Ambulatory Pediatric Cardiology

The ambulatory evaluation and management of pediatric patients with congenital heart disease (CHD) or a question of cardiac disease may be considered according to the age of the patient and the presenting concerns. Accordingly, the following sections are presented by pediatric age groups (fetal cardiology, newborns and infants [1 month to 2 years], toddlers and school-age children (2 years to 12 years], teenagers [12 to <16 years] and young adults [>16 years]). Within each age group, we review the components of cardiac evaluation and management of unrepaired, repaired, and palliated CHD, and common reasons for referral.

Fetal Cardiology

Care of patients with CHD often begins in utero since the assessment of the maternal-fetal unit with ultrasonography is part of prenatal care in developed nations. Many types of structural heart disease can be detected on routine fetal ultrasound and can be more clearly delineated by a detailed fetal echocardiogram. Once a diagnosis of CHD is made, pediatric cardiologists with expertise in fetal diagnosis and management generally partner with obstetricians to monitor the fetal clinical status and to advise obstetricians regarding a safe delivery strategy.

In general, CHD is well tolerated by the fetus, particularly given three vital fetal shunting pathways:

• the ductus venous

• the foramen ovale

• the ductus arteriosus

A limited but growing number of intrauterine procedures can be offered to parents to address complications of CHD in their pregnancy. In some cases, an arrhythmia will require intervention. In many cases, therapy involves treating the mother with antiarrhythmic medications that cross the placenta. Fetal cardiologists also generally meet with the parents to discuss the clinical implications of their child’s CHD.

Cardiac Evaluation of Newborns and Infants

Cardiologists consider the history and physical exam when determining whether further workup for possible or established congenital or acquired heart disease is needed. Both prenatal and postnatal history are considered when determining an infant’s risk for CHD.

Prenatal risk factors for CHD include:

• family history of CHD

• exposure to known teratogens

• maternal diseases (e.g., systemic lupus erythematosus and diabetes)

Postnatal historical risk factors include:

• cyanosis and tachypnea

• difficulties with feeding or postnatal growth and development

• family history of CHD, arrhythmia, or sudden death

• presence of other congenital abnormalities

Physical exam findings that should prompt consideration of CHD include:

• hypoxemia

• blood-pressure differential between the right arm and leg blood pressures (e.g., blood-pressure gradient >10-15 mm Hg between the right arm and the lower extremities, with the arm being higher than the leg, though not a definitive test, raises suspicion for coarctation of the aorta)

• hyperdynamic precordium

• pathological murmur

• hepatomegaly

• evidence of poor perfusion

Heart Murmurs

Murmurs may be either innocent or pathological:

• Innocent murmurs are characterized by the sound of blood passing through a structurally normal heart or vasculature (e.g., Still murmur, peripheral pulmonic stenosis).

  • Peripheral pulmonic stenosis is a systolic ejection-like murmur that is heard at the left upper sternal border and radiates to the bilateral axillae. The murmur is not associated with a click and is due to the relatively small size and acute angle of the branch pulmonary arteries in relation to the main pulmonary artery. It is considered a physiological murmur and typically disappears by age 1 year. If the murmur does not disappear, the infant should be reevaluated for true stenosis of the branch pulmonary arteries.

• Pathological murmurs are due to turbulent blood flow caused by a defect in heart structure (e.g., stenosis of a valve, regurgitation of a valve, an intracardiac shunt, or an extracardiac shunt). Pathologic murmurs tend to be systolic ejection murmurs, holosystolic murmurs, continuous murmurs, or diastolic murmurs.

Structural Heart Disease

Unrepaired Structural Heart Disease

Most infants with structural heart disease will not require surgical or catheter-based intervention prior to discharge from the hospital after birth. Ambulatory visits focus on monitoring these patients to determine if and when an intervention is needed. Two examples of structural heart disease that outpatient cardiologists frequently monitor are ventricular septal defects (VSDs) and tetralogy of Fallot (TOF).

• Ventricular septal defect: VSDs can occur anywhere in the ventricular septum and are classified by their location and size. Typically, a VSD yields a left-to-right shunt that leads to a volume load on the left heart structures. Shortly after birth, the pulmonary vascular resistance is high and the amount of shunting, even across a large VSD, is minimal. As pulmonary vascular resistance falls to normal levels during the first 8 weeks of life, the left-to-right shunt increases.

