History

The male:female ratio of coarctation is from 1.4:1 to 3:1.⁶⁹ Familial recurrence has occurred in siblings, in monozygotic twins, and in parent and child^70–75 and as autosomal dominant in four generations.⁷⁶ True coarctation and pseudocoarctation have been reported in siblings.⁷⁷ Turner’s syndrome (see section Physical Appearance) cannot be transmitted because of sterility, but seven women in three generations of one family had Turner’s syndrome attributed to loss of the short arm of one X chromosome that permitted transmission from phenotypically normal female carriers with a balanced X-1 translocation.⁷⁸ A peak seasonal incidence of coarctation is found from September through November and from January through March.⁷⁹ The reported rarity of coarctation in African Americans is open to question.^80,81

Coarctation of the aorta usually produces significant symptoms in early infancy^69,82,83 and after age 20 to 30 years.⁸⁴ Neonates with severe coarctation become acutely symptomatic when the ductus closes. Most who survive the hazards of infancy reach adulthood, although more than a quarter die by age 20 years, half by age 30 years, and more than three quarters by age 50 years.^33,84,85 Figures 8-24 and 8-26 are from patients aged 54 years, 62 years, and 70 years. Survival has been reported at age 74 years and 76 years.⁸⁶ Isolated atresia of the aortic arch was surgically repaired at age 65 years.⁸⁷ The longest recorded survival was Reynaud’s account (1828) of a 92-year-old man with coarctation.³ The anatomic illustrations in this report are noteworthy. However, examples of exceptional longevity should not obscure the inherent risk of coarctation that results in death at an average age of 33 years.

Figure 8-24 Close-up showing irregular scalloped notching of the inferior margins of posterior ribs in a 54-year-old man with coarctation of the aorta.

Figure 8-26 A, X-ray from a 62-year-old man with coarctation of the aorta distal to the left subclavian artery. Unmarked arrows in the right hemithorax identify subtle rib notching. The ascending aorta (AAo) is dilated, and calcium (Ca) appears in the aortic knuckle. The descending thoracic aorta (DAo) is convex to the left, which in part is age-related. An enlarged convex left ventricle (LV) occupies the apex. B, Thoracic aortogram shows a dilated and elongated ascending aorta (AAo) and complete obstruction at the coarctation site (CoARC). The aortic valve (AoV) is trileaflet. C, Lateral aortogram from a 70-year-old woman with complete obstruction at the coarctation site (Coarc). The left subclavian artery (LSA) is dilated.

Mild coarctation is not always benign, and severe coarctation is not always asymptomatic. A case in point, albeit rare, is a 20-year-old woman with severe coarctation, borderline hypertension, and no symptoms.⁸⁸ Except for symptomatic infants, patients tend to be clinically well when the diagnosis is first made. Initial suspicion requires little more than attention to upper and lower extremity arterial pulses and blood pressure (see section The Arterial Pulse). Nevertheless, delayed recognition is not uncommon,^89,90 and diagnoses have been made by chance in the fifth decade.⁹¹ Minor symptoms include epistaxis and leg fatigue. When coarctation compromises the orifice of the left subclavian artery in left-handed patients, muscular fatigue involves the left arm. Leg fatigue occurs in about half of patients, but claudication is reserved for abdominal coarctation. Patients are sometimes subjectively aware of amplified arterial pulsations in the neck, especially after effort or excitement. Dysphagia occurs when a retroesophageal right subclavian artery originates distal to the coarctation and passes behind the esophagus (see Figure 8-1C)⁹² or when coarctation is a component of a vascular ring.

Major symptoms are features of four eventualities: (1) congestive heart failure; (2) rupture or dissection of the aorta; (3) infective endarteritis or endocarditis; and (4) cerebral hemorrhage.^{83,84,93–95} Hypertension is chiefly responsible for morbidity and mortality with advancing age.⁸³ The incidence rate of cardiac failure is highest in infants^69,96 and is high again after the fourth decade.⁹⁷ In a review of 234 patients with coarctation of the aorta aged 1 day to 72 years, congestive heart failure occurred in two thirds of patients less than 1 year of age and more than age 40 years but in only 4% of patients between 1 year and 40 years of age.⁸³ Many, if not most, neonates and infants with congestive heart failure have a coexisting ventricular septal defect or patent ductus arteriosus.^98,99 In brief, more than 90% of infants and children with uncomplicated coarctation experience little or no difficulty.¹⁰⁰

When coarctation is juxtaductal or proximal to the neonatal ductus, continuity between the pulmonary trunk and descending aorta is maintained, so the femoral arterial pulses remain palpable.^6,96 When the ductus closes, the femoral pulses disappear, pulmonary blood flow is diverted into the lungs, the left ventricle is suddenly volume overloaded, and blood pressure and blood flow proximal to the coarctation suddenly increase. A high left atrial pressure opens the pliant valve of the foramen ovale, initiating a left-to-right shunt that imposes a volume load on the right ventricle that is already pressure overloaded because of pulmonary hypertension.¹⁰¹ Initial closure of the pulmonary arterial end of the ductus can leave the aortic end sufficiently patent to permit the proximal aorta to decompress.¹⁵ When the aortic end of the ductus closes, the isthmus is suddenly obstructed. Distal aortic pressure and flow fall, renal perfusion falls, and the renin-angiotensin system is activated.^65,102

Rupture or dissection of the aorta is a dramatic complication with peak incidence in the third and fourth decades.^83,85,94,97 The rupture originates either in a paracoarctation aneurysm^47,48,94 or above a coexisting bicuspid aortic valve because of an inherent medial abnormality of the ascending aorta (see Chapter 7).^48,94,97 Rupture of a postcoarctation aneurysm may be accompanied by bleeding into the esophagus that is announced by hematemesis and melena. In XO Turner’s syndrome (see section Physical Appearance), rupture or dissection of an ascending aortic aneurysm occurs because of an inherent medial abnormality,⁴⁸ whether or not a coexisting coarctation or a bicuspid aortic valve exists (Figure 8-9).^103–105 Aneurysms of intercostal arteries are almost always occult and relatively benign.⁴⁹ Pseudocoarctation has been regarded as a disorder that incurs little or no risk, but the malformation is not necessarily benign and is not necessarily pseudo (see previous discussion). Pseudocoarctation has been reported with Turner’s syndrome.¹⁰⁶ Cerebral arterial aneurysms are discussed in the section on cerebrovascular accidents (see subsequent discussion).

