Percutaneous Balloon-Expandable Stents for Sealing of Acute Aortic Dissection

Abstract

Acute aortic dissection is a highly lethal disease. When dissection involves only the descending aorta and there are no ischemic complications, medical management may be the treatment of choice. However, a high risk of expansion or rupture of the dissection remains. When renal or limb ischemic complications do appear, surgery has been the only option, despite high mortality and morbidity. Percutaneous placement of stents for sealing an acute aortic dissection might be an alternative to surgical treatment. We treated 2 patients with acute type B aortic dissection by stent-fixation of the proximal and distal descending aorta. In both patients, there was evidence of persistent flap fixation at midterm follow-up.

Acute aortic dissection is a life-threatening condition. ¹ Despite recent surgical advances, the treatment of choice for thoracic and abdominal aortic dissections remains uncertain, because surgical procedures entail significant morbidity and mortality. ¹ It has been argued that medical treatment might be a better choice than surgical repair in acute type B dissection. ^1–3 However, in 20% to 50% of patients who receive medical treatment, the aortic wall may expand within 1 to 5 years and may rupture spontaneously. ^1,4

Although endovascular stents have been used to treat congenital stenosis of the aorta ^5,6 and atherosclerotic aneurysms, ⁷ only a few cases have been reported in which stents were used for fixation of aortic dissection. ^7–11 Percutaneous stent sealing of the dissecting flap might provide an alternative to standard surgical treatment. We report our initial experience in 2 patients with symptomatic acute aortic dissection who received balloon-expandable stents to seal the proximal and distal openings of the aortic flaps.

Case Reports

Patient 1

In November 1998, during the postoperative period following a spinal column fixation (L5-S1 discectomy and arthrodesis), a 54-year-old man developed a hypertensive crisis with acute epigastric pain, fatigue, vegetative signs, and ischemic compromise of both lower extremities. Eleven years earlier, the patient had experienced an acute type B dissection and had undergone emergency surgical reconstruction of the descending aorta with a 24-mm woven Dacron tube, placed by the intraluminal sutureless method. Since then, the patient had remained asymptomatic on blood pressure control.

After clinical evaluation, the patient was transferred to the intensive care unit, where his blood pressure was controlled. Ischemic heart disease or a new acute dissection was suspected, and an emergency cardiac catheterization was performed. Left ventricular angiography showed a hypertrophic and hyperdynamic ventricle; coronary angiography showed a normal coronary tree. Aortography revealed a new acute dissection that began distal to the graft and affected both iliac arteries. Blood flow to the left renal and right iliac arteries was compromised. Due to the high risk associated with surgery, we decided to attempt to seal various segments of the spiral dissection with Palmaz™ balloon-expandable stents (Cordis Corporation, a Johnson & Johnson company; Warren, NJ). The patient gave informed consent.

Through a 14-F angiographic sheath, a 1st stent (P4014; length, 40 mm) was crimped onto a 15-mm diameter Maxi LD™ PTA Dilatation Catheter (Cordis). The stent was dilated at 5 atmospheres (atm) and placed at the origin of the right iliac artery, in order to facili-tate access to the aorta. Next, a second stent (P5014; length, 50 mm), crimped onto a 25-mm diameter Balt™ balloon (Balt; Montmorency, France), was advanced and deployed proximal to the origin of both renal arteries. Finally, a 3rd stent (P4014; length, 40 mm) was balloon-expanded at 4–5 atm to 25 mm just proximal to the aorto-iliac bifurcation (Fig. 1). Fixation of these flaps provided complete patency of the renal and iliac arteries. The patient's pain disappeared, and his condition stabilized. At discharge 7 days later, he was symptom free and normotensive on beta-blockers. At 20-month follow-up, he remained symptom free. A computed tomographic (CT) scan performed 10 months after treatment showed persistent flap fixation (Fig. 2). He refused late cardiac catheterization.

Fig. 1 Aortograms in postero-anterior projection from Patient 1, who had acute aortic dissection. The aorto-iliac bifurcation is shown before (A) and after (B) stent sealing of the distal part of the flap. A 1st stent, deployed at the true lumen of the right iliac artery, was needed for further aortic access.

Fig. 2 Computed tomographic scan of Patient 1 at 10-month follow-up shows the proximal (A) and distal (B) stent placement sites. Persistent flap fixations can be observed.

