Chest Radiography Pearls in Select Adult Congenital Heart Disease

Abstract

Congenital heart disease in adult patients (ACHD) includes individuals with native anatomic deformities and those who have benefited from corrective, ameliorative, or interventional heart and vascular interventions. Congenital heart disease is the most common birth defect, although with interventions most survive into adulthood. Newborns and children with complex congenital heart diseases that feature cyanosis fail to thrive, and once this is identified, heart failure can promptly undergo diagnostic evaluations and treatment. However, patients with simple congenital heart disease and subtle clinical signs and symptoms may escape diagnosis until adulthood or experience changes in their cardiac hemodynamics and physiology in settings such as pregnancy or newly diagnosed arrhythmias. The chest X-ray (CXR) is the most common X-ray among all radiological procedures. Individual features or a constellation of features on a CXR are often present in patients who have congenital heart disease. The ability to recognize these CXR features is a valuable skill for making the diagnosis of ACHD and for following these patients as they age, and can complement echocardiographic findings. When used well to diagnose ACHD, the CXR will be the sharpest arrow in the quiver.

1. Introduction

As a clinician interpreting a CXR, it is important to note if the image is well centered. This is determined when the upper dorsal vertebral spinous processes are equidistant from the heads of the clavicles and these spinous processes are visible in the center of the trachea. The depth of inspiration influences the transcardiac dimension. A good inspiration will permit at least 10 posterior ribs to be visualized through the aerated lung. A normal heart size will have a transcardiac dimension that is </= 50% of the transthoracic dimension. This is known as the cardiothoracic (C-T) ratio. The preferred CXR is obtained with the patient standing erect with the anterior chest apposing the CXR plate and the X-ray beam directed from posterior to anterior. In this posteroanterior (PA) image the C-T ratio is most accurate. When an anteroposterior (AP) CXR image is obtained, the C-T ratio is larger. This is due to the shadow of the heart splaying out as the X-ray beam enters the chest anteriorly and exposes the X-ray plate as more distant from the heart than when imaged in the PA fashion. The scapulae are visible, and seen to be underlying the upper lung fields in an AP CXR. When a lateral (Lat) CXR image is demonstrated, its pertinent features will be described. The C-T ratio from a PA CXR is a simple, reproducible and independent marker of disease severity and outcome in ACHD [1].

2. Discussion of Select Adult Congenital Heart Disease Cases

Each ACHD diagnosis will be presented first, describing its anatomy and physiology. Patient symptoms and pertinent physical examination findings will be discussed. Then the CXR(s) of an actual patient will be presented, highlighting important CXR features of this ACHD.

2.1. Congenital Complete Absence of the Left Portion of the Parietal Pericardium (CCALPPP)

Anatomy and Physiology of Congenital Complete Absence of the Left Portion of the Parietal Pericardium

The heart is normally anchored in the center of the chest by the pericardium. Between the visceral and the parietal pericardia is 25–50 mL of pericardial fluid, which reduces friction during cardiac contraction. When the left portion of the parietal pericardium is completely absent, the heart shifts to the left hemithorax and the patient often presents with paroxysmal, stabbing chest pain that is nonexertional [2]. This pain has been attributed to episodic torsion of the great vessels because the heart is unmoored. Physical examination usually reveals cardiac apical displacement by palpation. Heart sounds, including splitting of S2, are normal. There is often a soft ejection systolic murmur that is best heard at the left sternal border. Although CCALPPP might be an uncomfortable congenital heart disease, all 10 patients studied by Gatzoulis et al. [2] were alive and well more than 10 years after diagnosis. In cases where the left pericardial defect is partial, especially when there is a foramen-type partial absence of the left pericardium, the left atrium can herniate into the defect and strangulate the heart. When recognized, this partial defect must be remedied. The incidence of congenital absence of the pericardium, both complete and partial, is very rare. As many cases are asymptomatic, the majority of cases are recognized unwittingly at autopsy or during thoracotomy, when addressing a different problem [2]. The PA CXR in CCALPPP demonstrates levoposition of the heart, loss of the right heart border as it overlies the vertebral bodies, and prominence of the pulmonary artery segment (Figure 1).

