Pediatric cardiology

1

Is cardiac disease the most common cause of chest pain in children?

A cardiac cause of chest pain is very uncommon and represents less than 1% of cases in a published series. The most common identifiable causes involve musculoskeletal pain (e.g., strained intercostal muscles, costochondritis, Tietze syndrome, precordial catch syndrome), which occurs in one-quarter to one-half of cases. Other causes are pulmonary disease (e.g., asthma, cough illness, pneumonia, pleurisy), gastrointestinal disease (e.g., reflux, esophagitis, gastroenteritis), and miscellaneous diseases (e.g., sickle cell crisis, herpes zoster). Other possibilities include psychogenic (e.g., anxiety, hyperventilation/disordered breathing) and the always present idiopathic diseases (which may represent the largest category).

2

What is the clinical distinction between costochondritis and Tietze syndrome?

• Costochondritis involves sharp, anterior chest wall pain that emanates from multiple costochondral and costosternal junctions. Causes can be inflammatory, posttraumatic, or, less commonly, infectious (including bacterial or fungal). Because the costal cartilage is avascular, it is susceptible to infection after surgery or trauma. This can be delayed and insidious in presentation. Palpation and percussion over the affected areas typically reproduce the pain. Swelling is not a prominent feature.

• Tietze syndrome is a localized form of costochondritis, usually involving just one costochondral junction (typically the second or third costochondral junction). A tender, swollen (but not hot) 1- to 4-cm mass is frequently palpable at the site. Onset is more commonly related to trauma.

3

What are potential red flags that increase the likelihood of a cardiac cause for chest pain?

• Personal history of acquired or congenital cardiac disease

• Exertional syncope

• Exertional “cardiac-type” chest pain (e.g., centrally located with radiation to left arm/jaw, crushing pain or heaviness)

• Hypercoagulable or hypercholesterolemic state

• Family history of sudden death < 35 years, young-onset ischemic heart disease, inherited arrhythmias (such as long QT syndrome)

• Connective tissue disorders

• History of cocaine/amphetamine use

4

A child is brought to your office with a history of sharp, stabbing, localized chest pain that occurs at rest and resolves completely after 1 minute. There are no associated symptoms. What is the likely diagnosis?

Precordial catch syndrome, also called Texidor twinge after the original 1955 describer, may be an underappreciated phenomenon in children with characteristic features that often prompt extensive and unproductive diagnostic workups. It manifests as sudden-onset chest pain in children, very localized (patient points to area with one or two fingers), which occurs most commonly over the left sternal border, right anterior chest, or flanks with variation of site from episode to episode. The pain occurs typically at rest without provocation, is exacerbated by deep breaths (so the patient breathes very shallowly), and usually lasts 30 seconds to 3 minutes. Unlike cardiac, pulmonary, gastrointestinal, or chest wall causes, there is a paucity of associated symptoms (e.g., no palpitations, pallor, flushing, fever, tenderness, or near-syncope). Physical examination, when done during the episode, is normal. The cause is unknown. Pain may originate from the parietal pleura or chest wall (e.g., rib or cartilage), but is not cardiac or pericardial in origin. Ancillary testing, when done, is normal. Management is expectant with reassurance.

5

What is the significance of mitral valve prolapse (MVP)?

MVP occurs when one or both mitral valve leaflets billow excessively into the left atrium near the end of systole. Some studies show that up to 13% of normal children have some degree of posterior leaflet prolapse on echocardiography. There is a spectrum of anatomic abnormalities, the most minor of which are variations of normal. Children with clinical features of mitral valve insufficiency constitute the pathologic category. Whenever auscultation reveals the classic findings of MVP, referral to a pediatric cardiologist is recommended. This allows for evaluation of the child for possible accompanying cardiac abnormalities (e.g., mitral insufficiency, secundum atrial septal defects [ASDs]) and confirmation of the diagnosis.

6

What connective tissue diseases may be associated with MVP?

• Marfan syndrome

• Ehlers-Danlos syndrome

• Pseudoxanthoma elasticum

• Osteogenesis imperfecta

• Hurler syndrome

7

What are the common types of vascular rings and slings?

