Intravascular ultrasound imaging of an acute dissecting aortic aneurysm: A case report. Douglas M. Cavaye, F R A C S , Willianl J. French, M D , R o d n e y A. White, M D , R o b e r t D. L e r m a n , M D , C. M a r k M e h r i n g e r , M D , M a r w a n R. Tabbara, M D , and G e o r g e E. K o p c h o k , BS, Torrance, Calif. A case of acute dissecting aortic aneurysm is described in which intravascular ultrasonography was used at the time of aortography to produce real-time, 360 degree cross-sectional images of the aorta. The transmural vessel morphology visualized by this new catheterbased technology allowed confirmation of the diagnosis and identification of distal extension to the aortic bifurcation. The case demonstrates the unique potential of this modality in diagnosis and possible therapy in vascular diseases. (J VAse SuRc 1991; 13:510-2.)
A major variable in determining the treatment and outcome o f acute aortic dissection is the ana, tomic extent o f the lesion) Diagnostic techniques include angiography, CT scanning, magnetic resonance imaging (MRI), and transthoracic and transesophageal echocardiography. 2 Each o f these techniques has limitations related to the technique o f image production and resolution. >* A new catheterbased technology, intravascu!ar ultrasonography, i s a ' rapidly developing method for defining luminal ~d~;:~ transmural anatomy o f vascular structures, s-7 CASE R E P O R T A 63-year-old white woman came to the hospital with a 4-hour history of retrosternal crushing chest pain, with radiation to the upper back, partially relieved by sublingual nitroglycerin. There was no associated dyspnea or diaphoresis. Relevant past medical history included a thoracic aortic aneurysm for 8 years and systemic hypertension for 25 years. Medications included diltiazem, 120 mg daily, which she had not taken for 48 hours before admission to the hospital, and sublingual nitroglycerin as required. Examination revealed a moderately obese woman in mild distress. Bilateral brachial blood pressures were 110/50 mm Hg, and the heart rate was 58 beats per minute. All pulses were present, but with reduced volume in her left lower limb. There was a systolic ejection murmur and a right carotid bruit. Lung fields were clear to auscultation. No abdominal masses or bruits and no abdominal tenderness were found. An electrocardiogram (ECG) showed sinus bradycardia and nonspecific T wave changes. A portaFrom the Departments of Vascular Surgery (Cavaye, White, Tabbara, Kopchok), Cardiology (French, Lerman), and Radiology (Mehringer), Harbor/University of California at Los Angeles) Medical Center, Torrance. Reprint requests: RodneyA. White, MD, Harbor/UCLAMedical Center, 1000 West Carson St., Torrance, CA 90509. 24/1/26738 510
ble chest radiograph showed a cardiothoracic ratio of 0.60, with a markedly widened mediastinal aortic shadow. Urgent aortography via the right femoral artery confirmed a dissecting thoracic aortic aneurysm with an entry tear located immediately distal to the origin of the left subclavian artery and retrograde filling of the false lumen through the arch and ascending aorta to the aortic sinus (Fig. 1). The origin of the innominate artery was narrowed, and the other great vessels showed marked elongation and tortuosity..Descending aortography revealed absence of the intercostal vessels on the left and a narrowing of the left renal artery 2 cm distal to its origin. The dissection was thought to end just below the level of the renal arteries, enabling diagnosis of a Debakey type 1 acute aortic dissection.1 INTRAVASCULAR ULTRASOUND MATERIAL AND METHODS At the completion o f aortography, a 9.0F sheath was introduced into the right femoral artery by guide wire exchange, and an intravascular ultrasound catheter was inserted and advanced to the level o f the aortic bifurcation, images were obtained with a 65 cm long, 8.0F catheter containing a 20 M H z ultrasound transducer and rotating beam reflector at its tip (Cardiovascular Imaging Systems, C-VIS, Inc., Sunnyvale, Calif.) (Fig. 2). By advancing and withdrawing the catheter, real-time 360 degree crosssectional images of the aorta from the level o f the sixth thoracic vertebra to the bifurcation distally, and o f the right iliac arteries were obtained and displayed on a high-resolution grey-scale monitor. Before beginning the aortogram the patient consented to and was enrolled in a protocol approved by our institution's Research and H u m a n Subjects Committee for intravascular ultrasound examinations during other interventional procedures. Total time required~ for intravascular ultrasound examination was 15
Volume 13 Number 4 April 1991
Intravascular ultrasound-acute aortic dissection 511
Fig. 1. Left anteroblique arch aortogram shows the true lumen (single arrow) and false lumen (double arrows). Fig. 3. Intravascular ultrasound images of (A) the proximal descending aorta and (B) distal abdominal aorta, show aortic wall (single arrow), dissection flap (double arrows), and true and false lumens. The anterior wall ofthe aorta is on the bottom of the image. T, True lumen;F, false lumen.
