Clinical manifestations and diagnosis of coarctation of the aorta

INTRODUCTION — Coarctation of the aorta (CoA) is a narrowing of the descending aorta, which is typically located at the insertion of the ductus arteriosus just distal to the left subclavian artery (figure 1). This defect generally results in left ventricular pressure overload.

The clinical manifestations and diagnosis of CoA will be reviewed here. The management of CoA, including corrective treatment options and outcome, such as the risk of recurrent CoA, is discussed separately. (See "Management of coarctation of the aorta".)

EPIDEMIOLOGY — CoA accounts for 4 to 6 percent of all congenital heart defects with a reported prevalence of approximately 4 per 10,000 live births [1,2]. It occurs more commonly in males than in females (59 versus 41 percent) [3]. Most cases are sporadic.

PATHOGENESIS AND ETIOLOGY — Although CoA can rarely be acquired, the vast majority of CoA cases are congenital.

Pathogenesis — The precise pathogenesis is unknown. The two main theories for the development of congenital CoA are:

●Reduced antegrade intrauterine blood flow causing underdevelopment of the fetal aortic arch [4]

●Migration or extension of ductal tissue into the wall of the fetal thoracic aorta [5-7]

Pathologic examination of patients with congenital CoA reveals medial thickening and intimal hyperplasia at the coarctation site forming a posterolateral ridge that encircles the aortic lumen. There is also increasing evidence of a vascular wall defect in the ascending aorta of individuals with congenital CoA. Reported aortic wall abnormalities in neonates with CoA include increased stiffness and decreased distensibility, increased collagen and decreased smooth muscle mass in the prestenotic segment, and cystic medial necrosis [8-10]. The underlying mechanism for these arterial wall abnormalities is unknown. Genetic defects and/or intrauterine insults such as impaired blood flow that alter endothelial development may play a role and result in disturbances in the elastic properties and narrowing of the aorta. The intrinsic defect in the aortic wall appears to predispose to dissection or rupture in the ascending aorta or in the area of the coarctation repair.

Genetic factors — A genetic predisposition is suggested by reports of CoA occurring in family members [11-13] and by its association with Turner syndrome.

●Familial risk – There is evidence of an increased familial risk for congenital left ventricular outflow tract (LVOT) obstruction malformations including CoA [11,12]. This was shown in a study of family members of 124 patients with LVOT obstruction [11]. Thirty of the 351 (9 percent) relatives who were evaluated had asymptomatic LVOT obstruction structural heart defects that included abnormalities in the aortic arch (three), left ventricle (five), and aortic valve (21). Segregation analysis suggests these findings may be the result of one or more minor loci with rare dominant alleles.

●Turner syndrome – Approximately 5 to 15 percent of girls with CoA have Turner syndrome (loss of an X chromosome) [14,15]. Most girls with Turner syndrome have additional associated clinical findings (eg, congenital lymphedema, webbed neck, growth failure, renal anomalies (table 1 and picture 1)); however, in girls with mosaicism, other clinical findings may be absent [14]. Up to 30 percent of patients with Turner syndrome have CoA. Genetic testing for Turner syndrome (ie, karyotype analysis) should therefore be performed in female patients diagnosed with CoA. (See 'Turner syndrome' below and "Clinical manifestations and diagnosis of Turner syndrome".)

Acquired coarctation of the aorta — In addition to a congenital etiology, aortic narrowing can be an acquired abnormality due to inflammatory diseases of the aorta, such as Takayasu arteritis or, rarely, severe atherosclerosis [16-18]. The midthoracic or abdominal aorta is often the site of involvement in Takayasu arteritis [16,17]. (See "Clinical features and diagnosis of Takayasu arteritis".)

ANATOMY

Anatomical variants — Although most patients have a discrete narrowing of the descending aorta at the insertion of the ductus arteriosus, there is a spectrum of aortic narrowing that encompasses the usual discrete thoracic lesions, long-segmental defects, tubular hypoplasia, and, rarely, coarctation located in the abdominal aorta.

