39-year-old female with no significant past medical history presented to her primary care physician’s office with exertional dyspnea and fatigue since 2 months and intermittent atypical chest pain. She denied other possible cardiac symptoms (palpitations, paroxysmal nocturnal dyspnea, orthopnea, edema or syncope) and had no fever, weight loss or change in appetite.
On examination, she was comfortable and looked well with a blood pressure of 120/82, pulse of 70 bpm, respiratory rate of 14, no fever, and 100% saturation on room air. Jugular veins were not distended and there were no carotid bruit. Precordial examination revealed a normal non-displaced apex without thrills or heaves.
Auscultatory findings: An early diastolic heart sound was detected, especially with the patient seated and leaning forward (video-audio file 1 of phonocardiogram). Peripheral pulses were normal and there was no edema. The remaining physical examination was normal.
What is the most likely etiology of the diastolic heart sound?
Show Answer
The correct answer is: C. Tumor plop.
The four diastolic heart sounds presented in the options are the—the opening snap of rheumatic mitral stenosis, the third heart sound (S3) of left ventricular failure, the pericardial knock of constrictive pericarditis, and the tumor plop of left atrial myxoma.
Myxomas are the most common type of primary heart tumor.(1) The tumor is derived from multipotential mesenchymal cells and may cause a ball valve-type obstruction. About 80% of myxomas occur in the left atrium of the heart.Left atrial tumors thus may simulate mitral valve disease. Commonly observed symptoms include dyspnea and fatigue. Symptoms may be worse in certain body positions, due to motion of the tumor within the atrium .Constitutional symptoms (e.g., weight loss, fever) are reported due to the production of various cytokines and growth factors by the tumor. Only 4% remain completely asymptomatic.(2) Embolization of systemic or pulmonary circulation is a frequent phenomenon and is observed in about 30–40% of patients.(3)
On physical examination, a characteristic "tumor plop" may be heard early in diastole. This sound may also arise from ventricular inflow obstruction and associated increase in inflow blood velocity. Some patients may also have a low frequency diastolic murmur due to the functional mitral valve obstruction. Although similar in timing to mitral stenosis, the tumor plop differs from the mitral opening snap by its lower frequency sound. Though the character and intensity of the murmur due to myxoma may change with position,(4) the distinction between myxoma and mitral stenosis may be difficult.
An opening snap is a high pitched additional sound may be heard 50-100msec after the A2 (aortic) component of the second heart sound (S2), which correlates to the forceful opening of the mitral valve in mitral stenosis. This is often associated with mid diastolic rumbling murmur .The S3 is a low frequency sound occurs approximately 120 to 180 msec after S2. The pericardial knock occurs earlier than the S3 gallop, is louder and higher pitched than the S3. The knock is heard with the diaphragm over a larger area than the S3. The S3 is best heard with a lightly applied bell.
The etiology of the tumor plop sound may relate to tumor obstruction of the mitral orifice with associated high-velocity flow, although this is difficult to distinguish temporally from other reported causes such as sudden tensing of the tumor stalk or impact of the tumor against the septum.(5)
Transthoracic echocardiography on this patient revealed a large left atrial mass causing left ventricular in flow obstruction (video-audio file 2). {Transthoracic Doppler echocardiography (4 chamber view) is superimposed with audio from phonocardiography timing mitral valve closure to the first heart sound. High-velocity flow occurs with left atrial myxoma passage through the mitral orifice that appears coincident with the tumor plop sound.}
A 5 x 8 cm gelatinous left atrial mass attached to the inferior atrial septum was resected from the base and the residual atrial septal defect was closed. Myxoma was confirmed on histopathological study.
Video-audio file 3
shows 2D transthoracic echocardiography from the apical 4 chamber view post resection with normal heart sounds on phonocardiography.
File (video only) 4
shows 3D transthoracic echocardiography from the apical 4 chamber views pre and post tumor resection.
References
Vaideeswar, P.; Butany, JW. Benign cardiac tumors of the pluripotent mesenchyme. Semin Diagn Pathol. 2008;25: 20–8.
Meng Q, Lai H, Lima J, Tong W, Qian Y, Lai S. Echocardiographic and pathologic characteristics of primary cardiac tumors: a study of 149 cases. Int J Cardiol. 2002; 84:69–75.
Reynen K. Cardiac myxomas. N Engl J Med. 1995; 333:1610–1617.
Nasser WK, Davis RH, Dillon JC, Tavel ME, Helmen CH, Feigenbaum H, Fisch C. Clinical and pathologic features in nine cases. Am Heart J. 1972;83:694.
Kolluru A, Desai D, Cohen GI. The etiology of atrial myxoma tumor plop. J Am Coll Cardiol. 2011;57:e371.
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