minutes, and the patient suffered no discomfort or complications from the procedure. RESULTS
11
Fig. 2. Photograph (A) and schematic diagram (B) of the tip of the ultrasound catheter. The rotating mirror (1) sweeps the ultrasound beam produced by the fixed transducer (2) in a 360 degree arc, perpendicular to the tip of the catheter. 'The flexible guidewire (arrow) facilitates the intravascular p~Lssageof the catheter.
Intravascular ultrasonography provided clear images of the true and false lumens, the flap of tissue separating them, and the spiral nature of the dissection along the left posterolateral aspect of the aorta (Fig. 3). Catheter length (65 cm) prevented more proximal imaging. Because the distal extent of the dissection was shown by intravascular ultrasound examination to be at or beyond the level of the aortic bifurcation, an abdominal aortogram was performed before completing the procedure, which revealed left common iliac artery occlusion and absent left lumbar spinal arteries (Fig. 4). DISCUSSION Accepted diagnostic techniques in acute aortic dissection (angiography, CT and M R I scanning,
512
Cavaye et al.
Journal of VASCULAR SURGERY
MRI scanning is usually required. This often necessitates transporting the critically ill patient and increases the time required to complete the evaluations. Also, accurate assessment of the distal aorta by means of CT scanning involves multiple level contrast imaging in addition to the contrast material required for aortography. By allowing visualization of the vessel lumen and vessel wall at the time of angiography without the need for additional intravenous contrast or patient transport, intravascular ultrasound imaging provides an expedient method to define the anatomic locat/on and size of the dissecting transmural vessel morphology. Because it is currently an experimental device, its indications in clinical practice have not been clearly defined. In our experience it produces accurate images that can be used to augment the established diagnostic techniques. It may be especially u s e ~ when the diagnosis of aortic dissection is in doubt or when the distal extent is uncertain at the completion of aortography. We anticipate that it will become an adjunct to angiography, and that recourse to CT or MRI scanning will only be necessary when complicated disease exists in the ascending and transverse aortic arch. This case demonstrates the unique potential of the new catheter-based modality in the diagnosis of aortic dissection. Fig. 4. Abdominal aortogram shows nonfilling of left lumbar spinal arteries and left c o m m o n lilac artery occlusion.
transesophageal and transthoracic echocardiography) have limitations related to the techniques of image production and resolution. Angiography produces a contrast filled outline of the true and false lumens usually at different times, allowing identification of the entry site and proximal extent of the dissection in most cases, but not the distal extent. CT diagnosis is difficult when a flap is not easily seen, when there is similar blood flow through both the false and true lumens, or if thrombus obscures the false lumen? Magnetic resonance imaging requires significant time for image acquisition and may not be possible if the patient has certain types of metal implants. Transesophageal echocardiography is restricted in the upper part of the ascending aorta because of the overlying trachea and cannot be used to visualize the abdominal aorta. 4
Because of the difficulty in identifying the distal extent of dissection in Debakey types 1 and 3 acute aortic dissection by use of angiography alone, CT or
The intravascular ultrasound device used in this study was supplied by Cardiovascular Imaging Systems, Inc., (C-VIS), Sunnyvale, Calif. REFERENCES 1, Craw-ford ES, Crawford JL. Aortic dissection and dissecting aortic aneurysm. In: Tracy TM, ed. Diseases of the aorta. Los Angeles: Williams and Wilkins, 1984:168-214. .,', 2. Goldman AP, Kotler MN, Scanlon MH, et al. The complimentary role of magnetic resonance imaging, Doppler, echocardiography and computed tomography in the diagnosis of dissecting thoracic aneurysms. Am Heart J 1985;111:97081. 3. Mugge A, Werner DG, Laas J, et al. False negative diagnosis of proximal aortic dissection by computed tomography or angiography and possible explanations based on transoesophageal echocardiographic findings. Am J Cardiol 1990;65: 527-9. 4. Borner N, Erbel R, Braun B, et al. Diagnosis ofaortic dissection by transesophageal echocardiography. Am J Cardiol 1984;54: 1157-8. 5. Yock PG, Johnson EL, Linker DT. Intravascular ultrasound: development and clinical potential. Am J Cardiac Imaging 1988;2:185-93. 6. Kopchok GE, White RA, Guthric C, et al. Intraluminalvascular ultrasound: preliminary report of dimensional and morphologic accuracy. Ann Vasc Surg 1990;3:291-6. 7. White RA. Intravascular Ultrasound. In: Kadir S, ed. Current practice of interventional radiology. Philadelphia: BC Decker Inc (In press).