Associated cardiac lesions — CoA is usually accompanied by another cardiac lesion [19-21]. The relative frequency of associated cardiac lesions differs somewhat based upon the age of the population studied. In general, less than one-quarter of patients with CoA have isolated CoA without associated cardiovascular abnormalities. In infants and children, a considerable proportion of patients have associated complex congenital heart disease. In adults, bicuspid aortic valve is the most common associated defect.

In a large pediatric case series of 1892 patients from Boston Children's Hospital, approximately one-third of patients had other complex cardiac defects (including single ventricle variants [eg, hypoplastic left heart syndrome (figure 2)], atrioventricular [AV] canal defect (figure 3), or D-transposition of the great arteries [d-TGA] (figure 4)); 18 percent had a ventricular septal defect (VSD) [20]. In the 806 patients who were classified as uncomplicated CoA, other cardiac abnormalities included bicuspid aortic valve, atrial septal defect or patent foramen ovale, mitral regurgitation, aortic stenosis, aortic regurgitation, and mitral stenosis; only 17 percent of uncomplicated cases had no other cardiac problems.

In a case series of 216 infants (<1 year old), 48 percent of patients were diagnosed with complex CoA due to the presence of other cardiac defects including VSD, aortic and subaortic stenosis, AV canal defect, and d-TGA [21]. The remaining 113 patients were diagnosed with simple CoA; however, PDA occurred in 48 patients (42 percent). As a result, approximately one-third of affected infants did not have another detected cardiac anomaly. In this series, it is unclear whether an evaluation to detect the presence of bicuspid aortic valve was performed.

In a case series of 500 primarily adult patients evaluated with magnetic resonance imaging, 17 percent had no additional cardiovascular anomalies [19]. In this cohort, bicuspid aortic valves, arch hypoplasia, VSD, and PDA were detected in 60, 14, 13, and 7 percent of patients, respectively.

PATHOPHYSIOLOGY — CoA does not cause a hemodynamic problem in utero, as two-thirds of the combined cardiac output flows through the patent ductus arteriosus (PDA) into the descending thoracic aorta, bypassing the site of constriction at the isthmus (figure 5).

During the neonatal period, when the PDA and foramen ovale (between the right and left atria) begin to close, the cardiac output that must cross the narrowed aortic segment to reach the lower extremities steadily increases. With these changes the hemodynamic changes may range from mild systolic hypertension to severe heart failure depending upon the severity of the coarctation and upon the presence of other associated lesions.

At birth, the left ventricular afterload increases because of outflow tract obstruction resulting in increased systolic pressure in the left ventricle and proximal aorta. In cases of severe obstruction, the systolic pressure gradient may reach 50 to 60 mmHg at rest.

Several compensatory mechanisms arise to surmount the left ventricular outflow tract obstruction. These include left ventricular myocardial hypertrophy, which maintains normal systolic function and ejection fraction, and the development of collateral blood flow involving the intercostal, internal mammary, and scapular vessels, which circumvents the stenotic lesion [20,21]. However, in neonates with severe lesions, heart failure may develop because there is insufficient time for the development of myocardial hypertrophy or collateral blood flow.

Other cardiac lesions may add further strain on ventricular function. Valvar and subvalvar aortic stenosis may further increase left ventricular systolic pressure and afterload, whereas a large ventricular septal defect, PDA, or mitral regurgitation will increase left ventricular end-diastolic volume and preload, which subsequently leads to increased left ventricular end-diastolic pressure and to pulmonary artery hypertension. These patients with complex CoA are likely to develop heart failure and pulmonary artery hypertension.

CLINICAL MANIFESTATIONS

Manifestations according to age — The clinical manifestations of CoA vary in different age groups.