2.2. Pericardial Cysts

Anatomy and Physiology of Pericardial Cysts

Pericardial cysts are the third most common type of mediastinal mass [3]. Pericardial cysts are benign congenital anomalies of the middle mediastinum. Formation of a pericardial cyst is due to abnormal fusion of the mesenchymal lacunae during embryogenesis and occur in ~1 in 100,000 people. A pericardial cyst might also be a result of trauma [4]. As pericardial cysts are usually asymptomatic, they are most often incidentally found by CXR or by transthoracic echocardiography. A pericardial cyst is commonly located at the right cardiophrenic angle (Figure 2 and Figure 3). Other less common locations are the left costophrenic angle and anterior/posterior mediastinum. Symptoms that have been attributed to pericardial cysts include dyspnea, and palpitations. Albeit a rare occurrence, when a pericardial cyst ruptures it can cause pleuritic chest pain [5].

2.3. Coarctation of the Aorta

Anatomy and Physiology of Coarctation of the Aorta

Coarctation of the aorta (CoA) is a common congenital heart and vascular defect that accounts for 5–8% of all congenital cardiac defects [6]. Discrete CoA (Figure 4) consists of a short segment of narrowing in the region of the ligamentum arteriosum adjacent to the origin of the left subclavian artery [7]. Extensive collateral vessels often arise proximal to the obstruction and deliver blood distal to the obstruction sufficient for bodily function, albeit to a limited extent. Bicuspid aortic valve (BAV) and aortopathy are often found in patients who have CoA. When a patient is first diagnosed with CoA as an adult, the usual presentation is systemic arterial hypertension. When asked if they can keep up with their peers in a foot race, patients with CoA will respond “not in the long run”. This is due to claudication. Physical examination of the patient with CoA will show prominent neck pulsations and hypertension, often higher in the right arm than the left arm. Simultaneous palpation of the right brachial artery pulse and the right femoral artery pulse demonstrates a delayed femoral pulse. This is because the route is longer from the heart through the collaterals to the femoral artery than from the heart to the brachial artery. The systolic blood pressure (BP) is also decreased in the lower extremities compared to the right upper extremity. Auscultation in the upper chest, especially the upper posterior chest, will show a long systolic murmur (extending into diastole) across the coarctation. When a BAV is present, an ejection click, a systolic murmur of aortic stenosis and/or a diastolic murmur of aortic regurgitation may be present. The AP CXR in CoA may show a prominent curvilinear shadow along the mid-right sternal border that represents a dilated ascending aorta [6]. A “3-sign” adjacent to the area beneath the transverse arch and above the main pulmonary artery silhouette is often produced by an indentation at the site of the coarctation. Notching of the underside of ribs 3–9 is often found in CoA (Figure 5) and is due to compression of the ribs by enlarged and coiled intercostal arteries that serve as collaterals from the internal thoracic arteries to the descending aorta. The C-T ratio can be >0.5 when there is severe aortic regurgitation due to BAV. There often is straightening of the left heart border due to left ventricular hypertrophy from the increased systemic workload of hypertension from the CoA.

2.4. Scimitar Syndrome

Anatomy and Physiology of Scimitar Syndrome

Scimitar syndrome is a rare congenital cardiopulmonary abnormality that has been reported in 3–6% of patients with partial anomalous pulmonary venous drainage. In these patients, some of the pulmonary veins (usually veins draining the right lower lobe and less often also the right middle lobe or the entire right lung) drain into the upper part of the inferior vena cava (IVC), either above or below the diaphragm (Figure 6). The right lung may be hypoplastic and then receives its blood supply from the thoracic or abdominal aorta [8]. The shadow of the anomalous pulmonary vein (Figure 7) that enlarges from the right hilum as it courses towards the right hemidiaphragm and drains into the IVC has the same shape as a Turkish sword called a scimitar. Scimitar syndrome gets its name from the appearance of the PA CXR. It looks like there is a scimitar positioned to the right of the heart pointing to the right hemidiaphragm. While scimitar syndrome with hypoplastic lung and other congenital malformations is almost always diagnosed in childhood, when only partial anomalous pulmonary venous drainage is present, the patient may be asymptomatic and not recognized until a CXR is done in adulthood.

