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Visualization and identification of the left common carotid and left subclavian arteries: A transesophageal echocardiographic approach
Visualization and Identification of the Left Common Carotid and Left Subclavian Arteries: A Transesophageal Echocardiographic Approach Edward S. Katz, MD, Neal Konecky, MD, Paul A. Tunick, MD, Barry R Rosenzweig, MD, Robin S. Freedberg, MD, and Itzhak Kronzon, MD, New Tork, New Tork
q~ l r a n s e s o p h a g e a l echocardiography (TEE) is a wellaccepted modality for visualizing the aortic arch) -4 The proximal portions o f two distal aortic arch vessels are also often seen, but reliable identification of these vessels as either the left common carotid or subclavian artery has not been well described by TEE. The purpose o f this study was to evaluate the feasibility o f using TEE for visualizing and reliably identifying these two distal aortic arch vessels and to describe the clinical utility o f this method.
METHODS Fifty consecutive patients referred to our laboratory for various clinical indications were studied. TEE was performed in awake patients with no premedication other than topical 1% lidocaine spray, with a Sonos 1500 echocardiograph (Hewlett-Packard Co., Andover, Mass.) and a 5.0 MHz multiplane (omniplane) or biplane transducer. The aortic arch was visualized according to methods described previously.2'3 To identify aortic arch branch vessels, the imaging array was rotated to a longitudinal orientation (approximately 90 degrees) so that the aortic arch cross section appeared circular. The transducer was rotated leftward by counterclockwise rotation of the shaft of the probe to visualize the most distal portion of the aortic arch at its junction with the descending thoracic aorta. The transducer was then slowly rotated rightward by clockwise manipulation of the probe to visualize more proximal segments of the aortic arch. In this way, vessels were sequentially identified as they branched from the superior aspect of aortic arch. Each vessel was then followed cephalad by withdrawal of the transducer until images of the vessel could no longer be obtained. Color flow Doppler echocar-
From the Department of Medicine, New YorkUniversityMedical Center. Reprint requests:Edward S. I~tz, MD, NYU MedicalCenter, 560 First Ave., HW228, New York, NY 10016. Copyright © 1996 by the AmericanSocietyof Echocardiography. 0894-7317/96 $5.00 + 0 27/1/64962 58
diography was used to help identify the vessel lumen as it was tracked cephalad. Pulsed-wave Doppler echocardiography with up to 60-degree angle correction was performed in each vessel to identify the characteristic flow velocity patterns of either a common carotid or subclavian artery.
RESULTS The left subclavian artery was visualized in 36 (72%) o f 50 patients and could be followed cephalad for a mean distance of 5.0 cm from the aortic arch (range 3 to 7 cm). It was then noted to curve laterally away from the transducer (Figure 1, B). Identification of the left subclavian artery was confirmed with pulsedwave Doppler echocardiography in each case by recognition of a high-resistance flow velocity pattern characteristic of peripheral arteries. On spectral tracings this was characterized by systolic antegrade flow velocity with short early diastolic reversal and no antegrade diastolic flow velocity (Figure 1, D). The left c o m m o n carotid artery was visualized in 37 (74%) o f 50 patients and could be followed cephalad a mean o f 7.6 cm from the aortic arch (range 3 to 15 cm) (Figure 1, B). Pulsed-wave Doppler echocardiography confirmed its identity with a low-resistance flow velocity pattern characteristic o f the cerebral circulation (i.e., higher systolic and lower diastolic antegrade flow velocity) (Figure 1, E). In 31 (62%) of 50 patients, both the left common carotid and left subclavian arteries could be visualized. In two patients with aortic dissection, the aortic arch vessels could be visualized and identified by pulsed-wave Doppler echocardiography. In one of these patients with neurologic symptoms, the intimal flap could be clearly seen extending into the left carotid artery (Figure 2), whereas in the other patient with a reduced left upper extremity pulse, involvement o f the left subclavian artery by the dissection could be identified.
Journal of the AmericanSocietyof Echocardiography Volume 9 Number 1
Katz et al.