Neonates

●Critical coarctation – A neonate with severe or "critical" CoA may present with heart failure and/or shock when the patent ductus arteriosus (PDA) closes (image 1). These patients are pale, irritable, diaphoretic, and dyspneic with absent femoral pulses and, often, hepatomegaly. The pulses may be poor in all four extremities. Neonates with critical CoA may have differential cyanosis (ie, the oxygen saturation measured in the right arm [preductal] is higher than that in the leg [postductal]) due to right-to-left shunting across the PDA into the descending thoracic aorta. (See "Identifying newborns with critical congenital heart disease", section on 'Differential cyanosis'.)

Identification of these patients is essential in order to maintain patency of the ductus prior to surgical repair. In addition, immediate treatment is often required to stabilize patients with heart failure or shock. (See "Management of coarctation of the aorta", section on 'Neonates with critical coarctation' and "Diagnosis and initial management of cyanotic heart disease in the newborn", section on 'Prostaglandin E1' and "Neonatal shock: Management", section on 'Cardiac disease'.)

Neonatal sepsis is another important diagnosis to consider in neonates presenting with signs of shock. (See 'Differential diagnosis' below and "Clinical features, evaluation, and diagnosis of sepsis in term and late preterm neonates".)

●Less severe obstruction – Newborns with less severe CoA may remain asymptomatic, especially if there is a PDA. The diagnosis of CoA may be suspected based upon physical examination findings of diminished femoral pulses and/or cardiac murmur. Femoral pulses may be absent or delayed (when compared with the brachial pulse). A murmur may be associated with other cardiac defects, such as PDA, aortic stenosis, or ventricular septal defect (VSD). A systolic click may be heard due to a bicuspid aortic valve.

Older infants and children — Diagnosis is often delayed in older infants and children because physical findings are subtle and because most patients are asymptomatic. With careful history taking, some patients will report chest pain, cold extremities, and claudication with physical exertion. However, these are often noted after the diagnosis of CoA is made. Careful measurement of blood pressure and palpation of pulses in all four extremities suggest the clinical diagnosis with lower systolic blood pressure in the lower extremities compared with upper extremities and brachial or radial artery to femoral artery pulse delay. In young children, CoA may present with hypertension and/or murmurs resulting from collaterals or associated heart defects. Heart failure rarely occurs beyond the neonatal period.

Adults — In previously undiagnosed adults, the classic presenting sign is hypertension. Despite the variability in blood pressure in the upper and lower extremities, regional blood flow is generally maintained within normal limits by autoregulatory vasoconstriction in the hypertensive areas and by vasodilation in the hypotensive areas [22]. Most patients are asymptomatic unless severe hypertension is present, which may lead to headache, epistaxis, heart failure, or aortic dissection. In addition, claudication of the lower extremities can occur due to reduced flow, especially with physical exertion.

Natural history — Data on the natural history of CoA are largely derived from hospital postmortem records and from case series prior to the availability of operative repair (introduced in 1945) [23]. The average survival age of individuals with unoperated CoA was approximately 35 years of age, with 75 percent mortality by 46 years of age. Common complications in unoperated patients or in those operated on during later childhood or adulthood are systemic hypertension, accelerated coronary artery disease, stroke, aortic dissection, and heart failure. Causes of death include heart failure, aortic rupture, aortic dissection, endocarditis, endarteritis, intracerebral hemorrhage, and myocardial infarction [23]. Patients with an associated bicuspid aortic valve may also develop significant aortic stenosis, aortic regurgitation, and ascending aortic aneurysm. (See "Clinical manifestations and diagnosis of bicuspid aortic valve in adults".)

Physical findings — The findings of reduced systolic blood pressure in the lower extremities compared with upper extremities and radial artery to femoral artery pulse delay suggest a diagnosis of CoA, which is usually confirmed by echocardiography or alternate imaging modalities. (See 'Diagnosis' below.)

Blood pressure and pulses — The classic findings of CoA are systolic hypertension in the upper extremities, diminished or delayed femoral pulses (brachial-femoral delay), and low or unobtainable arterial blood pressure in the lower extremities (figure 6) [24]. (See "Evaluation of secondary hypertension" and "Definition and diagnosis of hypertension in children and adolescents", section on 'Technique of blood pressure measurement'.)