With large-volume shunts, infants will show signs of congestive heart failure. These signs include tachypnea, difficulty feeding, and failure to gain weight. Physical signs of an increased volume load include a hyperdynamic precordium, diastolic rumble, gallop, and enlarged liver with an edge that extends into the abdomen.

Infants with large, unrepaired VSDs are often seen every 2-4 weeks to evaluate and reevaluate for signs of heart failure. If symptoms develop, diuretics are often instituted to help infants manage the volume load on the left ventricle. Increasing the caloric density of feeds and instituting nasogastric feeds may help infants gain weight. Once maximal medical therapy is reached or the infant reaches approximately 5 kg, referral for surgical intervention is advised.

• Tetralogy of Fallot: The anatomy and physiology of TOF is important to understand. Many patients with TOF have normal oxygen saturations at birth, but as they grow and develop progressive obstruction to pulmonary blood flow, they will develop an increasing right-to-left shunt across the VSD, coupled with a progressive decline in oxygen saturation.

(Source: Facts about Tetralogy of Fallot. Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities 2019.)

Patients may also develop periods of dynamic obstruction to pulmonary blood flow (hypercyanotic spells or “tet spells”) that require medical interventions. These spells are characterized by a sudden decrease in pulmonary blood flow accompanied by profound cyanosis, may be provoked by severe agitation, and can be made worse by dehydration. Parents should be instructed (and quizzed) about the signs and symptoms of a tet spell as well as on interventions used to try to break a spell (including placing the infant in a knee-to-chest position and calling for emergency services). Emergency interventions include administration of supplemental oxygen, intravenous (IV) fluids, sedation with morphine, intubation, and if needed, agents to increase systemic vascular resistance (e.g., IV phenylephrine).

Patients with unrepaired TOF are typically seen every 2-4 weeks to monitor oxygen saturation and to assess the presence of tet spells and overall clinical status. Infants should be referred for surgical intervention when oxygen saturations begin to decline and are persistently below 85% or when the infant reaches a weight of 5 kg.

Repaired Structural Heart Disease

Some newborns require surgical repair prior to discharge from the hospital. Two examples of structural heart disease typically repaired prior to discharge as a newborn are:

• transposition of the great arteries

• coarctation of the aorta

Patients who have undergone complete repair are usually seen within 1 week of surgery to evaluate for the presence of postoperative complications such as pericardial or pleural effusions or infection. At the first postoperative visit, the patient’s clinical status and medications should be reviewed. Patients who were put on cardiopulmonary bypass for surgery will often be discharged from the hospital on a diuretic to assist with managing post-cardiopulmonary bypass edema. Depending on the patient’s postoperative hemodynamics, diuretics are often weaned during the immediate postoperative ambulatory visits.

The frequency of follow-up visits is determined by the patient’s clinical status. For example, a patient with a complete repair with no residual defects will be seen 1 to 2 months following the immediate postsurgical visit, again at 6 months, and then will often transition to annual visits. Patients with residual defects that may require subsequent interventions may be seen more frequently.

Palliated Structural Heart Disease

Not all CHD is amenable to a complete repair. Instead, palliative procedures are performed to stabilize pulmonary and systemic blood flow because in some circumstances, pulmonary or systemic blood flow is entirely ductal dependent. Without a palliative shunt or prostaglandins to maintain ductal patency, pulmonary or systemic flow would be compromised. A classic example of a palliative approach to CHD is the surgical management of hypoplastic left heart syndrome. This consists of a series of three surgeries.

• Hypoplastic left heart syndrome: An initial operation, most commonly the Norwood procedure, usually occurs several days after birth to stabilize systemic blood flow by anastomosing the pulmonary artery to the hypoplastic aorta and creating a shunt to provide pulmonary blood flow. The shunt may be either a Blalock-Taussig shunt or a Sano shunt.

Following the first surgical procedure, infants are closely monitored to determine the timing of their second-stage palliation with a bidirectional Glenn shunt. This high-risk “interstage period” is associated with a 5%-20% incidence of mortality. Intensive interstage monitoring permits timely interventions on impending complications and improved weight gain leading to earlier second-stage palliation.

Interstage monitoring can occur as an inpatient or outpatient. With outpatient monitoring, parents are instructed to weigh the infant daily and check their oxygen saturation. These numbers are reviewed by a clinician once or twice per week. Infants are also evaluated weekly by either the cardiologist or primary care doctor. Failure to achieve expected weight gain, or oxygen saturations above or below the expected range (75%-90%), will prompt a more extensive evaluation of the infant’s hemodynamics.