Vascular rings occur when the trachea and/or the esophagus is encircled by aberrant vascular structures. Vascular slings are compressions that are caused by nonencircling aberrant vessels ( Table 3.1 ).

8

What evaluations are commonly done if a vascular ring is suspected?

• Chest radiograph: For detection of possible right-sided aortic arch

• Barium esophagram: Previously considered the gold standard for diagnosis (before magnetic resonance imaging [MRI]); confirms external indentation of esophagus in up to 95% of cases ( Fig. 3.1 )

  

• MRI: Noninvasive and now used as the primary diagnostic modality

• Arteriogram: Precise delineation of vascular anatomy; rarely needed because of MRI

• Echocardiogram: Should not be relied on for identifying the ring itself, but important when evaluating for other congenital heart lesions that can occur in patients with vascular rings

9

How are cardiomyopathies classified in children?

• Dilated cardiomyopathy is the most common variety. Etiology is usually unknown. Anatomically, the heart is normal, but both ventricles are dilated. Older children exhibit symptoms of congestive heart failure (CHF). Infants demonstrate poor weight gain, feeding difficulty, and respiratory distress. In all pediatric age groups, a more acute presenting symptom can be shock.

• Hypertrophic cardiomyopathy with left ventricular (LV) outflow obstruction is also known as idiopathic hypertrophic subaortic stenosis and asymmetric septal hypertrophy. Of patients with this condition, most have some degree of LV outflow tract obstruction as a result of abnormal hypertrophy of the subaortic region of the intraventricular septum. Most of these defects are inherited in an autosomal dominant fashion.

• Hypertrophic cardiomyopathy without LV outflow obstruction is also usually of unknown etiology. It may be associated with systemic metabolic disease, particularly a storage disease. Cardiomegaly is a constant feature.

• Restrictive cardiomyopathy is associated with abnormal diastolic function of the ventricles. The ventricles may be of normal size, or they may be hypertrophied with normal systolic function. The atria are typically enlarged. The etiology is usually unknown, but restrictive cardiomyopathy may be seen with storage diseases.

10

What mineral is added to hyperalimentation fluids to prevent a potential cardiomyopathy?

Selenium is routinely added to hyperalimentation fluids to prevent selenium deficiency, which can be a cause of both skeletal muscle weakness and cardiomyopathy. This “acquired” heart disease has been described in patients on long-term hyperalimentation (before modern hyperalimentation); patients with acquired immunodeficiency syndrome (AIDS), chronic diarrhea, and wasting disease. It has also been described in children living in the Keshan County in northeast China, where the soil is naturally low in selenium. It is typically reversible with the addition of selenium to the diet or intravenous fluids.

11

What are the cardiac causes of sudden cardiac death in children and adolescents?

Sudden death occurs because of ventricular fibrillation in the setting of myocardial or coronary abnormalities or underlying primary rhythm disorders. The main structural causes are hypertrophic cardiomyopathy (particularly with extreme LV hypertrophy), anomalies of the coronary artery (congenital or acquired), Marfan syndrome, and arrhythmogenic right ventricular (RV) dysplasia/cardiomyopathy. Electrocardiogram (ECG) abnormalities that can lead to sudden death include Wolff-Parkinson-White (WPW) syndrome, prolonged QT syndrome, atrioventricular (AV) block, and Brugada syndrome (a genetic syndrome where the electrical activity of the heart is abnormal). Children with congenital heart disease (CHD) (e.g., severe aortic stenosis, Ebstein anomaly) are at higher risk for sudden death.

12

What historical features may identify the patient who is at risk for sudden death?

• Sudden death may be associated with previous symptoms of exertional chest discomfort; dizziness; or prolonged dyspnea with exercise, syncope, and palpitations.

• A family history of premature cardiovascular disease (< 50 years), hypertrophic or dilated cardiomyopathy, Marfan syndrome, long QT syndrome, other clinically significant arrhythmias, or sudden death may be elicited.

• Previous recognition of a heart murmur and elevated systemic blood pressure are significant findings.

13

What features in the preparticipation sports physical examination identify patients at risk for sudden death?