Figure 8-9 A, X-ray from a 28-year-old woman with 45 XO Turner’s syndrome, an aneurysm of the ascending aorta (Asc Ao), and a bicuspid aortic valve. B, Digital vascular image angiogram after injection of contrast material into the superior vena cava. The ascending aortic aneurysm ruptured 8 weeks later. (LV = left ventricle; DAo = descending aorta.)

Infective endarteritis or endocarditis is a major complication of coarctation of the aorta, although the more susceptible site is a coexisting bicuspid aortic valve (see Chapter 7).^83,97 Saccular septic aneurysms are occasional sequelae of infective endarteritis.⁹⁴

Cerebrovascular accidents are the fourth major eventuality in coarctation of the aorta.^83,93,107 Hypertension is not a necessary precondition because cerebral complications can occur with normotensive conditions long after successful repair. An aneurysm of the circle of Willis, first described in 1927,¹⁰⁸ is the chief offender (see Figure 8-7) and sets the stage for rupture and cerebral hemorrhage.¹⁰⁹ Less common, but not less important, are aneurysms in other cerebral arteries.⁹³ Infective endocarditis on a bicuspid aortic valve can give rise to septic cerebral aneurysms that rupture. Rarely and oddly, an unruptured intracranial aneurysm triggers musical hallucinations.¹¹⁰

Coarctation hypertension is a risk factor for premature atherosclerotic coronary artery disease (see Figure 8-4B; see previous discussion).^83,111,112 Evidence also exists of structural abnormalities of terminal intramural coronary arteries.¹¹¹ Gonadal dysgenesis of Turner’s syndrome reportedly increases atherosclerotic cardiovascular risk.¹¹³

Physical Appearance

An athletic appearance of chest and shoulders contrasts with narrow hips and thin legs. When coarctation compromises the origin of the left subclavian artery, the left arm tends to be small. General growth and development are impaired in infants with congestive heart failure.

XO Turner’s syndrome with its distinctive physical appearance (Figure 8-10) arouses suspicion of coarctation of the aorta.^114,115 Chromosomal patterns 45 XO and X-mosaicism are coupled with additional cardiac expressions.^116–119 Aortic rupture or dissection in Turner’s syndrome was mentioned previously (see Figure 8-9).^103,104,120 The typical XO Turner’s phenotypic female (Figure 8-11) is of short stature with webbing of the neck, absent or scanty auxiliary and pubic hair (ovarian dysgenesis), broad chest with widely spaced hypoplastic or inverted nipples, low anterior and posterior hairlines, small chin, prominent ears because of large auricles, cubitus valgus, short fourth metacarpals and metatarsals, distal palmar triaxial radii, narrow hyperconvex nails, and pigmented cutaneous nevi.¹¹⁵ Infants with Turner’s syndrome exhibit lymphedema of the neck with loose skin, puffiness of the dorsum of the hands and feet, and low hairlines.^115,121 Congenital heart disease is much more frequent in Turner’s syndrome with webbing of the neck than in Turner’s syndrome without webbing,^116,121 and coarctation of the aorta is eight times as frequent when Turner’s syndrome is accompanied by webbing of the neck.¹²¹ Noonan’s syndrome (Turner’s phenotype with normal genotype; see Figure 8-10) is only occasionally accompanied by coarctation of the aorta¹²² and rarely by ascending aortic aneurysm.^95,115,123 Systemic hypertension in Turner’s syndrome occurs without coarctation. Another distinctive physical appearance associated with coarctation of the aorta is the PHACE syndrome¹²⁴: P, posterior fossa brain malformations; H, hemangioma of the head or neck; A, arterial abnormalities of the head or neck; C, cardiac abnormalities, including coarctation of the aorta; E, eye abnormalities.

Figure 8-10 A, An 18-year-old man with Noonan’s syndrome (Turner’s phenotype with normal genotype). There is typical webbing of the neck. Long hair obscures low anterior and posterior hair lines. B, A 24-year-old man with Noonan’s syndrome and a dissecting aneurysm of the ascending aorta. There is a low posterior hairline, webbing of the neck, low-set auricles, and micrognathia.

Figure 8-11 Thirteen-year-old girl with 45 XO Turner’s syndrome and coarctation of the aorta. Physical appearance is characterized by short stature, webbing of the neck, absent pubic hair, wide-set nipples, and small chin. Bangs obscure a low anterior hairline.

Arterial Pulse

Abnormal differences in upper and lower extremity arterial pulses and blood pressure are hallmarks of coarctation of the aorta. If proper attention were paid to these pulses, few or no diagnoses would be missed.^90,125 Two methods have been advocated for comparison of upper and lower extremity arterial pulsations. One method compares femoral and radial pulses; the other method compares femoral and brachial pulses. Normally, radial and femoral pulses are sensed as synchronous, so that any femoral delay is considered abnormal. Positioning the patient’s wrist next to the groin is believed to facilitate comparison. In infants and newborns, the brachial artery is more readily palpated than the tiny radial artery, which is surrounded by subcutaneous fat pads (Figure 8-12B). The author’s preference is comparative palpation of brachial and femoral pulses, which is accomplished with placing a thumb on each (Figure 8-12A).¹²⁵ The slight delay in perceived arrival time of the normal femoral pulse (15 msec in adults, less in infants and children) is easily sensed as a norm against which even slight deviations can be judged. With palpation of the femoral pulse in an infant, the patient must be allowed to relax the legs voluntarily because forceful restraint can decrease or abolish a normal femoral pulse.

Figure 8-12 A, Palpation of brachial and femoral arteries as shown here is a useful way of comparing upper and lower extremity pulses. Application of the thumbs allows simultaneous or sequential palpation, which permits detection of subtle differences in amplitude and timing. B, Recommended method of simultaneous palpation of right and left brachial arterial pulses (arrows).

