Successful Percutaneous Endovascular Management of Acute Post-traumatic Superior Mesenteric Artery Dissection (full title below)

Successful Percutaneous Endovascular Management of Acute Post-traumatic Superior Mesenteric Artery Dissection Using a Transradial Approach

ABSTRACT: Acute aortic dissection extending into the superior mesenteric artery (SMA) following a blunt trauma is an extremely rare complication. We report a case of acute post-traumatic SMA dissection presented with an acute abdominal syndrome. Computed tomographic angiography and arteriography allowed a rapid diagnosis and urgent percutaneous endovascular intervention through transradial route. This approach saved a major surgical intervention and related morbidity. J INVASIVE CARDIOL 2010;22:E61–E64 Key words: superior mesenteric artery, traumatic dissection, transradial approach, stent
Non-penetrating injuries of the abdominal aorta are rare and only 25% of them result in aortic dissection.¹ Because the abdominal aorta is highly protected by virtue of its anatomical location, aortic dissection is usually associated with major trauma and damage to other structures.² The mortality rate with medical management is 75%.3 In most cases, emergent surgical management is considered because the problem is often fatal.² We report a case of a post-traumatic dissection of the abdominal aorta extending into the superior mesenteric artery (SMA) managed successfully by percutaneous endovascular stent placement through a transradial approach. Case 1. A 75-year old male was admitted to the emergency care unit with a history of a fall from a height 1 hour previously. His major complaints at the time of admission were acute abdominal pain with distension and severe backache. He was a known case of long-standing diabetes mellitus, coronary artery disease (CAD) and severe left ventricular (LV) dysfunction (ejection fraction of 15%). On examination, his heart rate was 120 beats/minute and his blood pressure was 110/70 mmHg. Cardiac auscultation revealed a loud S3 gallop. Abdominal examination revealed signs of paralytic ileus. Neurological examination was unremarkable. Abdominal sonography and a Doppler flow study revealed dilated bowel loops and possible dissection of the abdominal aorta at one point extending into the SMA. Urgent computed tomographic (CT) angiography confirmed a dissection of the abdominal aorta extending into the SMA and evidence of a fracture of the corresponding lumber vertebra (Figure 1). The orthopedic surgeon advised conservative management for the vertebral fracture. The vascular surgeon refused surgical intervention on the grounds of an unduly high risk due to the patient’s age, diabetes mellitus, CAD and severe LV dysfunction. Hence, the patient was referred to us for emergent percutaneous endovascular management. We chose the left radial approach. After puncturing the left radial artery, we deployed a 6 French (Fr) Radifocus sheath (Terumo Corp., Tokyo, Japan) using a standard technique. Aortography was performed to confirm the findings of the CT angiogram (Figure 2A). A 6 Fr sheath was exchanged over a 0.035 inch extra-stiff Amplatz wire (Boston Scientific Corp., Natick, Massachusetts) for a 7 Fr 90 cm long Pinnacle sheath (Terumo). The distal end of the sheath was kept in the abdominal aorta above the dissected segment (Figure 2B). A 0.014 inch BMW PTCA wire (Abbott Vascular, Santa Clara, California) was negotiated into the dissected segment, but it had a tendency to enter the false lumen, hence it was parked there (Figure 2C). We took a 0.014 inch Whisper extra-support PTCA wire (Abbott) to enter the true lumen. After several attempts, we were successful in introducing and parking it in the true lumen (Figure 2D). The dissection was stented using a 10 x 40 mm Smart self-expanding stent (Cordis Corp., Miami Lakes, Florida) (Figure 2E). Post-stenting angiography revealed a wide-open SMA, an adequately sealed dissection and brisk flow (Figure 2F). Subsequently, the patient recovered from mesenteric artery insufficiency and was discharged on the sixth day. Follow-up examination 6 months later revealed no signs or symptoms of SMA insufficiency and a normal flow pattern in the SMA on Doppler study. Discussion. The exact incidence of abdominal aortic dissection in blunt trauma is unknown, because many patients with intimal disruption do not reach the hospital alive. ² Killen has reported only one such case out of 1,320 patients with blunt abdominal trauma. ⁴ Two major mechanisms have been proposed to explain an abdominal aortic dissection during non-penetrating trauma: direct from the blunt trauma with aortic compression against bony structures of the spine, especially in seat-belt injuries, and indirect as a result of deceleration force, especially in high-speed collisions. ^5,6 Atheromatous aortic plaques are believed to be a possible contributing factor to abdominal aortic dissection, because less force is required to injure the intima over a plaque in a rigid atheromatous aorta. ⁷ In our patient, a fall from a height leading to direct injury from the blunt trauma with aortic compression against the vertebral column seems to have been the cause of aortic dissection. It is obvious from the vertebral fracture seen on the CT angiography plate (Figure 1). In view of his age, long-standing diabetes mellitus and severe CAD, this patient had elevated risk of a rigid atheromatous aorta, which further explains the mechanism of dissection. However, it is an extremely rare phenomenon to develop such a traumatic dissection of the abdominal