Manual of Cardiovascular Medicine

I.Patent ductus arteriosus—Introduction

A.The ductus arteriosus is fully developed by 6 weeks of gestation and connects the main pulmonary trunk with the descending aorta at approximately 5 to 10 mm distal to the origin of the left subclavian artery. The purpose of the patent ductus arteriosus (PDA) is to efficiently carry partially oxygenated blood from the right ventricle to the descending aorta and back to the placenta for oxygenation. This process diverts blood flow away from the lungs which would constitute wasted circulation and thus reduces the total workload of the fetal ventricles. A PDA occurs when the ductus arteriosus fails to close and regress after birth to form the ligamentum arteriosum. It occurs in 1:2,000 live births, but it is relatively uncommon among the adult population. In infants, it accounts for 10% to 12% of all congenital heart disease.

B.Natural history. The natural history depends on the size of the PDA, the direction of the shunt, and the development of any associated complications. At birth, 95% of patients with isolated PDA have left-to-right shunts and normal, or near-normal, pulmonary pressures. Patients with normal pulmonary artery pressures and no evidence of chronic left ventricular volume overload have a better prognosis. With a PDA, congestive heart failure (CHF) can occur because of chronic left heart volume overload because of excess dumping of arterial circulation back into the pulmonary circuit and subsequently the left chambers of the heart. In patients with death related to PDA, CHF is the most common cause. Development of right-to-left shunting is also an ominous sign because it reflects the development of advanced pulmonary vascular disease and associated elevation in right-sided cardiac pressures.

C.Risk factors. Factors that increase risk for PDA include maternal rubella infection, birth at high altitude, premature birth, female sex, and genetic factors. In infants born at <28 weeks of gestation, there is a 60% incidence of PDA, and PDAs are twice as common in females as they are in males. Most cases of PDA are seemingly sporadic, but it is likely a multifactorial inheritance with the requirement of genetic predisposition and an environmental trigger that is induced during a vulnerable period. In a family in which one child has a PDA, there is approximately a 3% risk of having a PDA in subsequent offspring.

II.Anatomy and pathophysiology

A.Embryology. The ductus arteriosus is a normal and essential component of cardiovascular development that originates from the distal sixth left aortic arch. A PDA is most commonly funnel shaped with the larger aortic end (ampulla) distal to the left subclavian artery, then narrowing toward the pulmonary end, with insertion at the junction of the main and left pulmonary arteries (Fig. 30.1). Closure usually begins at the pulmonary artery end which explains why the duct is most commonly conical toward the pulmonary artery entrance. With a right aortic arch, the ductus arteriosus more commonly connects the left innominate or subclavian artery with the left pulmonary artery or, alternatively, joins the right pulmonary artery and the aortic arch just distal to the right subclavian artery. Rarely, bilateral PDAs can also occur. On occasion, the insertion of the ductus is juxtaductal to the left subclavian artery. It varies in length and in the term fetus has a diameter of approximately 10 mm, similar to that of the descending aorta.

FIGURE 30.1 Patent ductus arteriosus. (From CCF Medical Arts—Courtesy of Joe Pangrace. Reprinted with permission, Cleveland Clinic Center for Medical Art & Photography © 2007–2018. All Rights Reserved.)

B.Fetal circulation. The presence of the ductus arteriosus in the fetal circulation is essential to allow right-to-left shunting of nutrient-rich, oxygenated blood from the placenta to the fetal systemic circulation, thereby bypassing the fetal pulmonary circuit. In the normal fetal circulation, oxygenated blood travels from the mother through the placenta to the fetus. The oxygen-rich blood traverses the fetal inferior vena cava, right atrium, right ventricle, and main pulmonary artery. The fetal pulmonary arteries are constricted and have high pulmonary vascular resistance. Oxygenated blood bypasses the fetal pulmonary circulation and enters through the ductus arteriosus to the lower resistance systemic circulation. Oxygenated blood then enters the fetal aorta distal to the left subclavian artery, perfuses the fetal systemic circulation, becomes deoxygenated, and returns to the maternal circulation. The ductus arteriosus is kept open by low arterial oxygen content and prostaglandin E2 (PGE2). The fetus has high circulating concentrations of prostaglandins, particularly PGE2, owing to low fetal pulmonary blood flow and decreased prostaglandin catabolism in the lungs, as well as to the fact that the placenta produces prostaglandins.