What is perceived as an abnormal delay of the femoral pulse in coarctation is not a delay in arrival time but instead a slow rate of rise to a delayed peak (Figure 8-13). The presence of a normal femoral pulse effectively eliminates all but mild coarctation, provided the aortic valve is functioning normally (see subsequent discussion). Palpation begins with applying to the brachial and femoral arterial pulses the amount of digital pressure necessary to elicit the maximal systolic impact.¹²⁵ Stiffness of the precoarctation aortic wall results in disproportionate systolic hypertension and forceful carotid and suprasternal notch pulsations, which are sensed by the patient and become increasingly apparent with age and exercise (see previous discussion).^59,61,62

Figure 8-13 A, Simultaneous direct brachial and femoral arterial pressure pulses from a 10-year-old boy and a 4-year-old boy with coarctation of the aorta. The femoral arterial pulses (Fem. art.) were palpable but smaller than the brachial arterial pulses (Brachial art.). The diastolic pressures virtually coincide. The important differences are systolic not diastolic. There is no delay in arrival time of the femoral pulse. B, The right brachial arterial pulse (humerale droite) and the left femoral arterial pulse (femoral gauche) are characteristic of aortic coarctation.

(From Maude Abbott’s Atlas of congenital cardiac disease. Montreal: Osler Library, McGill University; 1936. Reproduced with permission.)

Bicuspid aortic regurgitation reinforces the femoral pulse, which can be misjudged unless properly compared with the brachial pulse (Figure 8-14A).¹²⁶ Bicuspid aortic stenosis may not dampen the brachial arterial pulse because coarctation amplifies the ascending aortic and brachial arterial systolic pressures (Figure 8-14B).¹²⁶ Conversely, if aortic stenosis dampens the ascending aortic systolic pressure, evidence of coarctation is obscured (Figure 8-14C).¹²⁶

Figure 8-14 A, Pressure pulses from a 19-year-old man with severe coarctation of the aorta and bicuspid aortic regurgitation. The brachial arterial pressure (B.A.) is higher than the femoral arterial pressure (F.A.) because of the coarctation, although the femoral arterial pulse pressure is wide because of aortic regurgitation. B, A 38-year-old man with coarctation of the aorta and severe bicuspid aortic stenosis. The brachial pulse is amplified by the coarctation despite aortic stenosis. C, A 5-year-old boy with moderately severe bicuspid aortic stenosis and mild coarctation of the aorta. The proximal aortic, and therefore brachial arterial systolic pressure, is damped by aortic stenosis, but the femoral arterial systolic pressure is preserved because the coarctation was mild.

(From Glancy DL, Morrow AG, Simon AL, Roberts WC. American Journal of Cardiology 1983;51:537. With permission.)

The right and left brachial arteries should be compared with palpation and with cuff blood pressure (see Figure 8-12B). A decreased or absent left brachial arterial pulse indicates that the coarctation has compromised the lumen of the left subclavian artery (see Figure 8-1B) or is proximal to its origin (see previous discussion). In comparison of the two brachial pulses, account must be taken of normal systolic pressure differences of 10 to 15 mm Hg lower in the left arm.¹²⁵ Diminution or absence of the right brachial pulse implies that the right subclavian artery originates distal to the coarctation (see Figure 8-1C). Absence of both brachial arterial pulses signifies that coarctation is compromising the lumen of the left subclavian artery and that the right subclavian artery arises distal to the coarctation.¹²⁷ At birth, femoral arterial pulses are temporarily palpable if the coarctation is juxtaductal, if the ductus is distal to the coarctation, or if the aortic end of the ductus is patent.⁶ The abdominal aorta is readily palpable proximal to abdominal coarctation but is not palpable when coarctation is in the aortic isthmus. Pseudocoarctation leaves the arterial pulses normal because there is no aortic obstruction, although angulation at the level of the ligamentum arteriosum occasionally dampens the femoral pulses (see Figure 8-5).²²

Collateral arterial pulsations are specifically sought with patients who are old enough standing and bending forward with arms hanging at the sides while the examiner scrutinizes the patient’s back, especially around and between the scapulae.¹²⁸ A tangential light in a darkened room highlights subcutaneous collaterals in shadowed relief. Collateral arteries occasionally appear around the shoulders, along the right and left sternal borders, and rarely over the upper abdominal wall.

Cuff blood pressure is an important supplement to palpation of the arterial pulses. Blood pressure should be taken in the right arm, left arm, and leg. Correct cuff size is essential because improper size results in inaccurate readings.^{125,129–133} An undersized cuff overestimates and an oversized cuff underestimates intraarterial blood pressure by as much as 10 to 30 mm Hg.¹³³ The American Heart Association recommendations for cuff size¹³⁰ are shown in Table 8-1. References to cuff size apply to the width and length of the inner inflatable bladder, not to the cloth covering. Cuff size is determined by limb circumference, not by patient age. The width of the inflatable bladder within the cuff should be 40% of the circumference of the midpoint of the limb. The length of the inflatable bladder must be sufficient to encircle the limb without overlapping.^129,130

Table 8-1 Recommended Bladder Dimensions for Blood Pressure Cuff

* Midpoint is defined as half the distance from the acromion to the olecranon.

From Kirkendall WM, Feinleib M, Freis ED, Mark AL. AHA committee report: recommendations for human blood pressure determinations by sphygmomanometers. Circulation 1980;62:1146A. Reprinted with permission of the American Heart Association.

The examining room should be quiet, and the patient must be comfortable and reassured. Sufficient time should elapse for recovery from recent activity and tension. When an infant is quieted with a bottle or a pacifier, blood pressure can be obtained with the usual auscultatory method. An alternative is the flush technique, which requires two examiners.¹²⁹ An uninflated cuff is applied to the infant’s forearm, which is elevated while the limb distal to the cuff is massaged to induce blanching. The cuff is inflated above anticipated systolic pressure while the arm remains elevated and blanched. The arm is then slowly lowered into a horizontal position while the cuff is slowly deflated. The point at which the blanched hand becomes flushed is an estimate of the mean arterial pressure. Doppler ultrasound or oscillometric techniques can be used by a single examiner and accurately determine systolic and diastolic blood pressure.^90,129