• Marfanoid features : Tall and thin habitus, hyperextensible joints, pectus excavatum, click and murmur suggestive of MVP

• Pathologic murmurs (any systolic murmur grade 3/6 or greater, any diastolic murmur)

• Weak or delayed femoral pulses

• Arrhythmia: Rapid or irregular heartbeat

14

Name five disorders in which a screening ECG might identify a subject at risk for sudden death

• WPW syndrome: Short PR, delta wave, T-wave abnormalities leading to supraventricular tachycardia (SVT) and ventricular fibrillation

• Prolonged QT syndrome: Secondary to congenital channelopathy, electrolyte- or drug-induced abnormality leading to ventricular tachycardia and torsades de pointes

• Brugada syndrome: RV conduction delay with profound ST elevation in V ₁ –V ₃ leading to ventricular fibrillation

• Hypertrophic cardiomyopathy

• AV block

15

What is the likely diagnosis in a 10-year-old Little Leaguer who develops sudden cardiac arrest after being struck in the chest by a batted baseball?

Commotio cordis . This is a life-threatening arrhythmia that occurs as a result of a blunt, nonpenetrating direct blow to the chest. The precordial force is often only low or moderate and typically not associated with structural injury. Ventricular fibrillation is thought to occur when impact is applied during the vulnerable phase of repolarization, 15 to 30 milliseconds before the peak of the T wave. Prompt cardiopulmonary resuscitation (CPR) and defibrillation improve the chance of survival.

16

In which patients is syncope more likely to be of a cardiac nature?

• Sudden onset without any prodromal period of dizziness or imminent awareness

• Syncope during exercise or exertion

• History of palpitations or abnormal heartbeat before fainting

• Syncope leading to a fall that results in an injury

• Family history of sudden death

17

What arrhythmias may be associated with syncope?

See Table 3.2 .

18

What are the most common clinical signs of coarctation of the aorta ( Fig. 3.2 ) in older children?

• Differential blood pressure: arms > legs (100%)

  

• Systolic murmur or bruit in the back (96%)

• Systolic hypertension in the upper extremities (96%)

• Diminished or absent femoral or lower-extremity pulses (92%)

19

How much does peak exercise affect cardiac output?

Cardiac output is calculated by the formula: Cardiac output = Heart rate × Stroke volume (volume of blood ejected from the left ventricle/beat). Cardiac output at peak exercise will increase up to approximately five times the baseline value. In upright exercise, stroke volume increases early in exercise by 1.5 to 2 times baseline values but then plateaus at that level. Heart rate will also increase early in exercise and will continue to rise up to the maximum predicted value of 200 beats per minute at peak exercise.

20

What cardiac lesions can lead to thrombosis and stroke?

• Arrhythmias: Chronic atrial fibrillation, atrial flutter

• Cardiomyopathies: Decreased cardiac function is associated with increased risk for thrombus formation; therefore many of these patients are on aspirin or warfarin.

• Mechanical valves : These patients require lifelong anticoagulation.

• Patients with Fontan circulation are at increased risk for thrombosis.

• Patients with systemic-to-pulmonary shunts, such as Blalock-Taussig shunts, are at risk for shunt thrombosis.

• Patients with Kawasaki disease with coronary aneurysms are at risk for thrombosis in the coronary arteries.

21

What are two of the more common neuromuscular diseases in which a cardiac consultation is routinely recommended?

• Duchenne muscular dystrophy is an X-recessive disease with an abnormality in the dystrophin gene, which leads to muscle necrosis and fibrosis. Although the majority of deaths are due to respiratory insufficiency, death from cardiomyopathy can occur in up to 25% of patients. Symptoms of heart disease are typically hidden by the skeletal myopathy that masks any exercise-induced complaints such as shortness of breath with exertion. Therefore screening echocardiograms and ECGs are recommended for long-term follow-up.

• Friedrich ataxia is an autosomal recessive disorder involving a gene encoding frataxin, a mitochondrial protein. Symptoms include ataxia and muscle weakness, typically manifesting by 9 years of age. Cardiac abnormalities include both dilated and concentric cardiomyopathies. Atrial fibrillation and atrial flutter are commonly reported arrhythmias. Because muscle weakness and ataxia will prevent prolonged exertion, periodic echocardiograms and ECGs are recommended.

22

Why are chemotherapeutic agents that use arsenic of cardiac concern?