Figure 1 A, TEE longitudinal plane of the aortic arch (AA), which appears circular. Proximal portion of an aortic arch vessel (open arrow) is clearly seen branching from superior aspect of aortic arch to left, but certain identification of this vessel cannot be determined. B, Withdrawal of transducer cephalad allows imaging of two aortic arch vessels. Left carotid artery (LCA, curved arrow) extends superiorly into neck, whereas left subclavian artery (LSA, straight arrow) curves laterally away from transducer. C, Same image as B with color flow Doppler clearly demonstrating flow within vessels. D, Pulsed-wave Doppler spectral tracing of left subclaxdan artery demonstrates high-resistance flow velocity pattern with systolic antegrade flow velocity and early diastolic reversal of flow velocity. There is no antegrade diastolic flow velocity. E, Pulsed-wave Doppler spectral tracing of left common carotid artery demonstrates lowresistance flow velocity pattern with higher systolic and lower diastolic antegrade flow velocity. Pattern is characteristic of cerebral flow velocity pattern.
59
60 Katzet al.
Iournal of the American Society of Echocardiography January-February 1996
Figure 2 TEE of aortic arch (AA) (longitudinalview) of patient with type A aortic dissection. Intimal flap (small arrows) is clearlyseen extending into aortic arch vessel (bold arrow), which was followed cephalad and subsequently identified as carotid artery by pulsed-wave Doppler flow velocitypattern. DISCUSSION
Visualization of the aortic arch by TEE has been well dcscribed and its utility in delineating aortic arch diseases such as dissections-7 or atheromatous8 lo disease has been well documented. Often the most proximal portions of aortic arch branch vessels can also be seen, but the ability to identify these vessels correctly by TEE has not been described previously. Little attention has focused on imaging structures by TEE that are superior to the aortic arch. This may be because of the existence of other imaging modalitics that are adequate for visualizing these structures or discomfort to the patient when TEE imaging is performed high in the esophagus near the hypopharynx. In this study we describe a method not only for visualizing significant segments of the two distal aortic arch vessels by TEE but also for differentiating them based on their Doppler flow velocity patterns. The left carotid and left subclavian arteries could be visualized and identified in approximately three quarters of the patients. The carotid flow was identified on pulsed-wave Doppler echocardiography by a lowresistance flow velocity pattern characteristic of cerebral blood flow (higher systolic and lower diastolic antegrade flow velocity)) 1 The left subclavian pulsed-wave Doppler was differentiated from carotid flow by its high-resistance flow velocity pattern characteristic of peripheral arteries (systolic antegrade
flow with short early diastolic reversal and no antegrade diastolic flow velocity). ~2 Although other methods such as Duplex scanning,~ t-i3 angiography, and magnetic resonance imaging exist 13 for visualizing and defining disease of the aortic arch vessels, the ability to visualize and correctly identify these vessels by TEE may have important clinical applications. TEE is used routinely for diagnosing aortic dissection, and the high sensitivity of this technique has been well documented. 5"6 During this procedure, involvement of aortic arch vessels by the intimal flap could be established by two-dimensional TEE, whereas identification of these vessels could be made on the basis of Doppler flow velocity patterns. This would provide helpful information for planning the surgical procedure without resorting to other, and perhaps time-consuming, imaging tests. In our study we were able to diagnose aortic dissection with involvement of the left carotid artery (one patient) and the left subclavian artery (one patient). In addition, we routinely use TEE during surgery in patients undergoing cardiopulmonary bypass to explore the aortic arch for the presence ofatherosclerotic disease. We have previously reported the high risk of stroke in surgical patients with protruding atheromas of the aortic arch and predict that this might be the result of the dislodgement of plaque during manipulation and cannulation of the aortic arch. 8'~4The spatial relationship ofatheromatous dis-
Journal of the AmericanSocietyof Echocardiography Volume 9 Number 1
ease to the carotid artery may have important implications for stroke. Therefore the ability to reliably identify aortic arch vessels and their relationship to aortic arch atheromas may aid in planning surgical techniques to prevent cerebral embolization.
][(atz et al.