Primary Care Interventions in Infants

Certain subsets of infants with structural heart disease are candidates for palivizumab prophylaxis against respiratory syncytial virus.

Common Reasons for Referral of Newborns and Infants

Failure to thrive: A prominent feature of neonatal and infantile heart failure is failure to gain weight. Failure to thrive despite adequate caloric intake or accompanied by respiratory distress, pallor, or sweating with feeds raises concern for a potential cardiac etiology. Thus, it is common for infants who are failing to gain weight as expected to be referred for cardiac evaluation. Physical exam findings such as a hyperdynamic precordium, bounding or diminished pulses, murmur, and an enlarged liver are also indicative of possible underlying cardiac disease.

Brief resolved unexplained event (BRUE): The American Academy of Pediatrics (AAP) has defined a BRUE as an event in an infant younger than 1 year that is brief in nature and may include one or more of the following:

• cyanosis or pallor

• absent, decreased, or irregular breathing

• marked change in tone

• altered level of responsiveness

Such events are often terrifying for the observer. BRUEs often prompt a cardiac evaluation for underlying arrhythmia or CHD. In 2016, the AAP published guidelines for the evaluation and identification of infants at low risk for recurring events or serious underlying disorders. The guidelines recommend that clinicians may obtain an electrocardiogram (ECG) in infants categorized as low risk. Doing so may identify infants with a channelopathy such as long QT syndrome, Brugada syndrome, short QT syndrome, preexcitation abnormality, or cardiomyopathy. An echocardiogram is not recommended for such infants. A family history of sudden cardiac or congenital arrhythmia syndrome in a first-degree relative should prompt further evaluation of the infant.

Cardiac Evaluation of Toddlers and School-Age Children

The cardiac evaluation of toddlers and school-age children is similar to that of infants, using the history and physical exam to determine if further workup is needed.

The clinical history should include:

• brief review of in utero teratogen exposure and prenatal complications

• review of birth history

• review of health history during infancy for episodes of cyanosis, respiratory symptoms, and difficulty gaining weight

• questions about potential cardiac symptoms, including exercise intolerance, rapid breathing, palpitations, chest pain, and syncope

The physical exam should examine the child for:

• other congenital defects that may suggest syndromes associated with heart defects or acquired cardiac disease

• other physical exam findings that suggest the presence of heart disease, including hyperdynamic precordium, tachycardia, gallops, rubs, and pathological murmurs

Heart Murmurs

Most murmurs are innocent in nature and are frequently heard in toddlers and school-age children. New murmurs with a classic presentation that are heard in patients who are otherwise healthy and thriving can often be safely monitored without further testing. Common innocent murmurs at this age include:

• Vibratory or Still murmur has a musical quality and is more easily heard with the patient supine. It is typically midsystolic and limited to the lower left sternal border. It may be louder during times of fever and anemia. Many children will outgrow this murmur.

• Venous hum is a continuous murmur due to the sound of blood flowing through the jugular veins. It is heard best under the clavicles and disappears when the patient rotates their head 90 degrees to the side opposite of the murmur.

Red flags that should prompt a more comprehensive evaluation of a toddler/young child with a new murmur include but are not limited to:

• family history of congenital heart disease or cardiomyopathy

• murmur associated with hypoxia, syncope, or fever

• murmurs that are harsh or produce a thrill

• diastolic murmurs

Structural Heart Disease

Unrepaired Structural Heart Disease

Some structural heart diseases do not require repair during infancy. In such cases, the patient is generally followed by a cardiologist who will monitor for complications from the structural heart disease. The onset of symptoms or complications due to structural heart defects are often indications for either a surgical or transcatheter intervention. An example of a structural heart defect that is often monitored as a child progresses through toddlerhood through school age is a secundum atrial septal defect. Moderate-to-large defects rarely close spontaneously and will often cause a volume load on the right heart. Patients are typically referred for closure of a secundum defect as school-age children.

Repaired Structural Heart Disease

During the school-age years, most patients with successfully repaired CHD will be monitored yearly. Such visits will typically involve a review of the interval clinical history, physical examination, and an echocardiogram to assess for complications from the repair.

