Aortic Coarctation (Coa) is a narrowing of the thoracic aorta located at the inserction of the ducts arteriosus just after the left suclavian artery. It comprises 6-8% of all congenital cardiac lesions. The incidence is 3-4 cases out 10.000 live births and with male predominance [1]. Frequently is a discrete stenosis but can be a long segment end tortuous. It can occur isolated or associated with others congenital defects: bicuspid aortic valve, aortic arch hypoplasia, others arch anomalies, ventricular septal defects, mitral valve abnormalities, subaortic stenosis [2]. Various segments of the aortic arch develop from different embryologic origins. The aortic sac gives origin to paired pharingeal arches and the left fourth arch gives origin to the segment of trasnsverse aortic arch between the carotid and subclavian artery [3]. Several patients with this disease have been identified with gene mutations: NOTCH1, in cases of coarcyation of aorta and others left side malformations as bicuspid aortic valve, hypoplastic left heart syndrome. Also in others genetics syndromes as Turner, Noonan and Di George is high the association with coarctation of aorta [4].

Aortic coarctation is characterized by infolding of ductal tissue posteriorly composed of an intimal and medial component that can extend around the entire circunference of aorta. Histologic examination of juxtaductal coarcation reveals thick intimal and medial ridges that protrude posteriorly and lateral into the aortic lumen [5]. There is evidence of cystic medial necrosis and elastic fiber formation, which may form the basis of aoric dilatation, aneurysm formation and dissection [6]. The pathophisiological studies demonstrated abnormal histologic findings, impared vacular properties and inflammation. There is endotelial disfunction, abnormal elastic proprieties and reduced distensibility in the cardiac magnetic ressonance imaging [7].

The clinical manifestations it depends of the severity of the narowing. It may remain unnoticed throughout childhood or, in contrast, progress to heart failure and cardiogenic shock [8]. The clinical presentation usually follows one of three paterns: an infant with congestive heart failure, a child with heart murmur, or a child or adolescent with systemic arterial hypertension1. Coarctation of the aorta remains one of the more difficult cardac defects to diagnose prenatally. Prenatal diagnosis of coarctation allows for delivery in a center that can iniciate prostaglandin infusion to maintain ductal patency and later surgical repair. Undetected in the neonatal period, delayed diagnosis of Coa is associated with significant morbidity and mortality3. When the coarctation presents in infancy is always a catastrophic illness. Congestive heart failure and shock can occur suddenly as the ductus arteriosus closes. A large proportion of these infants have others structural lesions associated such ventricular septal defects or aortic stenosis. Cyanosis of lower limbs maybe observed if a right- to-left shunt is present [1]. It may presents later in childhood as systolic upper extremity hypertension or as heart murmur. Delayed diagnosis beyond infancy is common as physical findings may be subtle and most of these patients are assyntomatic. On careful examination can be noted dimishing femoral pulse relative to radial pulse and the blood pressure is decreased in lower extremities. Claudication with exercices, frequent headaches. In review of children with coarctation during a10 years period the median age of diagnosis was 10 years and the most commom causes for referral were hypertension or heart murmur. The correct diagnosis of coarctation was made by referring physical in only 14%9. The clinical presentation of native coarctation in adults depens on the severity of the lesion. Hemodynamically the increased afterload due to obstruction of the flow from the left ventricle may be accompanied by significant hypertension in the aorta and branch vessels proximal to the coarctation site. It may be associated with systemic ventricular disfunction vessel aneurism formation and effects of premature atherosclerosis. Distal to the coarctation there is dimished flow and colaterals may develop to supplement area of relative hypoperfusion [10].

Diagnosis

Eletrocardiogram is frequently normal. The finding of left ventricular hypertrophy in older children and adolescents will reflect the effects of long standing left ventricular pressure1.The chest X ray in infant with heart failure shows cardiomegaly, pulmonary vascular markings are increased. In older children and adolescentes the chest X-ray may be normal or mildly enlarged heart the descending aorta may be proeminent due to poststenotic dilatation. Rib notch may be found in older patients because of erosion of the inferior surfaces of posterior ribs by dilated and tortuous intercostal arteries1. Transthoracic echocardiogram is often the first-line modality to assess for suspect aortic coarctation due to easy accessibility. It can also assess for ventricular mass, systolic and diastolic function and others left side structures (mitral valve papillary muscle architecture, aortic valve). The color spectral Doppler can be used to localize the anatomy of coarctation and estimate the degree of narrowing. The severe coarctation may shows a typical sawtooth appearance. It can be calculated the peak instantaneous gradient across the coarcted segment10. Magnetic ressonance imaging (CMR) can provide very high quality image of severity and location of coarctation and quantitative data on biventricular volumes, mass and systolic function. It can estimate associated intracardiac shunts and detect collateral flow in the intercostal arteries. Also the magnetic ressonance identified clinically recoarctation and aneurysm formation and has been used to identify predictors of coarctation severity [11]. Cardiac catheterization can serve both diagnosis and treatment purposes. Cardiac catheterization remain a goldstand for evaluating coarctation and aortic arch anatomy, but is not necessary if noninvasive evaluation clearly delineates the lesions that are present. Cardiac computed tomography angiography (CTA) provides superior spatial resolution over other modalities and affords vantages in evaluation of vascular anatomy, aortic dimensions and morphology of the coronaries arteries [12]. For the adult who has undergone transcatheter intervention it can be used to assess luminal patency and long-term complications. The disvantages of CTA include the ionizing radiation and intravenous dye [10].