The radial/brachial and femoral pulses should be palpated simultaneously to assess timing and amplitude to search for the "brachial-femoral delay" of significant CoA (figure 6). (See "Examination of the arterial pulse", section on 'Unequal or delayed pulses'.)

Upper and lower extremity blood pressure measurement should also be performed; classically it is suggested that supine bilateral arm (brachial artery) blood pressures and prone right or left supine leg (popliteal) blood pressures be measured to search for differential pressure. However, in clinical practice it may not be feasible to obtain prone popliteal blood pressure, in this case an ankle blood pressure may be an alternative.

The site of origin of the left subclavian artery and the severity of the coarctation determine the pattern of pulse and blood pressure findings:

●In most cases, the origin of the left subclavian artery is proximal to the coarctation, resulting in hypertension in both arms (figure 1).

●Less often, the origin of the left subclavian artery is just distal to the coarctation, so the left brachial pulse is diminished and is equal to the femoral pulse. As a result, in this setting, comparing the blood pressure from the left arm and legs can be misleading, as the coarctation is proximal to the origin of the left subclavian artery.

●In approximately 3 to 4 percent of cases, both the right and left subclavian arteries originate below the area of coarctation, resulting in the blood pressures and pulses that are equally decreased in all four extremities.

●In mild CoA, all the pulses may be easily palpable, but there may be a delay in the femoral pulse compared with the brachial pulse.

●If the origin of the right subclavian artery is anomalously located distal to the coarctation, comparing blood pressure measurements between the right arm and leg may be misleading as they will be diminished to a similar degree.

●When CoA is accompanied by substantial collaterals, the femoral pulses may be less diminished, and the gradient (differential systolic blood pressures) across the coarctation may be less severe than expected for the degree of obstruction.

Ambulatory blood pressure monitoring can be useful for diagnosis and management of hypertension in patients with CoA [25]. (See "Ambulatory blood pressure monitoring in children" and "Out-of-office blood pressure measurement: Ambulatory and self-measured blood pressure monitoring".)

The mechanical obstruction to flow is largely responsible for the elevation of blood pressure in the upper extremities. In addition, renal hypoperfusion may lead to enhanced renin secretion and to subsequent volume expansion [26]. Volume expansion produces a further elevation in blood pressure, restoring renal perfusion and renin secretion toward normal.

Because other conditions can also cause unequal pulses and blood pressures (eg, atherosclerotic disease, aortic dissection), these disorders should also be considered when pulse and blood pressure discrepancies are found. (See 'Differential diagnosis' below and "Examination of the arterial pulse", section on 'Unequal or delayed pulses'.)

Cardiac examination — Cardiac auscultation may be normal if there are no associated cardiac abnormalities [24].

●The first and second heart sounds are usually normal. Rarely, pulmonary hypertension is present; when this occurs, the pulmonic component of the second heart sound is accentuated (movie 1). (See "Approach to the infant or child with a cardiac murmur", section on 'Heart sounds'.)

●There may be an ejection systolic click and a systolic ejection murmur from a bicuspid aortic valve (movie 2), which is heard best at the apex or left sternal border. (See "Approach to the infant or child with a cardiac murmur", section on 'Other sounds' and "Auscultation of heart sounds", section on 'Ejection sounds' and "Auscultation of cardiac murmurs in adults", section on 'Midsystolic ejection murmurs'.)

●A systolic murmur can extend beyond the second heart sound, at the left paravertebral interscapular area, due to flow across the narrow coarctation area.

●Continuous murmurs may be caused by flow through large collateral vessels. (See "Auscultation of cardiac murmurs in adults", section on 'Continuous murmurs'.)

●Systolic murmurs may be present due to coexisting cardiac defects (eg, PDA (movie 3), VSD (movie 4), or aortic stenosis (movie 5)).

