CLINICAL DECISION MAKING

Congenital Coarctation and Takayasu’s Arteritis: Aortic Stenting Employing Intravascular
Ultrasound

Joseph D. Kay, MD, Yasser Al-Khatib, MD, Martin P. O’Laughlin, MD, Michael H. Sketch Jr., MD, J. Kevin Harrison, MD
Joseph D. Kay, MD, Yasser Al-Khatib, MD, Martin P. O’Laughlin, MD, Michael H. Sketch Jr., MD, J. Kevin Harrison, MD
Case Report. A 23-year-old woman was admitted for evaluation and treatment of aortic coarctation. She was first noted to have a murmur in infancy but did well throughout her early childhood years and no intervention was recommended. She remained free of symptoms until her first pregnancy 6 years prior to the current admission. During the last trimester of her first pregnancy, she was noted to be hypertensive requiring medical treatment. Her pregnancy was brought to term without further problems, delivering a healthy baby girl. After her delivery and for the next 4 years she did not undergo further medical evaluation. During her second pregnancy, about 18 months prior to the current admission, she was again found to be hypertensive. This pregnancy was brought successfully to term with the use of antihypertensive medications. However, she had persistent hypertension after this pregnancy, which was difficult to control medically. She also complained of fleeting, sharp chest pain, which occurred at rest and occasionally with exertion. An echocardiogram was performed, which revealed a 40 mmHg peak Doppler gradient in her descending thoracic aorta, just distal to the left subclavian artery. She underwent an MRI of her chest, which showed about a 60% narrowing of the descending thoracic aorta just distal to the left subclavian artery, as well as moderate right and left subclavian stenosis. An erythrocyte sedimentation rate was elevated, and she was diagnosed with Takayasu’s arteritis. She was treated with prednisone and methotrexate. Cardiac catheterization and aortic angiography revealed 50% stenosis bilaterally in her subclavian arteries and a discrete “ shelf-like” stenosis followed by a more tubular stenosis of the descending thoracic aorta, just below the left subclavian artery origin. The findings were also consistent with Takayasu’s arteritis. Pressure measurements revealed a peak to peak gradient of 30 mmHg across this segment of the aorta. There was no coronary artery or renal artery stenosis. Based on these findings at catheterization and her persistent hypertension, she was referred to our institution for further evaluation and treatment of the stenosis in her thoracic aorta. On physical examination, she was a thin, young, Caucasian woman resting comfortably. The upper extremity blood pressure was 180/90 bilaterally with lower extremity palpable systolic pressure of 140 mmHg. Her medications included benazepril (Novartis, East Hanover, New Jersey), alendronate sodium (Merck, West Point, Pennsylvania), Prednisone, and Methotrexate (Lederle, Pearl River, New York). There was a 2/6 systolic murmur audible posteriorly along the left scapular border as well as bilateral subclavian bruits. Femoral pulses were diminished as were the posterior tibial and dorsalis pedis pulses. Laboratory data including CBC, electrolytes, renal function and ESR were all within normal range, and B-HCG was negative. After obtaining informed consent, the patient was taken to the cardiac catheterization laboratory where general anesthesia was induced. A 5 French (Fr) venous sheath was placed in the right femoral vein. Seven Fr and 6 Fr arterial sheaths were placed in the left and right femoral arteries respectively. A 6 Fr pigtail catheter (Cordis Corporation, Miami Lakes, Florida) was positioned in the distal aortic arch. A 7 Fr NIH cardio-marker catheter (Medtronic, Danvers, Massachusetts) was placed in the descending thoracic aorta just distal to the narrowed segment. The peak-to-peak gradient across this segment was 24 mmHg. Biplane angiograms of the distal aortic arch and descending thoracic aorta demonstrated the narrowed aortic segment with a “shelf-like” stenosis followed by a tubular narrowing (Figure 1). The 6 Fr right femoral arterial sheath was replaced with an 11 Fr, 80 cm long Mullins sheath (Cook, Bloomington, Indiana). This was passed across the narrowed aortic segment, with the distal tip in the aortic arch. An 8.5 Fr, 9 MHz intravascular ultrasound (IVUS) catheter was advanced through the Mullins sheath across the narrowed aortic segment. IVUS images were obtained from the distal aortic arch, across the narrowed segment of the aorta, as well as from the descending thoracic aorta distal to the stenosis. (Figures 2 and 3). The intravascular ultrasound images demonstrated significant narrowing of the aorta, with a minimum luminal diameter of 6 mm at the level of the “shelf-like” stenosis seen by angiography. The area of tubular stenosis was surprisingly severe as well with a luminal diameter of 8 mm throughout its length. The angiographically normal segment of the descending thoracic aorta, distal to the