Coarctation of the P. Syamasundar Rao, MD

Address the media and superimposed neointimal tissue. The local- Division of Pediatric Cardiology, The University of Texas/Houston ized constriction may form a shelf-like structure with an Medical School, 6431 Fannin, MSB 3.130, Houston, TX 77030, USA. eccentric opening or it may be a membranous curtain-like E-mail: [email protected] structure with a central or eccentric opening. The coarcta- Current Cardiology Reports 2005, 7:425–434 tion may be discrete, or a long segment of the aorta may be Current Science Inc. ISSN 1523-3782 Copyright © 2005 by Current Science Inc. narrowed; the former is more common. In the past, AC has been described as preductal (or infantile) type and post- ductal (or adult) type, depending upon whether the coarc- Coarctation of the aorta is an important, treatable cause of tation segment is proximal or distal to the ductus secondary . Its prevalence varies from 5% to arteriosus, respectively. However, a detailed review of the 8% of all congenital defects. This condition is most anatomy suggests that all coarctations are juxtaductal. often detected because of a murmur or hypertension found Dilatation of the immediately distal on routine examination. Delayed or absent femoral to the coarctation segment, poststenotic dilatation, is usu- and an arm/leg systolic blood pressure difference of 20 mm ally present. Varying degrees of hypoplasia of the isthmus Hg or more in favor of the arms may be considered as evi- of the aorta (the portion of the aorta between the origin of dence for aortic coarctation. The coarctation may be dem- the left and ) and trans- onstrated on a suprasternal notch two-dimensional verse aortic arch (the portion of the aorta between the ori- echocardiographic view along with increased Doppler flow gins of left common carotid and left subclavian artery) are velocities across the coarctation site. Cardiac catheteriza- present in the majority of patients with thoracic coarcta- tion reveals significant systolic pressure gradient (> 20 mm tion. Collateral vessels that connect arteries from the Hg) across the coarctation and angiography demonstrates upper part of the body to the vessels below the level of the degree and type of aortic narrowing. Aortic obstruc- coarctation may be seen; these may be present as early as a tion may be relieved by surgery or by transcatheter tech- few weeks of life. niques; the latter include balloon and stent implantation. In the past, surgery has been used exclusively, but because of morbidity and complications associated with Prevalence surgery, catheter techniques are increasingly used in the The prevalence of AC was found to vary between 5% to 8% management of aortic coarctation. Balloon angioplasty in of all congenital heart defects [1,2]. Slight male preponder- children and stents in adolescents and adults are becoming ance has been observed in older patients, although it is initial therapeutic options for management of coarctation. minimal in infants. Studies evaluating long-term follow-up results of the inter- ventional techniques are needed. Associated Defects Bicuspid may be seen in nearly two thirds of Introduction infants with AC, whereas only 30% of older children may Coarctation of the aorta is an important cause of secondary have such an anomaly. Mitral valve anomalies, although less hypertension and consequently, inclusion of this entity frequent than those of the aortic valve, are also seen with when discussing is appropriate. In AC. Some patients with AC may have cerebral aneurysms, this review, definition, pathology, prevalence, pathogenesis, predisposing them to development of cerebrovascular acci- pathophysiology, clinical features, noninvasive and invasive dents with severe hypertension later in life. AC is the most evaluation, treatment, and prognosis of aortic coarctation common cardiac defect seen in Turner’s syndrome. (AC) in children, adolescents, and adults is discussed.