Upper extremity blood pressure in infants and adults is usually recorded in the supine position, but a comfortable sitting position in a parent’s lap is acceptable for relaxation of infants and young children. Lower extremity blood pressure is best determined from the popliteal artery with the patient prone.¹²⁵ While the popliteal artery is palpated, a thigh cuff is applied and must be inflated slowly to avoid discomfort. The cuff is inflated to a level just above the brachial arterial systolic pressure until the popliteal pulse vanishes. Systolic and diastolic pressures are then estimated with auscultation of popliteal Korotkoff’s sounds. Diagnostic differences in arm and leg blood pressures are based on systolic levels when only systolic Korotkoff’s sounds are heard. However, the diastolic pressures are important in confirmation of accuracy because they are not significantly different in the upper and lower extremities (see Figure 8-13). When intraarterial systolic, diastolic, and mean brachial and femoral pressures are compared in healthy persons, no significant difference is found, although the femoral auscultatory systolic pressure is about 10 mm Hg higher than the direct femoral arterial pressure.¹³³ Differences between arm and leg systolic pressures in coarctation are exaggerated by exercise, which causes an increase in brachial arterial pressure, with no change or a reduction in femoral arterial pressure.¹³⁴

Measurements of blood pressure should be a routine part of the physical examination after infancy and are desirable in infants at least once.^90,135 Normal arterial pressure is based on age and gender.^129,136,137 The average systolic blood pressure in females rises to a plateau at around age 14 years and remains almost constant during the early reproductive years.¹³⁶ The average systolic blood pressure in males may not plateau until around age 20 years.^129,136,137 Diastolic pressure differences are in the same direction but smaller in degree.

From birth to 6 months, normal upper extremity blood pressure averages 80/45 mm Hg. From 2 years to puberty, the average upper extremity blood pressure is 90/60 to 100/60 mm Hg,^129,136 with the diastolic pressure more consistent than the systolic pressure. Coarctation of the aorta is accompanied by a progressive age-related increase in blood pressure, especially systolic, so the pulse pressure widens.^61,73

In pregnant females with coarctation, blood pressure fluctuations are similar in direction to fluctuations in uncomplicated pregnancy but occur from a higher baseline.¹³⁸ Coarctation is not a resistance vessel disease, so the incidence rate of toxemia is lower than in pregnant women with other forms of hypertension.^138,139 Gestational hypertension is related to a significant coarctation gradient.¹⁴⁰ Pregnancy increases the risk of aortic rupture and intracranial hemorrhage because gestational changes in connective tissue reinforce the medial abnormalities inherent in the arterial walls of coarctation.^48,138 In abdominal coarctation, hypertension is likely to be caused by renal artery stenosis rather than by the coarctation.²⁰

Jugular Venous Pulse

Prominent arterial pulsations can make assessment of the jugular venous pulse difficult; pulse is normal except in patients with coarctation and biventricular failure.

Precordial Movement and Palpation

The left ventricular impulse varies from normal to the sustained heaving impulse of pressure overload hypertrophy.¹²⁵ In symptomatic infants with biventricular failure, the right ventricular impulse is dynamic because the pressure overload of pulmonary hypertension is coupled with volume overload of a right-to-left shunt through the foramen ovale. Suprasternal notch systolic thrills are frequent in uncomplicated coarctation, but precordial thrills are generated by coexisting bicuspid aortic stenosis.

Auscultation

Coarctation of the aorta is associated with systolic, diastolic, and continuous murmurs (Figure 8-15). An ejection sound is an auscultatory sign of a coexisting bicuspid aortic valve (Figures 8-15 and 8-16). Systolic murmurs originate from three sources (see Figure 8-15): (1) arterial collaterals; (2) the coarctation itself; and (3) the brachiocephalic arteries. That murmurs can originate in collateral arteries is based on observations that localized superficial collateral murmurs are abolished by compression and that murmurs have been recorded from the surfaces of surgically exposed collateral arteries.¹⁴¹ A murmur cannot be generated across coarctation when obstruction is complete (see Figure 8-3B), but murmurs are prominent because arterial collaterals are well developed (see Figure 8-3A,C).¹⁴¹ The widespread anatomic distribution of the collateral arterial circulation accounts for the widespread thoracic distribution of accompanying murmurs.¹⁴² Collateral murmurs are crescendo-decrescendo and are delayed in onset and termination because they originate at a distance from the heart (Figures 8-15, 8-17, and 8-18).¹⁴¹ Widely distributed thoracic murmurs constitute presumptive evidence of collateral circulation, but in young children, collaterals may be well-developed without generating murmurs and in occasional adults with abundant collaterals, murmurs are inconspicuous.

Figure 8-15 Illustration of the principal murmurs that accompany coarctation of the aorta (COARC, Ao). At the lower left are auscultatory events associated with a bicuspid aortic valve: namely, an aortic ejection sound (E), a short midsystolic murmur (SM), and an early diastolic murmur (EDM) of aortic regurgitation. At the upper left are the continuous murmur (CONT) and the delayed systolic murmur (SM) that originate at the coarctation site and are heard posteriorly over the thoracic spine. On the right are collateral arterial murmurs (COLLAT) that are crescendo-decrescendo and delayed in onset and termination because their origins are at a distance from the heart. Collateral murmurs are shown on one side only as a matter of convenience. (S₁ = first heart sound; A₂ = aortic second sound.)

Figure 8-16 Phonocardiograms from a 10-year-old boy with coarctation of the aorta and a bicuspid aortic valve. In the second right intercostal space (2 RICS), there is an aortic ejection sound (E), a short midsystolic murmur (SM), and an early diastolic murmur (EDM) of bicuspid aortic regurgitation. The tracing from the mid back was recorded over the site of coarctation and shows a continuous murmur that is delayed in onset and extends into diastole (paired arrows).

Figure 8-17 Tracings from a 22-year-old man with coarctation of the aorta. The phonocardiogram from the mid back over the site of coarctation shows a systolic murmur that is delayed in onset and continues into diastole (paired arrows). The systolic murmur in the fourth left intercostal space (4LICS) originated in a left internal mammary collateral (see Figure 8-3). (CAR = carotid.)

Figure 8-18 Tracings from a 6-year-old boy with coarctation of the aorta. A, The phonocardiogram in the left axilla shows a delayed systolic murmur (SM) that originated in arterial collaterals. B, The phonocardiogram in the mid back over the vertebral column shows a delayed systolic murmur at the coarctation site. (CAR = carotid pulse; S₁ = first heart sound; S₂ = second heart sound.)