A major variable in determining the treatment and outcome o f acute aortic dissection is the ana, tomic extent o f the lesion) Diagnostic techniques include angiography, CT scanning, magnetic resonance imaging (MRI), and transthoracic and transesophageal echocardiography. 2 Each o f these techniques has limitations related to the technique o f image production and resolution. >* A new catheterbased technology, intravascu!ar ultrasonography, i s a ' rapidly developing method for defining luminal ~d~;:~ transmural anatomy o f vascular structures, s-7 CASE R E P O R T A 63-year-old white woman came to the hospital with a 4-hour history of retrosternal crushing chest pain, with radiation to the upper back, partially relieved by sublingual nitroglycerin. There was no associated dyspnea or diaphoresis. Relevant past medical history included a thoracic aortic aneurysm for 8 years and systemic hypertension for 25 years. Medications included diltiazem, 120 mg daily, which she had not taken for 48 hours before admission to the hospital, and sublingual nitroglycerin as required. Examination revealed a moderately obese woman in mild distress. Bilateral brachial blood pressures were 110/50 mm Hg, and the heart rate was 58 beats per minute. All pulses were present, but with reduced volume in her left lower limb. There was a systolic ejection murmur and a right carotid bruit. Lung fields were clear to auscultation. No abdominal masses or bruits and no abdominal tenderness were found. An electrocardiogram (ECG) showed sinus bradycardia and nonspecific T wave changes. A portaFrom the Departments of Vascular Surgery (Cavaye, White, Tabbara, Kopchok), Cardiology (French, Lerman), and Radiology (Mehringer), Harbor/University of California at Los Angeles) Medical Center, Torrance. Reprint requests: RodneyA. White, MD, Harbor/UCLAMedical Center, 1000 West Carson St., Torrance, CA 90509. 24/1/26738 510
ble chest radiograph showed a cardiothoracic ratio of 0.60, with a markedly widened mediastinal aortic shadow. Urgent aortography via the right femoral artery confirmed a dissecting thoracic aortic aneurysm with an entry tear located immediately distal to the origin of the left subclavian artery and retrograde filling of the false lumen through the arch and ascending aorta to the aortic sinus (Fig. 1). The origin of the innominate artery was narrowed, and the other great vessels showed marked elongation and tortuosity..Descending aortography revealed absence of the intercostal vessels on the left and a narrowing of the left renal artery 2 cm distal to its origin. The dissection was thought to end just below the level of the renal arteries, enabling diagnosis of a Debakey type 1 acute aortic dissection.1 INTRAVASCULAR ULTRASOUND MATERIAL AND METHODS At the completion o f aortography, a 9.0F sheath was introduced into the right femoral artery by guide wire exchange, and an intravascular ultrasound catheter was inserted and advanced to the level o f the aortic bifurcation, images were obtained with a 65 cm long, 8.0F catheter containing a 20 M H z ultrasound transducer and rotating beam reflector at its tip (Cardiovascular Imaging Systems, C-VIS, Inc., Sunnyvale, Calif.) (Fig. 2). By advancing and withdrawing the catheter, real-time 360 degree crosssectional images of the aorta from the level o f the sixth thoracic vertebra to the bifurcation distally, and o f the right iliac arteries were obtained and displayed on a high-resolution grey-scale monitor. Before beginning the aortogram the patient consented to and was enrolled in a protocol approved by our institution's Research and H u m a n Subjects Committee for intravascular ultrasound examinations during other interventional procedures. Total time required~ for intravascular ultrasound examination was 15
Volume 13 Number 4 April 1991
Intravascular ultrasound-acute aortic dissection 511
Fig. 1. Left anteroblique arch aortogram shows the true lumen (single arrow) and false lumen (double arrows). Fig. 3. Intravascular ultrasound images of (A) the proximal descending aorta and (B) distal abdominal aorta, show aortic wall (single arrow), dissection flap (double arrows), and true and false lumens. The anterior wall ofthe aorta is on the bottom of the image. T, True lumen;F, false lumen.
minutes, and the patient suffered no discomfort or complications from the procedure. RESULTS
11
Fig. 2. Photograph (A) and schematic diagram (B) of the tip of the ultrasound catheter. The rotating mirror (1) sweeps the ultrasound beam produced by the fixed transducer (2) in a 360 degree arc, perpendicular to the tip of the catheter. 'The flexible guidewire (arrow) facilitates the intravascular p~Lssageof the catheter.