C.Birth. Several changes occur at birth to initiate normal functional closure of the ductus arteriosus within the first 15 to 18 hours of life. Spontaneous respirations result in increased blood oxygen content and decreased pulmonary vascular resistance, resulting in increased blood flow to the lungs. Prostaglandin levels decrease because of placental ligation and increased metabolism of prostaglandins within the pulmonary circulation by prostaglandin dehydrogenase. The combination of increased oxygen content and lowered circulating prostaglandin levels usually results in closure of the ductus arteriosus. Generally, the ductus arteriosus is hemodynamically insignificant within 15 hours and completely closed by 2 to 3 weeks. The fibrotic remnant of this structure persists in the adult as the ligamentum arteriosum. Spontaneous closure of a PDA is unlikely in term infants after 3 months and in preterm infants after 12 months.

III.Clinical presentation

A.Symptoms. Severity of symptoms depends on the degree of left-to-right shunting, which in turn is determined by three interrelated factors: the size of the PDA, the pressure difference between the aorta and pulmonary artery, and the systemic and pulmonary vascular resistances. PDA size is categorized by the degree of left-to-right shunting determined by the pulmonary-to-systemic flow ratio: Q_p:Q_s (Table 30.1). Between 25% and 40% of patients with PDA are asymptomatic, especially those with a small PDA. They are often diagnosed by auscultation of a continuous murmur on examination or incidentally during diagnostic testing. With larger PDAs, symptoms may develop. The most common symptom is exercise intolerance followed by dyspnea, peripheral edema, and palpitations. Increased volume shunted left to right through the PDA increases left ventricular output. By Frank–Starling law, the resultant increase in preload will lead to a greater stroke volume. The left ventricle must compensate by hypertrophy and eventual dilation leading to overt left heart failure. Given the excess volume load in the LA and LV, functional mitral regurgitation and/or pulmonary edema may occur. PDA is more commonly associated with premature birth infants and/or respiratory distress because of two reasons: (1) decreased metabolic function of the immature lungs resulting in increased circulating concentrations of PGE2 and (2) increased sensitivity of the ductus arteriosus smooth muscle to PGE2. It can be difficult to clinically separate which signs and symptoms are due to lung disease from those that are due to a “silent” ductus arteriosus. Deterioration in ventilatory status of an infant recovering from neonatal respiratory distress syndrome or failure to show improved respiratory status at an age when they should start to recover from the primary pulmonary disease can be a hint of clinically significant PDA.

TABLE 30.1 PDA Size by Q_p:Q_s
Q_p:Q_s	Size
<1.5	Small
1.5–2.2	Moderate
>2.2	Large

PDA, patent ductus arteriosus.

B.Physical examination. Patients with PDAs may present with a wide range of physical findings. Pulse pressure may be wide because of diastolic runoff into the PDA, and peripheral pulses may be bounding. The jugular venous pressure is often normal with a small PDA, whereas with a large PDA, prominent a- and v-waves may be present. Precordial palpation often reveals a normal precordial impulse with a small PDA and a prominent left ventricular impulse with a large PDA. A harsh, continuous murmur may be heard at the left first or second intercostal space. The murmur envelops the second heart sound (S₂) and decreases in intensity during diastole. A small PDA has a soft, high-frequency, continuous murmur, whereas a large PDA classically has a machinery-like, loud murmur. With a large PDA, a mid-diastolic apical murmur may occur because of increased diastolic flow across the mitral valve. If pulmonary hypertension is present, a right ventricular lift may be present and the pulmonic component of S₂ will have increased intensity. The duration of the diastolic murmur reflects pulmonary artery pressures; elevated pulmonary artery pressures lead to a decreased gradient for left-to-right flow through the PDA during diastole, which results in a shorter diastolic murmur. As pulmonary pressure increases, the systolic component of the murmur shortens. Right-to-left flow may not generate a systolic murmur. For patients with a right-to-left shunt, a pathognomonic physical finding is differential cyanosis of the lower extremities and left hand.

