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Improved Evaluation of Left Ventricular Outflow Tract Obstruction by Transesophageal Echocardiography
Improved Evaluation of Left Ventricular Outflow Tract Obstruction by Transesophageal Echocardiography Matthew E. Schwinger, MD, and Itzhak Kronzon, MD, New York, N.Y.
T
ransesophageal echocardiography is a new technique that can visualize aspects of the heart and great vessels that are inadequately evaluated by transthoracic echocardiography. The left ventricular outflow tract is usually well visualized by transthoracic echocardiography. There, however, are cases in which the left ventricular outflow tract is not adequately evaluated by transthoracic echocardiography. This may be the result of insufficient image resolution obtained by the 2.5 to 3.5 MHz transducers used in transthoracic echocardiography studies or to inadequate penetration of sound. We report two cases in which transesophageal echocardiography was able to provide superior evaluation of left ventricular outflow tract disease. CASE REPORTS
Patient I A 44-year-old man with a murmur since childhood was referred for echocardiography at another institution after a single episode of palpitations and fatigue. The echocardiogram was interpreted as showing a bicuspid aortic valve. Doppler studies suggested severe aortic stenosis. The patient was referred to our institution for cardiac catheterization, which raised the suspicion of a subaortic membrane producing a mean gradient of 44 mm Hg. The patient was then referred for transthoracic echocardiography, which indeed suggested a subvalvular membrane. The mean gradient calculated by Doppler flow velocity measurement was 43 mm Hg. To better evaluate the aortic valve, the subvalvular membrane, and the exact location of obstruction to flow, transesophageal echocardiography was performed. It clearly demonstrated a normal tricuspid From the Deparnnent of Medicine, New York University Medical Center. Reprint requests: Itzhak Kronwn, MD, 560 First Avenue-Suite 2E, New York, NY 10016.
aortic valve. The subvalvular membrane was attached to the membranous septum and to the middle portion of the anterior mitral leaflet, tethering this lea£let (Figure l,A). Color Doppler flow mapping revealed turbulent flow that started at the membrane and filled the left ventricular outflow tract and aorta (Figure l, B). The flow column across the aortic valve was wide, indicating no obstruction to flow at this level. Patient2 A 68-year-old man with severe angina was referred to our institution for coronary artery bypass grafting after cardiac catheterization elsewhere revealed severe three-vessel coronary artery disease and a mild aortic stenosis. Postoperatively the patient had severe symptomatic orthostatic hypotension with a 50 mm Hg decrease in systolic blood pressure on arising from bed. Transthoracic echocardiography was a poor quality study with nondiagnotic two-dimensional images. Continuous wave Doppler recording of left ventricular outflow tract velocity revealed that the velocity peaked late in systole at 3 m/ sec, raising a suspicion of dynamic left ventricular outflow tract obstruction. Transesophageal echocardiography clearly revealed asymmetric septal hypertrophy and systolic anterior motion of the mitral valve (Figure 2, A). Color Doppler flow mapping demonstrated turbulent flow distal to where the mitral valve strikes the septum (Figure 2, B). The left ventricle was hyperdynamic. The patient was then treated with propranolol (lnderal) and veraeamil with resolution of his symptoms. DISCUSSION
Transesophageal echocardiography can play a significant role in the evaluation of diseases of the left ventricular outflow tract. Anatomic abnormalities can be visualized in far greater detail, even when transthoracic echocardiography is of diagnostic quality, as in the first case. Transesophageal echocardi191
192 Schwinger and Kronzon
Journal of the Americau Society of Echocardiography
Figure 1 A, Two-dimensional transesophageal echocardiogram. Membrane (m) is shown in left ventricular outflow tract (ot). It is attached to membranous septum and anterior mitral leaflet (a). Subvalvular orifice diameter measures 6 mm. LA, Left atrium; LV, left ventricle. B, Color Doppler transesophageal echocardiogram. High velocity flow in left ventricular outflow tract begins at subaortic membrane (white arrow). There is a wide flow column through the aortic valve indicating normal-sized valve orifice (black arrows). R V, Right ventricle; other abbreviations as in A.