The coarctation itself is responsible for a systolic murmur¹⁴¹ that correlates with the size of the coarctation, and the localized posterior position over the thoracic spine correlates with the coarctation site (see Figures 8-15 and 8-18B). Typical isthmic coarctation generates a posterior murmur at the level of the fourth or fifth thoracic spinous process (see Figures 8-15 through 8-18).¹⁴¹ In infants, murmurs are typically absent, except in this posterior location. Heart failure causes the coarctation murmur to decrease or disappear.

Infants are best examined prone, and older patients are examined prone or in a relaxed sitting position that minimizes muscle tremor. Posterior auscultation begins in the midline at the upper thoracic spine and descends to the midthoracic and lumbar spine. The murmur overlying a coarctation is soft and high-frequency, so detection is best achieved with the stethoscopic diaphragm or firm pressure of the bell. As severity increases, the short posterior thoracic systolic murmur lenthens (see Figures 8-15 and 8-18B) and continues into diastole (see Figures 8-15 through 8-17). When the coarctation diameter decreases to 2.5 mm, the murmur occupies all of the cardiac cycle.¹⁴¹ The continuous murmur is soft and high-frequency, so assessment requires a quiet room and a cooperative patient. Rarely, the coarctation murmur is loud enough to radiate to the anterior chest.¹⁴¹ A loud brachiocephalic systolic murmur accompanied by a thrill is heard in the suprasternal notch, and prominent systolic murmurs are heard over the right and left subclavian arteries. A short low-frequency to medium-frequency diastolic murmur over the left ventricular impulse is caused by a decrease in interpapillary distance, which culminates in the single papillary muscle of a parachute mitral valve (see previous discussion; see Chapter 9).³⁷ The murmur of abdominal coarctation is heard anteriorly in the epigastrium or just below and posteriorly over the lower thoracic or lumbar spine.²⁰ Pseudocoarctation generates a systolic murmur posteriorly over the site of the aortic kink (see Figure 8-5).^23,143

The second heart sound in coarctation of the aorta is either single or normally split with increased intensity of the aortic component. A loud single second sound in the second left interspace is the result of augmented aortic valve closure (see Figure 8-16). In symptomatic infants with pulmonary hypertension, the loud single second sound is the summation of aortic and pulmonary components.

Fourth heart sounds reflect the afterload-induced left ventricular hypertrophy of coarctation. Third heart sounds or summation sounds occur in infants with heart failure and a rapid heart rate.

Electrocardiogram

Electrocardiographic patterns are related to two age-groups: namely, symptomatic neonatal coarctation and coarctation after childhood. Left atrial P wave abnormalities occur in adults (Figure 18-19), and right atrial P wave abnormalities occur in symptomatic infants (Figure 8-20). The mean QRS axis in adults is normal, although axis is occasionally leftward in older patients (Figure 8-21). Right axis deviation with right ventricular hypertrophy is typical of the electrocardiogram in symptomatic infants with right ventricular pressure and volume overload (see previous discussion). Right ventricular hypertrophy that persists beyond infancy is rare in uncomplicated coarctation.

Figure 8-20 Electrocardiogram from a 6-year old-boy with coarctation of the aorta and congestive heart failure in infancy (see Figure 8-18). The QRS axis is rightward. There is a tall right atrial P wave in lead 1. Right ventricular hypertrophy is manifested by a tall monophasic R wave in led V₁ and deep S waves in left precordial leads.

Figure 8-21 Electrocardiogram from a 41-year-old man with coarctation of the aorta. The QRS axis is horizontal. There are broad left atrial P waves in leads 1 and 2. Left ventricular hypertrophy is manifested by deep S waves in right precordial leads and tall R waves with ST segment depressions and T wave inversions in left precordial leads.

Left ventricular hypertrophy is characterized by tall R waves and low, flat, or inverted T waves in left precordial leads (see Figure 8-19). Prominent coved ST segment depressions with deeply inverted T waves are exceptional (see Figure 8-21) and imply coexisting bicuspid aortic stenosis. Prominent left precordial Q waves suggest the volume overload of bicuspid aortic regurgitation.

Figure 8-19 Electrocardiogram from a 23-year-old man with coarctation of the aorta. The QRS axis is normal. There is a broad left atrial P wave in lead 2. Left ventricular hypertrophy is suggested by the sum of the S wave in V₁ and the R wave in V₅.

X-Ray

In asymptomatic infants and young children, the x-ray is normal. The descending thoracic aorta is a straight line that runs parallel to the left edge of the vertebral column, but in children and young adults, the postcoarctation descending thoracic aorta has a distinctive leftward convexity that is accompanied by dilation of the left subclavian artery (Figure 8-22).¹⁴⁴ The x-ray in symptomatic infants discloses pulmonary venous congestion with dilation of the right ventricle and the right and left atria (Figure 8-23). Left ventricular size remains normal or nearly so.

Figure 8-22 X-ray from a 3-year-old boy with coarctation of the aorta (COARC). The child was too young to have development of rib notching, but the radiologic diagnosis can be suspected because the descending aorta (DA) is convex to the left and the left subclavian artery (LSA) is dilated—the figure 3 sign.

Figure 8-23 A, X-ray from a 1-month-old male with coarctation of the aorta, congestive heart failure, and a left-to-right shunt through a patent foramen ovale. There is pulmonary venous congestion. An enlarged right ventricle (RV) occupies the apex, and a dilated right atrium (RA) forms the right lower cardiac border. B, Lateral chest x-ray from a 4-month-old female with 45 XO Turner’s syndrome, coarctation of the aorta, congestive heart failure, and a left-to-right shunt through a foramen ovale. The left atrium (LA) is enlarged. The retrosternal space is occupied by a dilated right ventricle (RV), but the left ventricle is not enlarged. The crural portions of the diaphragm are flat (curved white arrows) because the lungs were hyperinflated.

Notching of the ribs is a classic radiologic sign of coarctation caused by collateral flow through dilated, tortuous, pulsatile posterior intercostal arteries (Figures 8-3, 8-24, and 8-25). Notches vary from rib to rib and from patient to patient and may be single, multiple, shallow, deep, broad, or narrow.^41,135 Notching originates in posterior intercostal arteries that run in intercostal grooves (see Figure 8-24), so the anterior ribs are spared because anterior intercostal arteries do not run in intercostal grooves.^135,145 Rarely, the superior margin of a rib is notched because of contact with an overhanging intercostal artery.¹⁴⁶ Rib notching seldom appears before age 6 years, although exceptional examples have been described as early as 2 years of age.^41,145,147

Figure 8-25 X-ray from a 23-year-old man with coarctation of the aorta (COARC). Arrows point to notching on the undersurfaces of the posterior ribs. The ascending aorta (Ao) is dilated. The left subclavian artery (LSA) dilated above the coarctation, and the descending aorta (DA) is dilated below the coarctation, forming a figure 3.