C.Complications. The most common complications of PDA include CHF, infective endarteritis, PDA aneurysm, and pulmonary hypertension. CHF occurs through volume overload of the left side of the heart and may be accompanied by atrial fibrillation. Vegetations generally develop on the pulmonary side of the PDA, and septic lung emboli may occur. Typical organisms include Streptococcus viridans and Staphylococcus aureus. Untreated PDAs with audible murmurs have a risk of infective endocarditis of 0.45% per year after the second decade. Spontaneously occurring aneurysms of the ductus arteriosus have been reported, although they are typically seen in association with endarteritis or among very young or very old patients. Pulmonary hypertension develops as a result of increased pulmonary vascular flow from a large PDA with significant left-to-right flow. Elevation in right-sided pressures may eventually result in Eisenmenger physiology, right-to-left flow, and isolated cyanosis and clubbing of lower extremities (occurring in 5% of unrepaired PDA patients) with signs of pulmonary hypertension.

D.Differential diagnosis. The differential diagnosis of PDA includes ventricular septal defect associated with aortic insufficiency, aortopulmonary window, pulmonary atresia with systemic collateral vessels, innocent venous hum, and arteriovenous communications such as pulmonary arteriovenous fistula, coronary artery fistula, systemic arteriovenous fistula, and ruptured sinus of Valsalva aneurysm.

IV.Laboratory testing

A.Hematology. Blood laboratory results are generally unremarkable, although compensatory erythrocytosis may be present in the setting of long-standing cyanosis resulting from a right-to-left shunt.

B.Electrocardiogram (ECG). ECG is neither sensitive nor specific for PDA. The ECG for a patient with a small PDA is often normal. Depending on the duration and hemodynamic significance of the PDA, electrocardiographic criteria for left atrial enlargement or left ventricular hypertrophy may be present. If pulmonary hypertension exists, the ECG may demonstrate right ventricular hypertrophy or right atrial enlargement.

C.Chest radiography (CXR). CXR is neither sensitive nor specific for PDA. A normal chest radiograph implies a small, hemodynamically insignificant PDA. With a large PDA, left atrial and left ventricular enlargement may be present, as well as increased pulmonary vascularity. With right-to-left shunting from pulmonary hypertension, the main pulmonary artery is frequently enlarged. The PDA occasionally appears as a separate convexity between the aortic knob and the pulmonary trunk. Calcification of the PDA may be visualized in older individuals.

V.Diagnostic testing. Standard two-dimensional transthoracic echocardiography (TTE) combined with Doppler is the preferred initial diagnostic modality because of its low cost and noninvasive nature. Transesophageal echocardiography (TEE) may be required in subjects with suboptimal echocardiographic windows. Cardiac catheterization is typically reserved for therapeutic intervention.

A.TTE has a 42% sensitivity and 100% specificity for the diagnosis of PDA. The suprasternal notch view is usually best for demonstrating the PDA, particularly its aortic origin. The complete course of a PDA may be difficult to follow in some patients because of its tortuosity. Color Doppler imaging can often reveal flow between the descending aorta distal to the left subclavian artery and the pulmonary trunk. It is imperative to demonstrate color Doppler flow within the pulmonary artery, typically on a high parasternal short-axis view. Color Doppler and continuous wave Doppler help determine the direction of flow in the PDA. The timing of flow (systolic or diastolic) depends on pressure gradients between the systemic and pulmonary circulation. Quantitative assessment of shunt velocity is valuable to estimate the degree of restriction across the PDA. This measurement becomes important when planning transcatheter intervention. Diastolic aortic flow reversal is seen in the descending aorta if the shunt is significant. Associated left atrial and left ventricular enlargement also suggests a hemodynamically significant lesion.

B.TEE may be required if TTE windows are suboptimal or nondiagnostic. TTE and TEE have nearly 100% specificity for the diagnosis of PDA, but TEE has a much higher sensitivity (97%) than TTE (42%).

