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Spontaneous Left Atrial Echocardiographic Contrast in Mitral Stenosis: Early Disappearance After Valve Replacement
Spontaneous Left Atrial Echocardiographic Contrast in Mitral Stenosis: Early Disappearance After Valve Replacement Paolo Voci, MD, Giovanni Scibilia, MD, Federico Bilotta, MD, Bruno Maugeri, MD, Quintilio Caretta, MD, Corrado Mercanti, MD, Benedetto Marino, MD, and Attilio Reale,t MD, FESC, FACC, Rome) Italy
We describe a patient with mitral stenosis and severely enlarged left atrium. Transthoracic echocardiography showed a false image of intraatrial thrombus, whereas transesophageal echocardiography showed massive spontaneous left atrial contrast. Intraoperative transesophageal echocardiography was performed. During cardioplegic arrest the contrast was enhanced, but it gradually and completely cleared 15 minutes after cardiopulmonary by-pass arrest. Transesophageal echocardiography is a useful technique for the study of intraatrial masses and may bring a new dimension to tissue characterization studies. (J AM Soc ECHOCARDIOGR 1991;4:648-50.)
Transesophageal echocardiography, in comparison with transthoracic echocardiography, provides a better visualization of the cardiac structures near the esophagus l,2 and may help in differentiating dynamic phenomena such as intra-atrial spontaneous contrast from fixed images of intracavitary thrombus. 3,4 This article describes a patient with mitral stenosis and severely enlarged left atrium. Transthoracic echocardiography showed a false image of intra-atrial thrombus, whereas transesophageal echocardiography showed an entirely different pattern of echoes, attributable to massive spontaneous contrast, which was reversible early after mitral valve replacement. CASE REPORT
A 71-year-old man with severe mitral valve stenosis (New York Heart Association functional class IV) was admitted to our department. The transthoracic echocardiogram showed a slightly calcified mitral valve. The Doppler-estimated pressure gradient between the left atrium and the left ventricle was 23 From the Section of Cardiology II and the Department of Cardiac Surgery, La Sapienza University of Rome. tDeceased. Reprint requests: Paolo Voci, MD, Istituto di Cardiochirurgia, Policlinico Umberto I, Universita degli Studi di Roma La Sapienza, Viale del Policlinico, 00161 Rome, Italy. 27/1131449
648
(protodiastolic), 14 (mesodiastolic), and 10 (telediastolic). The calculated orifice area was 0.6 cm2 • There were no Doppler signs of mitral regurgitation. The left atrium was extremely enlarged, with a posterior-anterior diameter of 11 cm. A hyperechogenic area, suggestive of an intracavitary thrombus, was found on the posterolateral wall of the left atrium. At cardiac catheterization the diagnosis of severe mitral stenosis was confirmed, but left atriography after pulmonary angiography showed no evidence of intra-atrial thrombus. Intraoperative transesophageal echocardiographic monitoring showed the presence of massive spontaneous contrast in the left atrium but no fixed images of intracavitary thrombus (Figure 1, A through E). The entire left atrium was filled with a freely moving spontaneous contrast. Echo-silent blood entered the left atrium from the pulmonary veins (Figure 1, B). A central low-velocity jet of mitral incompetence (detected by neither transthoracic Doppler echocardiography nor angiography) advanced to the midportion of the left atrium (Figure 1, C). The contrast was enhanced during cardioplegic arrest (Figure 1, D and E) and was removed entirely by left atrial venting. After left atriotomy no intracavitary thrombus was found and the mitral valve was replaced with a Carpentier-Edwards bioprosthesis No. 31. The contrast reappeared during weaning from cardiopulmonary bypass, but with lower intensity. It cleared gradually and completely 15 minutes after cardiopulmonary bypass arrest (Figure 1, F).
Volume 4 Number 6 November-December 1991
Spontaneous left atrial echo contrast 649
Figure 1 Intraoperative transesophageal echocardiography showing the massive contrast in the enlarged left atrium (A through E). B, "Echo-silent" blood enters the left atrium from the right pulmonary veins. C, A central washout jet of mitral incompetence advances to the midportion of the left atrium. D, The left atrial cavity echogenicity is enhanced during cardioplegic arrest. E, Echo-silent blood entering from the left pulmonary veins joins the jet of mitralt"egurgitation. F, The contrast is no longer present in the left atrium 15 minutes after weaning from cardiopulmonary bypass. LA, Left atrium; MV, mitral valve; LV, left ventricle.