Typical coarctation distal to the left subclavian artery results in bilateral notching between the third and the eighth posterior ribs, but rarely above the third or below the ninth rib (Figures 8-25 and 8-26A).¹³⁵ Anatomic variations of the coarctation site are accompanied by variations in the radiologic patterns. The development of arterial collaterals depends on patency of the ipsilateral subclavian artery; so when the left subclavian lumen is compromised, ipsilateral collaterals fail to develop, and unilateral rib notching is confined to the right hemithorax (Figure 8-27).^135,145 Anomalous origin of the right subclavian artery distal to the coarctation (see Figure 8-1C) results in failure of collateral development in the right hemithorax, so unilateral notching is confined to the left hemithorax.^92,145 Lateral x-rays show retrosternal notching or scalloping caused by dilated tortuous internal mammary arteries (see Figure 8-3A,B).^41,147 When coarctation is in the abdominal aorta, notching, if present at all, is confined to the lower ribs.¹⁴⁸

In older children and adults with coarctation, the ascending aorta is moderately to markedly dilated (see Figure 8-25).¹⁴⁷ In XO Turner’s syndrome, the ascending aorta may be aneurysmal (see Figure 8-9). The proximal and distal paracoarctation aorta are typically dilated (see Figure 8-2).^41,48,144 Postcoarctation aortic dilation is sometimes aneurysmal, and calcification is occasionally visible in the wall of the aneurysm. The combination of a dilated left subclavian artery proximal to the coarctation and a dilated aorta distal to the coarctation produces a figure 3 silhouette in the x-ray (see Figures 8-22 and 8-25).^41,144 The mirror image of the figure three sign is seen when the left subclavian artery and descending aorta indent a barium esophagram (Figure 8-28).^41,147 The left subclavian cannot dilate when its lumen is compromised by the coarctation, so dilation of the distal paracoarctation aorta exists alone (see Figure 8-27). A retroesophageal aberrant right subclavian artery is sometimes identified as a posterior indentation of the barium esophagram.¹³⁵

Figure 8-28 Right anterior oblique view from a 6-year-old boy with coarctation of the aorta. The barium esophagram exhibits the E sign (arrows) caused by compression from the dilated left subclavian artery above and the dilated descending aorta below. The E sign is the mirror image of the 3 sign (see Figure 8-25).

The kinked aorta of pseudocoarctation has a transverse arch and a descending aorta that form a large 3 sign above and below the kink (see Figure 8-5).^{24,77,143,149} Pseudocoarctation is conspicuous, but rib notching is conspicuous by its absence (see Figure 8-5).

Echocardiogram

Transthoracic and transesophageal echocardiography with Doppler scan interrogation and color flow imaging (Figures 8-29 [and video 8-1], 8-30, and 8-31) permit segment-by-segment analysis of the ascending aorta, the aortic arch, the brachiocephalic arteries, the aortic isthmus, and the proximal descending aorta from birth to maturity. ^150,151 A long segment of luminal narrowing can be identified. The suprasternal notch window with color flow imaging is identifies the coarctation by a zone of localized accelerated flow and by providing the target through which the continuous wave Doppler beam can be aligned to determine the gradient (see Figures 8-29A,B, 8-30, and 8-31).^150,151 Peak systolic velocity reflects the maximal systolic gradient, and persistent high-velocity diastolic forward flow indicates severity (see Figures 8-29B and 8-31B).^150–152 The Doppler pattern across the coarctation is affected by reduced proximal aortic compliance.¹⁵³ Color flow identifies the level at which laminar flow becomes turbulent (see Figure 8-29C). An echocardiographic diagnosis of coarctation can be made in utero.¹² In the fetus and neonate, normal tapering of the aortic isthmus⁹ can be mistaken for isthmic obstruction, and artifacts from the ductus insertion sometimes make interpretation difficult.¹⁵¹ The relationship between the site of coarctation and the aortic insertion of the ligamentum arteriosum establishes preductal, juxtaductal, or postductal location.¹⁵¹

Figure 8-29 Schematic illustration of aortic coarctation with corresponding echocardiograms: A, Images from a 5-year-old boy with coarctation of the aorta. The two-dimensional echocardiogram identifies the coarctation. B, Continuous wave Doppler scan shows systolic turbulence across the coarctation that continued through most of diastole. C, Color flow image from a 3-year-old boy showing an abrupt change from laminar flow to turbulent flow at the coarctation site (Coarc) (Video 8-1). (Ao = aorta.)

Figure 8-30 Echocardiogram (suprasternal notch) from a 10-month-old male with coarctation of the aorta (Coarc), localized distal to the left subclavian artery (LSCA). (Trans Ao = transverse aorta; Desc Ao = descending aorta.)

Figure 8-31 A, Echocardiogram from a12-year-old boy with coarctation of the aorta (Coarc.) distal to the left subclavian artery (LSCA). The transverse aorta (Tr. Ao.) tapers toward the isthmus. Distal to the coarctation, the descending aorta (Desc. Ao.) is dilated. B, Continuous wave Doppler scan from a 27-year-old man with coarctation of the aorta.