Patient 2

In December 1998, a 48-year-old man, asymptomatic for hypertension, was admitted to the hospital because of acute and prolonged chest and back pain. His blood pressure was 190/100 mmHg. His electrocardiogram and enzyme levels were normal. A CT scan showed an extensive thoraco-abdominal aortic dissection. The entry site was beneath the origin of the left subclavian artery, and the dissection extended spirally into both iliac arteries. At first, medical treatment was selected, under intensive care management. However, the patient experienced repeated episodes of chest and lumbar pain. Therefore, we decided to attempt percutaneous stent sealing of the dissection at the entry site and at the distal abdominal aorta. The patient gave informed consent.

Following diagnostic aortograms, a high-support guidewire was advanced through the true lumen to the ascending aorta. Under angiographic guidance provided by a subclavian catheter introduced percutaneously from the left brachial artery, a Palmaz™ stent (P4014; length, 40 mm) was advanced retrogradely over the guidewire to the upper mouth of the dissection. The stent was expanded to 30 mm in diameter by a CBV Balt balloon. However, this stent did not attach and migrated proximally when the balloon catheter was manipulated. The stent was captured with another semi-inflated 35-mm diameter balloon catheter (CBV Balt) and deployed as close as possible to the dissection's entry site. Next, a 2nd Palmaz stent (P5014; length, 50 mm) was introduced, anchored inside the 1st one, and balloon-expanded at the entry site at 4–5 atm to 35 mm in diameter (Fig. 3). Finally, a 3rd Palmaz stent (P4014; length, 40 mm) was balloon-expanded to 25 mm in diameter at the aorto-iliac bifurcation. Aortic angiography confirmed adequate sealing of the entry site and the distal aorta. The patient became stable and normotensive. A computed tomographic scan before discharge showed stabilization of the flap. After 19 months of follow-up, he remains asymptomatic. Follow-up cardiac catheterization and CT scanning performed 9 months after treatment provided evidence that the dissection had sealed at the stented segments (Figs. 4 and 5).

Fig. 3 Angiograms of the aortic arch (60° left-anterior-oblique projection) from Patient 2, whose acute aortic dissection originated distal to the left subclavian artery. The lesion is shown before (A) and after (B) stent sealing.

Fig. 4 In Patient 2, follow-up total aortographic reconstruction (2 contrast injections in postero-anterior projection) shows persistent sealing of the dissection at the stented segments.

Fig. 5 Serial computed tomographic scans from Patient 2 of the proximal and distal levels of the descending aorta. At baseline condition (A and B), a clear dissection flap can be identified at both levels. After treatment (C and D), and at 9-month follow-up (E and F), proximal and distal flaps are fixed by the stent.

Discussion

Type B acute aortic dissection may be managed by the use of antihypertensive and negative inotropic drugs, which may help to prevent aortic rupture. However, when mesenteric, renal, or peripheral vascular ischemic complications appear, surgical repair is required, despite high mortality rates. ⁴

Several experimental studies have shown the potential for percutaneous treatment of the dissected aorta, either with placement of self- or balloon-expandable endovascular stents, or with puncture and balloon fenestration of the intimal flap. ^12–15 Following these experimental findings, both percutaneous techniques have been applied to manage patients with symptomatic aortic dissections. ^{7–11, 16–18} In most instances, the stents were implanted at the aortic branches to manage ischemic complications, but in a few patients, the stents were intended to seal the dissection.

Two recent series have shown promising results in patients who underwent transluminal endovascular stent insertion for aortic dissection. ^{10, 11} Both studies found that elective stent treatment of type B (descending) aortic dissection was safe and effective in most patients. It is hoped that adequate stent fixation of the entry site will also reinforce and scaffold a weak aortic wall, providing permanent free flow within the true lumen. However, the long-term efficacy of this treatment is not yet known. If degenerative changes in the wall continue to expand the aorta, the stent might become inefficient in permanently sealing the dissection.

In our 2 patients, the sealing of proximal and distal dissecting flaps by means of stent placement stabilized the acute clinical condition and prevented ischemic complications. These dual-level fixations should also induce thrombosis of the false lumen. After 19 and 20 months, respectively, both patients remain symptom free and have not experienced any major cardiovascular events. Late angiograms from 1 patient and CT scans from both demonstrated persistent sealing of the flap at the entry and distal aorta sites.

At present, there are no commercially available stents specifically designed for closing aortic dissections. Large aortas require large stent diameters, and, at present, balloon expansion capabilities are limited by the available percutaneous technology. Due to these limitations, only very carefully selected patients should be considered for stent sealing of acute aortic dissection at the present time.

In our 2 patients, stent fixation of the aortic dissection flap persisted at midterm follow-up. This suggests that stent treatment of acute aortic dissection may be an alternative to surgery in selected patients. Greater experience and longer-term information are needed.