DISCUSSION
Transesophageal echocardiography opens a new window to the study of cardiac structures and function
that avoids the high-impedance acoustic interfaces that affect the classical transthoracic approach. Moreover, because of ultrasonic attenuation, the cardiac chambers far from the chest wall are poorly visualized
650
Journal of the American Society of Echocardiography
Voci et al.
by transthoracic echocardiography and fine changes in ultrasound reflection may be lost. In our patient, transthoracic echocardiography falsely suggested an intra-atrial thrombus instead of a more complex phenomenon of ultrasound reflection involving the entire left atrium. Transesophageal echocardiography demonstrated that the echoproducing "mass" was secondary to blood stagnation, which progressively cleared after mitral valve replacement. It is well known that flowing blood is "silent" to two-dimensional echocardiographic imaging, whereas stagnating blood increases ultrasonic scattering in vitro. 5 Transesophageal echocardiography may bring a new dimension to tissue characterization studies by improving the image quality and increasing the signal-to-noise ratio. Theoretically, the analysis of integrated backscatter signals may be used in evaluation of the concentration of cellular components of the blood. 5 This information is of potential prognostic significance in cardiology. A final consideration regards the detection of mitral incompetence by transesophageal echocardiography alone. It is well known that transthoracic echocardiography is less accurate than transesophageal echocardiography in the diagnosis of mitral regurgitation. Transthoracic Doppler echocardiography is affected by chest wall impedance, distance from the
atrioventricular plane and, in the presence of calcified or prosthetic valves, by the "flow-masking phenomenon." The discrepancy with cineventriculography may be explained by the superior sensitivity of contrast-enhanced echocardiography in detecting small jets of valvular regurgitation. 6
REFERENCES 1. Mitchell MM, Sutherland GR, Gussenhoven AI, et al. Trans·
2.
3.
4.
5.
6.
esophageal echocardiography. J AM Soc ECHOCARDIOGR 1988;1:326-77. Voci P, Maniet AR, Bilotta F, et al. Transesophageal echocardiography: the expanding role of ultrasounds in the oper· ating room. Cardiologia 1989;34:653-9. Seward JB. Cardiac tumors and thrombus: transesophageal echocardiographic experience. In: Erbel R, Khanderia BK, Brennecke R, Meyer I, Seward JB, Tajik AI, eds. Transesophageal echocardiography. Berlin: Springer Verlag, 1989: 120-8. Curtius JM. Intracardiac source of embolism. In: Erbel R, Khanderia BK, Brennecke R, Meyer I, Seward JB, Tajik AI, eds. Transesophageal echocardiography. Berlin: Springer Verlag, 1989:115-9. Yuan YW, Shung KK. Ultrasonic backscatter from whole blood. 1. Dependence on shear rate and hematocrit. J Acoust Soc Am 1988;84:52-8. Beard JT, Byrd BR. Saline contrast enhancement of trivial Doppler tricuspid regurgitation signal for estimating pulmonary artery pressure. Am J Cardiol 1988;62:486-8.
We describe a patient with mitral stenosis and severely enlarged left atrium. Transthoracic echocardiography showed a false image of intraatrial thrombus, whereas transesophageal echocardiography showed massive spontaneous left atrial contrast. Intraoperative transesophageal echocardiography was performed. During cardioplegic arrest the contrast was enhanced, but it gradually and completely cleared 15 minutes after cardiopulmonary by-pass arrest. Transesophageal echocardiography is a useful technique for the study of intraatrial masses and may bring a new dimension to tissue characterization studies. (J AM Soc ECHOCARDIOGR 1991;4:648-50.)
Transesophageal echocardiography, in comparison with transthoracic echocardiography, provides a better visualization of the cardiac structures near the esophagus l,2 and may help in differentiating dynamic phenomena such as intra-atrial spontaneous contrast from fixed images of intracavitary thrombus. 3,4 This article describes a patient with mitral stenosis and severely enlarged left atrium. Transthoracic echocardiography showed a false image of intra-atrial thrombus, whereas transesophageal echocardiography showed an entirely different pattern of echoes, attributable to massive spontaneous contrast, which was reversible early after mitral valve replacement. CASE REPORT
A 71-year-old man with severe mitral valve stenosis (New York Heart Association functional class IV) was admitted to our department. The transthoracic echocardiogram showed a slightly calcified mitral valve. The Doppler-estimated pressure gradient between the left atrium and the left ventricle was 23 From the Section of Cardiology II and the Department of Cardiac Surgery, La Sapienza University of Rome. tDeceased. Reprint requests: Paolo Voci, MD, Istituto di Cardiochirurgia, Policlinico Umberto I, Universita degli Studi di Roma La Sapienza, Viale del Policlinico, 00161 Rome, Italy. 27/1131449
648
(protodiastolic), 14 (mesodiastolic), and 10 (telediastolic). The calculated orifice area was 0.6 cm2 • There were no Doppler signs of mitral regurgitation. The left atrium was extremely enlarged, with a posterior-anterior diameter of 11 cm. A hyperechogenic area, suggestive of an intracavitary thrombus, was found on the posterolateral wall of the left atrium. At cardiac catheterization the diagnosis of severe mitral stenosis was confirmed, but left atriography after pulmonary angiography showed no evidence of intra-atrial thrombus. Intraoperative transesophageal echocardiographic monitoring showed the presence of massive spontaneous contrast in the left atrium but no fixed images of intracavitary thrombus (Figure 1, A through E). The entire left atrium was filled with a freely moving spontaneous contrast. Echo-silent blood entered the left atrium from the pulmonary veins (Figure 1, B). A central low-velocity jet of mitral incompetence (detected by neither transthoracic Doppler echocardiography nor angiography) advanced to the midportion of the left atrium (Figure 1, C). The contrast was enhanced during cardioplegic arrest (Figure 1, D and E) and was removed entirely by left atrial venting. After left atriotomy no intracavitary thrombus was found and the mitral valve was replaced with a Carpentier-Edwards bioprosthesis No. 31. The contrast reappeared during weaning from cardiopulmonary bypass, but with lower intensity. It cleared gradually and completely 15 minutes after cardiopulmonary bypass arrest (Figure 1, F).