Pathogenesis Definition and Pathology The exact mechanism by which AC is produced is not Coarctation of the aorta is defined as a congenital cardiac clearly understood [3]. Two hypotheses are most com- anomaly consisting of a constricted aortic segment com- monly invoked: hemodynamic and ectopic ductal tissue. In prising localized medial thickening with some infolding of the first hypothesis, an abnormal preductal flow or abnor- 426 Hypertension mal angle between the ductus and coarctation are invoked. Palpation of the brachial and femoral artery pulses simulta- Spontaneous postnatal closure of the ductus arteriosus neously will reveal decreased and delayed or absent femoral completes the development of aortic obstruction. A high pulses. Blood pressure in both arms and one leg must be incidence of AC in patients with determined; a pressure difference of more than 20 mm Hg in decreased antegrade aortic flow in utero and virtual absence favor of the arms may be considered evidence for AC. of AC in patients with right heart obstructions would lend The LV impulse may be increased. A thrill is usually felt credence to the hemodynamic hypothesis. Abnormal exten- in the suprasternal notch. The first and second heart sion of ductal tissue into the aorta (ectopic ductal tissue) sounds are usually normal in isolated aortic coarctation. has been postulated to create coarctation shelf, and with Because of the large percentage (up to 60%) of patients ductal closure, development of aortic coarctation. This the- with AC have associated , an ejection ory, however, does not explain the variable degrees of isth- systolic click may be heard at the apex and left mid and mic and aortic arch hypoplasia seen with AC. right upper sternal borders; this click is constant and does not change with respiration. An ejection systolic murmur may be heard best at the left or right upper sternal borders, Pathophysiology but is usually heard best over the back in the left interscap- In children, adolescents, and adults, the mode of presenta- ular region. Sometimes, a faint continuous murmur may tion is hypertension or systolic murmur. The aortic be heard in the left interscapular region, secondary to con- obstruction is deemed to have developed slowly with evi- tinuous flow in the coarcted segment or on the back (sec- dence for development of left ondary to flow in the collateral vessels). (LVH) and collateral circulation. The mechanism for devel- opment of hypertension is not clearly understood; mechanical obstruction and rennin-angiotensin–medi- Noninvasive Assessment ated humoral mechanisms have been postulated [3]. Chest radiograph Mechanical obstruction theory explains the increased Chest roentgenogram may show significant cardiomegaly blood pressure by postulating that a higher blood pressure or the heart size may be normal. Rib-notching secondary is required to maintain flow through the coarcted segment to collateral vessels may also be seen. Other roentgeno- and collateral vessels. The stroke volume, ejected into the graphic features include a “3” sign on a highly penetrated limited aortic receptacle, produces a higher pressure proxi- chest radiograph (frontal view) or inverted “3” sign of the mal to coarctation. However, this theory does not explain barium-filled esophagus. 1) the lack of relationship between the degree of elevation of blood pressure and the magnitude of obstruction, 2) Electrocardiogram increased peripheral vascular resistance distal to the site of The electrocardiogram may be normal or it may show LVH. obstruction, and 3) delayed or lack of reduction of blood Sometimes the LVH may be manifested by increased S pressure following relief of obstruction. waves in leads V5 and V6, the so-called posterobasal LVH. Humoral theory postulates activation of the rennin- angiotensin system secondary to reduction of renal blood -Doppler studies flow and appears to explain most of the clinical features. Echocardiographic imaging usually reveals the coarctation However, measurement of plasma rennin activity both in in suprasternal notch, two-dimensional echocardiographic animal models and human subjects did not show consis- views. Increased Doppler flow velocity in the descending tently elevated plasma rennin levels. The reason for the aorta by continuous wave Doppler and a demonstrable inability to demonstrate elevation of rennin levels may be jump in velocity at the coarcted segment by pulsed-Dop- related to lack of inadequate accounting for salt intake, pos- pler technique are usually present. Instantaneous peak ture, extracellular fluid volume, and sympathetic influences pressure gradients across the AC can be calculated by on rennin release. More recent studies did demonstrate employing a modified Bernoulli equation [6]: abnormalities in rennin-angiotensin-aldosterone systems. ∆ ()2 2 In addition, activation of central sympathetic nervous sys- P = 4V2 – V1 tem may also be responsible for hypertension of AC. where ⌬ P is peak instantaneous gradient and V2 and V1 are peak flow velocities in the descending aorta distal to Clinical Features coarctation (continuous-wave Doppler) and proximal to Most often, the coarctation is identified because of a murmur the coarctation (pulsed Doppler), respectively. or hypertension detected on routine examination. The AC is not frequently recognized by the primary care physician [4,5], MRI/MR angiography and consequently it is recommended that palpation of femo- These studies are useful in demonstrating the anatomy ral pulses and measurement blood pressure be undertaken clearly. If the clinical and noninvasive evaluation outlined during routine examination to avoid delay in the diagnosis. above indicates the need for intervention, I usually go ahead Coarctation of the Aorta • Rao 427 with catheterization and angiography, and perform interven- promptly rather than attempting to treat hypertension tional procedures. If the data are not clear, then MRI or MR with antihypertensive medications, although some clini- angiography are performed to define the problem further. cians use such an approach.