Summary

Coarctation of the aorta is not overlooked if attention is paid to upper and lower extremity arterial pulses and blood pressure during routine physical examination. The diagnosis is evident when systemic hypertension is accompanied by reduced femoral pulses. Aortic coarctation is a widespread disorder in which isthmic obstruction is only one of an array of abnormalities that include abnormalities of the proximal and distal paracoarcration aorta, the ascending and transverse aorta, the coronary arteries, the conduit arteries (radial, brachial, carotid), and the retinal vascular bed, in addition to systemic hypertension, dissecting aneurysm, cerebral aneurysms, and vascular rings. Minor symptoms include headache, epistaxis, and leg fatigue. Major complications are congestive heart failure, especially in infants; rupture or dissection of the paracoarctation aorta; infective endarteritis; and rupture of an aneurysm of the circle of Willis. The physical appearance of XO Turner’s syndrome increases the probability of coarctation. Pulse pressure proximal to the coarctation increases with age, resulting in conspicuous carotid and suprasternal notch pulsations. Collateral arterial pulsations should be sought beneath the skin, especially around the scapulae. Tortuous U-shaped retinal arterioles are distinctive. A left ventricular impulse occupies the apex. A right ventricular impulse is reserved for symptomatic infants with heart failure, pulmonary hypertension, and a right-to-left shunt across a patent foramen ovale. Auscultatory signs include widespread thoracic systolic murmurs through arterial collaterals and a posterior systolic or continuous murmur over the coarctation site. Systolic murmurs are especially prominent in the suprasternal notch and along the left sternal border over internal mammary collaterals. Auscultatory signs in infants are limited to the posterior interscapular murmur over the coarctation. Electrocardiographic criteria for left ventricular hypertrophy reflect increased afterload. Right ventricular hypertrophy characterizes the electrocardiogram of symptomatic infants. Notching of the third to eighth posterior ribs is a radiologic feature of major diagnostic importance but is seldom present before age 6 years. Dilation of the left subclavian artery and the proximal descending aorta is a useful radiologic sign in children too young to have rib notching. Transthoracic and transesophageal echocardiograms with Doppler scan interrogation and color flow imaging are used to identify the coarctation and determine its severity.

History

Complete interruption of the aortic arch is estimated to occur in 19 per million live births according to the New England Regional Infant Cardiac Program.¹⁷⁹ Males and females are equally represented.^155,156,160 Recurrence has been reported in siblings,^180–183 and a 2.5% recurrence rate of congenital heart disease has been reported in siblings of patients with type B interruption.¹⁸⁴

The typical clinical picture is represented by a neonate who becomes acutely ill as the ductus closes, prompting a sudden increase in pulmonary blood flow and a sudden decrease in circulation to the trunk and lower limbs.^156,160,167 The result is shock, acidosis, renal failure, intracranial hemorrhage,¹⁷⁴ and a mean survival time of 4 to 10 days.^156,160,161 Three quarters of infants who do not undergo operation are dead within a month, with only 10% reaching their first birthday.^155,160,185 Occasional survivals into childhood, adolescence, and young adulthood have been reported,^{168,175,176,184,186,187} with three patients surviving to their early or mid thirties.^156,177,188 Interruption of the aortic arch or aortic arch atresia without patent ductus arteriosus or ventricular septal defect resembles severe coarctation.^87,167,176 Rupture of an intracranial aneurysm was reported in a teenager¹⁸⁹ and in an adult.¹⁹⁰

Physical Appearance

Cyanosis is inconspicuous until the acute advent of congestive heart failure. Differential cyanosis caused by right-to-left ductal flow into the descending aorta is, with rare exception, canceled by the left-to-right shunt through the ventricular septal defect (see Figure 8-32),^{155,159,160,168} a mechanism that was recognized in 1852 by Greig,¹⁹¹ who wrote:

A 22q 11.2 deletion and the DiGeorge syndrome (see Chapter 28, Figure 28-6), which consists of hypoplastic mandible, defective ears, short philtrum, and aplasia or hypoplasia of the thymus and parathyroid glands, are associated with type A or type B interruption.^{108,170,192–195}

Arterial Pulse

Femoral arterial pulses are maintained because of continuity between the pulmonary trunk, ductus, and descending aorta (see Figure 8-32).^160,168,186 A reduction in femoral pulses signifies ductal constriction, which initially may be intermittent.¹⁶⁸ When the left subclavian artery originates from the descending aorta (type B), ductal constriction reduces the left brachial pulse in addition to the femoral pulse. Anomalous origin of the right subclavian artery places the right brachial pulse in the distal low pressure zone.¹⁶⁵ On the rare occasion of interruption of the aortic arch or arch atresia without patent ductus or ventricular septal defect, palpation of the systemic arterial pulses is analogous to palpation in coarctation of the aorta.^{127,167–169,175,176} When interruption occurs proximal to both subclavian arteries (anomalous origin of the right subclavian), the carotid pulses are bounding, but the brachial and femoral pulses are diminished or absent.^127,169,176 If either or both subclavian arteries originate proximal to the interruption, the arms are hypertensive, the carotid pulses are bounding, and the femoral pulses are weak or absent.^167,176

Precordial Movement and Palpation

An isolated right ventricular impulse is palpated in infants with interruption of the aortic arch because of obligatory pulmonary hypertension and is associated with a nonrestrictive patent ductus arteriosus and ventricular septal defect. A left ventricular impulse is absent despite the left-to-right shunt at ventricular level because blood entering the pulmonary trunk is diverted through the ductus into the descending aorta rather than through the pulmonary circulation into the left side of the heart (see Figure 8-32). Interruption of the aortic arch without patent ductus or ventricular septal defect results in a left ventricular impulse analogous to coarctation of the aorta.¹⁷⁶

Auscultation

Murmurs are negligible or absent.¹⁶⁰ The ductus is silent because the shunt is entirely right-to-left through a single nonrestrictive arterial conduit formed by continuity of the pulmonary trunk, ductus, and descending aorta. Murmurs originating through the ventricular septal defect are early systolic, decrescendo, and grade 3/6 or less.^186,196 A continuous murmur has been attributed to collateral circulation that connects the ascending and descending aortas.¹⁸⁶ Diastolic murmurs from pulmonary hypertensive pulmonary regurgitation¹⁶⁰ are introduced by a loud pulmonary component of the second heart sound. Interruption of the aortic arch without a ductus or ventricular septal defect presents with auscultatory signs similar to those of imperforate coarctation, with widespread collateral murmurs that include the head, especially behind the ears.^167,176,197

Electrocardiogram

Peaked right atrial P waves and right ventricular hypertrophy are electrocardiographic features in the neonate with interruption of the aortic arch, ventricular septal defect, and patent ductus arteriosus (Figure 8-35).¹⁹⁶ Biventricular hypertrophy is in response to left ventricular volume overload and persistent right ventricular pressure overload (Figure 8-36).¹⁶⁰ Interruption without patent ductus or ventricular septal defect results in right ventricular hypertrophy in infants¹²⁷ but left ventricular hypertrophy in older patients.