In infants with heart failure, a prominent right ventricular impulse is typical. In older children and adults, the left ventricular impulse is palpable and sustained, and pulsations may be palpable in the intercostal spaces from large collateral arteries. (See "Examination of the precordial pulsation" and "Approach to the infant or child with a cardiac murmur", section on 'Palpation of the chest'.)

Noncardiac manifestations

Turner syndrome — Female patients should be examined for the dysmorphic features of Turner syndrome (see "Clinical manifestations and diagnosis of Turner syndrome", section on 'Clinical manifestations'):

●Neonates may have congenital lymphedema of the hands and feet, a webbed neck, and a low hairline

●Older girls and women are typically short with a broad, shield-shaped chest and with widely spaced nipples (picture 1)

Genetic testing for Turner syndrome (ie, karyotype analysis) should be performed in all girls diagnosed with CoA because of the high rate of association (approximately 5 to 15 percent of female patients) and because clinical findings suggestive of Turner syndrome may be absent in girls with mosaicism [14,15]. (See "Clinical manifestations and diagnosis of Turner syndrome", section on 'Diagnosis'.)

Intracranial aneurysms — Adult patients with CoA are at increased risk for intracranial aneurysms [27-30]. The magnitude of risk of subarachnoid hemorrhage from rupture of intracranial aneurysms in patients with CoA is uncertain.

●Adult patients with CoA – Several studies using magnetic resonance angiography (MRA) or computed tomography angiography have demonstrated intracranial aneurysms in approximately 10 percent of adult patients, which is substantially higher than the 2 to 3 percent risk reported in the general population. The risk is greatest in older patients and those with hypertension [29,30]. (See "Unruptured intracranial aneurysms", section on 'Epidemiology'.)

●Pediatric patients with CoA – In contrast, there does not appear to be an increased risk of intracranial aneurysms among children with CoA who undergo treatment early in life. In a study of 80 children with CoA, treated with surgical or endovascular intervention in early childhood (mean age of 2.6 years), MRA performed at mean age of 15.7 years found no evidence of aneurysms in any of the enrolled patients [31].

Spinal subarachnoid hemorrhage — Dilated collateral arteries within the spinal canal may also accompany CoA. These vessels can compress the spinal cord or can rupture, causing a clinical picture of spinal subarachnoid hemorrhage [32-34].

Aortic aneurysm and dissection — Aortic aneurysm and dissection are uncommon long-term complications associated with CoA. This issue is discussed separately. (See "Management of coarctation of the aorta", section on 'Aortic aneurysm, dissection, and rupture'.)

Electrocardiography and radiography findings — Most patients will undergo initial testing that includes electrocardiography (ECG) and chest radiography. However, the diagnosis is generally confirmed by echocardiography. In some cases, particularly adults and those with complex conditions, cardiovascular magnetic resonance imaging (CMR) or computed tomography are used to confirm the diagnosis, delineate the length of coarctation, assess aortic size, and help plan intervention. (See 'Echocardiography' below and 'Cardiovascular magnetic resonance/computed tomography' below.)

Electrocardiogram — ECG varies with age of the patient and severity of the lesion. Even in neonates and young infants with a severe defect, the ECG may be normal and may display the age-appropriate right ventricular hypertrophy. Sometimes biventricular hypertrophy is seen. In older children and adults, the ECG either may be normal or may show left ventricular hypertrophy, with increased voltage and ST and T wave changes in the left precordial leads. The ECG will occasionally show right ventricular conduction delay [35]. (See "Left ventricular hypertrophy: Clinical findings and ECG diagnosis".)

Chest radiograph — The chest radiograph varies with age and severity of the coarctation.

●In infants with heart failure, the chest radiograph shows generalized cardiomegaly with increased pulmonary vascular markings due to pulmonary venous congestion (image 1).

●In older children and adults, the heart size may be normal, but the following abnormalities are often present:

•Notching of the posterior one-third of the third to eighth ribs due to erosion by the large collateral arteries. Rib notching increases with age and usually becomes apparent between the ages of 4 and 12 years (image 2). Notching is not seen in the anterior ribs because the anterior intercostal arteries are not located in costal grooves [24].