C.Cardiac catheterization is generally discouraged for diagnostic purposes. In the most recent American College of Cardiology/American Heart Association (ACC/AHA) 2008 guidelines, there is a class III recommendation against using cardiac catheterization to diagnose uncomplicated PDA with adequate noninvasive imaging. Rarely, PDAs that remain undiagnosed by physical examination or noninvasive testing may be diagnosed during left heart or right heart cardiac catheterization by recognizing the unexpected course of the catheter as it crosses the PDA by measuring a step-up in the oxygen saturation at the level of the left pulmonary artery or by documenting pulmonary opacification by descending aortography.

1.A PDA is best demonstrated by a descending aortogram performed in the lateral projection with a standard angiographic catheter positioned just below the ductal ampulla. If biplanar imaging is used, the right anterior–oblique cranial projection is sometimes helpful.

2.A PDA can be crossed from the main pulmonary artery or from the descending aorta, with the latter being easier and best guided by the lateral projection. Oximetric sampling typically demonstrates an increase in saturation in the main pulmonary artery compared with the right ventricle. Pulmonary artery and right ventricular pressures may be slightly elevated but typically remain below systemic levels. The presence of systemic pulmonary pressures generally indicates severe and advanced pulmonary vascular disease.

D.Magnetic resonance imaging (MRI) and computed tomography may be useful in defining the anatomy in patients with unusual PDA geometry and in patients with associated abnormalities of the aortic arch.

VI.Therapy. Treatment differs depending on whether the individual is a preterm infant or not. Given the sensitivity of the PDA to prostaglandins in the premature infant, indomethacin (a prostaglandin synthesis inhibitor) can be administered to close the PDA. The use of oral, or preferably, intravenous indomethacin to constrict the PDA has led to successful nonsurgical closure in a large proportion of treated infants, with the best results administered before 10 days of age in preterm infants. This medication is not effective in term infants or older individuals.

In the event that medical treatment is unsuccessful or not possible, surgical or catheter closure can be performed. ACC/AHA 2008 guidelines for adults with congenital heart disease recommend closure of PDA (catheter or surgical) if there is left atrial or left ventricular enlargement or if pulmonary arterial hypertension (PAH) is present with net left-to-right shunt (class I) or of an asymptomatic small PDA by catheter device (class IIa). PDA closure is contraindicated in patients with PAH and right-to-left shunt. Successful closure of PDA generally results in a good prognosis and may prevent adverse left ventricular remodeling resulting from volume overload.

The shape and size of a PDA determine the mode of therapy. Small- or moderate-caliber PDAs are generally closed percutaneously with coils. Large PDAs may require the Amplatzer Duct Occluder (ADO) or surgery. Heavily calcified PDAs represent a relative contraindication to surgical closure because of an increased risk of bleeding and incomplete closure with surgery. Cardiopulmonary bypass may be required for heavily calcified PDAs. PDAs with significant right-to-left shunts and Eisenmenger physiology should generally not be closed. In patients with pulmonary vascular resistance >8 U/m², lung biopsy has been recommended to determine candidacy for closure. However, even histologically severe pulmonary vascular disease may resolve after closure of the PDA. Reactivity of the pulmonary vascular bed to pulmonary vasodilating agents or significant reduction in pulmonary artery pressure during test occlusion may signal reversibility of pulmonary hypertension, but the absence of these findings does not rule out the possibility of reversibility in the long term, and natural history may be significantly altered by treating with pulmonary vasoactive medications.

A.Since the early 1990s, transcatheter techniques have become the first-line therapy for most PDAs. Many centers use single or multiple stainless steel coils to achieve complete closure. Numerous devices have been adapted or are under clinical investigation to allow transcatheter closure of larger defects. These procedures can often be performed on an outpatient basis, and complete closure rates at follow-up generally exceed 90% to 95% in most studies. The mortality rate is typically <1% at experienced centers. Success has been reported even when ductal calcification has been apparent, but large clinical series are lacking.

