6 Special Problems

I. CONGESTIVE HEART FAILURE

Congestive heart failure (CHF) is a clinical syndrome in which the heart is unable to pump enough blood to the body to meet its needs, to dispose of systemic or pulmonary venous return adequately, or a combination of the two.

A. CAUSES

The heart failure syndrome may arise from diverse causes. Common causes of CHF are volume and/or pressure overload caused by either congenital or acquired heart disease, as well as myocardial diseases. By far the most common causes of CHF in infancy are congenital heart diseases (CHDs). Beyond infancy, myocardial dysfunction of various etiologies is an important cause of CHF. Tachyarrhythmias and heart block can also cause heart failure at any age.

1. Congenital heart disease. Volume overload lesions such as ventricular septal defect (VSD), patent ductus arteriosus (PDA), and endocardial cushion defect (ECD) are the most common causes of CHF in the first 6 months of life. In infancy the time of the onset of CHF varies predictably with the type of defect. Table 6-1 lists common defects according to the age at which CHF develops. Large left-to-right shunt (L-R shunt) lesions, such as VSD and PDA, do not cause CHF before 6 to 8 weeks of age because the pulmonary vascular resistance (PVR) does not fall low enough to cause a large shunt until this age. CHF may occur earlier in premature infants (within the first month) because of an earlier fall in the PVR. Note that children with tetralogy of Fallot (TOF) do not develop CHF and that children with atrial septal defect (ASD) rarely develop CHF in the pediatric age group, although ASD causes CHF in adulthood.

2. Acquired heart disease. Acquired heart disease of various etiologies can lead to CHF. Common entities (with the approximate time of onset of CHF) are as follows:

a. Viral myocarditis (in toddlers, occasionally in neonates with fulminating course)

b. Myocarditis associated with Kawasaki disease (1 to 4 years of age)

c. Acute rheumatic carditis (school-age children)

d. Rheumatic valvular heart diseases, such as mitral regurgitation (MR) or aortic regurgitation (AR) (older children and adults)

e. Idiopathic dilated cardiomyopathy (any age during childhood and adolescence)

f. Doxorubicin cardiomyopathy (months to years after chemotherapy)

g. Cardiomyopathies associated with muscular dystrophy and Friedreich ataxia (older children and adolescents)

3. Miscellaneous causes

a. Metabolic abnormalities (severe hypoxia, acidosis, hypoglycemia, hypocalcemia) (newborns)

b. Hyperthyroidism (any age)

c. Supraventricular tachycardia (SVT) (early infancy)

d. Complete heart block associated with CHDs (the newborn period or early infancy)

e. Severe anemia (any age), hydrops fetalis (neonates), and sicklemia (childhood and adolescence)

f. Bronchopulmonary dysplasia (BPD) with right-sided failure (the first few months of life)

g. Primary carnitine deficiency (2 to 4 years)

h. Acute cor pulmonary caused by acute airway obstruction (early childhood)

i. Acute systemic hypertension with glomerulonephritis (school-age children)

TABLE 6-1 CAUSES OF CONGESTIVE HEART FAILURE DUE TO CONGENITAL HEART DISEASE ACCORDING TO THE TIME OF OCCURRENCE

TIME OF OCCURRENCE	CAUSES
At birth	Hypoplastic left heart syndrome (HLHS)
At birth	Volume overload lesions (e.g., severe TR or PR, large systemic AV fistula)
First week	Transposition of the great arteries (TGA)
	PDA in small premature infants
	HLHS (with more favorable anatomy)
	TAPVR, particularly those with pulmonary venous obstruction
	Critical AS or PS
	Others: systemic AV fistula
1–4 weeks	COA (with associated anomalies)
	Critical AS
	Large L-R shunt lesion (e.g., VSD, PDA) in premature infants
	All other lesions listed above
4–6 weeks	Some L-R shunt lesions, such as ECD
6 weeks-4 months	Large VSD
	Large PDA
	Others: anomalous left coronary artery from the PA

ECD, endocardial cushion defect.