Arsenic may cause prolonged QT and lead to torsades de pointes (a specific form of ventricular tachycardia in patients with a prolonged QT interval) and ventricular fibrillation. Periodic ECG monitoring is recommended in these patients.

23

What risk is increased for children with Williams syndrome who undergo sedation?

Sudden death . Common cardiovascular abnormalities in Williams syndrome include supravalvular aortic stenosis, peripheral pulmonary branch stenosis, and coarctation of the aorta. Coronary abnormalities include coronary ostial stenosis and diffuse coronary artery stenosis or dilatation. The risk for sudden death is increased in patients with coronary artery abnormalities, including Williams syndrome, as well as those with combined aortic and pulmonary artery stenosis.

24

You see an asymptomatic 5-year-old girl with Turner syndrome, and the parents report that coarctation of the aorta was ruled out when she was 1 month of age. Does she need to return to the cardiologist?

Yes . General categories of cardiac disease in Turner syndrome include:

• Congenital heart disease : Most commonly coarctation of the aorta, bicuspid aortic valve, aortic stenosis, and hypoplastic left heart syndrome

• Aortic arch disease : Coarctation of the aorta, aortic dilatation, and aortic dissection

• Premature atherosclerosis associated with the following risk factors: estrogen deficiency, increased incidence of obesity, hypertension, and metabolic syndrome

Guidelines for girls with Turner syndrome recommend cardiac evaluation, including echocardiogram, in all patients at the time of diagnosis. In the absence of a bicuspid aortic valve or significant heart disease, periodic screening for aortic dilatation with echocardiogram and/or cardiac MRI is recommended.

25

Why does an infant suspected of having tuberous sclerosis require a cardiology evaluation?

Tuberous sclerosis affects multiple organs, including the heart. Cardiac problems include rhabdomyomas and an increased frequency of both atrial and ventricular arrhythmias. Rhabdomyomas most commonly occur in the ventricles but may occur in any of the four chambers. They can be detected during fetal scanning and tend to regress spontaneously over the first few years of life. Patients are usually asymptomatic unless the tumors are large or interfere with valve function. Symptomatic patients have been successfully treated with surgery. Effective therapy with sirolimus, an immunosuppressive agent, has been reported in children with large rhabdomyomas.

26

Do cancer survivors who have undergone chemotherapy require long-term cardiac follow-up while they are in remission?

Yes . Long-term cancer survivors have an increased risk for development of a cardiomyopathy. Heart disease is one of the most common causes of noncancerous death in cancer survivors. High-risk groups include females and patients who received higher doses of anthracycline. The Children’s Oncology Group recommends ongoing cardiac monitoring while receiving cardiotoxic therapy and every 1 to 5 years after the completion of therapy.

27

What noncardiopulmonary diseases are associated with pulmonary hypertension?

• Chronic thromboembolic disease

• Connective tissue disease

• Human immunodeficiency virus (HIV) infection

• Portal hypertension

• Schistosomiasis

• Hematologic disorders: chronic hemolytic anemia, myeloproliferative disorders, splenectomy

• Systemic disorders: sarcoidosis, pulmonary histiocytosis, lymphangioleiomyomatosis

• Metabolic disorders: glycogen storage disease, Gaucher disease, thyroid disorders

• Others: tumor, fibrosing mediastinitis, chronic renal failure, drug- and toxin-induced

28

What is portopulmonary hypertension?

Approximately 5% of patients with portal hypertension also develop pulmonary hypertension, which is known as portopulmonary hypertension . Risk factors for portopulmonary hypertension include female sex, positive serology for autoimmune disease (antinuclear antibodies), autoimmune hepatitis, or chronic hepatitis C infection.

29

Can a patient with heart disease simultaneously be polycythemic and iron deficient?

Yes . Patients with cyanotic heart disease may develop both clinical entities. Initially, as a response to cyanosis, the hematocrit rises. In patients who then develop iron deficiency, the hematocrit may initially remain elevated, but the mean corpuscular volume (MCV) will start to decrease before there is a drop in hematocrit. Detailed studies of iron stores will show low iron and ferritin levels. Children with a history of poor nutrition or blood loss (e.g., previous surgery) are especially at risk for developing iron deficiency.