2.
3.
Limitations
Imaging significant segments of the aortic arch vessels and recording Doppler flow patterns can be accomplished only with either biplanar or multiplanar TEE transducers with longitudinal imaging capability. The left carotid and left subclavian arteries could not be visualized in approximately 25% of the patients, and in only 62% of patients were we able to identify both the left carotid and left subclavian arteries. Inability to visualize these vessels was caused by either simple anatomic variations or excessive gagging by the patient as the TEE probe was withdrawn, making imaging impossible. In addition, the right brachiocephalic artery could not be visualized roufinely at its branch point from the aortic arch. This was likely because of the interposition of the trachea between the esophagus and the proximal aortic arch. Last, abnormal Doppler flow velocity patterns may be seen in diseased aortic arch vessels. For example, the low-resistance carotid flow velocity pattern typical of normal carotid arteries may convert to a highresistance pattern in the presence of a severely occluded internal carotid artery. Therefore caution must be exercised in not confusing this abnormal common carotid flow with a normal systemic arterial flow pattern.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Conc~s~n
We have described a method for visualizing and identifying the left common carotid and left subclavian arteries by TEE two-dimensional imaging and pulsed-wave Doppler echocardiography. This method can be applied successfully in the majority of patients and may have important clinical applications. REFERENCES
1. Seward JB, Khanderia BK, Oh JK, et al. Transesophageal echocardiography: technique, anatomic correlations, imple-
13.
14.
61
mentation, and clinical applications. Mayo Clin Proc 1988; 63:649 80. Seward JB, Khanderia BK, Edwards MD, Oh JK, Freeman WK, Tajik AJ. Biplanar transesophageal echocardiography: anatomic correlations, image orientation, and clinical applications. Mayo Clin Proc 1990;65:1193-213. Seward JB, Khanderia BK, Freedman WK, et al. Multiplane transesophageal echocardiography: image orientation, examination technique, anatomic correlations, and clinical implications. Mayo Clin Proc 1993;68:523-51. Blanchard DG, Kimura BJ, Dittrich HC, DeMaria AN. Transesophageal echocardiography of th.: aorta. JAMB, 1994;272:546-51. Nienaber CA, Von Kodolitsch Y, Nicolas V, Piepho A, Brockhoff DH, Spielman t/2. The diagnosis of thoracic aortic dissection by non-invasiveimaging procedures. New Engl J Med 1993;328:1-9. Nienaber CA, Spielman RP, Von Kodolitsch Y, et aI. Diagnosis of thoracic aortic dissection: magnetic resonance imaging versus transesophageal echocardiography. Circulation 1992;85:434-47. Erbel R. Role oftransesophageal echocardiography in dissection of the aorta and evaluation of degenerative aortic disease. CardioI Clin 1993;11:461-73. Katz ES, Tunick PA, Rusinek H, Ribakove G, Spencer FC, Kronzon I. Protruding aortic atheromas predict stroke in elderly patients undergoing cardiopulmonary bypass: experience with intraoperative transesophageal echocardiography. J Am Coll Cardiol 1992;20:70-7. Karalis DG, Chandrasekaran K, Victor MF, Ross JI, Mintz GS. Recognition and embolic potential ofinn'aaortic atherosclerotic debris. J Am Coil Cardiol 1991;17:73-8. Tunick PA, Perez JL, Kronzon I. Protruding atheromas in the thoracic aorta and systemic embolization. ?ran Intern Med 1991;17:73-8. Fell G, Phillips DJ, Chikos PM, Harley JD, T]aick BL, Strandness DE Jr. Ultrasound duplex scanning for disease of the carotid artery. Circulation 1981;64:1191-5. Gerlock A~ Jr, Giyanani V, Krelos C. Noninvasive assessment of upper extremity vascular lesions. In: Applications of noninvasive vascular techniques. Philadelphia: WB Saunders, 1988:448. Spartera C, Morettini G, Marino G, et al. Detection of interhal carotid artery stenosis: comparison of 2D-MR angiography, duplex scanning, and arteriography. J Cardiovasc Surg 1993;34:209-13. Ribakove GH, Katz ES, GallowayA, et al. Surgical implications of transesophageal echocardiography to grade the atheromatous aortic arch. Ann Thorac Surg 1992;53:7~;8-63.
