ultrasound in the diagnosis of left atrial myxoma

DOI 10.1378/chest.79.3.322 1981;79;322-326Chest

D R Boughner and J A Persaud ultrasound in the diagnosis of left atrial myxoma.Transcutaneous continuous wave Doppler

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Transcutaneous Continuous Wave Doppler

322 BOUGHNER, PERSAUD CHEST, 79: 3, MARCH, 1981

Ultrasound in the Diagnosis of Left Atrial

Myxoma*Derek R. Boughner, M.D., Ph.D.,t and Joan A. Persaud

Six cases of left atrial myxoma were studied using trans-

cutaneous, continuous-wave, low-frequency Dopplerultrasound. The recordings, made from the suprasternalnotch and the cardiac apex, showed characteristic de-

L eft atrial myxoma often can mimic the clinical

and hemodynamic features of mitral valve dis-

ease’4 and, until recently, could only be diagnosed

with certainty at cardiac catheterization. The intro-

duction of time-motion echocardliography has made

the diagnosis of these tumors simpler and more ac-

curate, although difficulties with the technique may

occasionally be encountered.4’5 Two-dimensional

echocardiography has provided further accuracy,6

but the high equipment costs have limited its avail-

ability.

This report outlines the value of an alternative,

relatively inexpensive ultrasound technique-con-

tinuous-wave Doppler ultrasound-for supporting

the noninvasive diagnosis of left atrial myxoma. The

technique has proved useful in other cardiac disor-

ders by providing an ancillary method of confirming

and grading such lesions as aortic insufficiency,7

mitral insufficiency,8 mitral stenosis,9 and idiopathic

hypertrophic subaortic stenosis.1#{176} To our knowl-

edge, its value in the diagnosis of atrial myxoma has

not been described.

METhOD

Six patients with left atrial myxoma were studied. Eachpatient underwent the following procedures: (1) standardtime-motion echocardiography preoperatively and postopera-tively, (2) transcutaneous, low-frequency, 2.2 MHz, continu-ous-wave directional Doppler ultrasound recordings preoper-

atively and postoperatively, (3) preoperative angiography,

and (4) successful surgical removal of the tumor.

The time-motion echocardiograjn and the continuous-waveDoppler recordings could not be made simultaneously, since

the repetition rate of the echocardiograph equipment pro-

#{176}From the Cardiac Investigation Unit� University Hospital,Departments of Medicine and Biophysics, University ofWestern Ontario, London, Ontario, Canada.

fOntario Heart Foundation Senior Research Fellow,Manuscript received January 31; revision accepted April 28.Reprint requests: Dr. Boughner, Cardiac Investigation Unit,University Hospital, FOB 5339, Terminal A, London, On-tario, Canada N6A 5A5

flections that coincided with tumor motion and provideda useful ancillary technique for noninvaslvely confirm-

ing the echocardlographic diagnosis of adrial myxoma.

duced continuous interference on the Doppler recording. The

recordings were therefore made separately but within min-utes of each other. Both suprasternal and apical Doppler

recordings were made. The suprasternal recordings, which

provided the aortic blood velocity estimates, were performedwith the transducer positioned in the suprasternal notch andaimed downwards and posteriorly so that the beam crossedthe descending aortic arch at an angle approximately parallelto blood flow.7,8,11,12 Doppler ultrasound provides a veloc-ity estimate of intravascular blood flow by measuring the

frequency of a sound beam reflected from moving RBCs. The

reflected frequency is compared with the frequency original-

ly emitted, and the resulting frequency shift, which is direct-

1y proportional to the absolute velocity of the cells, is re-corded. The accuracy of the velocity estimate so obtained is

affected primarily by the angle of incidence of the soundbeam with the moving particles. The ultrasound beam, aimedat the aortic arch from the suprasternal notch, crosses theaorta at an angle nearly parallel to blood flow so that a goodestimate of blood velocity is obtained. The equipment usedfor the study was “directional,” being able to differentiateflow away from the transducer from flow toward the trans-ducer.

The normal Doppler aortic blood velocity pattern has a

parabolic contour with a rapid rise in blood velocity onsettingwith the first heart sound and rapid fall to zero velocity

coincident with the dicrotic notch of the carotid pulsetracing.7’8 Little blood flow is normally recorded in diastole,and the tracing is generally free of deflections during this

period.The Doppler tracings made at the cardiac apex, with the

transducer aimed posteriorly and medially toward the mitral

valve orifice, have a pattern that is totally different from theaortic blood velocity pattern.9’13 Such tracings show an onsetof blood flow toward the transducer with the opening of themitral valve and the abrupt cessation of flow with the onset of

the first heart sound. Systolic velocity away from the trans-ducer may be recorded if the ultrasound beam crosses theleft ventricular outflow tract.