stenotic areas, measured 14 mm in luminal diameter. Based on the > 50% luminal narrowing measured at the coarctation segment, her hypertension, and the 40 mmHg gradient between the upper and lower extremities on physical prior to inducing general anesthesia, it was elected to proceed with stenting of the narrowed segment. The length of the narrowed segment, measured angiographically with the NIH cardio-marker catheter used as a reference, was approximately 40 mm. A 40 mm long Johnson and Johnson Palmaz XL stent (Cordis) was crimped onto a 12 mm x 4 cm Blue Max balloon (Boston Scientific/Scimed, Maple Grove, Minnesota). The balloon mounted stent was passed across the narrowed segment through the Mullins sheath over a 0.035 x 260 cm Amplatz Super Stiff ST guidewire (Medi-tech/Boston Scientific). The stent was positioned at the narrowed aortic segment and exposed by withdrawing the Mullins sheath. The stent was deployed to a diameter of 12 mm at 10 atmospheres pressure. The stent was further expanded using a 14 mm x 4 cm XXL balloon at 8 atmospheres pressure (Medi-tech/Boston Scientific). Aortography following stenting is shown in Figure 4. The Mullins sheath was repositioned across the stented segment and the IVUS catheter was re-advanced through the sheath to the distal aortic arch. The IVUS images showed complete apposition of the stent against the aortic endothelium with a 14 mm diameter lumen throughout the stented segment, equal to the diameter of aorta beyond the stented segment. There was no evidence of aortic dissection proximal to, within, or distal to the stented segment (Figure 5). Post-procedurally, the patient had no further problems with hypertension, with upper extremity blood pressures of 114/78 mmHg. She did, however, report bilateral peripheral blurred vision 24 hours after the procedure. She also reported right upper extremity numbness and transient, mild right upper extremity weakness. Neurologic examination was unremarkable. Non-contrast head CT revealed no abnormality. The blurred vision, as well as the upper extremity weakness, resolved at 48-hours post-procedure. She was discharged on Plavix 75 mg orally a day for four weeks and aspirin 325 mg orally a day for a minimum of 6 months. How Would You Manage This Case? John W. Moore, MD, MPH Director, Cardiac Catheterization Laboratories St. Christopher’s Hospital for Children Philadelphia, Pennsylvania I would like to congratulate the authors for their lucid case presentation and their excellent result of stenting an aortic coarctation in a young adult with Takayasu’s Arteritis. I substantially agree with their strategy and technique, and I would have also elected to perform aortic stenting in this patient. Nevertheless, in my view, two issues merit some discussion. First, is stenting an appropriate treatment in Takayasu’s Arteritis? Most operators are currently comfortable stenting native congenital coarctations of the aorta. However, Takayasu’s Arteritis has a completely different histopathology, and the arteritis may be active or in remission. As one would expect, there is little available published experience with this problem. There are a few reports of experiences with angioplasty,1 which suggest that angioplasty alone may be effective and safe. Available reports of stenting involve small numbers of patients or are anecdotal,2 but have generally suggested that stenting may be effective and safe. My belief is that stenting is more effective and safer than angioplasty in this setting, and it has numerous advantages over any surgical strategy. I’m with the authors. Second, technical issues merit some discussion. The authors did not mention whether they used heparin, and if so, how much, and whether they measured activated clotting times during the procedure. Given the apparent transient neurological phenomena, which occurred after the procedure, these details are particularly important to include in the case description. The intravascular ultrasound (IVUS) pictures and findings are interesting. But how were they useful or important? Did the IVUS images provide information about aortic wall thickness or composition, which was reassuring to the operators? Is IVUS better than angiography for detecting dissections after stent placement? There should be some benefit from prolonging the procedure and using a larger arterial sheath than needed for stent placement. Finally, many operators would use a balloon-in-balloon (BIB) catheter for stent placement. A 14 mm outer balloon BIB catheter is available, and has important advantages. It facilitates more accurate stent positioning, and there is less flaring of the ends of the stent during inflation, reducing the risk of dissection. Nevertheless, who can argue with an excellent result? REFERENCES 1. Tyagi S, Khan AA, Kaul UA, Arora R. Percutaneous transluminal angioplasty for stenosis of the aorta aortic arteritis in children. Pediatr Cardiol 1999;20:404–410. 