•Indentation of the aortic wall at the site of coarctation with pre- and post-coarctation dilatation, which can produce a "3" sign, which may be seen on chest radiograph or aortogram (image 3 and image 4). Barium swallow, which is not performed routinely, may show a "reverse 3" or "E" sign.

DIAGNOSIS

Prenatal diagnosis — It is challenging to detect CoA by antenatal ultrasound because only 10 percent of the fetal cardiac output flows across the defect (figure 5) [36-38]. In addition, the presence of the patent ductus limits the ability to detect any pressure gradient at the coarctation site, and may also make the anatomic narrowing less marked. If the diagnosis is made, it can be made as early as at 16 to 18 weeks of gestational age. The presence of a long segment coarctation or other cardiac findings (eg, small left ventricle, small mitral annulus, or dilated right ventricle) improves detection.

In a study of 90 infants with isolated critical CoA born in Sweden between 2003 and 2012, only three cases were diagnosed prenatally despite 97 percent of pregnant women in Sweden having a second-trimester ultrasound [39]. The ultrasound assessment included a four-chamber view of the fetal heart in all cases; whereas the practice of obtaining views of the outflow tract was steadily introduced during the study period, with 65 percent of units routinely applying this practice by the end of the 2012.

Antenatal detection by echocardiography appears to be improved by serial studies that use transverse views of the aortic and ductal arches, which compare the ratio of the aortic and ductal arches with normative data [40]. Fetuses with CoA compared with those without CoA were more likely to have a lower ratio of the distal aortic isthmus to arterial duct diameters. (See "Congenital heart disease: Prenatal screening, diagnosis, and management", section on 'Advanced fetal cardiac evaluation'.)

Postnatal diagnosis — The clinical diagnosis of CoA is based upon the characteristic findings of systolic hypertension in the upper extremities, diminished or delayed femoral pulses (brachial-femoral delay), and low or unobtainable arterial blood pressure in the lower extremities. The diagnosis is confirmed by noninvasive imaging methods, particularly echocardiography.

Echocardiography — In most patients, high-quality transthoracic two-dimensional and Doppler echocardiography can establish the diagnosis and severity of CoA, including in neonates with a patent ductus arteriosus [25,41-43]. Echocardiography can also detect associated cardiac defects, including aortic hypoplasia, and can be used for follow-up after repair [41,42].

In the high parasternal or suprasternal long axis view, a discrete area of narrowing (posterior shelf) within the lumen of the proximal descending thoracic aorta is typically visualized (image 5). Color and pulsed Doppler echocardiography can localize the area of coarctation by demonstrating increased velocities and turbulence, as well as forward diastolic flow.

Continuous wave Doppler can estimate the severity of CoA based upon the maximal flow velocity across the narrow area, by calculating the pressure gradient across the coarctation with appropriate correction for velocity proximal to the site of coarctation. The severity of CoA can also be estimated by calculating the ratio of the maximal velocity across the coarctation (in the suprasternal view) to the peak velocity in the abdominal aorta (in the subcostal view) [41]. Of note, the presence of collateral blood flow may diminish the gradient across the coarctation; the gradient may be less severe than expected for the degree of obstruction. Therefore, indications for intervention are not based solely upon gradient. (See "Management of coarctation of the aorta", section on 'Indications for intervention'.)

Identification of characteristic diastolic run-off should be included in the routine evaluation for CoA because low amplitude, undulating, continuous Doppler flow within the descending thoracic aorta below the area of coarctation and within the abdominal aorta provides indirect evidence of CoA. Abnormal flow in collateral vessels may also be detected by color flow and pulsed-wave Doppler. Pulsed-wave Doppler assessment of the abdominal aorta in patients with CoA generally demonstrates reduced and delayed systolic amplitude with persistent flow during diastole. This finding may be the first clue to the echocardiographic diagnosis of CoA.