q~ l r a n s e s o p h a g e a l echocardiography (TEE) is a wellaccepted modality for visualizing the aortic arch) -4 The proximal portions o f two distal aortic arch vessels are also often seen, but reliable identification of these vessels as either the left common carotid or subclavian artery has not been well described by TEE. The purpose o f this study was to evaluate the feasibility o f using TEE for visualizing and reliably identifying these two distal aortic arch vessels and to describe the clinical utility o f this method.
METHODS Fifty consecutive patients referred to our laboratory for various clinical indications were studied. TEE was performed in awake patients with no premedication other than topical 1% lidocaine spray, with a Sonos 1500 echocardiograph (Hewlett-Packard Co., Andover, Mass.) and a 5.0 MHz multiplane (omniplane) or biplane transducer. The aortic arch was visualized according to methods described previously.2'3 To identify aortic arch branch vessels, the imaging array was rotated to a longitudinal orientation (approximately 90 degrees) so that the aortic arch cross section appeared circular. The transducer was rotated leftward by counterclockwise rotation of the shaft of the probe to visualize the most distal portion of the aortic arch at its junction with the descending thoracic aorta. The transducer was then slowly rotated rightward by clockwise manipulation of the probe to visualize more proximal segments of the aortic arch. In this way, vessels were sequentially identified as they branched from the superior aspect of aortic arch. Each vessel was then followed cephalad by withdrawal of the transducer until images of the vessel could no longer be obtained. Color flow Doppler echocar-
From the Department of Medicine, New YorkUniversityMedical Center. Reprint requests:Edward S. I~tz, MD, NYU MedicalCenter, 560 First Ave., HW228, New York, NY 10016. Copyright © 1996 by the AmericanSocietyof Echocardiography. 0894-7317/96 $5.00 + 0 27/1/64962 58
diography was used to help identify the vessel lumen as it was tracked cephalad. Pulsed-wave Doppler echocardiography with up to 60-degree angle correction was performed in each vessel to identify the characteristic flow velocity patterns of either a common carotid or subclavian artery.
RESULTS The left subclavian artery was visualized in 36 (72%) o f 50 patients and could be followed cephalad for a mean distance of 5.0 cm from the aortic arch (range 3 to 7 cm). It was then noted to curve laterally away from the transducer (Figure 1, B). Identification of the left subclavian artery was confirmed with pulsedwave Doppler echocardiography in each case by recognition of a high-resistance flow velocity pattern characteristic of peripheral arteries. On spectral tracings this was characterized by systolic antegrade flow velocity with short early diastolic reversal and no antegrade diastolic flow velocity (Figure 1, D). The left c o m m o n carotid artery was visualized in 37 (74%) o f 50 patients and could be followed cephalad a mean o f 7.6 cm from the aortic arch (range 3 to 15 cm) (Figure 1, B). Pulsed-wave Doppler echocardiography confirmed its identity with a low-resistance flow velocity pattern characteristic o f the cerebral circulation (i.e., higher systolic and lower diastolic antegrade flow velocity) (Figure 1, E). In 31 (62%) of 50 patients, both the left common carotid and left subclavian arteries could be visualized. In two patients with aortic dissection, the aortic arch vessels could be visualized and identified by pulsed-wave Doppler echocardiography. In one of these patients with neurologic symptoms, the intimal flap could be clearly seen extending into the left carotid artery (Figure 2), whereas in the other patient with a reduced left upper extremity pulse, involvement o f the left subclavian artery by the dissection could be identified.
Journal of the AmericanSocietyof Echocardiography Volume 9 Number 1
Katz et al.