2. Bali HK, Bhargava M, Jain AK, Sharma BK. De novo stenting of descending thoracic aorta in Takayasu arteritis: Intermediate-term follow-up results. J Invas Cardiol 2000;12:612–617. Ziyad M. Hijazi, MD, MPH Chief, Section of Pediatric Cardiology University of Chicago Children’s Hospital Chicago, Illinois I read with interest the paper “Congenital Coarctation and Takayasu’s Arteritis: Aortic Stenting Employing Intravascular Ultrasound” by Kay et al. This paper illustrates a very nice case of Takayasu’s arteritis type 1 affecting a 23-year-old woman. I agree with the catheter management strategy in this patient. However, I would have studied the subclavian arteries using the intravascular ultrasound to look for stenosis. Although Figures 1 and 4 do not indicate significant narrowing of the origin of the left subclavian, it was mentioned in the paper that this patient, by MRI of the chest, had moderate right and left subclavian stenosis. Furthermore, by angiography at the referring center, she had 50% stenosis bilaterally in her subclavian arteries. Why did the authors elect not to even evaluate the subclavian arteries by selective angiography and intravascular ultrasound? Another potential treatment option would have been implantation of a covered stent. Since the area of coarctation was distal to the left subclavian artery origin, I would have considered a covered graft (balloon-expandable or self) to prevent neointimal proliferation and restenosis. Finally, I would have considered the use of 3-dimensional intravascular imaging to determine the exact length of the abnormal area of coarctation. This technology is readily available in many centers performing coronary interventions. P. Syamasundar Rao, MD Saint Louis University School of Medicine Division of Pediatric Cardiology St. Louis, Missouri The preceding report describes excellent results of stent deployment in a 23-year-old with coarctation of the aorta. My compliments to the authors for the superior result. The diagnosis of Takayasu’s arteritis may be correct because of multiple vessel involvement, long segment narrowing and elevated phase reactants, although beginning signs of the disease in infancy and thoracic rather than abdominal coarctation may raise some doubts of the accuracy of the diagnosis. Whatever the basic diagnosis is, it is clear that there is definitive aortic obstruction causing significant symptomatology both during and after pregnancy. Thus, there is clear-cut indication to relieve the aortic obstruction. Of the three methods of intervention available at the present time, namely balloon angioplasty, intravascular stent and surgery, my preference is also stent, similar to that adopted by Kay et al. Discussion of reasons for such a choice is beyond the scope of this presentation. However, the methodological approach that we take for the procedure is slightly different from that used by Kay et al. We generally perform the stent implantation procedure under conscious sedation instead of general anesthesia. We initially place sheaths in the right femoral vein and artery, perform diagnostic catheterization, and confirm the clinical and echocardiographic diagnosis. We do not use the additional left femoral artery site. After arterial entry, heparin is administered and the activated clotting time (ACT) is monitored and maintained between 200–250 seconds. Following measurement of pressure gradient across the coarctation, we perform selective aortic arch angiography using marker pigtail catheter (Cordis Corporation, Miami Lakes, Florida) with radiopaque markers 10 mm apart, so that accuracy with which the measurement of aortic segments are made is improved; this is not too dissimilar to that used in preceding report. We would ordinarily attempt to perform the stent deployment through a much smaller sheath than the 11 French sheath used by the authors. The smallest sized sheath that will allow passage of a stent-mounted balloon catheter is selected. The reason for the selection of a smaller sheath is to avoid/minimize arterial damage. Even in the adult population, smaller sheaths have a lesser tendency to develop femoral artery occlusion.1 Based on the measurements obtained by the authors, a stent with an expanded diameter of 14 mm and a length of approximately 40 mm, as selected by the authors, is appropriate. Because of longitudinal rigidity2 and the potential for balloon rupture3 and arterial injury4 associated with Palmaz stents, we avoid using them. In this case, we would select a 36 mm long IntraStent DoubleStrut LD (IntraTherapeutics, St. Paul, Minnesota) for implantation. There is no discernable shortening of this stent with expansion. This stent is mounted on a 14-7 balloon-in-balloon (BIB) catheter (NuMED, Hopkinton, New York). This BIB catheter has an inner balloon diameter of 7 mm and an outer balloon diameter of 14 mm. The stent can be easily crimped on the deflated balloon of the BIB catheter and will pass through a 9 French sheath. Our preference is to implant the stent with a balloon diameter of the desired final stent diameter in order to prevent inadvertent