Because most patients with CoA have associated cardiac anomalies, echocardiographic evaluation should include detailed aortic and cardiac chamber measurements, identification of aortic valve anatomy, and identification of other potential associated lesions such as ventricular septal defect, subvalvular aortic stenosis, and mitral valve deformity.

Cardiovascular magnetic resonance/computed tomography — Cardiovascular magnetic resonance imaging (CMR) or computed tomography angiography (CTA) clearly defines the location and severity of CoA, as well as collateral vessels (image 6) [41]. CMR also may accurately identify patients with significant pressure gradient across the coarctation [44,45].

In children with CoA, echocardiography often provides adequate anatomic and hemodynamic information for the surgeon or interventional cardiologist without the need for a further imaging study. However, CMR or CTA is generally used as a complementary diagnostic tool in adolescent and adult patients, and provides important anatomic data prior to intervention. In adults with CoA (repaired or unrepaired), CMR or CTA is recommended for initial and follow-up imaging of the aorta [25]. CMR can also detect associated cardiac abnormalities and can be used for serial follow-up after surgical repair or balloon angioplasty [42]. CMR is generally preferred over CTA to decrease the lifetime radiation burden. If CMR is contraindicated, CTA imaging may be used to diagnose CoA.

In adults, cranial MR angiography (or CTA) is also appropriate to search for intracranial aneurysms. (See 'Intracranial aneurysms' above.)

Cardiac catheterization — Given the accuracy of noninvasive methods for diagnosis and determination of severity [46], cardiac catheterization for isolated CoA in children is generally performed in conjunction with a therapeutic intervention (eg, stent placement) (image 4 and image 7 and image 8) [46]. Catheterization may also be necessary for evaluation of patients with CoA that is associated with complex cardiac defects.

In adults, cardiac catheterization is indicated when associated coronary artery disease is suspected.

DIFFERENTIAL DIAGNOSIS — The differential diagnosis for CoA varies based upon the clinical presentation:

●Neonatal shock – Important causes of neonatal shock include:

•Other severe left-sided obstructive cardiac lesions (eg, hypoplastic left heart syndrome and severe critical aortic valve stenosis) (see "Hypoplastic left heart syndrome: Anatomy, clinical features, and diagnosis" and "Valvar aortic stenosis in children")

•Sepsis (see "Clinical features, evaluation, and diagnosis of sepsis in term and late preterm neonates")

•Perinatal asphyxia (see "Perinatal asphyxia in term and late preterm infants")

Additional causes of neonatal shock are summarized in the table (table 2). Echocardiography distinguishes CoA from these disorders. The diagnostic approach to neonates presenting with shock is discusses separately. (See "Neonatal shock: Etiology, clinical manifestations, and evaluation".)

●Unequal pulses and blood pressures – In patients with unequal pulses and blood pressures, the differential diagnosis includes:

•Obstructive peripheral arterial diseases (eg, from atherosclerosis, or arterial thrombosis from prior catheterization) (see "Clinical features and diagnosis of lower extremity peripheral artery disease")

•Prior surgical ligation (eg, history of classic Blalock-Thomas-Taussig shunt)

•Aortic dissection (see "Clinical features and diagnosis of acute aortic dissection")

•Supravalvar aortic stenosis (see "Valvar aortic stenosis in children")

Echocardiography distinguishes CoA from these disorders.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Congenital heart disease in infants and children".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or email these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword[s] of interest.)

●Basics links (see "Patient education: Aortic coarctation in adults (The Basics)" and "Patient education: Aortic coarctation in children (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Prevalence – Coarctation of the aorta (CoA) is a common malformation accounting for 4 to 6 percent of all congenital heart defects with a prevalence of 4 per 10,000 live births. (See 'Epidemiology' above.)