Cardiac catheterization and selective Surgical therapy cineangiography Since the introduction of surgical correction by Crafoord Although not required for diagnosis, cardiac catheteriza- and Nylin, and Gross and Hufnagel in the mid-1940s, sur- tion is helpful in demonstrating the anatomic nature of the gical therapy has become the treatment of choice for aortic aortic obstruction (discrete vs long segment), assessing the coarctation. A variety of techniques have been used in extent of collateral circulation, determining the presence repairing AC and these include resection and end to end and severity of associated lesions (especially in the neo- anastomosis, subclavian flap angioplasty, prosthetic patch nates and infants), and more recently as a prerequisite to aortoplasty, and tubular bypass grafts. Several other modifi- the consideration of transcatheter intervention. cations of the initially described techniques have been uti- Elevation of LV and ascending aortic peak systolic lized to improve the results of the operation. The type of pressures with a peak to peak systolic pressure gradient surgical procedure used depends upon the age of the across the coarcted segment are usually found. A peak to patient, aortic arch anatomy, and preference of the surgeon. peak gradient in excess of 20 mm Hg is generally consid- Although surgical correction has improved the prognosis of ered indicative of significant obstruction. However, the patients with coarctation, there still remain problems asso- magnitude of the gradient is not necessarily indicative of ciated with surgical correction, which include operative the degree of narrowing because the gradient is depen- mortality and morbidity, recoarctation, aneurysms in all dent not only upon the extent of aortic narrowing but types of coarctation repair [8], particularly well-docu- also on the size and number of collateral vessels. In addi- mented following prosthetic patch angioplasty [9], devel- tion, cardiac output and the state of ductus arteriosus, opment of paraplegia, paradoxical hypertension, and particularly in the neonate and young infant, also deter- vascular complications related to subclavian flap repair. mine the pressure gradient. Despite these problems surgical repair is considered by Selective aortic root or aortic arch angiography is nec- many as a therapeutic option of choice in the treatment of essary to clearly demonstrate the aortic narrowing. Aor- aortic coarctation. Some groups, including ours, consider tography is useful in demonstrating the type of AC balloon angioplasty as initial therapy of choice and reserve (diffuse, long segment, or aortic kinking [pseudocoarcta- surgical intervention for those coarctations that 1) involve tion]), extent of collateral circulation, the size of ductus the long segment of the aorta, 2) are completely or almost arteriosus, if patent, and presence and degree of hypopla- completely occluded such that no catheter or guide wire can sia of transverse aortic arch and aortic isthmus. If thoracic be passed across the coarcted segment, and 3) are associated coarctation is not demonstrated despite clinical features with a large and ventricular septal of coarctation or if neurofibromatosis is suspected, defect, which requires prompt surgical intervention for the abdominal aortography may be needed to demonstrate primary cardiac problem. There is no consensus with regard (or exclude) abdominal coarctation. to whether surgical or balloon therapy is the preferred treat- ment for AC. The issues related to balloon angioplasty and stenting coarctation segment are addressed below. Treatment Significant hypertension or congestive heart failure are indi- Balloon angioplasty cations of intervention. Surgical relief of the aortic obstruc- Since the initial descriptions of balloon angioplasty of tion and catheter interventional techniques (balloon neonatal postmortem native aortic coarctation, postsurgi- angioplasty and stents) are available alternatives. Asymp- cal AC, and native coarctation, a large number of investiga- tomatic patients should undergo the procedure electively. If tors reported their experiences with balloon angioplasty