Figure1: Volume rendering tridimensional reconstruction of the arterial phase of a CT angiography of an 8 month old patient showing the posterior view of the heart and a near lower normal limit diameter aortic arch following a normal path. The picture also shows a focal reduction of the isthmus portion of the aorta (coarctation). After the isthmus, the descending aorta follows an anatomical path and has a normal diameter.

Treatment

Indications for intervention either surgical or transcatheter therapy are significant hypertension or/and congestive heart failure along with a peak-to peak systolic gradient greater than 20mmHg across the stenosis in the catheter laboratory or mean systolic greater than 20 mm Hg by echocardiography [13]. Pharmacological treatment is necessary to significant hypertension and congestive heart failure. In neonates with severe aortic obstruction the initial medical management includes infusion of prostsglandin E (PGE) 0,05-0,1 mcg/kg/ min intravenously to keep ductus wide open and blood flow to the lower body [3]. Surgery has remained as the gold stand in neonates, because of significant incidence of recurrence. In infants less than 3 months balloon angilasty provides successful palliation in cases of critical congestive heart failure [13]. The catheter intervention has preferred in children, adolescents and adults. Introducton of covered stent has made the intevention safer. It is associated with significant immediate and long-term complication and is imperative for the interventionist to understand the minutiae of the method to perform it correctly and minimize complications. Balloon with bailout stenting is preferred in children and primary stenting remains the preferred modality of coaorctation treatment in adults [14]. Several factors need to be considered in selecting the most appropriated method for repair, including age, anatomy of the transverse and descending aorta, history of previous repair. And expertise. In a large observational study out of the Congenital Cardiovacular Consortium, outcomes of surgical, stent, balloon and stent angioplasty for native coarctation in 350 patients across 36 institutions were compared. Balloon angioplasty was notable for higher rate of acute and longer-term aortic wall injury [15].

Diagnosis nd surveillance for later complication after the repair requires intermitente 3 D assessment including CMR or CTA to assess for aneyrism, pseudoaneurysm, recoarctation, stent fracture10. A large single-center series described long-term outcome of 819 patients (mean age at repair 17, 2+ 13, 6 years) who underwent isolated operative repair of coarctation between 1946 and 2005 at Mayo Clinic. The survival rates were 93%, 86% and 74% at 10, 20 and 30 years after primary repair, respectively which were significant lower than age and sex- matched controls. The most common causes of death were coronary artery disease, heart failure, brain-vascular accident, rupture of aneurysm [16]. Systemic hypertension: It is one of the major long-term morbidity after repair of aortic coarctation, especially in patients whose repair are performed later in life and those wih a residual narrowing. When hypertension is detected at rest, re-coartation must be excluded. If there is no evidence of recoarctation is indicated medical treatment10. In a systematic review on hipertension after Co A repair the mean prevalence was 47, 3% (20-70%). A progressive character was of the hypertension was found, futhermore if studies are included with 24 hours blood pressure recording [17]. Reduced aortic distensibility is associated with high central aortic pressure in youg adults after coarctation repair [18]. Recoarctation refers to restenosis after an inicially successful interventiont. Symptoms sugestive of recoarctation are headaches or claudication, although many patients are assymptomatic. The rate of recoarctation is up to 34% after surgery and is seen primarily in children, usually due to inadequate aortic wall grow at the site of repair when surgery is performed before the aorta has reached adult size [19]. Following balloon angioplasty, children are also at greater risk for recoarctation compared with aduts, with the rates up to 50% in infants and neonates, compared with in young adults 9% due to elastic recoil in young patients [20]. Discrete coarctation in older children and adults is treated with percutaneous balloon angioplasty, although surgical repair may be necessary for complex cases, including long- segment recoarctation, hypoplastic aortic arch and associated aneurysm [10]. Na aortic aneurysn may develop at the site of previous coarctation years after surgery, balloon dilatation or stent implantation of native coarctation. The rate of aneurysn formation is 3-20% [17]. The most patients, aneurysm or pseudo aneurysm repair requires surgical intervention with ressection of the aneurysm and graft placement [21]. Left ventricular dysfunction can occur despite successful repair and normotension and have been shown in cases of increased left ventricular mass and diastolic dysfunction. Left ventricular contractile reserve in response to exercice is also abnormal and related to exaggered blood pressure response to exercice [22].