Figure 1 A, TEE longitudinal plane of the aortic arch (AA), which appears circular. Proximal portion of an aortic arch vessel (open arrow) is clearly seen branching from superior aspect of aortic arch to left, but certain identification of this vessel cannot be determined. B, Withdrawal of transducer cephalad allows imaging of two aortic arch vessels. Left carotid artery (LCA, curved arrow) extends superiorly into neck, whereas left subclavian artery (LSA, straight arrow) curves laterally away from transducer. C, Same image as B with color flow Doppler clearly demonstrating flow within vessels. D, Pulsed-wave Doppler spectral tracing of left subclaxdan artery demonstrates high-resistance flow velocity pattern with systolic antegrade flow velocity and early diastolic reversal of flow velocity. There is no antegrade diastolic flow velocity. E, Pulsed-wave Doppler spectral tracing of left common carotid artery demonstrates lowresistance flow velocity pattern with higher systolic and lower diastolic antegrade flow velocity. Pattern is characteristic of cerebral flow velocity pattern.
59
60 Katzet al.
Iournal of the American Society of Echocardiography January-February 1996
Figure 2 TEE of aortic arch (AA) (longitudinalview) of patient with type A aortic dissection. Intimal flap (small arrows) is clearlyseen extending into aortic arch vessel (bold arrow), which was followed cephalad and subsequently identified as carotid artery by pulsed-wave Doppler flow velocitypattern. DISCUSSION
Visualization of the aortic arch by TEE has been well dcscribed and its utility in delineating aortic arch diseases such as dissections-7 or atheromatous8 lo disease has been well documented. Often the most proximal portions of aortic arch branch vessels can also be seen, but the ability to identify these vessels correctly by TEE has not been described previously. Little attention has focused on imaging structures by TEE that are superior to the aortic arch. This may be because of the existence of other imaging modalitics that are adequate for visualizing these structures or discomfort to the patient when TEE imaging is performed high in the esophagus near the hypopharynx. In this study we describe a method not only for visualizing significant segments of the two distal aortic arch vessels by TEE but also for differentiating them based on their Doppler flow velocity patterns. The left carotid and left subclavian arteries could be visualized and identified in approximately three quarters of the patients. The carotid flow was identified on pulsed-wave Doppler echocardiography by a lowresistance flow velocity pattern characteristic of cerebral blood flow (higher systolic and lower diastolic antegrade flow velocity)) 1 The left subclavian pulsed-wave Doppler was differentiated from carotid flow by its high-resistance flow velocity pattern characteristic of peripheral arteries (systolic antegrade
flow with short early diastolic reversal and no antegrade diastolic flow velocity). ~2 Although other methods such as Duplex scanning,~ t-i3 angiography, and magnetic resonance imaging exist 13 for visualizing and defining disease of the aortic arch vessels, the ability to visualize and correctly identify these vessels by TEE may have important clinical applications. TEE is used routinely for diagnosing aortic dissection, and the high sensitivity of this technique has been well documented. 5"6 During this procedure, involvement of aortic arch vessels by the intimal flap could be established by two-dimensional TEE, whereas identification of these vessels could be made on the basis of Doppler flow velocity patterns. This would provide helpful information for planning the surgical procedure without resorting to other, and perhaps time-consuming, imaging tests. In our study we were able to diagnose aortic dissection with involvement of the left carotid artery (one patient) and the left subclavian artery (one patient). In addition, we routinely use TEE during surgery in patients undergoing cardiopulmonary bypass to explore the aortic arch for the presence ofatherosclerotic disease. We have previously reported the high risk of stroke in surgical patients with protruding atheromas of the aortic arch and predict that this might be the result of the dislodgement of plaque during manipulation and cannulation of the aortic arch. 8'~4The spatial relationship ofatheromatous dis-
Journal of the AmericanSocietyof Echocardiography Volume 9 Number 1
ease to the carotid artery may have important implications for stroke. Therefore the ability to reliably identify aortic arch vessels and their relationship to aortic arch atheromas may aid in planning surgical techniques to prevent cerebral embolization.
][(atz et al.
2.
3.