of neither hypertension nor heart failure are present, elective native aortic coarctation. The technique of balloon angio- surgical or balloon therapy between the ages of 2 and 5 plasty is described elsewhere [9–11]. years is suggested. Waiting beyond 5 years of age is not advisable because of evidence for residual hypertension if Immediate results the aortic obstruction is relieved after 5 years of age [7]. Despite an initial report of poor results [12], subsequent experience with balloon angioplasty appears encouraging Medical management at initial presentation and has been detailed elsewhere [9,13,14]. Reduction of In patients with congestive heart failure, initial treatment, pressure gradient across the coarctation and increase in the consisting of anticongestive measures including digitalis size of the coarctation segment are observed in all age preparations and diuretics should be promptly instituted groups. An example of improvement in angiographic [3]. If hypertension (rather than heart failure) is the clini- appearance is shown in Figure 1. The femoral pulses, cal problem, it is better to relieve the aortic obstruction which had been either absent or markedly reduced and 428 Hypertension

Figure 1. Selected cine frame from a posteroan- terior view of left ventricular (LV) cineangiogram (A) showing discrete aortic coarctation (white arrow) in a 6-year-old child. Following balloon angioplasty (B), aortogram revealed no evidence for significant residual coarctation (black arrow). Ao—aorta; DAo—descending aorta. (From Rao [9]; with permission.)

delayed (when compared with brachial ) become pal- gradient between arms and legs (Fig. 2) were found in the pable with increased pulse volume after balloon angio- majority of patients. plasty. The patients who were in heart failure improved as did their hypertension. None of our patients required Results in adult patients immediate surgical intervention. Although balloon angioplasty of AC has most frequently been used in infants and children, it has been used in adult Intermediate-term follow-up patients as well. Lababidi et al. [20] were the first to apply Several investigators have reported 1- to 2-year follow-up this technique in an adult patient (27-year-old man), which results, reviewed previously [9,13,14,15•]; these studies resulted in reduction of peak systolic pressure gradient suggest continued improvement. From our own study across the coarctation from 70 to 15 mm Hg, angiographic [15•], 60 patients were followed; the residual peak gradi- improvement, and reduced hypertension (190/124 mm Hg ents 14 ± 11 (mean ± SD) months following angioplasty vs 130/80 mm Hg). They subsequently reported their remained low at 16 ± 15 mm Hg. These gradients continue experience with balloon dilatation of native coarctation in to be lower (P < 0.001) than those prior to angioplasty (46 eight consecutive adults, aged 19 to 30 years (25 ± 5 years) ± 17 mm Hg) and are slightly higher (P < 0.05) than the [21]. The systolic pressure gradient across the coarctation gradients (11 ± 9 mm Hg) immediately following angio- was reduced from 48 ± 19 mm Hg to 7 ± 5 mm Hg. The size plasty (Fig. 2). Angiographically measured coarctation seg- of the coarcted segment increased from 6.8 ± to 2.2 mm to ment remained wide. There is only a modest increase (11 ± 15.2 ± 5.0 mm. No complications were encountered. Clini- 9 vs 16 ± 15 mm Hg; P < 0.05) in peak gradients for the cal and echocardiographic-Doppler follow-up 1 year after group as a whole, but when individual patient values are the procedure revealed good result with no more than 15 examined 15 (25%) of the 60 patients had evidence for mm Hg peak systolic blood pressure difference, measured by recoarctation, defined as a peak to peak systolic pressure cuff, between arms and legs. They concluded that results in gradient in excess of 20 mm Hg. The incidence of recoarcta- young adults are similar to those observed in children; bal- tion is higher in neonates (five [83%] of six; P < 0.01) and loon angioplasty should be considered as an option to infants (seven [39%] of 18; P = 0.011) than children (three surgical intervention; and follow-up