dislodgement/displacement during placement of a second balloon catheter. Also, the expense associated with the extra balloon catheter is saved. Self-expanding (i.e., Wallstents) is another option,5 but we do not have any personal experience in the use of this stent. Taking the above consideration into account, we initially place a 9 French long blue Cook sheath (Cook, Bloomington, Indiana) with a radiopaque marker at the tip and position the tip beyond the level of coarcted segment over an already placed, extrastiff 0.035´´ Amplatz guidewire (Cook). The selected stent is crimped onto the 14-7 BIB catheter and introduced carefully through the valve of the sheath without displacing the stent. The stent mounted balloon is advanced over the guidewire, but within the sheath and positioned such that the coarcted segment is centered onto the stent, using bony landmarks. The sheath is withdrawn, uncovering the stent. If there is uncertainty of the location of the stent, a test injection through the sheath is performed. Initially, the inner 7 mm balloon is inflated, and if necessary, the stent position readjusted, followed by inflation of the outer balloon, thus, implanting the stent. The pressure of inflation used is limited to the manufacturer’s recommended level. Both balloons are then deflated. The balloon catheter is gently advanced and the outer balloon re-inflated to ensure that the proximal end of the stent is well-positioned against the aortic walls. The balloon catheter is withdrawn into the sheath by advancing the sheath on the balloon as described elsewhere.6 Next, the balloon catheter is centered over the lower end of the stent, sheath tip withdrawn and outer balloon re-inflated, again to ensure that the lower end of the stent is well apposed to the aortic wall. The balloon catheter is removed (as described above). Throughout the above maneuvers, an assistant holds the guidewire in place. We then insert a 5 or 6 French monorail multi-track catheter (Braun, Bethlehem, Pennsylvania) over the guidewire.7 Pressure measurements across the stent are recorded to ensure relief of the pressure gradient. The catheter is re-advanced proximal to the stent and the angiography is repeated. If there is any discernable gap between the stent and aortic wall, a larger diameter balloon is positioned within the stent and inflated to ensure that the stent is well apposed to the aortic wall. Finally, the catheters and sheaths are removed and pressure dressing is applied. Alternatively, a vascular occlusion device8 is used to achieve arterial hemostasis. The patient is observed until the morning following the procedure and a chest roentgenogram and echocardiogram, along with Doppler, are performed prior to discharge. Platelet-inhibiting doses of aspirin (325 mg/day) are administered for 6–12 weeks. In summary, I agree with Kay and his associates in regard to the choice of stent deployment for treatment of the long segment coarctation. The method that we use to implant the stent is slightly different in that we 1) use conscious sedation instead of general anesthesia, 2) utilize the 9 French sheath instead of an 11 French sheath for stent delivery, 3) employ a BIB catheter instead of two separate balloon catheters (Blue Max and XXL) to deploy the stent in an attempt to decrease the probability of stent displacement and reduce the cost, 4) select IntraStent DoubleStrut LD stent instead of Palmaz XL stent in order to prevent balloon rupture and increase stent flexibility, and 5) acquire post-stent implantation pressure and angiographic data via a multi-track catheter. However, Kay’s results are excellent, and I can’t argue with success.
References
1. Metz D, Meyer P, Touati C, et al. Comparison of 6-F with 7-F and 8-F guiding catheters for selective coronary angioplasty: Results of prospective, multicenter, randomized trial. Am Heart J 1997;134:131–137. 2. Rao PS. Stents in treatment of aortic coarctation (editorial). J Am Coll Cardiol 1997;30:1853–1855. 3. Hijazi ZM, Al-Fadley F, Geggel RL, et al. Stent implantation for relief of pulmonary artery stenosis: Immediate and short-term results. Cathet Cardiovasc Diagn 1996;38:16–23. 4. Evans J, Saba Z, Rosenfeld H, et al. Aortic laceration secondary to Palmaz stent placement for treatment of superior vena cava syndrome. Cathet Cardiovasc Intervent 2000;49:160–162. 5. Bali HK, Bhargava M, Jain AK, Sharma BK. De novo stenting of descending thoracic aorta in Takayasu arteritis: Intermediate-term follow-up results. J Invas Cardiol 2000;12:612–617. 6. Recto MR, Ing FF, Grifka RG, et al. A technique to prevent stent displacement during subsequent catheter and sheath manipulation. Cathet Cardiovasc Intervent 2000;49:297–300. 7. Bonhoeffer P, Piechaud J, Stumper O, et al. The multi-track angiography catheter: A new tool for complex catheterization in congenital heart disease. Heart 1996;76:173–177. 8. Sharke KL. Comparison of major complication rates associated with four methods of arterial closure. Am J Cardiol 2000;85:1024–1025.