30

What conditions are associated with an elevated troponin level?

Cardiac troponin is a cardiac-specific protein. Abnormally high serum concentrations can signify damage to the cardiac myocytes. The subtypes cTnI and cTnT are the most commonly measured troponins used by clinical laboratories. cTnI and cTnT are typically elevated in myocardial infarction, ischemia due to hypotension from sepsis, and in up to one-third of children with chronic heart failure. Cardiac troponins can be elevated in both ischemic and nonischemic disease, including acute coronary syndrome, CHF, myocarditis/pericarditis, arrhythmias, heart transplant rejection, myocardial contusion, and after the administration of cardiotoxic drugs.

31

What is the significance of an elevated B-type natriuretic peptide (BNP)?

BNP is a biomarker that is predominantly secreted in the ventricular myocardium in response to increased wall stress. It is secreted as pro-BNP and then cleaved into active and inactive forms. It is useful in determining the role of cardiac involvement in acute cardiopulmonary processes. It can be increased in similar diseases as those listed earlier for troponin (question 30). In addition, BNP can be elevated in patients with diastolic dysfunction and acute respiratory distress syndrome, which do not usually cause increased troponin levels.

32

How does fetal circulation differ from neonatal circulation?

• Intracardiac and extracardiac shunts are present (i.e., placenta, ductus venosus, foramen ovale, and ductus arteriosus).

• The two ventricles work in parallel rather than in series.

• The right ventricle pumps against a higher resistance than the left ventricle.

• Blood flow to the lung is only a fraction of the RV output.

• The lung extracts oxygen from the blood instead of adding oxygen to the blood.

• The lung continually secretes a fluid into the respiratory passages.

• The liver is the first organ to receive maternal substances (e.g., oxygen, glucose, amino acids).

• The placenta is the major route of gas exchange, excretion, and acquisition of nutritional substances.

• The placenta provides a low-resistance circuit.

33

What prenatal maternal factors may be associated with cardiac disease in the neonate?

See Table 3.3 .

34

In a cyanotic newborn, what test can help distinguish pulmonary disease from cyanotic CHD?

Hyperoxia test . The infant is placed on 100% oxygen, and an arterial blood gas level is obtained. A Pa o ₂ of greater than 100 mm Hg is usually achieved in infants with primary lung disease, whereas a Pa o ₂ of less than 100 mm Hg is characteristic of heart disease. Typically, children with cyanotic heart disease also have a low or normal P co ₂ , whereas children with lung disease have an elevated P co ₂ . However, the hyperoxia test does not usually distinguish children with cyanotic heart disease from those with persistent pulmonary hypertension.

35

Which congenital heart lesions commonly appear with cyanosis during the newborn period?

Independent pulmonary and systemic circulations (severe cyanosis)

• Transposition of great arteries with an intact ventricular septum

Inadequate pulmonary blood flow (severe cyanosis)

• Tricuspid valve atresia

• Pulmonary valve atresia with intact ventricular septum

• Tetralogy of Fallot

• Severe Ebstein anomaly of the tricuspid valve

Admixture lesions (moderate cyanosis)

• Total anomalous pulmonary venous return

• Hypoplastic left heart syndrome (HLHS)

• Truncus arteriosus

36

How do pulmonary vascular markings on a chest radiograph help in the differential diagnosis of a cyanotic newborn with suspected cardiac disease?

The chest radiograph may help differentiate the types of CHDs. An increase or decrease in pulmonary vascular markings is indicative of the amount of pulmonary blood flow:

Decreased pulmonary markings (diminished pulmonary blood flow)

• Pulmonary atresia or severe stenosis

• Tetralogy of Fallot

• Tricuspid atresia

• Ebstein anomaly

Increased pulmonary markings (increased pulmonary blood flow)

• Transposition of great arteries

• Total anomalous pulmonary venous return

• Truncus arteriosus

37

What ECG findings suggest specific congenital heart conditions?

• Left axis deviation: Endocardial cushion defects (both complete AV canal and ostium primum ASDs), tricuspid atresia

• WPW syndrome (abnormal electrical pathway): Ebstein anomaly, l -transposition of the great arteries (L-TGA)

• Complete heart block: L-TGA, polysplenia syndrome, maternal lupus

38

What chest radiograph findings ( Fig. 3.3 ) are considered characteristic for various CHDs?