B. CLINICAL MANIFESTATIONS

The diagnosis of CHF relies on several sources of clinical findings, including history, physical examination, and chest x-ray (CXR) films. Cardiomegaly is almost always present on CXR films. Echo studies are the most helpful noninvasive studies, confirming the diagnosis, cause, and severity of CHF.

Plasma levels of natriuretic peptides, atrial natriuretic peptide (ANP), and B-type natriuretic peptide (BNP) are increased in most adult patients with dyspnea from heart failure but not in dyspnea caused by pulmonary disease. Plasma levels of these peptides are normally elevated in the first weeks of life. Although increased levels of BNT and the N-terminal segment of its pro-hormone (NT-ProBNT) have been reported in most children with CHF, the usefulness of data on the levels of these peptides appears limited because an appropriate reference range has not been established. The levels of these peptides are different depending on the commercial testing kits used.

1. Poor feeding of recent onset, tachypnea, poor weight gain, and cold sweat on the forehead suggest CHF in infants. In older children, shortness of breath, especially with activities; easy fatigability; puffy eyelids; or swollen feet may be presenting complaints.

2. Physical findings can be divided by pathophysiologic subgroups.

a. Compensatory responses to impaired cardiac function

(1) Tachycardia, gallop rhythm, weak and thready pulse, and cardiomegaly on CXR films

(2) Signs of increased sympathetic discharges (growth failure, perspiration, and cold wet skin)

b. Signs of pulmonary venous congestion (left-sided failure) include tachypnea, dyspnea on exertion (or poor feeding in small infants), orthopnea in older children, and rarely wheezing and pulmonary crackles.

c. Signs of systemic venous congestion (right-sided failure) include hepatomegaly and puffy eyelids. Distended neck veins and ankle edema are not seen in infants.

3. Cardiomegaly on CXR films is almost always present, except when the pulmonary venous return is obstructed; in that case pulmonary edema or venous congestion will be present.

4. The ECG is not helpful in deciding whether one is in CHF, although it may be helpful in determining the cause.

5. Echo studies confirm the presence of chamber enlargement or impaired left ventricle (LV) function and help determine the cause of CHF.

C. MANAGEMENT

The treatment of CHF consists of (1) elimination of the underlying causes or correction of precipitating or contributing causes (e.g., infection, anemia, arrhythmias, fever, hypertension); (2) general supportive measures; and (3) control of heart failure state by inotropic agents, diuretics, or afterload-reducing agents.

1. Treatment of underlying causes or contributing factors

a. When surgically feasible, treatment of underlying CHDs or valvular heart disease is the best approach for complete cure.

b. Antihypertensive treatment for hypertension.

c. Antiarrhythmic agents or cardiac pacemaker therapy for arrhythmias or heart block.

d. Treatment of hyperthyroidism if it is the cause of CHF.

e. Antipyretics for fever.

f. Antibiotics for a concomitant infection.

g. Packed cell transfusion for anemia (to raise the hematocrit to ≥35%).

2. General measures. Nutritional supports are important. Infants in CHF need significantly higher caloric intakes than recommended for average children. The required calorie intake may be as high as 150 to 160 kcal/kg/day for infants in CHF.

a. Increasing caloric density of feeding may be required, and it may be accomplished with fortification of feeding (Box 6-1).

b. Frequent small feedings are better tolerated than large feedings in infants.

c. If oral feedings are not well tolerated, intermittent or continuous nasogastric (NG) feeding is indicated. To promote normal development of oral-motor function, infants may be allowed to take calorie-dense oral feeds throughout the day and then be given continuous NG feeds overnight.

d. In older children, salt restriction (<0.5 g/day) and avoidance of salty snacks (chips, pretzels) and table salt are recommended. Bed rest remains an important component of management. The availability of a television screen and computer games for entertainment ensures bed rest in older children.

3. Drug therapy. Three major classes of drugs are commonly used in the treatment of CHF in children: diuretics, inotropic agents, and afterload-reducing agents.

a. Diuretics

(1) Diuretics remain the principal therapeutic agent to control pulmonary and systemic venous congestion. Diuretics only reduce preload and improve congestive symptoms; they do not improve cardiac output or myocardial contractility (Fig. 6-1). There are three main classes of diuretics that are commercially available.