2.5. Sinus Venosus Atrial Septal Defect

Anatomy and Physiology of Sinus Venosus Atrial Septal Defect

Sinus venosus atrial septal defect (SVASD) is the least common of the three main types of atrial septal defect (ostium secundum, ostium primum and sinus venosus). SVASD is located highest in the atrial septum and is also known as Defect Superior to Fossa Ovalis. This defect is in the region where the superior vena cava (SVC) joins the right atrium (Figure 8) and is often accompanied by anomalous termination of the right upper pulmonary vein(s) in the SVC near its right atrial junction or in the right atrium near the SVC junction [9]. As is seen in all ASDs, the resulting left-to-right shunting in SVASD increases the right atrial size and right ventricular size. A large shunt will present with dyspnea, fatigue, exercise intolerance, palpitations and/or syncope [7]. Physical examination may include a left parasternal heave, a pulmonary systolic flow murmur and fixed splitting of the second heart sound. The CXR may show right ventricular enlargement, right atrial enlargement, a prominent pulmonary artery segment and increased pulmonary vascularity (Figure 9). In the presence of a large left-to-right shunt, the volume of blood that is pumped to the lungs may be two or more times the volume pumped systemically. This is reflected on the PA CXR by the size of the pulmonary artery segment exceeding that of the aorta.

2.6. Ostium Secundum Atrial Septal Defect

Anatomy and Physiology of Ostium Secundum Atrial Septal Defect

An atrial septal defect (ASD) is among the most common congenital heart defects. A persistent ASD in the region of the fossa ovalis is called ostium secundum atrial septal defect (OSASD) and it comprises 75% of all ASDs. An OSASD (Figure 8) is different from a Patent Foramen Ovale (PFO), which is an interatrial communication in which the septum primum covering the fossa ovalis overlaps the superior limbic band of the septum secundum [10]. A PFO is usually closed when the pressure in the left atrium exceeds the pressure in the right atrium, but it opens when right atrial pressure exceeds left atrial pressure. A native OSASD results in left-to-right shunting across the defect, right ventricular volume overload and pulmonary overcirculation. A large left-to-right shunt may result in flow-related pulmonary artery hypertension and pulmonary vascular obstructive disease may develop in adult years [10]. The initial adult presentation of OSASD is most often characterized by symptoms of dyspnea and palpitations. Physical examination includes a precordial lift, a systolic pulmonary flow murmur and, usually, fixed splitting of S2. The PA CXR may show right atrial enlargement, a prominent pulmonary artery segment and increased pulmonary vascularity (Figure 10). In the presence of pulmonary vascular obstructive disease the CXR will demonstrate pruning of peripheral pulmonary arteries.

2.7. Congenitally Corrected Transposition of the Great Arteries

Anatomy and Physiology of Congenitally Corrected Transposition of the Great Arteries

Congenitally corrected transposition of the great arteries (CCTGA) is also known as L-Transposition of the Great Arteries (L-TGA). It comprises less than 1% of congenital heart disease. This rare congenital heart defect is composed of atrioventricular discordance and ventriculoarterial discordance (Figure 11). These two discordances correct each other, hence the word corrected is included in the name [11]. In the presence of only one of these discordances cyanosis will result, but this cyanosis is corrected by the two discordances coinciding. In CCTGA the anatomic right ventricle serves as the systemic ventricle, a function it is not fit to perform. The thin-walled anatomic right ventricle dilates when facing systemic blood pressure and its tricuspid valve, the systemic atrioventricular valve, regurgitates into the left atrium. This leads to systemic ventricular failure. The anatomic left ventricle serves as the pulmonary ventricle. The pulmonary trunk in CCTGA is positioned to the right of the ascending aorta and the ascending aorta is to the left of normal. Together, these great artery malpositions account for their narrowed transverse dimension above the atria and ventricles on a PA CXR of CCTGA (Figure 12). Some patients with CCTGA may have variable position in the chest, with up to 20% having dextrocardia where the cardiac apex is pointing to the right.