aorta involving the SMA and extending deep into it, although a few cases of spontaneous SMA dissection have been reported in the literature. ⁸ The combined use of real-time abdominal ultrasonography and Doppler-flow studies were effective means to suspect an intimal flap in the abdominal aorta extending into the SMA. However, to establish the diagnosis, contrast-enhanced CT scanning and angiography were performed, which helped us to evaluate the proximal and distal limits of the dissection and also to rule out aortic thrombosis, false aneurysm and aortic rupture. Aortography performed through a left radial approach, providing a better image of the dissection and important details including the length and extent of the dissection in the SMA, the approximate area and orientation of the false lumen, as well as the precise diameter of the SMA. Optimal management of a traumatic SMA dissection remains controversial because of the paucity of data. Medical management with anticoagulation to prevent thrombus formation and bowel ischemia may achieve symptomatic relief in patients with mild symptoms. ⁸ However, chronic anticoagulation therapy, despite often being effective in preventing thrombosis, failed to halt the progression of disease and aneurysmal dilatation in some cases during long-term follow up.^9,10 Given the invasive nature of the surgery, it is reasonable to reserve it for patients with compelling indications including bowel necrosis, impending arterial rupture or increasing size of the aneurysmal dilatation of the SMA despite anticoagulation therapy.¹¹ The vascular surgeon deemed our patient ineligible for surgery due to his multiple risk factors and comorbidities. We accepted the patient for emergent percutaneous endovascular stent placement and performed it successfully via a left radial approach. Our center uses the radial approach for practically all coronary as well as peripheral interventions including infradiaphragmatic interventions (renal, iliac, superficial femoral, etc.). We wanted to deploy the distal end of a 7 Fr Pinnacle 90 cm long sheath just above the origin of the SMA in this patient. It was possible because we chose a left radial approach, since it eliminates the length of the aortic arch.¹² The aims of percutaneous endovascular management in such a situation are to prevent the extension of dissection and to reestablish SMA flow by obliterating the false lumen, which may extend distally and involve several branches, particularly their ostia.^13,14 These goals can only be achieved by both ensuring coverage of the entry point by stenting the dissected main trunk and dilatation of the distally involved segments by balloon angioplasty. Furthermore, it has been suggested that endovascular treatment is only suitable for short segments of a dissection.¹⁴ However, we demonstrated here an effective use of a long, self-expanding stent to seal a large SMA dissection successfully through the radial route. It not only obliterated a significant length of the false lumen, but also ensured adequate coverage of the entry point and obviated the need for dilatation of the distally involved segments by balloon angioplasty. This simple approach was effective in providing immediate and persistent relief of symptoms, thus further expanding the horizon of emergent endovascular management for a rare traumatic SMA dissection. A 0.014 inch BMW PTCA wire was used to enter the true lumen, however, it had a tendency to enter the false lumen. After parking it in the false lumen, we deliberately chose a hydrophilic 0.014 inch Whisper PTCA wire to enter the true lumen. After several careful attempts, we successfully entered it. One wire kept in the false lumen provided us with a roadmap for successful introduction of another wire into the true lumen. Technically, it was easy to deploy a bulky self-expanding Smart stent over a 0.014 inch Whisper wire in the dissected segment through a left radial approach. The choice of self-expanding stent was made, keeping the weakened vessel wall of the dissected segment in mind, as this stent has a relatively weak radial force and a less traumatic edge. To ensure proper coverage of the entry site, we positioned the proximal end of the stent around 1 cm from the proximal end of the false lumen, overhanging in the abdominal aorta, so as to avoid the influences of proximal shortening of the stent and inadvertent migration during deployment. Conclusion. In conclusion, our case demonstrated that traumatic SMA dissection can be rapidly and reliably diagnosed by noninvasive imaging modalities like abdominal ultrasonography, Doppler study and CT scanning. Because of the paucity of data, the optimal treatment strategy is still uncertain. However, percutaneous endovascular treatment appear to be a safe, efficient and less-invasive option for treating a traumatic SMA dissection. It is also possible to deploy a relatively bulky self-expanding stent through transradial approach, thus making it a less-invasive option.

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From the *Total Cardiovascular Solutions Private Limited, Ahmedabad, India, §Department of Cardiology, Sheth V.S. General Hospital, Ahmedabad, India. The authors report no conflicts of interest regarding the content herein. Manuscript submitted September 8, 2009 and accepted September 25, 2009. Address for correspondence: Tejas Patel, MD, FACC, FSCAI, FESC, Professor and Head, Department of Cardiology, NHL Municipal Medical College, Sheth V.S. General Hospital, Ahmedabad-380 006, India. E-mail: tejaspatel@tcvsgroup.org