and Mmode ultrasonic evidence of mitral valve prolapse. In such cases the presence of a normal E-F slope and isolated late diastolic subvalvular "mass effect" may provide clues for proper diagnosis.

CHEST, 78: 1, JULY, 1980

ACKNOWLEDGMENTS: We wish to acknowledge the technical assistance of Ms. Kathy Tustison, Ms. Sydney Peebles, Ms. Carole Crevier, Mr. Denzil Solomon, Ms. Ida Mack, Ms. Joanne Riley, Ms. Saundra Morgan, and Ms. Betty Kjellberg.

1 Chang S: M-Mode Echocardiographic Techniques and Pattern Recognition. Philadelphia, Lea and Febiger, 1976 2 Feigenbaum H: Echocardiography. Philadelphia, Lea and Febiger, 1976, p 456 3 Gramiak R. Nanda NC: Mitral valve. In Gramiak R. Waag RC (eds): Cardiac Ultrasound. St. Louis, CV Mosby Co, 1976, p47 4 Nasser WI(, Davis RH, Dillon JC, et al: Atrial myxoma: 2. Phonocardiographic, echocardiographic, hemodynamic and angiographic features in nine cases. Am Heart J 83:81Q824,1972 5 DeMaria AN, Vismara LA, Miller RR. et al: Unusual echographic manifestations of right and left heart myxomas. Am J Med 59 :713-720, 1975 6 Marpole DGF, Kloster FE, Bristow JD, et all Atrial myxoma: A continuing diagnostic challenge. Am J Cardiol 23:597-602,1969 7 Carter JB, Cramer R Jr, Edwards IE: Mitral and tricuspid lesions associated with polypoid atrial tumors, including myxoma. Am J Cardiol33:914-919, 1974 8 Harvey WP: Clinical aspects of cardiac tumors. Am J CardioI21:328-343,1968

MITRAL VALVE PROLAPSE 89