(a) Thiazide diuretics (e.g., chlorothiazide, hydrochlorothiazide), which act at the proximal and distal tubules, are no longer popular.

(b) Rapid-acting diuretics (e.g., furosemide, ethacrynic acid) are the drugs of choice. They act primarily at the loop of Henle (“loop diuretics”).

(c) Aldosterone antagonist (e.g., spironolactone) acts on the distal tubule to inhibit sodium-potassium exchange. This drug has value in preventing hypokalemia produced by other diuretics and thus is used in conjunction with a loop diuretic. However, when angiotensin-converting enzyme (ACE) inhibitors are used, spironolactone should be discontinued to avoid hyperkalemia.

(2) Table 6-2 shows dosages of commonly available diuretic preparations. Side effects of diuretic therapy include hypokalemia (except when used with spironolactone) and hypochloremic alkalosis. These side effects predispose to digitalis toxicity.

b. Rapidly acting inotropic agents

(1) In critically ill infants with CHF, rapidly acting catecholamines with a short duration of action are preferable to digoxin. Dosages of this class of inotropic agents are suggested in Table 6-3.

(2) Amrinone is a noncatecholamine agent that exerts its inotropic effect and vasodilator effects by inhibiting phosphodiesterase (see Appendix E for dosage). Thrombocytopenia is a side effect; the drug should be discontinued if the platelet count falls below 150,000/mm³.

c. Digitalis glycosides

(1) Dosage of digoxin

(a) Digoxin increases the cardiac output (or contractile state of the myocardium), thereby resulting in an upward and leftward shift of the ventricular function curve relating cardiac output to filling volume of pressure (Fig. 6-1). Use of digoxin in infants with large L-R shunt lesions (e.g., large VSD) is controversial because ventricular contractility is normal in this situation. However, studies have shown that digoxin improves symptoms in these infants, perhaps because of other actions of digoxin, such as parasympathomimetic action and diuretic action.

(b) The total digitalizing dose (TDD) and maintenance dosage of digoxin by oral and intravenous routes are shown in Table 6-4. A high dose may be needed in treating SVT, in which the goal of treatment is to delay atrioventricular (AV) conduction. The maintenance dose is more closely related to the serum digoxin level than is the digitalizing dose, which is given to build a sufficient body store of the drug and to shorten the time required to reach the pharmacokinetic steady state.

(2) How to digitalize. One half of the total digitalizing doses are followed by one fourth and then the final one fourth of the total digitalizing dose at 6- to 8-hour intervals. The maintenance dose is given 12 hours after the final total digitalizing dose. An ECG strip before starting the maintenance dose is advised. This results in a pharmacokinetic steady state in 3 to 5 days. When an infant is in mild heart failure, the maintenance dose may be administered orally without loading doses; this results in a steady state in 5 to 8 days. A baseline ECG (rhythm and PR interval) and serum electrolytes are recommended. Hypokalemia and hypercalcemia predispose to digitalis toxicity.

(3) Monitoring for digitalis toxicity by ECG. With the relatively low dosage recommended in Table 6-4, digitalis toxicity is unlikely unless there are predisposing factors for the toxicity (Box 6-2). Serum digoxin levels obtained during the first 3 to 5 days after digitalization tend to be higher than those obtained when the pharmacokinetic steady state is reached. Therefore, detection of digitalis toxicity is best accomplished by monitoring with ECGs, not by serum digoxin levels during this period. Box 6-3 lists ECG signs of digitalis effects and toxicity. In general the digitalis effect is confined to ventricular repolarization, whereas toxicity involves disturbances in the formation and conduction of the impulse.

(4) Serum digoxin levels. Therapeutic ranges of serum digoxin levels for treating CHF are 0.8 to 2 ng/mL. Blood for serum digoxin levels should be drawn just before a scheduled dose or at least 6 hours after the last dose; samples obtained earlier than 6 hours after the last dose will give a falsely elevated level.

d. Afterload-reducing agents

(1) Reducing afterload tends to augment the stroke volume without a great change in the inotropic state of the heart and therefore without increasing myocardial oxygen consumption. Combined use of an inotropic agent, a vasodilator, and a diuretic produces most improvement in both inotropic state and congestive symptoms (Fig. 6-1).