• Boot-shaped heart: Tetralogy of Fallot

  

• Egg-shaped heart: Transposition of great arteries

• Snowman silhouette: Total anomalous pulmonary venous return (supracardiac)

39

What are the common ductal-dependent cardiac lesions?

Ductal-dependent pulmonary blood flow

• Critical pulmonary valve stenosis

• Pulmonary atresia

• Tetralogy of Fallot with severe pulmonary stenosis

• Tricuspid atresia with pulmonary stenosis or pulmonary atresia

Ductal-dependent systemic blood flow

• Coarctation of the aorta

• HLHS

• Interrupted aortic arch

40

What types of CHDs are associated with the right aortic arch?

• Tetralogy of Fallot with pulmonary atresia (50%)

• Truncus arteriosus (35%)

• Classic tetralogy of Fallot (25%)

• Double-outlet right ventricle (25%)

• Single ventricle (12.5%)

41

Which genetic syndromes are most commonly associated with CHD?

See Table 3.4 .

42

When does the ductus arteriosus (DA) close in well newborn infants?

The DA begins to constrict shortly after birth. At 24 hours of life, approximately 50% of infants will no longer have detectable flow across the DA by echocardiography. At 72 hours of life, the vast majority of newborn infants no longer have detectable flow across the DA. The DA initially closes functionally, meaning that blood no longer flows across the vessel, but it closes anatomically with fibrosis of the vessel at approximately 2 to 3 weeks of life. Therefore, if the DA closes despite significant CHD, it may be reopened with pharmacologic therapy using prostaglandin E ₁ only before full anatomic closure.

43

Describe the clinical manifestations of a large patent ductus arteriosus (PDA)

• Tachypnea and tachycardia

• Abnormal renal function

• Bounding pulses

• Hyperdynamic precordium

• Wide pulse pressure

• Continuous murmur (older child)

• Systolic murmur (premature infant)

• Labile oxygenation (premature infant)

• Apnea (premature infant)

44

How commonly do PDAs occur in premature infants?

They are clinically evident in 40% to 60% of infants with birth weights of 501 to 1500 g.

45

How can you explain a Pa o ₂ of more than 400 mm Hg in a blood sample from an umbilical catheter in a newborn with transposition of the great arteries?

A very elevated Pa o ₂ can be observed if an umbilical vein catheter has passed from the inferior vena cava to the right atrium and into the left atrium. The P o ₂ in the left atrium represents the pulmonary venous oxygenation and not the arterial oxygen level. In cyanotic heart disease, the alveolar and pulmonary vein P o ₂ values are usually normal. It is the arterial oxygenation concentration that is severely diminished in children with cyanotic heart disease.

46

How do the presenting symptoms of ventricular septal defect (VSD) and ASD differ?

• VSD : In an infant with a large VSD, signs of CHF generally appear at 4 to 8 weeks of age, when the pulmonary vascular resistance drops and pulmonary blood flow increases. CHF is due to a large left-to-right shunt and increased pulmonary blood flow and may be associated with failure to thrive or recurrent respiratory infections. The child with a small VSD may have a systolic murmur during the first few weeks of life. These infants do not develop CHF, and spontaneous closure often occurs.

• ASD: Most children with an isolated ASD are not clinically diagnosed until they are 3 to 5 years old. Most are asymptomatic at the time of diagnosis. Rarely, infants with an ASD demonstrate signs of CHF during the first year of life.

47

Why is it not always possible to auscultate a murmur in an infant with a VSD on the first day of life?

Murmurs are generated by high-velocity or highly turbulent blood flow. The blood flow across a VSD increases in velocity over the first several days of life as the pulmonary arterial pressure decreases in the transition from fetal to postnatal life. In utero, the pulmonary artery pressure is higher than the systemic arterial pressure and is approximately equal to the systemic pressure shortly after birth. However, the pulmonary artery pressure decreases dramatically over the first several days of life leading to a larger systemic to pulmonary pressure gradient. As the pressure gradient increases, the blood flow across the VSD increases in velocity and the murmur becomes more apparent.

48