Figure 8-35 Electrocardiogram from a 3-day-old male with complete interruption of the aortic arch. There is a tall peaked right atrial P wave in lead 2. Right ventricular hypertrophy is represented by the tall monophasic R wave in lead V₁ and the deep S wave in lead V₆. Biventricular hypertrophy is represented by the large biphasic RS complexes in the mid precordial leads.

Figure 8-36 Electrocardiogram from a 6-month-old female with complete interruption of the aortic arch. There are tall peaked right atrial P waves in leads 2, 3, and aVF. Right ventricular hypertrophy is represented by the tall notched R wave in lead V₁ and the deep S wave in lead V₆. The prominent Q wave and well-developed R wave in lead V₆ are evidence of left ventricular volume overload. Biventricular hypertrophy is represented by large equidiphasic RS complexes in leads V_2-4, which are half standardized.

X-Ray

The cardiac silhouette enlarges and pulmonary venous congestion develops rapidly when closure of the ductus arteriosus suddenly causes an increase in pulmonary blood flow and volume overload of the left ventricle. The aortic knuckle is absent because the ascending aorta is small and ascends vertically (Figures 8-37 and 8-38).¹⁶³ The trachea is not deviated by an aortic arch and is therefore midline.¹⁶³ The x-ray shows increased pulmonary venous and pulmonary arterial vascularity with enlargement of the left ventricle (Figures 8-37 and 8-39).^186,196 Isolated interruption of the aortic arch without a ductus or a ventricular septal defect is radiologically similar to coarctation of the aorta, including rib notching.^164,167,197 Whether the notching is bilateral or unilateral depends on the site of interruption, the origin of the subclavian arteries, and the length of survival.^163,164

Figure 8-37 X-rays from the 6-month-old female whose electrocardiogram is shown in Figure 8-36. A, Prominent pulmonary soft tissue densities represent venous congestion in addition to increased pulmonary arterial vascularity. The pulmonary trunk is dilated in contrast to the inconspicuous ascending aorta, and the right atrium is markedly enlarged. B, In the left anterior oblique projection, the right and left ventricles are both enlarged.

Figure 8-38 A, Echocardiogram from a neonate with complete interruption of the aortic arch distal to the left carotid artery. The ascending aorta (AAo) rises vertically, exhibits no curvature, and branches as the right carotid (RC) and left carotid artery (LC). B, The aortogram shows a small ascending aorta that rises vertically and exhibits no curvature. The right carotid artery (RC) and the left carotid artery (LC) are as in the echocardiogram. (PT = pulmonary trunk.)

Figure 8-39 X-ray from a 2-day-old male with complete interruption of the aortic arch. The lungs show pulmonary venous congestion. The patient is slightly rotated to the left, increasing the prominence of the ascending aorta (Ao) and right atrium (RA) and decreasing the prominence of the left ventricle (LV). The density at the right thoracic inlet is thymus (arrow).

Echocardiogram

Echocardiography with Doppler scan interrogation and color flow imaging is used to identify the major segments of the thoracic aorta, visualize the patent ductus and the ventricular septal defect, and distinguish interruption of the aortic arch from coarctation with tubular hypoplasia. In type C interruption, echocardiography is used to identify antegrade flow in the right carotid and basilar arteries and retrograde flow in the left carotid artery.¹⁹⁸ Echocardiography is used to identify type B interruption of a right aortic arch.¹⁹⁹

A normal aorta exhibits a continuous smooth curvature from its ascending to its descending portion, but when the arch is interrupted distal to the left carotid artery (type B), the ascending aorta rises vertically, exhibits little curvature, and bifurcates into the innominate and left carotid arteries,¹⁷⁰ with the carotid appearing as an index finger pointing upward (see Figure 8-38). When the arch is interrupted distal to the left subclavian artery (type A), the ascending aorta exhibits a slight curvature and gives off three branches (the innominate, the left carotid, and the left subclavian arteries)¹⁷⁰ because the right subclavian artery is prone to anomalous origin (Figure 8-40). A useful echocardiographic observation is the discrepancy between the small caliber of the ascending aorta and conspicuous dilation of the pulmonary trunk. The image created by continuity of pulmonary trunk, ductus, and descending aorta superficially resembles an uninterrupted aortic arch, but identification of the origins of the right and left pulmonary arterial branches, together with absence of brachiocephalic branches, prevents error (see Figure 8-40).¹⁷⁰ Characterization of a ventricular septal defect is an important part of the echocardiographic examination. An intact ventricular septum with an interrupted aortic arch prompts search for an aortopulmonary window.¹⁷⁰ A malaligned ventricular septal defect is associated with posterior and leftward deviation of the conal septum and varying degrees of subaortic narrowing.^170,171,200

Figure 8-40 Echocardiogram from a 7-month-old female with complete interruption of the aortic arch. The ascending aorta (AAo) gives rise to the innominate artery (IA) and to the left carotid artery (LCA) distal to which the arch was interrupted. The pulmonary trunk (PT) is continuous with the descending aorta (DAo) via a patent ductus arteriosus (PDA).

Summary

The typical clinical picture of interruption of the aortic arch is an acyanotic neonate who initially appears well but who suddenly becomes ill when the ductus arteriosus constricts and deprives the trunk and lower limbs of arterial circulation, while diverting pulmonary arterial blood into the lungs and into the left side of the heart. Tachypnea and symmetric cyanosis develop, the femoral pulses disappear, and the chest x-ray exhibits pulmonary venous congestion with progressive cardiac enlargement. When the interruption is proximal to the left subclavian artery, the left brachial arterial pulse disappears as well. No murmur or inconspicuous early systolic decrescendo murmur is found through the ventricular septal defect. The electrocardiogram shows peaked right atrial P waves and right ventricular hypertrophy, but if survival permits, biventricular hypertrophy emerges. Echocardiography is used to identify the interrupted arch. The ascending aorta takes a straight cephalad course and is small compared with the dilated pulmonary trunk. Continuity between pulmonary trunk, ductus, and descending aorta create a smooth unbroken contour. A leftward and posterior malaligned ventricular septal defect is the rule when interruption is between the left carotid and left subclavian arteries. An aortopulmonary window is likely if the ventricular septum is intact.