Endograft Exclusion of Acute Descending Thoracic Aortic Dissection

The critical role of IVUS in this complicated presentation.

By Rodney A. White, MD; Carlos E. Donayre, MD; Irwin Walot, MD; George Kopchok, BS; Arash Keyhani, DO; Omid Jazaeri, MD; and Joe Chauvapun, MD
 

CASE STUDY

A 53-year-old man with acute chest pain was evaluated in the emergency department of a regional hospital and was diagnosed with an acute descending aortic dissection associated with abdominal pain and suspected visceral ischemia. His left leg was ischemic, and his white blood cell count was 30,000 with elevated serum lactate levels. The patient was expediently transferred to Harbor-UCLA Medical Center where a computed tomography (CT) scan showed a descending thoracic aortic dissection with anatomy amenable to endograft exclusion. There was a near-complete collapse of the true lumen in the mid-descending thoracic aorta, which was the cause of the visceral and limb ischemia (Figure 1).

Approximately 10 hours after the onset of symptoms, the patient presented urgently and was transported to the endovascular suite for intravascular ultrasound (IVUS) interrogation and potential endoluminal graft treatment. He was consented for entry into a single-center Investigational Device Exemption trial approved by the US Food and Drug Administration for evaluation of Valiant thoracic endograft devices (Medtronic, Inc., Minneapolis, MN) for the treatment of aortic pathology.

TREATMENT
Bilateral groin incisions were made, and the common femoral arteries were isolated. There was no pulse in the left common femoral artery. An atraumatic wire was advanced through the right common femoral artery, and with IVUS guidance, the wire was found to lie in the true lumen along the entire length of the thoracoabdominal aorta as the wire was advanced. At the level of the diaphragm, the aorta had a collapsed true lumen severely limiting flow to the visceral and renal arteries (Figure 2). In the descending thoracic aorta, there was a compressed true lumen with the origin of the dissection several centimeters distal to the subclavian artery, with a retrograde dissection to the level of the left subclavian. The transverse and ascending aorta were normal, and the diameter of the aorta was 31 mm at the level of the left carotid artery.

IVUS was used to identify the origin of the brachiocephalic vessels. There was an adequate length of descending thoracic aorta distal to the origin of the left carotid artery to secure the device and cover the retrograde component and the proximal entry site of the dissection. Over a Meier wire (Boston Scientific Corporation, Natick, MA), which had been passed through the central guidewire lumen of the IVUS and positioned in the true lumen along the entire length of the aorta, a 200-cm-long, 34-mm internal diameter Valiant thoracic stent graft was positioned at the deployment site. Using an angiographic catheter positioned in the ascending aorta from the right brachial artery, the position of the brachiocephalic vessels as identified via IVUS was confirmed (Figure 3). The device was deployed at the chosen site with the aid of 36 mg of adenosine given through a peripheral IV, which was administered to arrest the heart during deployment.

Deployment of the device just distal to the origin of the left carotid artery was confirmed using angiographic images through the innominate artery catheter and by IVUS examination (Figures 4 and 5). Inspection of the descending thoracic aortic lumen after deployment of the device demonstrated significant enlargement of the true lumen of the aorta along the entire length with reperfusion of the visceral, renal, and common femoral arteries.

After reperfusion of the true lumen, the procedure was completed. An exploratory laparotomy was performed to evaluate intra-abdominal pathology based on the patient's significantly elevated white blood cell count, lactate levels, and acidosis with a pH level of 7.26. An ischemic right colon was identified, and a colon resection was performed.

After the procedures, the patient recovered without incident, and perfusion of the true lumen to all major branch vessels remained as confirmed on a CT scan obtained 2 days after the procedure (Figure 6).

SUMMARY
This case demonstrates the potential for endoluminal graft treatment of complicated acute descending thoracic aortic dissections associated with visceral and limb ischemia. IVUS was a critical component of the procedure by identifying the path of the true lumen along the length of the thoracoabdominal aorta and aiding deployment of the endograft at the chosen location. IVUS not only expedited the precise deployment of the device in the true lumen, but it also identified the entry tears and the extent of retrograde dissection near the subclavian artery. IVUS also enabled device deployment using only 50 mL of contrast. It clearly demonstrated the etiology of the visceral and lower limb ischemia related to the collapse of the true lumen and documented immediate reperfusion of the true lumen with significant increase in size and pulsatility of the true lumen after device deployment. An additional benefit of IVUS was the demonstration of significantly decreased flow in the false lumen by increased echogenicity associated with decreased flow.

The case demonstrates the benefit of endograft exclusion of a descending thoracic aortic dissection with reperfusion of vital organs and lower extremities so that the extent of persistent ischemia, such as the colon pathology in this case, enabled expedient resection of the colon with identification of the extent of pathology.

Rodney A. White, MD, is Vascular Surgery Division Chief, Vascular Surgery Fellowship Program Director, and Vice Chairman of Research, Harbor-UCLA Medical Center, and Professor of Surgery, David Geffen School of Medicine at UCLA in Torrance, California. He has disclosed that he is a paid consultant to and receives research support from Medtronic, Inc., and Volcano Corporation. Dr. White may be reached at (310) 222-2704; rawhite@ucla.edu.

Carlos E. Donayre, MD, is a vascular surgeon with the Department of Surgery, Harbor-UCLA Medical Center in Torrance, California. He has disclosed that he is a paid consultant to and receives research support from Medtronic, Inc., and Volcano Corporation. Dr. Donayre may be reached at cdonayre@cox.net.

Irwin Walot, MD, is a radiologist with the Department of Radiology, Harbor-UCLA Medical Center in Torrance, California. He has disclosed that he is a paid consultant to Medtronic, Inc., and receives research support from Medtronic, Inc., and Volcano Corporation. Dr. Walot may be reached at drwalot@cox.net.

George Kopchok, BS, is a research associate at Harbor-UCLA Medical Center in Torrance, California. He has disclosed that he is a paid consultant to and receives research support from Medtronic, Inc., and Volcano Corporation. Mr. Kopchok may be reached at geokopchok@earthlink.net.

Arash Keyhani, DO, is a vascular surgeon with the Department of Surgery, Harbor-UCLA Medical Center in Torrance, California. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. Dr. Keyhani may be reached at arash.keyhani@gmail.com.

Omid Jazaeri, MD, is a fellow with the Department of Surgery, Harbor-UCLA Medical Center in Torrance, California. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. Dr. Jazaeri may be reached at jazeri@mac.com.

Joe Chauvapun, MD, is a vascular surgeon with the Department of Surgery, Harbor-UCLA Medical Center in Torrance, California. He has disclosed that he receives research support from Medtronic, Inc., and Volcano Corporation. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. Dr. Chauvapun may be reached at joechauvapun@yahoo.com.

 

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