(2) Afterload-reducing agents may be used not only in infants with a large-shunt VSD, AV canal, or PDA but also in patients with dilated cardiomyopathies, myocardial ischemia, postoperative cardiac status, severe MR or AR, and systemic hypertension. Dosages and the site of action of the afterload-reducing agents are presented in Table 6-5.

e. Other drugs

(1) β-Adrenergic blockers

(a) As reported in adults, β-adrenergic blockers have been shown to be beneficial in some pediatric patients with chronic CHF who were treated with standard anticongestive drugs. Adrenergic overstimulation, often seen in patients with chronic CHF, may have detrimental effects on the failing heart by inducing myocyte injury and necrosis. However, β-adrenergic blockers should not be given to those with decompensated heart failure.

(b) When added to standard medical therapy for CHF, carvedilol, a nonselective β-adrenergic blocker with additional α1-antagonist activities, has been shown to be beneficial in children with idiopathic dilated cardiomyopathy, chemotherapy-induced cardiomyopathy, postmyocarditis myopathy, muscular dystrophy, and postsurgical heart failure (e.g., Fontan operation). Metoprolol was also beneficial in dilated cardiomyopathy. See Appendix E for the dosages and side effects of carvedilol and metoprolol. Propranolol added to conventional treatment for CHF was also beneficial in a small number of infants with large L-R shunts at the dose of 1.6 mg/kg per day.

(2) Carnitine, which is an essential cofactor for transport of long-chain fatty acids into mitochondria for oxidation, has been shown to be beneficial in some cases of dilated cardiomyopathy. The dosage of L-carnitine used was 50 to 100 mg/kg/day, given BID or TID orally (maximum daily dose 3 g).

4. Surgical management. If medical treatment as outlined previously does not improve CHF caused by CHD within a few weeks to months, one should consider either palliative or corrective cardiac surgery for the underlying cardiac defect when technically feasible. Cardiac transplantation is an option for a patient with progressively deteriorating cardiomyopathy despite maximal medical treatment.

BOX 6-1 METHODS OF INCREASING CALORIC DENSITY OF FEEDINGS

1. Human milk fortifier (Enfamil, Mead Johnson), 1 packet per 25 mL of breast milk ≡ 24 kcal/oz

2. Formula concentration to 24 kcal/oz by:

a. 1 cup powdered formula + 3 cups water or

b. 4 oz ready-to-feed + ½ scoop powdered formula

3. Supplementation of formula to 26–30 kcal/oz is accomplished in the following manner.

a. Fat modular products

(1) Medium chain triglycerides (MCT) oil (Mead Johnson), 8 kcal/mL

(2) Microlipid (safflower oil emulsion, Mead Johnson), 4.5 kcal/mL

b. Low-osmolality polymers

(1) Polycose (Ross), 23 kcal/tablespoon

(2) Moducal (Mead Johnson), 30 kcal/tablespoon

4. Pediasure (Ross), 30 kcal/oz ready-to-feed (for children over 1 year of age)

From Wright GE, Rochini AP: Primary and general care of the child with congenital heart disease, ACC Current Journal Review 89–93, March/April 2002.

FIG. 6-1 Effects of anticongestive medications on the Frank-Starling relationship for ventricular function. In normal persons with a normal heart, cardiac output increases as a function of ventricular filling pressure (upper curve). In patients with heart failure the normal relationship between the cardiac output (stroke volume) and filling pressure (preload) is shifted lower and to the right such that a low-output state and congestive symptoms may coincide. Congestive symptoms (dyspnea, tachypnea) may appear even in a normal heart if the filling pressure reaches a certain point. At one extreme the addition of a pure inotropic agent, such as digoxin, primarily increases the stroke volume with minimal impact on filling pressure (so that the patient may still have congestive symptoms). Conversely, the addition of a diuretic primarily decreases the filling pressure (with improved congestive symptoms) but without improving cardiac output. Clinically, it is common to use multiple classes of agents (usually a combination of inotropric agents, diuretics, and vasodilators) to produce both increased cardiac output and decreased filling pressure.