Intravascular ultrasonography provided clear images of the true and false lumens, the flap of tissue separating them, and the spiral nature of the dissection along the left posterolateral aspect of the aorta (Fig. 3). Catheter length (65 cm) prevented more proximal imaging. Because the distal extent of the dissection was shown by intravascular ultrasound examination to be at or beyond the level of the aortic bifurcation, an abdominal aortogram was performed before completing the procedure, which revealed left common iliac artery occlusion and absent left lumbar spinal arteries (Fig. 4). DISCUSSION Accepted diagnostic techniques in acute aortic dissection (angiography, CT and M R I scanning,
512
Cavaye et al.
Journal of VASCULAR SURGERY
MRI scanning is usually required. This often necessitates transporting the critically ill patient and increases the time required to complete the evaluations. Also, accurate assessment of the distal aorta by means of CT scanning involves multiple level contrast imaging in addition to the contrast material required for aortography. By allowing visualization of the vessel lumen and vessel wall at the time of angiography without the need for additional intravenous contrast or patient transport, intravascular ultrasound imaging provides an expedient method to define the anatomic locat/on and size of the dissecting transmural vessel morphology. Because it is currently an experimental device, its indications in clinical practice have not been clearly defined. In our experience it produces accurate images that can be used to augment the established diagnostic techniques. It may be especially u s e ~ when the diagnosis of aortic dissection is in doubt or when the distal extent is uncertain at the completion of aortography. We anticipate that it will become an adjunct to angiography, and that recourse to CT or MRI scanning will only be necessary when complicated disease exists in the ascending and transverse aortic arch. This case demonstrates the unique potential of the new catheter-based modality in the diagnosis of aortic dissection. Fig. 4. Abdominal aortogram shows nonfilling of left lumbar spinal arteries and left c o m m o n lilac artery occlusion.
transesophageal and transthoracic echocardiography) have limitations related to the techniques of image production and resolution. Angiography produces a contrast filled outline of the true and false lumens usually at different times, allowing identification of the entry site and proximal extent of the dissection in most cases, but not the distal extent. CT diagnosis is difficult when a flap is not easily seen, when there is similar blood flow through both the false and true lumens, or if thrombus obscures the false lumen? Magnetic resonance imaging requires significant time for image acquisition and may not be possible if the patient has certain types of metal implants. Transesophageal echocardiography is restricted in the upper part of the ascending aorta because of the overlying trachea and cannot be used to visualize the abdominal aorta. 4
Because of the difficulty in identifying the distal extent of dissection in Debakey types 1 and 3 acute aortic dissection by use of angiography alone, CT or
The intravascular ultrasound device used in this study was supplied by Cardiovascular Imaging Systems, Inc., (C-VIS), Sunnyvale, Calif. REFERENCES 1, Craw-ford ES, Crawford JL. Aortic dissection and dissecting aortic aneurysm. In: Tracy TM, ed. Diseases of the aorta. Los Angeles: Williams and Wilkins, 1984:168-214. .,', 2. Goldman AP, Kotler MN, Scanlon MH, et al. The complimentary role of magnetic resonance imaging, Doppler, echocardiography and computed tomography in the diagnosis of dissecting thoracic aneurysms. Am Heart J 1985;111:97081. 3. Mugge A, Werner DG, Laas J, et al. False negative diagnosis of proximal aortic dissection by computed tomography or angiography and possible explanations based on transoesophageal echocardiographic findings. Am J Cardiol 1990;65: 527-9. 4. Borner N, Erbel R, Braun B, et al. Diagnosis ofaortic dissection by transesophageal echocardiography. Am J Cardiol 1984;54: 1157-8. 5. Yock PG, Johnson EL, Linker DT. Intravascular ultrasound: development and clinical potential. Am J Cardiac Imaging 1988;2:185-93. 6. Kopchok GE, White RA, Guthric C, et al. Intraluminalvascular ultrasound: preliminary report of dimensional and morphologic accuracy. Ann Vasc Surg 1990;3:291-6. 7. White RA. Intravascular Ultrasound. In: Kadir S, ed. Current practice of interventional radiology. Philadelphia: BC Decker Inc (In press).