2.8. Congenitally Corrected Transposition of the Great Arteries Presenting as an Adult after a Long Hiatus from Pediatric Care

Anatomy and Physiology of Congenitally Corrected Transposition of the Great Arteries

The anatomy and physiology of CCTGA without additional congenital heart disease is described in the section above. In the majority of cases of CCTGA, other congenital structural cardiac anomalies coexist. These concomitant anomalies are ventricular septal defect (VSD), which occurs 70% of the time (usually perimembranous), an Ebstein-like systemic tricuspid valve, and pulmonary stenosis (PS), which occurs 40% of the time [7]. Figure 13 and Figure 14 showcase representative chest X-rays. The primary complications of adult patients with CCTGA are systemic atrioventricular valve regurgitation and complete atrioventricular electrical conduction block (third degree AV block).

2.9. Congenital Agenesis of the Right Pulmonary Artery

Anatomy and Physiology of Congenital Agenesis of the Right Pulmonary Artery

Unilateral pulmonary artery agenesis (UPAA) is a rare congenital anomaly that has minimal or no symptoms and is usually diagnosed in adulthood. When it is associated with other cardiovascular abnormalities it is usually diagnosed in childhood. In a study of military recruits in Greece over 4 years [13], 6 male patients, aged 17–20 years-of-age, were identified to have UPAA by a unilateral hyperlucent lung on PA CXR. Follow-up digital subtraction angiography made the diagnosis in all cases. The UPAA was on the left in four patients and on the right in two patients. In the absence of pulmonary arterial blood flow, the lung remains viable via bronchial arteries (most often branches of the descending aorta), although not serving hemoxygenation. The work capacity is challenged by only one lung receiving pulmonary arterial blood flow. Figure 15 is a posteroanterior CXR of congenital agenesis of the right pulmonary artery.

2.10. Persistent Left Superior Vena Cava

Anatomy and Physiology of Persistent Left Superior Vena Cava

Persistent Left Superior Vena Cava (PLSVC) is a congenital anomaly that results from failure of closure of the left anterior cardinal vein. In these patients, both right and left brachiocephalic veins drain into the PLSVC [14]. The PLSVC drains into the right atrium via the coronary sinus. PLSVC is the most common thoracic venous anomaly [15]. It is often diagnosed as an incidental finding when a CXR is done after the placement of a central venous catheter or pulmonary artery catheter. It can be suspected when the coronary sinus is found to be enlarged by echocardiography. When a dilated coronary sinus is noted, and PLSVC is suspected, injection of agitated saline individually into the right and the left antecubital veins is performed while imaging the heart with a somewhat posteriorly-angled apical four-chamber image. If there is a PLSVC, the enlarged coronary sinus is opacified first, followed by the right atrium. If the PLSVC is not associated with other congenital cardiac anomalies, it is usually asymptomatic and hemodynamically insignificant. An absent right superior vena cava can pose management difficulties during various cardiovascular procedures that involve accessing the heart via the superior vena cava, such as placement of a pacemaker wire, bicaval cannulation for cardiopulmonary bypass or venous cannulation for extracorporeal membrane oxygenation, among others. Figure 16 and Figure 17 represent CXRs of persistent left superior vena cava.