(Adapted from Cohn JN, Franciosa JS: Vasodilator therapy of cardiac failure [first of two parts]. N Engl J Med 297:27–31, 1977.)

TABLE 6-2 DIURETIC AGENTS AND DOSAGES

PREPARATION	ROUTE	DOSAGE
Thiazide Diuretics
Chlorothiazide (Diuril)	Oral	20–40 mg/kg/day in two divided doses
Hydrochlorothiazide (HydroDIURIL)	Oral	2–4 mg/kg/day in two divided doses
Loop Diuretics
Furosemide (Lasix)	IV	1 mg/kg/dose
Furosemide (Lasix)	Oral	2–3 mg/kg/day in two or three divided doses
Ethacrynic acid (Edecrin)	IV	1 mg/kg/dose
Ethacrynic acid (Edecrin)	Oral	2–3 mg/kg/day in two or three divided doses
Aldosterone Antagonists
Spironolactone (Aldactone)	Oral	3 mg/kg/day in two or three divided doses

DRUG	ROUTE AND DOSAGE	SIDE EFFECTS
Epinephrine (Adrenalin)	IV 0.1–1 μg/kg/min	Hypertension, arrhythmias
Isoproterenol (Isuprel)	IV 0.1–0.5 μg/kg/min	Peripheral and pulmonary vasodilation
Dobutamine (Dobutrex)	IV 5–8 μg/kg/min	Little tachycardia and vasodilation, arrhythmias
Dopamine (Inotropin)	IV 5–10 μg/kg/min	Tachycardia, arrhythmias, hypertension, or hypotension
		Dose-related cardiovascular effects of dopamine (μg/kg/min):
		Renal vasodilation (2–5)
		Cardiac (5–15)
		Vasoconstriction (15–20)

TABLE 6-4 ORAL DIGOXIN DOSAGE FOR CONGESTIVE HEART FAILURE

PATIENT	TDD^* (μG/KG)	MAINTENANCE^*^† (μG/KG/DAY)
Premature babies	20	5
Neonates	30	8
Less than 2 years	40–50	10–12
More than 2 years	30–40	8–10

* IV dose is 75% of the oral dose.

† Maintenance dose is 25% of the TDD in two divided doses. TDD, total digitalizing dose.

From Park MK: The use of digoxin in infants and children with specific emphasis on dosage, J Pediatr 108:871–877, 1986.

TABLE 6-5 DOSAGES OF VASODILATORS

DRUG	ROUTE AND DOSAGE	COMMENTS
Arteriolar Vasodilators
Hydralazine (Apresoline)	IV: 0.15–0.2 mg/kg/dose, every 4–6 hr (maximum 20 mg/dose) Oral: 0.75–3 mg/kg/day, in 2–4 doses (maximum 200 mg/day)	May cause tachycardia; may be used with propranolol May cause gastrointestinal symptoms, neutropenia, and lupuslike syndrome
Venodilators
Nitroglycerin	IV: 0.5–1 μg/kg/min (maximum 6 μg/kg/min)	Start with small dose and titrate based on effects
Mixed Vasodilators
Captopril (Capoten)	Oral: Newborn: 0.1–0.4 mg/kg, TID-QID Infant: Initially 0.15–0.3 mg/kg, QD-QID; titrate upward if needed; max dose 6 mg/kg/24 hr Child: Initially 0.3–0.5 mg/kg, BID-TID; titrate upward if needed; max 6 mg/kg/24 hr Adolescents and adults: Initially 12.5–25 mg, BID-TID; increase weekly if needed by 25 mg/dose to max dose 450 mg/24 hr	May cause hypotension, dizziness, neutropenia, and proteinuria Dose should be reduced in patients with impaired renal function
Enalapril (Vasotec)	Oral: 0.1 mg/kg, once or twice daily	Patient may develop hypotension, dizziness, or syncope
Nitroprusside (Nipride)	IV: 0.3–0.5 μg/kg/min; titrate to effects (max dose 10 μg/kg/min)	May cause thiocyanate or cyanide toxicity (e.g., fatigue, nausea, disorientation), hepatic dysfunction, or light sensitivity