1.Percutaneous coil occlusion. Percutaneous coils were developed in 1992 and are the preferred treatment for older children and adults with PDAs <3.5 mm in diameter. Embolization coils have thrombogenic strands spanning the coils and are placed across the PDA to occlude flow. Advantages include low cost, small-caliber venous access, and easy implantation. Advances include detachable coils and development of a snare-assisted technique, both of which allow assessment and fine-tuning to ensure correct coil position before actual release of the coil. The coils are loaded at the tip of a catheter, the catheter is placed in the PDA under fluoroscopic guidance, and the coils are then deployed. Selected coil sizes are 2 to 2.5 times the narrowest diameter of the PDA. With moderate-sized or large-sized PDAs, multiple coils may be used. However, as PDA size becomes larger (>3.5 to 4.0 mm), percutaneous, 0.038-in. coils become a less desired closure option, and alternative therapies become preferred. Although complete closure is usually accomplished with a single coil in children, multiple coils are frequently needed for complete closure in the adult. Although coil embolization may occur, the snare-assisted technique is almost always successful at percutaneous removal of the coil.

2.The ADO, a cone-shaped plug occluder made of thrombogenic wire mesh delivered with a 5F to 7F venous system, is the preferred device for percutaneous closure of moderate to large PDAs. The ADO stents the PDA, and blood is forced to flow through the center of the device, which is lined with thrombogenic wire mesh. The PDA then essentially clots off. Advantages include simple implantation, ability to retract the ADO into the sheath and redeploy if needed, and high success rates. There is an 89% occlusion rate on postprocedure day 1 and 97% to 100% complete occlusion after 1 month.

3.Complications of transcatheter closure are rare. The most common complication is embolization of the coil or device. Embolized coils can usually be retrieved; but even when this is impossible, adverse consequences are rare. Other potential complications include flow disturbance in the pulmonary artery or aorta from device protrusion, hemolysis from high-velocity residual shunting, vascular access complications, and infection.

B.Surgical closure. In 1938, the first successful closure of a PDA was performed, which, coincidentally, was the first repair of a congenital heart defect. Surgical closure is the most effective method for complete closure and is usually performed without cardiopulmonary bypass by double ligation and division of the PDA. In addition, it has been shown to be the most cost effective over time with fewer complications compared with transcatheter occlusion methods. Ligation may be performed without division, but there is a risk of recanalization of the PDA in up to 20% of cases. In neonates and premature infants, ligation without division is performed because of the small size of the structures. With continued advances in percutaneous closure devices, surgery has become second-line therapy for most adults with PDAs. If surgery is necessary, the procedure is >95% successful and has a low complication rate. The operative mortality rate is <1%. However, the thoracotomy approach can be painful for adults and necessitates inpatient recovery. Newer surgical techniques such as transaxillary thoracotomy and video-assisted thoracoscopic ligation have improved surgical morbidity.

C.Antibiotic prophylaxis. The most recent guidelines from the AHA recommend antibiotic prophylaxis for endarteritis only in the setting of transcutaneous closure of the PDA for 6 months after the procedure; and prophylaxis is not recommended for those with repaired PDA without residual shunt.

D.Follow-up. If immediate duct closure is demonstrated after the procedure, a 6-month follow-up with TTE should suffice to assess for residual flow through the PDA. If residual shunt exists after the procedure, TTE should be performed every 2 to 3 months and early repeat attempt of complete closure considered, depending on the size of the residual shunt or the presence of hemolysis. For long-term follow-up, annual transthoracic echocardiograms are adequate.

VII.Coarctation of the Aorta. Coarctation of the aorta (CoA) has been found at autopsy in approximately 1 in every 1,550 individuals. It accounts for 5% to 10% of congenital heart disease and occurs more frequently in whites (7:1) and males (2:1). The disorder is typically diagnosed in childhood but may go undetected well into adulthood. Most patients develop persistent systemic hypertension, often as children, and are at risk for premature coronary artery disease. Cases usually occur sporadically, but an autosomal-dominant inheritance pattern has been observed. It is frequently associated with bicuspid aortic valve, and coarctation should be excluded in patients with bicuspid aortic valve and hypertension. Coarctation also occurs in 15% to 35% of patients with Turner syndrome. Potential catastrophic complications include aortic rupture or dissection and cerebral berry aneurysm rupture.

VIII.Anatomy. CoA usually consists of a narrowing in the region of the ligamentum arteriosum, the remnant of the ductus arteriosus, just distal to the origin of the left subclavian artery. Most coarctations, therefore, are juxtaductal. The exact anatomy, however, varies, and the coarctation may include a long segment, the transverse arch, or the abdominal aorta. Rarely, tortuosity of the arch is identified. The main anatomic substrate is a prominent posterior shelf of the aorta, composed predominantly of thickened media.