ography may be the only readily available way to diagnose left ventricular outflow tract obstruction (short of performing cardiac catheterization) when diagnostic transthoracic echocardiography images cannot be obtained, as in the second case. The higher
resolution of transesophageal echocardiography color Doppler flow mapping provides pathophysiologic information in addition to the anatomic abnormalities. Transesophageal echocardiography has become ac-
Volume 2 Number 3 May-June 1989
Evaluation of LVOT obstruction
193
Figure 2 A, Two-dimensional transesophageal echocardiogram, systolic frame. Anterior mitral leaflet (lat;ge arrows) is in contact with hypenrophied interventricular septum (S) creating obstruction between LV cavity and OT. Ao, Aona; other abbreviations as in previous figures. B, Color Doppler transesophageal echocardiogram, systolic frame. High velocity flow begins (white arrow) where mitral valve strikes interventricular septum. Wide flow column is present through normal aortic valve (black arrows). Small jet of mitral regurgitation is also present (open arrow). Abbreviations as in previous figures.
cepted for the evaluation of cardiovascular disorders that cannot be evaluted by transthoracic echocardiography, such as dissection in the descending aorta 1 and thrombi in the left atrium. 2 Two recent reports 3.4 have demonstrated that transesophageal echocardi-
ography provides significant additional morphologic and hemodynamic information in patients with subaortic membranes. We can now include evalution of left ventricular outflow tract disease in the list of indications for transesophageal echocardiography
Journal of the American Society of Echocardiography
194 Schwinger and Kronzon
when the transthoracic echocardiographic study not fully informative.
IS
REFERENCES l. Erbel R, Rennollet H, Engberding R, et a!. Detection of
aortic dissection by transesophageal echocardiography: a multicenter cooperative study [Abstract]. Circulation 1988;78 (suppl 11):297. 2. Aschenberg W, Schluter M, Kremer P, Schroder E, Siglow V,
Bleifeld W. Transesophageal two-dimensional echocardiography for the detection of left atrial appendage thrombus. J Am Coil Cardiol1986;7:163-6. 3. Sutherland GR, Poppele G, Langenstein B, Taams M, Roelandt J, Hanrath P. Transesophageal echo, an improved diagnostic technique for subaortic membranes [Abstract]. Circulation 1988;78(suppl 11):441. 4. Poppele G, Kruger W, Langenstein B, Hanrath P. Membranous subvalvular aortic stenosis. Its detection by transthoracic and transesophageal 2-D Doppler echocardiography. Dtsch Med Wochenschr 1988;113:1224-8.
T
ransesophageal echocardiography is a new technique that can visualize aspects of the heart and great vessels that are inadequately evaluated by transthoracic echocardiography. The left ventricular outflow tract is usually well visualized by transthoracic echocardiography. There, however, are cases in which the left ventricular outflow tract is not adequately evaluated by transthoracic echocardiography. This may be the result of insufficient image resolution obtained by the 2.5 to 3.5 MHz transducers used in transthoracic echocardiography studies or to inadequate penetration of sound. We report two cases in which transesophageal echocardiography was able to provide superior evaluation of left ventricular outflow tract disease. CASE REPORTS
Patient I A 44-year-old man with a murmur since childhood was referred for echocardiography at another institution after a single episode of palpitations and fatigue. The echocardiogram was interpreted as showing a bicuspid aortic valve. Doppler studies suggested severe aortic stenosis. The patient was referred to our institution for cardiac catheterization, which raised the suspicion of a subaortic membrane producing a mean gradient of 44 mm Hg. The patient was then referred for transthoracic echocardiography, which indeed suggested a subvalvular membrane. The mean gradient calculated by Doppler flow velocity measurement was 43 mm Hg. To better evaluate the aortic valve, the subvalvular membrane, and the exact location of obstruction to flow, transesophageal echocardiography was performed. It clearly demonstrated a normal tricuspid From the Deparnnent of Medicine, New York University Medical Center. Reprint requests: Itzhak Kronwn, MD, 560 First Avenue-Suite 2E, New York, NY 10016.