Limitations
Imaging significant segments of the aortic arch vessels and recording Doppler flow patterns can be accomplished only with either biplanar or multiplanar TEE transducers with longitudinal imaging capability. The left carotid and left subclavian arteries could not be visualized in approximately 25% of the patients, and in only 62% of patients were we able to identify both the left carotid and left subclavian arteries. Inability to visualize these vessels was caused by either simple anatomic variations or excessive gagging by the patient as the TEE probe was withdrawn, making imaging impossible. In addition, the right brachiocephalic artery could not be visualized roufinely at its branch point from the aortic arch. This was likely because of the interposition of the trachea between the esophagus and the proximal aortic arch. Last, abnormal Doppler flow velocity patterns may be seen in diseased aortic arch vessels. For example, the low-resistance carotid flow velocity pattern typical of normal carotid arteries may convert to a highresistance pattern in the presence of a severely occluded internal carotid artery. Therefore caution must be exercised in not confusing this abnormal common carotid flow with a normal systemic arterial flow pattern.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Conc~s~n
We have described a method for visualizing and identifying the left common carotid and left subclavian arteries by TEE two-dimensional imaging and pulsed-wave Doppler echocardiography. This method can be applied successfully in the majority of patients and may have important clinical applications. REFERENCES
1. Seward JB, Khanderia BK, Oh JK, et al. Transesophageal echocardiography: technique, anatomic correlations, imple-
13.
14.
61
mentation, and clinical applications. Mayo Clin Proc 1988; 63:649 80. Seward JB, Khanderia BK, Edwards MD, Oh JK, Freeman WK, Tajik AJ. Biplanar transesophageal echocardiography: anatomic correlations, image orientation, and clinical applications. Mayo Clin Proc 1990;65:1193-213. Seward JB, Khanderia BK, Freedman WK, et al. Multiplane transesophageal echocardiography: image orientation, examination technique, anatomic correlations, and clinical implications. Mayo Clin Proc 1993;68:523-51. Blanchard DG, Kimura BJ, Dittrich HC, DeMaria AN. Transesophageal echocardiography of th.: aorta. JAMB, 1994;272:546-51. Nienaber CA, Von Kodolitsch Y, Nicolas V, Piepho A, Brockhoff DH, Spielman t/2. The diagnosis of thoracic aortic dissection by non-invasiveimaging procedures. New Engl J Med 1993;328:1-9. Nienaber CA, Spielman RP, Von Kodolitsch Y, et aI. Diagnosis of thoracic aortic dissection: magnetic resonance imaging versus transesophageal echocardiography. Circulation 1992;85:434-47. Erbel R. Role oftransesophageal echocardiography in dissection of the aorta and evaluation of degenerative aortic disease. CardioI Clin 1993;11:461-73. Katz ES, Tunick PA, Rusinek H, Ribakove G, Spencer FC, Kronzon I. Protruding aortic atheromas predict stroke in elderly patients undergoing cardiopulmonary bypass: experience with intraoperative transesophageal echocardiography. J Am Coll Cardiol 1992;20:70-7. Karalis DG, Chandrasekaran K, Victor MF, Ross JI, Mintz GS. Recognition and embolic potential ofinn'aaortic atherosclerotic debris. J Am Coil Cardiol 1991;17:73-8. Tunick PA, Perez JL, Kronzon I. Protruding atheromas in the thoracic aorta and systemic embolization. ?ran Intern Med 1991;17:73-8. Fell G, Phillips DJ, Chikos PM, Harley JD, T]aick BL, Strandness DE Jr. Ultrasound duplex scanning for disease of the carotid artery. Circulation 1981;64:1191-5. Gerlock A~ Jr, Giyanani V, Krelos C. Noninvasive assessment of upper extremity vascular lesions. In: Applications of noninvasive vascular techniques. Philadelphia: WB Saunders, 1988:448. Spartera C, Morettini G, Marino G, et al. Detection of interhal carotid artery stenosis: comparison of 2D-MR angiography, duplex scanning, and arteriography. J Cardiovasc Surg 1993;34:209-13. Ribakove GH, Katz ES, GallowayA, et al. Surgical implications of transesophageal echocardiography to grade the atheromatous aortic arch. Ann Thorac Surg 1992;53:7~;8-63.