studies (longer than 1 [8%] of 36); 10 of these children underwent repeat balloon year) are required. Other reports followed [22–33], which angioplasty and two patients underwent surgical resection, are tabulated in Table 1. Based on the review of these publi- all with good result. Aneurysms developed in three (5%) of cations, the conclusion drawn by Attia and Lababidi [21] are 58 who underwent follow-up catheterization and angio- appropriate but, aortic perforation and dissection during the plasty; one of these patients required surgical excision of procedure and aneurismal formation at follow-up are also the aneurysm and the other two are followed clinically. seen in adults. Therefore, it is prudent to 1) avoid manipula- tion to tips of the catheters and guide wires in the region of Long-term follow-up freshly dilated coarctation, 2) chose an appropriate-sized There are scant data on long-term follow-up after balloon balloon (no larger than the diameter of the descending aorta angioplasty of native coarctation [15•,16–18], reviewed at the level of the diaphragm), and 3) monitor for elsewhere [19•]. Despite the problems of recoarctation development of aneurysms, which, if found, should be and aneurysms, some requiring repeat intervention at closely followed by repeated angiography or MRI. intermediate-term follow-up, the long-term follow-up results (5–9 years) appear encouraging, in that there was Recoarctation minimal incidence of late recoarctation and no late aneu- Residual and recurrent obstructions cannot be easily dis- rysm formation. Near-normal blood pressure and low tinguished from each other and the term recoarctation may Coarctation of the Aorta • Rao 429 with 19 children was 49 ± 16 mm Hg two balloon, repeat requiring restenosis aneurysm small a developed follow-up recoarctations Comments mo /mean n 8/12 No complications duration, duration, Follow-up: Follow-up: † FU Post (mean ± mm Hg* (mean SD) Pre Gradient across coarctation coarctation across Gradient Range y Age, Mean ± SD N 49 20 ± 7 ‡ 66 ± 23 11 ± 7 6 ± 6 49/122 Repeat balloon in four & aneurysms in four . [22]. 95 ± 22 18–31 ‡ 9± 11 10 ± 13 ‡/‡ combined group the for gradient Pre-BA . [30] . [30] 19 29 14–67 21 49 ± ± 8 5 ‡ 19/20 result suboptimal had patient One § . [29] 23 33 15–58 46 ±14 10±10 10± 7 22/33one aneurysmin and three Recoarctation in et al . [28] . [28] 29 25 14–54 18 62 ± 13 21± ± 13 14 29/48 aneurysm for one surgery and death One . [32] . [32] 17 36 16–67 50 22± ± 9 5 ‡ ‡/59 postoperative in all three Unsuccessful et al . [31] . [31] 16 28 15–60 51 18 18 16/88 surgery required patient One [33] et al et . [27] . [27] 13 ± 14 30 16–61 30 69 ± 8 ± 10 ‡ 9/20 surgery requiring aneurysms Two

. [25] 23 9 23 ± 15–55 19 66 ± ± 8 8 8 ± 9 22/15 developed two perforation, aortic One . [26] 8 ± 12 28 18–56 12 71 ± 9 14 ± ± 9 20 4/6 one restenosis aneurysms, No . [24] 35 7 23 ± 14–37 23 81 ± ± 13 15 ± 13 16 26/13 aneurysms Three . [23] 7 ± 14 29 14–49 22 59 ± 7 13 ± 9 6 ± 7/6 6-mo at patient in one dissection Intimal

et al et al et . et al et al et al et et al et et al et al et et al et Includes patientspreviously reported1992. in Systolic pressure difference between arms legs. and arms between difference pressure Systolic Datagiven. not Attia and Lababidi [21] Lababidi and Attia 8 5 25 ± 19–30 19 48 ± ± 5 7 15 < BA—balloon angioplasty; FU—follow-up; Pre—prior to angioplasty; Post—immediately after angioplasty. after Post—immediately angioplasty; to Pre—prior FU—follow-up; angioplasty; BA—balloon Study for except †. catheterization cardiac at measured gradient pressure *Peak systolic peak to † ‡ § Suarez de Lezo Lezo de Suarez Erbel Kale Fawzy Phadke Schrader Tyagi Tyagi deGiovanni deGiovanni Koerselman Koerselman Paddon Paddon Walhout Fawzy Table 1. Results of balloon angioplasty of aortic coarctation in adult patients 430 Hypertension