A.Embryology. The exact embryonic origin remains uncertain, but two main theories exist. The first suggests that the narrowing is caused by aberrant ductal tissue that constricts the aorta at the time of ductal closure. The second proposes that aortic hypoplasia develops as a consequence of reduced blood flow in utero.

B.Associated cardiac defects include bicuspid aortic valve in 50% to 85% of cases, valvular and subvalvular aortic stenoses, ventricular septal defects, PDA, and congenital malformations of the mitral valve (i.e., smaller orifice, supravalvular ring, and parachute mitral valve resulting from a single papillary muscle). Multiple left-sided heart lesions may be associated with CoA and are often referred to as the Shone complex.

C.Associated extracardiac defects include intracranial aneurysms, especially within the circle of Willis (3% to 5% of cases), hemangiomas, hypospadias, and ocular defects.

IX.Clinical presentation

A.Symptoms. For patients with CoA who survive to adulthood, symptoms are usually negligible and nonspecific. Patients may complain of headaches, nosebleeds, cool extremities, leg weakness, or claudication with exertion. More serious manifestations include angina and heart failure.

B.Physical examination

1.A thorough cardiovascular examination may identify a systolic ejection murmur at the left upper sternal border that radiates to the intrascapular area located immediately anterior or posterior to the CoA. The murmur may be longer in systole and even continue into diastole, depending on the degree of obstruction. Increased flow through the collateral intercostal arteries can produce a continuous murmur appreciated diffusely over the precordium.

2.Upper extremity hypertension is often present, usually in conjunction with diminished and delayed femoral pulsations. CoA should always be considered in the differential diagnosis of refractory hypertension, especially in younger patients.

3.Funduscopic examination may demonstrate a “corkscrew” tortuosity of the retinal arterioles.

X.Diagnostic testing

A.The ECG is frequently normal but may demonstrate manifestations of long-standing hypertension, such as left ventricular hypertrophy and left atrial enlargement.

B.Chest radiography. Cardiomegaly, dilated ascending aorta, and prominent pulmonary vasculature are common. Rib notching usually develops by 4 to 12 years of age and is caused by enlarged intercostal collaterals. The classic “3” or inverted-E sign is pathognomonic for CoA and is created by a dilated left subclavian artery above the CoA and poststenotic dilation of the aorta below the CoA.

C.Echocardiography is most useful in infants and children. In adults, the suprasternal notch view is most helpful; color Doppler can be used to localize the site of turbulence. Continuous wave Doppler can assess the pressure gradient. If severe narrowing is present, persistence of flow in diastole (widening of the flow profile from systole into diastole) is seen by continuous wave Doppler in the aorta below the coarctation, such as in the abdominal aorta. This is a useful method to ascertain the presence of significant coarctation, even if imaging the direct site of the obstruction is impossible. A complete study should measure left ventricular size and ascending aortic size, determine aortic valve anatomy and function, and identify any potential associated congenital anomalies. TEE can also better define the anatomy if TTE proves inadequate.

D.MRI provides excellent anatomic and hemodynamic information (Fig. 30.2). MRI is increasingly utilized as a first-line investigation before catheterization, particularly in adults. This enables the precise anatomy to be delineated and helps in the decision making regarding surgery or catheterization as treatment options. Serial MRI scans may be used to follow results of therapeutic procedures. It is also useful in evaluating the intracranial vessels for associated berry aneurysms.

FIGURE 30.2 Magnetic resonance imaging of aorta showing coarctation in typical position in descending thoracic aorta.

E.Cardiac catheterization provides excellent image data and pressure information and is often more reliable than echocardiography in adults. An aortic angiogram in left anterior–oblique or caudal and direct lateral projections usually best defines the lesion. Pressures should be obtained in the left ventricle and the ascending aorta, and the gradient across the lesion should be measured. A pullback pressure of >20 mm Hg signifies hemodynamic significance and usually warrants intervention if concomitant clinical factors allow. A gradient of >50 mm Hg generally mandates intervention. The presence of collateral vessels may falsely diminish the gradient.