aortic valve. The subvalvular membrane was attached to the membranous septum and to the middle portion of the anterior mitral leaflet, tethering this lea£let (Figure l,A). Color Doppler flow mapping revealed turbulent flow that started at the membrane and filled the left ventricular outflow tract and aorta (Figure l, B). The flow column across the aortic valve was wide, indicating no obstruction to flow at this level. Patient2 A 68-year-old man with severe angina was referred to our institution for coronary artery bypass grafting after cardiac catheterization elsewhere revealed severe three-vessel coronary artery disease and a mild aortic stenosis. Postoperatively the patient had severe symptomatic orthostatic hypotension with a 50 mm Hg decrease in systolic blood pressure on arising from bed. Transthoracic echocardiography was a poor quality study with nondiagnotic two-dimensional images. Continuous wave Doppler recording of left ventricular outflow tract velocity revealed that the velocity peaked late in systole at 3 m/ sec, raising a suspicion of dynamic left ventricular outflow tract obstruction. Transesophageal echocardiography clearly revealed asymmetric septal hypertrophy and systolic anterior motion of the mitral valve (Figure 2, A). Color Doppler flow mapping demonstrated turbulent flow distal to where the mitral valve strikes the septum (Figure 2, B). The left ventricle was hyperdynamic. The patient was then treated with propranolol (lnderal) and veraeamil with resolution of his symptoms. DISCUSSION
Transesophageal echocardiography can play a significant role in the evaluation of diseases of the left ventricular outflow tract. Anatomic abnormalities can be visualized in far greater detail, even when transthoracic echocardiography is of diagnostic quality, as in the first case. Transesophageal echocardi191
192 Schwinger and Kronzon
Journal of the Americau Society of Echocardiography
Figure 1 A, Two-dimensional transesophageal echocardiogram. Membrane (m) is shown in left ventricular outflow tract (ot). It is attached to membranous septum and anterior mitral leaflet (a). Subvalvular orifice diameter measures 6 mm. LA, Left atrium; LV, left ventricle. B, Color Doppler transesophageal echocardiogram. High velocity flow in left ventricular outflow tract begins at subaortic membrane (white arrow). There is a wide flow column through the aortic valve indicating normal-sized valve orifice (black arrows). R V, Right ventricle; other abbreviations as in A.
ography may be the only readily available way to diagnose left ventricular outflow tract obstruction (short of performing cardiac catheterization) when diagnostic transthoracic echocardiography images cannot be obtained, as in the second case. The higher
resolution of transesophageal echocardiography color Doppler flow mapping provides pathophysiologic information in addition to the anatomic abnormalities. Transesophageal echocardiography has become ac-
Volume 2 Number 3 May-June 1989
Evaluation of LVOT obstruction
193
Figure 2 A, Two-dimensional transesophageal echocardiogram, systolic frame. Anterior mitral leaflet (lat;ge arrows) is in contact with hypenrophied interventricular septum (S) creating obstruction between LV cavity and OT. Ao, Aona; other abbreviations as in previous figures. B, Color Doppler transesophageal echocardiogram, systolic frame. High velocity flow begins (white arrow) where mitral valve strikes interventricular septum. Wide flow column is present through normal aortic valve (black arrows). Small jet of mitral regurgitation is also present (open arrow). Abbreviations as in previous figures.
cepted for the evaluation of cardiovascular disorders that cannot be evaluted by transthoracic echocardiography, such as dissection in the descending aorta 1 and thrombi in the left atrium. 2 Two recent reports 3.4 have demonstrated that transesophageal echocardi-
ography provides significant additional morphologic and hemodynamic information in patients with subaortic membranes. We can now include evalution of left ventricular outflow tract disease in the list of indications for transesophageal echocardiography
Journal of the American Society of Echocardiography
194 Schwinger and Kronzon
when the transthoracic echocardiographic study not fully informative.
IS
REFERENCES l. Erbel R, Rennollet H, Engberding R, et a!. Detection of
aortic dissection by transesophageal echocardiography: a multicenter cooperative study [Abstract]. Circulation 1988;78 (suppl 11):297. 2. Aschenberg W, Schluter M, Kremer P, Schroder E, Siglow V,
Bleifeld W. Transesophageal two-dimensional echocardiography for the detection of left atrial appendage thrombus. J Am Coil Cardiol1986;7:163-6. 3. Sutherland GR, Poppele G, Langenstein B, Taams M, Roelandt J, Hanrath P. Transesophageal echo, an improved diagnostic technique for subaortic membranes [Abstract]. Circulation 1988;78(suppl 11):441. 4. Poppele G, Kruger W, Langenstein B, Hanrath P. Membranous subvalvular aortic stenosis. Its detection by transthoracic and transesophageal 2-D Doppler echocardiography. Dtsch Med Wochenschr 1988;113:1224-8.