Palliated Structural Heart Disease

Patients with palliated structural heart disease are usually seen on a more frequent basis. Patients who have undergone a bidirectional Glenn shunt for the palliation of a single ventricle will often be seen every 3-6 months for clinical monitoring of complications of the physiology created by the Glenn shunt. A key component in the evaluation of Glenn shunt patients is the oxygen saturation. The ideal oxygen saturation range for Glenn shunt patients is 75%-85%. A sustained decrease or increase in the patient’s oxygen saturation indicates a potential problem with pulmonary blood flow. As part of the outpatient evaluation of Glenn shunt patients, cardiologists will determine the timing of referral for the third-stage palliation, called the Fontan procedure. This procedure typically occurs between 3-4 years of age and involves disconnecting the inferior vena cava from the heart and anastomosing it to the pulmonary artery. After this operation, only oxygenated blood is pumped through the heart, while the deoxygenated blood passively flows to the lungs via the Fontan and Glenn pathways.

Common Reasons for Cardiology Referral in Children

Medical clearance for stimulant medication prescription: Stimulant medications generally have minimal cardiac side effects. In general, they increase the heart rate by 1-2 bpm and increase the systolic blood pressure (SBP) and diastolic blood pressure (DBP) by 3-4 mm Hg.

The AAP has published recommendations regarding cardiac screening in children for whom treatment with stimulant medication is being considered. Such recommendations were prompted by reports of sudden cardiac death (SCD) in patients taking stimulant medications for ADHD. The AAP concluded in 2008 that SCD in persons taking medications for ADHD was rare and did not occur at higher rates than in the general population. As such, they recommended a history and physical exam focused on potential cardiac comorbidities that may predispose a patient to SCD. They did not recommend a screening ECG.

In 2008, the American Heart Association (AHA) also published guidelines that also recommended a careful history and physical examination to screen for signs and symptoms of arrhythmia or other undiagnosed structural heart disease. They, however, do recommend a screening ECG.

Clinical history factors that require evaluation prior to initiation of stimulant medications include:

• palpitations

• near or frank syncope

• use of arrhythmogenic medications

• family history of sudden death

• conditions such as hypertrophic cardiomyopathy, long QT syndrome, Wolff-Parkinson-White syndrome, and Marfan syndrome

For patients with CHD or history of arrhythmia, the decision to use stimulant medications should be made in concert with the patient’s cardiologist. The AHA recommendations consider it reasonable to use stimulant medications as long as there are not current hemodynamics or arrhythmic concerns.

Palpitations: Palpitations as a complaint are uncommon in toddlers and children younger than 10 years. If present, an evaluation for arrhythmia would be indicated.

Chest pain: Chest pain due to cardiac disease is rare in any pediatric population. Common considerations of cardiac causes of chest pain in this age group include pericarditis and myocarditis. Less common causes include connective tissue disorders that can lead to aortic dissection, structural heart disease involving systemic outflow obstruction, and, rarely, congenital or acquired anomalies of the coronary arteries (such as complications from Kawasaki disease).

Syncope: Like palpitations, syncope is a relatively infrequent presenting complaint in children younger than 10 years and should prompt consideration of cardiac etiologies such as arrhythmia, pulmonary hypertension, cardiomyopathy, and structural heart disease.

Heart murmurs: A heart murmur heard on exam is a common reason for referral to cardiologists. Most murmurs are innocent in nature and are frequently heard in toddlers and school-age children.

Cardiac Evaluation of Teenagers and Young Adults

The cardiac evaluation of teenagers and young adults, like that of infants and school-age children, uses elements of the clinical history and physical examination to determine if further cardiac evaluation is needed. However, the history focuses less on the prenatal and infancy time periods.

The clinical history focus is:

• cardiac symptoms

• exercise tolerance

• family history

The physical exam includes:

• assessment of vital signs

• full cardiac exam to evaluate for murmurs and perfusion

• more-extensive testing as indicated based on the findings from the history and physical exam

Structural Heart Disease

Unrepaired Structural Heart Disease

Very few structural heart diseases present in adolescents and young adults. Examples of late-presenting structural heart disease include subaortic membranes and atrial septal defects.

• A subaortic membrane is an acquired defect in which a membrane forms beneath the aortic valve and over time can cause severe obstruction to cardiac output.

• An atrial septal defect is a hole between the two atrium. There are several types of atrial septal defects. If the defect is small, no intervention may be required. If the defect is large, it will create a volume load for the right ventricle, which will dilate. Such defects should be closed. This is often a catheter-based procedure, but for some types of atrial septal defects and very large defects, surgical closure is required.

Repaired and Palliated Structural Heart Disease

In general, an outpatient cardiologist manages repaired or palliated structural heart disease. For well-repaired heart defects with no residual defects, patients continue to be seen annually or biannually for a history, physical examination, and echocardiogram. For palliated heart disease or patients with residual defects, follow-up may be more frequent.