RESULTS

The echocardiograms in five of the six cases

showed multiple layered echoes from both the mitral

orifice during dliastole (Fig 1 and 2) and the left

atrium during systole and diastole (Fig 2). At sur-



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CHEST, 79: 3, MARCH, 1981 DIAGNOSIS OF LEFT ATRIAL MYXOMA 323

FscunE 1. Echocardiogram from a 39-year-old woman with large left atrial myxoma.Multiple layered echoes within mitral ori-fice during diastole.

Ficunx 2. Echocardiogram from a 33-year-old woman with small left atrialmyxoma. A few layered echoes appear with-in mitral orifice after valve opening is com-plete.

gery, these five patients had the largest tumors,

measuring from 4.0 to 6.3 cm in their longest axes. In

the sixth case, the echocardiogram (Fig 3) showed

findings compatible with a small myxoma.14 Layered

ethoes appeared within the mitral valve orifice after

the leaflets had opened, while no abnormal echoes

could be recorded from within the left atrium.

The patient had no abnormalities on physical exam-

ination and was complaining only of extrasystoles.

At surgery, a small myxoma measuring 3.0 X 2.8 X 2

cm was removed.

In the five patients with larger tumors, the echoes

from the left atrium demonstrated the pattern of

tumor motion during the cardiac cycle (Fig 3). The

tumors moved posteriorly into the atrium at the

onset of systole and then anteriorly downward into

the mitral orifice early in diastole. The latter motion

corresponded with the “tumor piop” recorded on the

phonocardiogram 100 msec after the aortic compo-

nent of the second heart sound.’5

The Doppler aortic blood velocity recordings in

those five patients showed a prominent artifact not

observed in normal subjects or in patients with other

disorders. A prominent deflection “toward” the

transducer coincident with the first heart sound was

noted, followed by the normal pattern of aortic

blood velocity. A second prominent deflection “away

from” the transducer occurred coinciding with the

“tumor plop” on the phonocardiogram (Fig 4).

These prominent deflections, which were separate

from the blood velocity recording, disappeared in all

patients postoperatively and were absent or only



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324 BOUSHNER, PERSAUD CHEST, 79: 3, MARCH, 1981

Ficunsi 3. A, left. Mitral valve echogram from a 47-year-old woman with left atrial myxomashowing multiple layered echoes within orifice. B, right. Echocardiograph tracing at level

of aortic root showing motion of tumor mass within left atrium. ECG, phonocardiogram,and Doppler aortic velocity tracing recorded minutes later are superimposed. For purposesof illustration a single cardiac cycle from recording was cut and placed on echo tracing.This has been divided and aligned so that relationship of QRS complex to various wave

forms has been preserved. QRS complex on echogram is partially obscured by atrial wallechoes. Tumor can be seen to move posteriorly relative to transducer coincident with firstheart sound, and anteriorly toward transducer at time of “tumor plop” on phonocardiogram.

Movements coincide with deflections (shaded spikes) on the Doppler aortic velocity tracingas illustrated. Movement “toward” transducer plotted inverted, and “away from” transduceris upright. Forward blood velocity in aortic arch “away from” transducer in systole is plottedupright (shaded area).

suggestive in the sixth patient with the small myxo- transducer.1’ In addition, large deflections at the

ma. onset of transvalvular flow were recorded, indicating

At the apex, the Doppler recordings showed the the movement of the tumor mass toward the trans-

reported pattern of diastolic blood flow toward the ducer, and at the end of dliastole there was a similar

FIGURE 4. Aortic arch blood velocity trac-ing from 39-year-old woman (Fig 1).

Recordings were made from suprasternalnotch before and after operative removalof large atrial myxoma. Forward flow insystole (upright shaded areas) was nor-mal in both instances. Large deflections“toward” and “away from” transducer

(shaded spikes), coincident with first

heart sound and tumor plop, respectively,were recorded preoperatively and absentpostoperatively. Tracing enhanced forreproduction.



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.

CHEST, 79: 3, MARCH, 1981 DIAGNOSIS OF LEFT ATRIAL MYXOMA 325

FIGURE 5. Mitral orifice blood velocity from 36-year-old manrecorded by placing transducer at cardiac apex and aimingbeam posteriorly and medially until peak diastolic velocityhas been obtained. Flow through valve onsets with a largedeflection “toward” the transducer (shaded area) as atrialtumor moves downward into orifice and ends with similar(shaded) deflection “away from” transducer at onset of

systole. Enhanced for reproduction.

deflection, indicating movement of the tumor mass

away from the transducer as valve closure occurred

(Fig 5). This pattern was clearly evident in the

patient with the small myxoma where Doppler re-

cordings from the suprasternal notch had been nor-

mal. A variable amount of systolic flow “away from”

the transducer was usually recorded representing

either a minor degree of mitral regurgitation or the

outflow tract blood velocity.