XI.Therapy. Several factors need to be taken into account when deciding on optimal therapy for CoA, including the age of the patient, the anatomy of the coarctation, any prior CoA operations, and the local surgical expertise. Whatever mode of treatment is chosen, the presence of postprocedural upper extremity hypertension influences survival.

A.In general, medical therapy for CoA has very limited utility, but it may be useful in a supportive role along with mechanical treatment. Hypertension should be medically treated, with the goal of controlling blood pressure and preventing end-organ damage.

B.Percutaneous management

1.Percutaneous balloon angioplasty is generally less effective than surgery for treatment of primary coarctation. Neonates and infants treated with angioplasty experience high rates of recurrent CoA (about 50% to 60%) and aneurysm formations (5% to 20%); therefore, surgical repair is preferred in this patient population. Likewise, balloon angioplasty of the unoperated coarctation in adults is controversial, with data suggesting higher rates of restenosis and aneurysm formation compared with surgical repair. Procedural complications can include acute aortic rupture (rare), aortic dissection, femoral artery trauma, recurrent coarctation (8%), and aneurysm formation (8% to 35%). The suspected mechanism for late aneurysm formation is intimal tear at the site of cystic medial necrosis within the coarctation site. It should be noted that the clinical impact of aneurysm formation is unclear, as most defects are small and have a low risk of rupture. Percutaneous angioplasty, however, is the preferred therapy for recurrent postsurgical coarctation. The procedure is successful in reducing the gradient to <20 mm Hg in approximately 80% of interventions, with only a 1.5% incidence of late aneurysm formation.

2.Stent implantation. Theoretically, stent implantation may mitigate the development of aneurysm or dissection for a few reasons. By apposing the torn intima to the media and through dispersion of force, stenting may limit vascular trauma. It can also oppose the vascular recoil of the coarcted segment and avoid overdilation. By allowing the use of smaller balloons and graded inflations in staged procedures, stents may also reduce rates of aneurysm formation. Early and intermediate outcomes are promising, with a good safety and efficacy profile as well as lower rates of restenosis and aneurysm formation compared with balloon angioplasty. Despite the lack of long-term outcome data, stenting has become the preferred treatment modality in adults and adult-sized adolescents with native CoA. For recoarctation, balloon angioplasty with or without stenting is preferred in adults as well, as long as the anatomy is suitable.

C.Surgery remains the therapy of choice in neonates and infants. Three types of surgical repair have been used for correction of CoA: resection of the stenosed segment with end-to-end anastomosis, use of a subclavian flap, and patch aortoplasty. The approach with the best long-term outcome and sustained resolution of obstruction has been resection of the stenosed segment with end-to-end anastomosis. This approach carries with it the lowest risk of recurrent CoA (3%) and late aneurysm formation (rare). Paradoxical hypertension and bowel ischemia may occur in the postoperative period. Major surgical complications include paraplegia caused by perioperative spinal cord ischemia (0.4% to 1%), residual coarctation, aneurysm formation at the site of repair, and, rarely, death. Survival rates of >90% at 10 years and 84% at 20 years have been reported. Late deaths after surgical repair are related primarily to coronary artery disease, CHF, and aneurysm rupture. Young age favorably influences outcomes after surgery.

XII.Follow-up. Lifelong follow-up is indicated after the diagnosis of CoA is established, especially after any type of mechanical repair. Key issues to be cognizant of include the progression of hypertension either at rest or with exercise, development of CoA recurrence, aneurysm formation, left ventricular dysfunction, and associated aortic valve dysfunction and aortopathy when bicuspid valve is present. In patients repaired at older ages, hypertension commonly persists despite treatment by percutaneous intervention or surgery. Serial echocardiography is an important component of follow-up. Advanced imaging modalities such as computed tomography or MRI are used increasingly post repair to screen for aortic wall complications, with a preference for MRI given the radiation and contrast issues. Therefore, these patients should be considered “treated” and not “cured” despite repair.

ACKNOWLEDGMENTS: The authors thank Drs. Adam S. Goldberg, Richard A. Krasuski, Michael S. Chen, J. Donald Moore, Adrian W. Messerli, Matthew A. Kaminski, and Arman Askari for their contributions to earlier editions of this chapter.