II. CHILD WITH CHEST PAIN

Although chest pain does not indicate serious disease of the heart or other systems in most pediatric patients, in a society with a high prevalence of atherosclerotic cardiovascular disease it can be alarming to the child and parents. Physicians should be aware of the differential diagnosis of chest pain in children and should make every effort to find a specific cause before making a referral to a specialist or reassuring the child and the parents of the benign nature of the complaint.

A. CAUSE AND PREVALENCE

Table 6-6 lists the frequency of the causes of chest pain in children according to organ systems. The three most common causes of chest pain in children are costochondritis, trauma to or muscle strain of the chest wall, and respiratory diseases, especially those associated with coughing. These three conditions account for 45% to 65% of cases of chest pain in children. Chest pain of cardiac origin occurs in only 0% to 4% of children with complaint of chest pain. Box 6-4 is a partial list of possible causes of noncardiac and cardiac chest pain in children. Psychogenic causes are less likely found in children younger than 12 years old; such causes are more likely to be found in females older than 12 years of age.

TABLE 6-6 FREQUENCY OF CAUSES OF CHEST PAIN IN CHILDREN

CAUSE	INCIDENCE (%)
Idiopathic	12–45
Costochondritis	9–22
Musculoskeletal trauma	21
Cough, asthma, pneumonia	15–21
Psychogenic	5–9
Gastrointestinal system	4–7
Cardiac disorder	0–4
Sickle cell crisis	2
Miscellaneous	9–21

BOX 6-4 CAUSES OF CHEST PAIN IN CHILDREN AND ADOLESCENTS

B. CLINICAL MANIFESTATIONS

1. Idiopathic chest pain. No cause can be found in 12% to 45% of patients, even after a moderately extensive investigation. In children with chronic chest pain a cardiac cause is less likely to be found.

2. Noncardiac causes of chest pain. Identifiable noncardiac causes of chest pain are found in 56% to 86% of reported cases, most often in the thorax and respiratory system (Table 6-6).

a. Costochondritis

(1) Costochondritis is found in 9% to 22% of children with chest pain. It is more common in girls than boys and may persist for several months. It is characterized by mild to moderate anterior chest pain, usually unilateral but occasionally bilateral. The pain may radiate to the remainder of the chest and back and may be exaggerated by breathing or physical activities. Physical examination is diagnostic; the clinician finds a reproducible tenderness on palpation over the chondrosternal or costochondral junctions. It is a benign condition.

(2) Tietze syndrome is a rare form of costochondritis characterized by a large, tender, fusiform (spindle-shaped), and nonsuppurative swelling at the chondrosternal junction. It usually affects the second and third costochondral junctions.

b. Musculoskeletal. A history of vigorous exercise, weight lifting, or direct trauma to the chest and the presence of tenderness of the chest wall or muscles clearly indicate muscle strain or trauma.

c. Respiratory

(1) Respiratory causes (10% to 20% of cases) may result from lung pathology, pleural irritation, or pneumothorax. A history of severe cough, tenderness of intercostal or abdominal muscles, and crackles or wheezing on examination suggests a respiratory cause of chest pain.

(2) Exercise-induced asthma. The response of the asthmatic patient to exercise is quite characteristic. Strenuous exercise for 3 to 8 minutes causes bronchoconstriction in virtually all asthmatic subjects, especially when the heart rate rises to 180 beats per minute. Symptoms may include coughing, wheezing, dyspnea, and/or pain. Patients also complain of limited endurance during exercise. Exercise-induced bronchospasm provocation test is diagnostic.

d. Gastrointestinal. Gastroesophageal reflux (GER) may produce burning substernal pain that worsens with a reclining posture or abdominal pressure. In young children, ingested foreign bodies (such as coins or caustic substances) may cause chest pain. Cholecystitis presents with postprandial pain referred to the right upper quadrant of the abdomen and part of the chest.

e. Psychogenic. Psychogenic causes of chest pain are more likely seen in female adolescents. Often a recent stressful situation parallels the onset of the chest pain: a death or separation in the family, a serious illness, a disability, a recent move, failure in school, or sexual molestation. However, a psychological cause of chest pain should not be lightly assigned without a thorough history taking and a follow-up evaluation. Psychological or psychiatric consultation may be indicated.

f. Miscellaneous

(1) The precordial catch (Texidor’s twinge or stitch in the side), a one-sided chest pain, lasts a few seconds or minutes and is associated with bending or slouching.