DIscussioN

The echocardiograms from the five patients with

large tumors were typical for atrial myxoma, while

the sixth tracing from the patient with the small

myxoma was highly suggestive. In all patients, the

Doppler technique provided supporting evidence

for the myxoma diagnosis, with final confirmation

being provided by angiography and surgery. Despite

the success of the echo technique in these patients,

there is the potential for the unwary echocardiog-

rapher to confuse a variety of lesions with a myx-

oma. Such difficulties have been described in pa-

tients with bacterial endocarditis and large mitral

vegetations,4’5’16 redundant prolapsing mitral valve,5

calcific mitral stenosis,4 and a calcified mobile

left atrial thrombus.4’5 However, our experience

has shown that normal Doppler ultrasound record-

ings are the rule in patients with bacterial endocar-

ditis and mitral prolapse, while the apical Doppler

pattern in mitral stenosis has an appearance charac-

teristic for that disorder9 with no evidence of the

large deflections seen in atrial myxoma. Thus, the

Doppler technique could be helpful in differentiat-

ing these lesions. We have had no opportunity to

study a patient with a mobile atrial thrombus, but

suspect that the Doppler technique would be of

little value there, since both a myxoma and a clot

of that type would represent mobile atrial masses.

Ball valve prostheses produce deflections on the

aortic Doppler recording similar to those seen with

an atrial myxoma.7 With an aortic valve prosthesis,

movement of the ball produces vibrations on the

suprastemal notch recordings that coincide with the

heart sounds-a sharp motion “toward” the trans-

ducer coincident with the first heart sound and a

similar spike “away from” the transducer coincident

with the second sound. Although their timing differs

from that seen with an atrial myxoma, the mecha-

nism by which the Doppler artifact is produced

appears to be similar. A ball or disc valve prosthesis

in the mitral position produces a pattern8 identical

in timing to that seen with a myxoma.

The size of the tumor moving within the left

atrium apparently is important in producing the

changes in the aortic velocity tracing. In our patient

with the smallest tumor, the Doppler recordings

from the suprasternal notch were normal, while the

other five patients, with tumors measuring from 4

cm to 6.3 cm in their longest axes, all had easily

identifiable abnormalities.

Our interpretation of the Doppler recordings

made from the suprasternal notch was as follows.

The defiections recorded before the onset of systole

and then again in early diastole did not represent

movement of blood within the aorta, since the aortic

valve was closed in both instances. These deflections

were more likely artifacts produced by motion of the

whole mediastinum in response to the movement of

the tumor, in much the same way that heart sounds

produce high-amplitude, low-frequency tissue vi-

brations. The latter are specifically filtered out by

the equipment. Thus, the downward movement of

the tumor coming to rest within the mitral orifice

caused a downward movement of the mediastinal

structures lying in the path of the ultrasound beam

producing a large deflection “away from” the trans-

ducer. Similarly, as the tumor mass came to rest

within the left atrium at end diastole, it produced

vibrations “toward” the transducer.

This interpretation of the aortic velocity record-

ings was supported by the motion of the tumor

visualized on the echocardiogram (Fig 3), where

the movements coincided with the Doppler deflec-

tions, and was further supported by the apical

Doppler recordings that looked directly at the mo-



326 BOUGHNER, PERSAUD CHEST, 79: 3, MARCH, 1981

bile tumor mass. In the latter case, the direction of

the deflections was reversed relative to the trans-

ducer, since the transducer was then positioned at

the cardiac apex, ie, below the tumor.

In addition, we noted that the initial mediastinal

vibration recorded by the Doppler equipment was

coincident with the first heart sound. This supports

the concept that a loud first heart sound, common in

left atrial myxoma, is due in part to movement of

the tumor mass.’4 The second deflection occurring

in early diastole was coincident with the “tumor

plop” recorded on the phonocardiogram. In the pa-

tient with a small myxoma, these vibrations were

absent, and physical examination was normal.

In summary, previous studies have shown that

continuous-wave Doppler ultrasound is a helpful,

noninvasive technique that can provide useful quali-

tative information in some patients with valvular

and myocardial disorders.7’#{176} In this study, we have

demonstrated the ability of that technique to pro-

vide supportive evidence regarding the presence of a

left atrial myxoma.

ACKNOWLEDGMENT: The authors wish to thank theOntario Heart Foundation for their support and the BachSimpson Co. Ltd. for providing the ultrasound equipment.

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DOI 10.1378/chest.79.3.322 1981;79; 322-326Chest

D R Boughner and J A Persaudatrial myxoma.

Transcutaneous continuous wave Doppler ultrasound in the diagnosis of left

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