1. Beekman RH. Coarctation of the aorta. In Allen HD, Driscoll D, Shaddy RE et al editors. Moss and Adams’s Heart Disease in infancy children and adolescentes: including fetus and young adults. 2013; 2: 8.
2. Teo LL, Cannell T and Babu-Narayan SV et al. Prevalence of association of cardiovascular abnormalities in 500 patients with aoric coarctation referred for magnetic ressonance imaging to a terciary center. Pediatr Cardiol. 2011; 32: 1120-7.
3. Arya B and Maskatia AS. Coarctation of the aorta: prenatal assessmente postnatal management and neonatal outcomes. Seminars Perinatology. 2022; 46: 1-8.
4. Freylikhman O, Tatarinova T and Smolina N et al. Variants in NOTH1 gene in patients with aortic coarctation. Congent heart Dis. 2014; 9: 391-6.
5. Edwards JE and Christensen NA. Pathologic considerations of coarctation of aorta. Proc Staff Meet Mayo Clinic.1948; 23: 3324-32.
6. Isner JN, Donaldson RF and Fulton D et al. Cystic medial necrosis in coarctation of aorta: a potential fator contributing to adverses consequences observed after percutaneous balloon angioplasty of coacrtation sites. Circulation. 1987; 75: 689-95.
7. Gardiner HM, Celermajer DS and Sorensen KE et al. Arterial reactivity is significantly impairedin normotensive young adults after successful repair of aortic coarctation in childhood. Circulation. 1994; 89: 1745-50.
8. Herdy GVH. Coarctation of the aorta: its importance for pediatricians and cardiologists. International J cardiovacs Sciences. 2019; 31: 578-9.
9. Strattford MA, Griffiths SP and Gersony WM. Coarctation of aorta: a study in delayed detention. Pediatrics. 1982; 69: 159-63.
10. Kim YY and Andrade L and Cook SC. Aortic coarctation Cardiol Clin. 2020; 38: 337-51.
11. Horn JJ, Ordvas K and Reddy GP. Velocity-encoded cine MR imaginging in aortic coarctation; functional assessment of hemodynamic events. Radiographics. 2008; 28: 407-16.
12. Krieger EV, StoutKK and Grosse-Wortman L. How to image congenital left heart obstruction in adults. Circ Cardiovasc Imaging. 2017; 10: 004271.
13. Rao PS. Neonatal (and infant) coarctation of the aorta: managemenr challenges. Research and Reports in Neonatology. 2020; 10: 11-22.
14. Sinha SC. Tran’s catheter intervention for coarctationof aorta: current status. Indian J Clin Cardiol. 2021; 2: 44-50.
15. Forbes TJ, Kim DW and Du W et al. Comparison of surgical,Sten and bolloon angioplasty treatment of native coarctation of the aorta: na observational study by the CCISC ( Congenital Cardiovascular Interventional Study Consortium). J Am Coll. Cardiol. 2011; 58: 2664-74.
16. Brown ML, Bukhart HM and Connoly HM. et al. Coarctation of aorta: lifelong surveillance is mandatory followin gsurgical repair. J Am Coll Cardiol. 2013; 62: 1020- 5.
17. Panzer J, Bove T, Kristof V and Wolf D. Hypertension after coarctation repair- a systematic review. Transl Pediatr. 2022; 11: 270-9.
18. Kowalski R, Lee MGY and Doyle LW et al. Reduced aortic distensdibility is associated with higher aortic carotid wave transmission and central aortic systololic pressure in young adults after coarctation repair. J Am Heart Assoc. 2019; 8: e011411.
19. Choudhary P, Caniffe C and Jackson DJ et al. Late outcomes in adults with coarctation of the aorta Heart. 2015; 101: 1190-5.
20. Chen SS, Dimopoulos K and Alonso-Gonzalez R e al. Prevalence and prognostic implication of restenosis or dilatationat the aortic coarctation repair site assessed by cardiovascular MRI in adults patients late after coarctatin repair. Int J Cardiol. 2014; 173: 209-15.
21. Taggard NW, Minahan M, Cabalka AK et al. Immediate oucomes of covered stent placed for treatment or prevention of aotic wall injury associated with coarctation of the aorta (COAST II). JAAC Cardiovascular Interv. 2016; 9: 484-93.
22. Li VW, Chen RH and Wong WR et al. Left ventricular contractile reserve in young adults long-term after repair of coarctation of the aorta. Am J Cardiol. 2015; 115: 348- 53.