Intravascular stents Vascular stenotic lesions can be opened up by balloon angioplasty, but because of elastic recoil of the vessel wall, the vessel lumen may return to the predilatation size follow- ing withdrawal of the balloon catheter. Such recoil and vas- cular dissection, if any, following balloon dilatation can be circumvented by implantation of endovascular stents. Initially, stents were used in the treatment of peripheral arte- rial disease and coronary artery stenotic lesions in adults [39]. The technique was then extended to the treatment of other stenotic vessels including aortic coarctation [40,41•]. Despite reasonably good short- and long-term results of balloon angioplasty, some problems remain, including rest- enosis, probability of aortic rupture, formation of aneurysms, and inability to effectively treat long-segment tubular narrowing. Because of these and other reasons, endovascular stenting of AC has gained acceptance over the past decade Figure 2. Bar graph demonstrating immediate and follow-up results after balloon angioplasty of aortic coarctation. Peak to peak systolic [42–48,49••,50–57,58••]. The perceived advantages of pressure gradients across the coarctation in mm Hg (mean + SEM) are stents over balloon angioplasty are 1) the ability to expand shown. Note significant (P < 0.001) drop in the gradient following tubular long-segment coarctation and hypoplastic isthmus angioplasty (Pre, prior to vs post, immediately following). The gradient and distal transverse aortic arch, 2) ability to increase increases (P < 0.05) slightly at a mean follow-up to 15 mo (range, 4– 56 mo). However, these values are lower (P < 0001) than prior to coarcted segment diameter independent of the intimal tear, angioplasty. At late follow-up (LFU), 6 months to 9 years (median 5 y) 3) ability to decrease the probability of restenosis, 4) preven- following balloon angioplasty, blood pressure-measured arm-leg peak tion of dissection of a torn intimal flap by facilitating apposi- pressure difference is lower than catheterization measured peak gradi- tion of the intima against the media, and 5) prevention of ents prior to (P < 0.001) balloon angioplasty and those obtained at aneurysms because of support of a weakened aortic wall with intermediate-term follow-up (P < 0.01). FU—follow-up; Pre—pre- angioplasty; Post—post-angioplasty. (From Rao [3]; with permission.) the stent and neointima. To my knowledge, O’Laughlin et al. [42] were the first to report use of a stent for treatment of aortic coarctation, be used to describe both these entities and is defined as although the results in a 12-year-old child were marginal. peak to peak systolic pressure gradient in excess to 20 mm Subsequently, a number of other workers [42– Hg with or without angiographically demonstrable nar- 48,49••,50–57,58••] reported use of stent in AC with rowing [34]. Recoarctation may take place both following encouraging results. surgical correction and balloon angioplasty. The indication for employing stents are 1) long-seg- Development of recoarctation following surgery is ment coarctation, 2) associated hypoplasia of the isthmus independent of the type of surgical repair [35]; it has been or aortic arch, 3) tortuous coarctation with malalignment observed following resection with end to end anastomosis, of proximal with distal aortic segment, and 4) recurrent subclavian flap angioplasty, prosthetic patch repair, subcla- AC or an aneurysm following prior surgical or balloon vian artery turn-down procedure, and interposition tube therapy. Because of issues related to growth and the need grafts. The reported incidence of recoarctation has varied, for large sheaths for implantation, most cardiologists limit depending on the study. In the article by Pinzon et al. [8], stent usage to adolescents and adults. reporting on a large number of patients, recoarctation occurred in 23% of patients studied. The younger the child Immediate results at surgery, the higher is the probability for recoarctation. Reduction of peak systolic pressure gradients and increase There is general agreement among cardiologists that bal- in the diameter of the coarcted segment (Table 2) have loon angioplasty is the treatment of choice for postsurgical been demonstrated following stent implantation. Stenting aortic coarctation. The immediate and follow-up results of was found effective in postsurgical and postballoon reco- balloon angioplasty for postsurgical recoarctation