Landmark Articles–Patent Ductus Arteriosus

Bilkis AA, Alwi M, Hasri S, et al. The Amplatzer duct occluder: experience in 209 patients. J Am Coll Cardiol. 2001;37:258–261.

Fisher RG, Moodie DS, Sterba R, et al. Patent ductus arteriosus—long-term follow-up: nonsurgical versus surgical treatment. J Am Coll Cardiol. 1986;8:280–284.

Gray DT, Fyler DC, Walker AM, et al. Clinical outcomes and costs of transcatheter as compared with surgical closure of patent ductus arteriosus. The patent ductus arteriosus closure comparative study group. N Engl J Med. 1993;329:1517–1523.

Krichenko A, Benson LN, Burrows P, et al. Angiographic classification of the isolated, persistently patent ductus arteriosus and implications for percutaneous catheter occlusion. Am J Cardiol. 1989;63:877–879.

Warnes CA, Williams RG, Bashore TM, et al. ACC/AHA 2008 guidelines for the management of adults with congenital heart disease: executive summary. Circulation. 2008;118:2395–2451.

Key Reviews–Patent Ductus Arteriosus

Brickner ME, Hillis LD, Lange RA. Medical progress: congenital heart disease in adults: first of two parts. N Engl J Med. 2000;342:256–263.

Connelly MS, Webb GD, Sommerville J, et al. Canadian Consensus Conference on Adult Congenital Heart Disease, 1996. Can J Cardiol. 1998;14:395–452.

Krasuski RA. Patent ductus arteriosus closure. J Interv Cardiol. 2006;19:S60–S66.

Schneider DJ, Moore JW. Patent ductus arteriosus. Circulation. 2006;114:1873–1882.

Book Chapters–Patent Ductus Arteriosus

Moore P, Brook MM. Patent ductus arteriosus. In: Allen HD, Driscoll DJ, Shaddy RE, et al, eds. Moss and Adams’ Heart Disease in Infants, Children, and Adolescents, Including the Fetus and Young Adult. 8th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2013:722–746.

Mullins CE, Pagotto L. PDA. In: Garson A, Bricker JT, Fisher DJ, et al, eds. The Science and Practice of Pediatric Cardiology. 2nd ed. Baltimore, MD: Williams & Wilkins; 1998:1181–1197.

Landmark Articles–Coarctation

Blackford LM. Coarctation of the aorta. Arch Intern Med. 1928;41:702–735.

Campbell M, Baylass JH. The course and prognosis of coarctation of the aorta. Br Heart J. 1956;18:475–495.

Carr JA. The results of catheter-based therapy compared with surgical repair of adult aortic coarctation. J Am Coll Cardiol. 2006;47:1101–1107.

Cowley CG, Orsmond GS, Feola P, et al. Long-term, randomized comparison of balloon angioplasty and surgery for native coarctation of the aorta in childhood. Circulation. 2005;111:3453–3456.

Fawzy ME, Awad M, Hassan W, et al. Long-term outcome (up to 15 years) of balloon angioplasty of discrete native coarctation of the aorta in adolescents and adults. J Am Coll Cardiol. 2004;43:1062–1067.

Key Reviews–Coarctation

Aboulhosn J, Child JS. Left ventricular outflow obstruction: subaortic stenosis, bicuspid aortic valve, supravalvular aortic stenosis, and coarctation of the aorta. Circulation. 2006;114:2412–1422.

Inglessis I, Landzberg MJ. Interventional catheterization in adult congenital heart disease. Circulation. 2007;115:1622–1633.

Relevant Book Chapters–Coarctation

Beekman RH III. Coarctation of the aorta. In: Allen HD, Driscoll DJ, Shaddy RE, et al, eds. Moss and Adams’ Heart Disease in Infants, Children, and Adolescents, Including the Fetus and Young Adult. 8th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2013:1044–1059.

Morriss MJH, McNamara DG. Coarctation of the aorta and interrupted aortic arch. In: Garson A, Brickner JT, Fisher DJ, et al, eds. The Science and Practice of Pediatric Cardiology. 2nd ed. Baltimore, MD: Williams & Wilkins; 1998:1317–1346.