●Pathogenesis – CoA is generally congenital in origin. The underlying pathogenesis is unknown. There may be a genetic predisposition based upon familial risk of left ventricular outflow tract obstructive malformations, including CoA, and upon the association of Turner syndrome with CoA. There are rare acquired causes. (See 'Pathogenesis and etiology' above.)

●Anatomy – There is a spectrum of anatomic variants from the usual discrete thoracic lesions to long-segmental defects, tubular hypoplasia, and, rarely, coarctation of the abdominal aorta. CoA is usually accompanied by another cardiac lesion including bicuspid aortic valve, ventricular septal defect, or patent ductus arteriosus (PDA). (See 'Anatomy' above.)

●Presentation – The postnatal presentation varies depending upon the age of the patient and the severity of the lesion. (See 'Manifestations according to age' above.)

•Neonates with critical CoA present with heart failure and/or shock when the PDA closes. Pulses may be poor in all four extremities and differential cyanosis may be noted (ie, the oxygen saturation measured in the right arm [preductal] is higher than that in the leg [postductal]). Neonates with less severe CoA may be asymptomatic if there is a persistent PDA.

•Older infants and children are often asymptomatic and present with hypertension, murmurs caused by collateral blood flow or associated heart defects, or symptoms of chest pain or claudication.

•Hypertension is the typical presenting sign in adults. Claudication and headaches may also be noted in adults with unrepaired CoA.

●Natural history – Common complications in unoperated patients or in those operated on during later childhood or adulthood are systemic hypertension, accelerated coronary artery disease, stroke, aortic dissection, and heart failure. Patients with an associated bicuspid aortic valve may also develop significant aortic stenosis, aortic regurgitation, and ascending aortic aneurysm. (See 'Natural history' above.)

●Associated conditions

•Intracranial aneurysms – Adult patients with CoA are at increased risk for intracranial aneurysms. The risk of is greatest in older patients and those with hypertension. (See 'Intracranial aneurysms' above and "Unruptured intracranial aneurysms".)

•Turner syndrome – Genetic testing for Turner syndrome (ie, karyotype analysis) should be performed in all girls diagnosed with CoA because of the high rate of association (approximately 5 to 15 percent of female patients) and because clinical findings suggestive of Turner syndrome may be absent in girls with mosaicism. (See 'Turner syndrome' above and "Clinical manifestations and diagnosis of Turner syndrome", section on 'Diagnosis'.)

●Physical findings – The classical physical findings of CoA are systolic blood pressure which is lower in the lower extremities compared with the upper extremities and/or radial (or brachial) artery to femoral artery pulse delay. (See 'Physical findings' above.)

●Radiographic findings – Chest radiographic findings vary with age and severity of CoA. In infants with heart failure, the chest radiograph usually shows generalized cardiomegaly with increased pulmonary vascular markings due to pulmonary venous congestion (image 1). In older children and adults, the heart size may remain normal, but other findings include rib notching and the "3" sign (indentation of the aortic wall at the site of coarctation with pre- and post-coarctation dilatation) (image 2 and image 3). (See 'Chest radiograph' above.)

●Diagnosis

•Prenatal diagnosis – The prenatal diagnosis of CoA is challenging as it is difficult to detect aortic narrowing because only 10 percent of the fetal cardiac output flows through the thoracic aorta. (See 'Prenatal diagnosis' above.)

•Postnatal diagnosis – The diagnosis of CoA is generally confirmed by two-dimensional and Doppler transthoracic echocardiography. In adolescents, adults, and some pediatric cases, cardiovascular magnetic resonance imaging (CMR) or computed tomography angiography (CTA) (image 6) are used as a complementary diagnostic tool. CMR and CTA define the location and length of obstruction and identify collateral vessels and other associated lesions such as aortic dilatation. (See 'Postnatal diagnosis' above and "Management of coarctation of the aorta", section on 'Monitoring'.)

ACKNOWLEDGMENTS — The editorial staff at UpToDate acknowledge Brojendra N Agarwala, MD, QiLing Cao, MD, and Emile Bacha, MD, FACS, who contributed to an earlier version of this topic review.