are arctations as well as in native coarctations. Improvement in essentially similar to those of native coarctation and have the size of hypoplastic isthmus or transverse aortic arch been reviewed in detail elsewhere [19•,35,36]. and exclusion of the aneurysm, if such is present, also Restenosis following balloon angioplasty also appears occurred after stent placement. to be aged-dependent; the younger the child, the greater In the first series of 10 patients published by Suarez de is the probability for recoarctation [15•,34]. We Lezo et al. [44] in 1995, the peak systolic pressure gradient [15•,19•,37] and others [16] recommend repeat balloon across the coarctation decreased from 43 ± 12 to 2 ± 3 mm dilatations in such cases, whereas still others [38] prefer Hg (P < 0.001). The ratio of isthmus/descending aorta surgical intervention. increased from 0.65 ± 0.14 to 1 ± 0.08 following the proce- Coarctation of the Aorta • Rao 431 Post Pre Pre C o a r c t a t i o ns e g m e n t mm Hg Post Pre Mean gradient ± SD, SD, ± gradient Mean < 0.001) P Post- balloon < 0.01). P Post of Type coarctation Native (range) Mean age ± SD, y ± SD, age Mean n 48 14 ± 12 (0.1–45) 31 6 11 12 ± 42 3 ± 4 4 ± 2 12 ± 2 Patients implantation, implantation, undergoing stent stent undergoing † [44] 10 5 ± 4 (0.1–43) 6 2 2 12 ± 43 2 ± 3 * 12 ± 4 [49••] [50] 17 11 ± 4 (0.4–15) 8 5 4 50 ± 25 2 ± 2 5 ± 2 14 ± 4 et al. et al. [53] 27 30 ± 13 (14–63) 19 7 1 20 46 ± 3 ± 5 7 ± 4 17 ± 2 [55] 56 22 ± 9 (8–49) 51 1 4 50 ± 20 5 ± 8 ‡ ‡ et al. [52] 33 19 ± 14 (5–60) 6 27 0 25 ± ‡ 5 ± ‡ 8 ± 4 13 ± 4 [56] 34 16 ± 8 (4–36) 13 19 2 12 ± 32 4 ± 11 § § [51] 17 21 ± 14 (4–45) 6 11 0 26 ± 11 5 ± 6 7 ± 2 11 ± 3 [46] 6 20 ± 5 (13–34) 2 4 0 37 ± 17 13 ± 23 9 ± 2 16 ± 3 [58••] 21 24 ± 11 (‡) 21 0 0 47 ± 20 1 ± 1 4 ± 3 13 ± 2 [48] 9 30 ± 18 (14–63) 2 7 0 20 37 ± 4 ± 4 9 ± 3 15 ± 3 [57] 21 29 ± 11 (18–61) 0 0 21 22 ± 68 8 ± 4 4 ± 1 14 ± 2 et al. et al. et al. et al. et et al. et al. et al. et al. et al. No data are available but the ratio of coarctation site to descending aorta increased from 0.46 ± 0.16 to 0.92 ± 0.16 ( Includes 10 patients previously reported by the authors in 1995. No data are available. Study *Nodata areavailable, butthe ratio of isthmus/descending aortachanged from 0.65± 0.141± to 0.08 ( † ‡ § Suarez de LezoSuarez de Bulbul Magee Pre—priorstent to deployment; Post—immediately after stent deployment. Ebeid Ebeid Suarez de LezoSuarez de Marshall Marshall Thanopoulos Tyagi Tyagi Harrison Hamdan Pedra Ledesma Ledesma Table 2.Table publications from selected of aortic coarctation treatment of stent Results 432 Hypertension dure. Similar results have been reported subsequently by prevent balloon ruptures and perforation of other cardio- other investigators which are listed in Table 2. vascular structures. Positioning the guidewire into the right or left subclavian artery may avoid excessive curva- Complications ture, thus may prevent balloon rupture. Flexible [59–61] Vessel disruption [44], displacement of stent instead of rigid Palmaz (Cordis, Miami Lakes, FL) stents [44,49••,51,56], and aneurysms [49••,50] may occur, are being utilized, and rightly so. Selected stent diameter but infrequent. Balloon rupture [43,56] resulting in at implantation should be at least twice the diameter of inadequate stent expansion and stent migration has narrowest aortic segment to prevent stent displacement been reported but may be prevented by avoiding curva- during implantation. ture of the balloon/stent assembly, use of newer stents Relief of obstruction both acutely and at follow-up with less injurious ends [59–61] and by the use of bal- with a low incidence of major complications is well dem- loon in balloon catheters. Because of large size sheath onstrated in several studies. Meticulous attention to the required, loss of pulse [44,49••,52] and bleeding from technique and adoption of new technology may further puncture site [46,51] may occur. Use of vascular closure reduce the incidence of complications. Recoarctation rate devices may help circumvent this problem. Rare compli- at follow-up appears to be low. Re-expansion of the stent cations included myocardial