Volume 4 Number 6 November-December 1991
Spontaneous left atrial echo contrast 649
Figure 1 Intraoperative transesophageal echocardiography showing the massive contrast in the enlarged left atrium (A through E). B, "Echo-silent" blood enters the left atrium from the right pulmonary veins. C, A central washout jet of mitral incompetence advances to the midportion of the left atrium. D, The left atrial cavity echogenicity is enhanced during cardioplegic arrest. E, Echo-silent blood entering from the left pulmonary veins joins the jet of mitralt"egurgitation. F, The contrast is no longer present in the left atrium 15 minutes after weaning from cardiopulmonary bypass. LA, Left atrium; MV, mitral valve; LV, left ventricle.
DISCUSSION
Transesophageal echocardiography opens a new window to the study of cardiac structures and function
that avoids the high-impedance acoustic interfaces that affect the classical transthoracic approach. Moreover, because of ultrasonic attenuation, the cardiac chambers far from the chest wall are poorly visualized
650
Journal of the American Society of Echocardiography
Voci et al.
by transthoracic echocardiography and fine changes in ultrasound reflection may be lost. In our patient, transthoracic echocardiography falsely suggested an intra-atrial thrombus instead of a more complex phenomenon of ultrasound reflection involving the entire left atrium. Transesophageal echocardiography demonstrated that the echoproducing "mass" was secondary to blood stagnation, which progressively cleared after mitral valve replacement. It is well known that flowing blood is "silent" to two-dimensional echocardiographic imaging, whereas stagnating blood increases ultrasonic scattering in vitro. 5 Transesophageal echocardiography may bring a new dimension to tissue characterization studies by improving the image quality and increasing the signal-to-noise ratio. Theoretically, the analysis of integrated backscatter signals may be used in evaluation of the concentration of cellular components of the blood. 5 This information is of potential prognostic significance in cardiology. A final consideration regards the detection of mitral incompetence by transesophageal echocardiography alone. It is well known that transthoracic echocardiography is less accurate than transesophageal echocardiography in the diagnosis of mitral regurgitation. Transthoracic Doppler echocardiography is affected by chest wall impedance, distance from the
atrioventricular plane and, in the presence of calcified or prosthetic valves, by the "flow-masking phenomenon." The discrepancy with cineventriculography may be explained by the superior sensitivity of contrast-enhanced echocardiography in detecting small jets of valvular regurgitation. 6
REFERENCES 1. Mitchell MM, Sutherland GR, Gussenhoven AI, et al. Trans·
2.
3.
4.
5.
6.
esophageal echocardiography. J AM Soc ECHOCARDIOGR 1988;1:326-77. Voci P, Maniet AR, Bilotta F, et al. Transesophageal echocardiography: the expanding role of ultrasounds in the oper· ating room. Cardiologia 1989;34:653-9. Seward JB. Cardiac tumors and thrombus: transesophageal echocardiographic experience. In: Erbel R, Khanderia BK, Brennecke R, Meyer I, Seward JB, Tajik AI, eds. Transesophageal echocardiography. Berlin: Springer Verlag, 1989: 120-8. Curtius JM. Intracardiac source of embolism. In: Erbel R, Khanderia BK, Brennecke R, Meyer I, Seward JB, Tajik AI, eds. Transesophageal echocardiography. Berlin: Springer Verlag, 1989:115-9. Yuan YW, Shung KK. Ultrasonic backscatter from whole blood. 1. Dependence on shear rate and hematocrit. J Acoust Soc Am 1988;84:52-8. Beard JT, Byrd BR. Saline contrast enhancement of trivial Doppler tricuspid regurgitation signal for estimating pulmonary artery pressure. Am J Cardiol 1988;62:486-8.