2.11. Ebstein Anomaly

Anatomy and Physiology of Ebstein Anomaly

Ebstein anomaly (EA) involves anatomic and functional abnormalities of the tricuspid valve and right ventricle. EA is a rare congenital malformation that accounts for approximately 1% of all congenital defects of the heart [7]. The clinical presentation of native EA depends on the extent of deformity of the tricuspid valve, the size and function of the right ventricle, the size of the right atrium, the degree of tricuspid regurgitation, the presence and degree of valvular pulmonary stenosis, right atrial pressure and presence or absence of right-to-left shunt. Patients who first present as an adult with EA most commonly complain of dyspnea on exertion, fatigue, arrhythmias, and right heart failure. When EA is accompanied by an ASD or patent foramen ovale (PFO) the patient may be variably cyanotic, especially with exertion. Paradoxical emboli may result. Because EA is often accompanied by one or more accessory pathways and there is marked right atrial enlargement, supraventricular tachycardia should be anticipated in adults with EA. Other associated cardiac anomalies include ventricular septal defects and right ventricular outflow tract obstruction. Physical examination is different from patient to patient with EA. In the presence of an ASD or PFO central cyanosis may be present. Due to low cardiac output peripheral cyanosis may be present. Because the tricuspid valve is usually apically displaced into the right ventricle, the right atrium is large and compliant. Thus, despite the presence of severe tricuspid regurgitation the jugular venous pressure is often normal. A right parasternal lift may be palpated. Cardiac auscultation demonstrates a loud S1 and there may be one or more ejection clicks. The murmur of tricuspid regurgitation is holosystolic and located at the lower left sternal border. The CXR may be normal in mild cases of EA. In more severe cases there is marked C-T ratio enlargement (Figure 18). The right atrium is markedly enlarged and the cardiac contour is globular. The lung fields are clear and the pulmonary vascularity is decreased because the volume of blood pumped to the pulmonary arteries is decreased.

2.12. Severe Pulmonary Valve Stenosis

Anatomy and Physiology of Severe Pulmonary Valve Stenosis

Valvular PS is usually an isolated lesion that occurs in 7–12% of all congenital heart disease cases [7]. The most common form of valvular PS features a dome-shaped pulmonary valve with a narrow central opening but a preserved, mobile valve mechanism. The pulmonary trunk is dilated and the jet from the stenotic valve favors flow to the left pulmonary artery branch. The PS gradient is categorized as mild when peak gradient is <36 mmHg, moderate when 36–64 mmHg, and severe when >64 mmHg. Valvular PS usually presents as an asymptomatic systolic murmur, but severe PS often features intolerance to exercise. Physical examination in a patient with severe PS is usually characterized by an elevated jugular venous pressure with a prominent A wave, an RV heave, and a long, loud systolic flow murmur with wide splitting of S2, if the P2 component is audible. In a study of 87 children aged 4–14 years-of-age with valvular pulmonary stenosis proven by cardiac catheterization, CXR evidence of poststenotic dilatation of the pulmonary trunk (Figure 19) and the left pulmonary artery branch, together with a normal or increased left- sided perihilar pulmonary vascularity, was essential for the diagnosis of valvular pulmonary stenosis [16]. These CXR findings of PS increased with age of the child, but no correlation between these radiographic observations and the severity of the stenosis was found. These same CXR findings are noted in the adult with valvular PS.

2.13. Marfan Syndrome

Marfan syndrome (MFS) is an autosomal dominant, highly penetrant condition that is caused by pathogenic variants in FBN1, which encodes fibrillin-1, a major structural component of extracellular matrix in connective tissues [17]. The major manifestations of MFS are asymptomatic aortic root aneurysms, aortic dissections, dislocation of the ocular lens (ectopia lentis) and skeletal abnormalities which include overgrowth of long bones and thoracic cage deformities. It is important to know these major manifestations in order to suspect the presence of MFS in a patient who has no symptoms. This can be done by inspection or by learning a family history of sudden death due to aortic rupture.

Anatomy and Physiology of Marfan Syndrome

In the majority of patients with MFS, thoracic aortic disease starts with enlargement of the aortic root and progressively enlarges to form an aneurysm (Figure 20 and Figure 21). This is the most life-threatening manifestation of MFS. Since medications can retard aortic enlargement, early identification affords optimal care. While long limbs and hyperextensible joints can be assessed by inspection, the CXR can assess thoracic cage deformities and aortic size.