infarctation [52], and [63] to treat residual or recoarctation and growth related retroperitoneal hemorrhage [56]. narrowing appears feasible, safe and effective, although such is based on limited experience. Comparison of Follow-up results stents with balloon angioplasty was undertaken in a few In most studies, there was only a short-term and incom- studies [58••,64,65]; these studies suggest that stents may plete follow-up in a limited number of patients. However, be more effective than balloon angioplasty. Based on the a few studies [49••,52,55,56] examined results of more available data, stenting AC appears to be preferred alter- than 20 patients at a mean follow-up of 2 years or longer. native to surgical or balloon therapy in the adolescent The pressure gradients across the coarctation site (blood and young adult. pressure, Doppler, or catheterization) remained low and systemic hypertension decreased both in degree and fre- Covered stents quency with consequent decrease in the need for antihy- There is extremely limited experience in the use of covered pertensive medications. No evidence for recoarctation, stents in the management of aortic coarctation [66–70]. aneurismal formation, or stent fracture/displacement was Different types of stents were used and include Jostent observed, although no systematic or complete follow-up grafts (Jomed International, Helsingborg, Sweden), C-P was achieved in the majority of studies. Residual or recur- stents (NuMed, Hopkinton, NY), and AneuRx (Medtronic, rent obstruction was present in a few patients and in these Minneapolis, MN) to treat aortic coarctation. The indica- successful redilatation with larger balloons was accom- tions for intervention are similar to those used for balloon plished. Detailed angiographic studies by Suarez de Lezo et angioplasty and deployment of standard stent. The indica- al. [49••] revealed no detectable neointimal proliferation tions for use of covered stents are postangioplasty aneu- in 75% patients; in the remaining patients focal neointi- rysm, tortuous aortic arch, and isthmus, associated patent mal ridge formation was observed at ends of the stent caus- ductus arteriosus, prior surgical conduit, Takayasu’s arteri- ing minimal restenosis. Segmental analysis of the aorta tis and extremely narrow (subatretic) coarcted segment. revealed increase in nonstented segments of the aorta, con- When the assessed risk for development of aneurysm or sistent with normal growth. Two (7%) young patients dissection is high, covered stent should be utilized. The developed small new aneurysms, which were obliterated results of the limited use of covered stent appear to be by coil placement following angiographic detection. The good [66–70]. Some of the stents can only be expanded to overall follow-up results were encouraging, however. 18 mm in diameter. Also, the stent shortens when expanded to larger diameters. Use of covered stents has Comments also another disadvantage in that the vessels arising from Stent therapy appears to be an attractive method for treat- the aorta are blocked. Based on the currently available ment of recurrent coarctation or aneurysm formation data, the covered stents may be useful in highly selected following prior surgical or balloon intervention and for patients with aortic coarctation. long-segment hypoplasia. Most cardiologists use stents in adolescents and adults, although a few have advocated their use in younger children. The selection of the type of Conclusions and Prognosis stent and the type of balloon catheter used for stent The immediate prognosis is good for isolated aortic coarc- deployment appears to be evolving [40,62]. Balloon- tation. The majority of mortality is related to severity of expandable instead of self-expandable stents are pre- associated defects. Once aortic obstruction is relieved by ferred. Use of balloon in balloon catheters for stent deliv- surgical or balloon therapy, the significance of associated ery appears to be gaining momentum in an attempt to defects should be evaluated and treatment instituted based Coarctation of the Aorta • Rao 433

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