Due to the >95% survival rate following surgery for CHD, young adults with CHD are the fastest-growing population in ambulatory pediatric cardiology practices. As children with CHD progress through adolescence toward adulthood, it is important that they continue to receive follow-up care from an expert in the field of CHD and they should be transitioned to a cardiologist with training in adult congential heart disease. In 2018, the AHA published guidelines for the management of adults with CHD (ACHD). These guidelines provide specific recommendations for routine evaluation, screening tests, and indications for transcatheter and surgical interventions in ACHD patients.

Common Reasons for Referral in Adolescents and Young Adults

Sports screening: In 2015, the AHA published eligibility and disqualification recommendations for competitive athletes with cardiovascular abnormalities. The guidelines cover the key components of the clinical history and physical examination that should guide the pre-sports participation evaluation. They also discuss the role and controversy surrounding a preparticipation ECG. Currently, AHA guidelines do not recommend a preparticipation ECG, but European societies do, based on data from Italy showing that screening ECGs were associated with a decrease in sudden cardiac death in athletes.

Hypertension: Cardiologists are frequently asked to evaluate teenagers with hypertension. The reasons for such referrals are twofold:

• to evaluate the patient for the presence of coarctation of the aorta as a cause of hypertension

• to evaluate the patient for secondary effects of hypertension on cardiac structure and function

In many cases, hypertensive pediatric patients with no associated heart disease are managed by other subspecialists (such as nephrologists or endocrinologists). In some cases, however, outpatient cardiologists manage hypertension in pediatric patients. Echocardiography is recommended to assess for cardiovascular effects of hypertension. In 2017, the AAP published guidelines for the evaluation and management of hypertension in pediatric patients.

Syncope: Syncope is common in teenagers and young adults. Cardiac causes of syncope are rare but include structural heart disease, myocardial dysfunction, and arrhythmia.

• Red flags for possible cardiac etiologies include:

  • syncope without presyncopal symptoms

  • syncope associated with palpitations, chest pain, or during exercise

  • syncope without a pulse or requiring CPR

Hyperlipidemia: Coronary artery disease is a leading cause of morbidity and mortality in developed countries. Although this has traditionally been thought of as a problem of adulthood, data suggest that atherosclerosis begins in childhood. The AAP and the National Heart, Lung, and Blood Institute (NHLBI) recommend universal lipid panel screening in pediatric patients between ages 9-11 years and again 17-21 years. Screening should begin earlier in patients with a history of early cardiovascular disease. Although rare, homozygous familial hypercholesterolemia is a serious condition that causes very high low-density lipoprotein levels (LDL) and can lead to very early onset of cardiovascular events. The guidelines include a table of acceptable, borderline-high, and high plasma lipid, lipoprotein, and apolipoprotein concentrations for children and adolescents (Table 9-1).

For patients with abnormal levels, two fasting lipid panels should be obtained. Treatment depends on exact levels, as well as additional risk factors. Patients with borderline levels start with dietary changes. Statin medications are often first-line therapy. Patients should be referred to a preventive pediatric cardiologist for management.

Palpitations: Palpitations are also a common complaint in teenagers. The history, physical exam, and baseline ECG should be considered in determining whether further workup is needed. If there is a concern for an underlying arrhythmia, a number of ambulatory arrhythmia-monitoring tools are available, including Holter monitors, and external and implantable looping recorders. Atrioventricular nodal reentrant tachycardia is an example of an arrhythmia that is more commonly seen in adolescents.

Chest pain: Chest pain is a common complaint in adolescent patients and only rarely due to a cardiac cause. A focused history and physical examination are often sufficient to determine whether further workup of cardiac causes is indicated.

The history should include a description of the chest pain including its duration, quality, severity, and precipitating and relieving factors. Evaluation should include:

• past medical history with focus on the presence of respiratory illness, sickle cell disease, history of Kawasaki disease, and hypercholesterolemia

• family history, including the presence of early cardiac death, arrhythmias, cardiomyopathy, connective tissue disorders, or familial hypercholesterolemia

• social history, including drug abuse (especially cocaine), trauma, and psychological disorders

Indications for referral to a cardiologist for the evaluation of chest pain include abnormalities of cardiac exam, and chest pain that is associated with exercise; palpitations; abnormal ECG findings; a connective tissue disorder; a history of heart surgery or Kawasaki disease; or a family history of familial hypercholesterolemia, arrhythmias, SCD, or connective tissue disorders.