2.14. Tetralogy of Fallot (toF)

Anatomy and Physiology of Tetralogy of Fallot

Tetralogy of Fallot (toF) is the most common cyanotic congenital heart disease in infants. Its four components include subpulmonary infundibular stenosis, a ventricular septal defect (VSD), an overlying aorta that straddles the VSD, and right ventricular hypertrophy (Figure 22), because the workload of the right ventricle is essentially at systemic pressure. As an infant and child, patients with toF are functionally limited, and are commonly treated surgically to palliate or to repair the defects. Accordingly, most children with toF will live well into adulthood [18]. These adult patients with toF are among the most commonly seen by cardiologists who practice ACHD, but these patients might also visit a general cardiologist or a general physician. One of the most common problems encountered by a patient late after toF repair is progressive dilatation of the right ventricle [12] in the setting of important pulmonary valvular regurgitation. Other less common complications include arrhythmias, aortopathy, tricuspid or aortic valve regurgitation, ventricular septal patch leak, and left ventricular systolic dysfunction. It is essential for the physician who follows an adult patient with toF that was repaired as a child, who develops progressive right ventricular dilatation, to recognize that pulmonary valve regurgitation is the usual cause and it is remediable. Uncorrected, this progressive right ventricular enlargement can lead to potentially lethal ventricular arrhythmias. Figure 23 and Figure 24 represent PA and lateral CXR of repaired toF.

2.15. Patent Ductus Arteriosus with Eisenmenger Syndrome

Anatomy and Physiology of Patent Ductus Arteriosus with Eisenmenger Syndrome

Patent Ductus Arteriosus (PDA) is a persistent communication between the aorta and the pulmonary artery, long after this vital fetal connection should have closed a few days after birth. Unoperated patients may present with a heart murmur or symptoms of shortness of breath and easy fatigue. A patient with a large and unrestricted PDA may present with Eisenmenger physiology with differential cyanosis (cyanosis of the lower extremities with normal upper extremity nailbeds) and clubbing [7]. The murmur of a moderate or large PDA is a continuous machinery murmur. In the presence of pulmonary artery hypertension (PAH) only a systolic murmur is heard. In the presence of a PDA with a large left-to-right shunt the blood pressure has a wide pulse pressure. When there is PAH from a PDA with right-to-left shunting at ductal level, lower extremity clubbing and cyanosis is found. Be sure to examine the feet. The CXR in PDA depends on the size of the shunt. A prominent proximal pulmonary artery segment indicates elevated pulmonary artery pressure (Figure 25 and Figure 26). An enlarged left atrium and enlarged left ventricle indicate a significant PDA with left-to-right shunting. Calcification in the region of the ductus should be noted because it may rupture during surgical repair [7]. Eisenmenger syndrome typically appears later in life, but patients with a large PDA are among the earliest congenital heart disease patients to present with Eisenmenger syndrome. These patients require close follow-up. Due to a high maternal mortality, pregnancy is not recommended in the presence of Eisenmenger syndrome [7]. Surgery with general anesthesia must be conducted in patients with Eisenmenger syndrome only in centers with expertise, as a fall in systemic pressure with induction of anesthesia might exacerbate the right-to-left shunt and cause prolonged systemic hypoxia, and potentially lethal vital organ injury.

3. Conclusions

Congenital heart disease (CHD) is composed of a broad spectrum of anatomic deformities. The anatomy and physiology of each congenital heart disease must be understood so that it can be corroborated with a patient’s complaints and physical examination to make a diagnosis. The CXR is a pictorial demonstration of cardiac, great vessel, and pulmonary anatomy and physiology. Thus, the CXR is like a memorable figure that clarifies what is described in the caption. Recall how rib notching can lead to the diagnosis of coarctation of the aorta, and how increased pulmonary vascularity can lead to a diagnosis of a left-to-right shunt. In additional to findings of the clinic exam, the diagnosis of ACHD can be further facilitated with echocardiography and tomographic imaging. ACHD deals with making a diagnosis of CHD that was not recognized until adulthood, and with following the course of patients with CHD who were diagnosed, and possibly surgically treated, at a young age. Knowledge of potential postoperative complications is required in order to recognize these complications on serial CXRs as a patient ages with CHD. Recall severe pulmonary valve regurgitation with right ventricular enlargement leading to malignant ventricular arrhythmias in the adult patient who underwent complete repair of tetralogy of Fallot as a child. Clinicians who know CXRs in ACHD will carry the sharpest arrow in their quiver, and use it to hit the target and take the best care of their patients.