(2) Slipping rib syndrome (resulting from excess mobility of the eighth to tenth ribs, which do not directly insert into the sternum).

(3) Mastalgia in some male and female adolescents.

(4) Pleurodynia (devil’s grip) is an unusual cause of chest pain caused by coxsackievirus infection.

(5) Herpes zoster is another unusual cause of chest pain.

(6) Spontaneous pneumothorax and pneumomediastinum are rare respiratory causes of acute chest pain. Children with asthma, cystic fibrosis, or Marfan syndrome are at risk. Inhalation of cocaine can provoke pneumomediastinum and pneumothorax.

(7) Hyperventilation can produce chest discomfort and is often associated with paresthesia and light-headedness.

3. Cardiac causes of chest pain. Cardiac chest pain may be caused by ischemic ventricular dysfunction, pericardial or myocardial inflammatory processes, or arrhythmias, and these cardiac causes occur in 0% to 4% of cases (Box 6-4). Table 6-7 summarizes important clinical findings of cardiac causes of chest pain in children.

a. Ischemic myocardial dysfunction

(1) Congenital heart defects. Severe aortic stenosis (AS), subaortic stenosis, severe pulmonary stenosis (PS), and pulmonary hypertension (Eisenmenger syndrome) may cause ischemic chest pain. The pain is usually associated with exercise and is a typical anginal pain.

(2) Mitral valve prolapse. Chest pain associated with mitral valve prolapse (MVP) is usually a vague, nonexertional pain of short duration, located at the apex, without a constant relationship to effort or emotion. Occasionally, supraventricular or ventricular arrhythmias may result in cardiac symptoms, including chest discomfort. Nearly all patients with Marfan syndrome have MVP. A midsystolic click with or without a late systolic murmur is the hallmark of the condition.

(3) Cardiomyopathy. Hypertrophic and dilated cardiomyopathy can cause chest pain from ischemia, with or without exercise, or from rhythm disturbances.

(4) Coronary artery disease. Coronary artery anomalies, either congenital (aberrant or single coronary artery, coronary artery fistula) or acquired (aneurysm or stenosis of the coronary arteries as a result of Kawasaki disease, or as a result of previous cardiac surgery involving the coronary arteries) can rarely cause chest pain.

(5) Cocaine abuse. Cocaine blocks the reuptake of norepinephrine with an increase in circulating levels of catecholamines causing coronary vasoconstriction. Cocaine also induces the activation of platelets, increases endothelin production, and decreases nitric oxide production. These effects collectively produce anginal pain, infarction, arrhythmias, or sudden death.

b. Pericardial or myocardial disease

(1) Pericarditis. Older children with pericarditis may complain of a sharp, stabbing precordial pain that worsens when they lie down and improves after they sit and lean forward. Echo examination is usually diagnostic.

(2) Myocarditis. Acute myocarditis often involves the pericardium to a certain extent and can cause chest pain.

c. Arrhythmias. Chest pain may result from a variety of arrhythmias, especially with sustained tachycardia resulting in myocardial ischemia. Even without ischemia, children may consider palpitation or forceful heartbeats as chest pain. In this situation, chest pain may be associated with dizziness and palpitation.

TABLE 6-7 IMPORTANT CLINICAL FINDINGS OF CARDIAC CAUSES OF CHEST PAIN

C. DIAGNOSTIC APPROACH

A careful history taking and physical examination will suffice to rule out cardiac causes of chest pain in most cases and often find a specific noncardiac cause of the pain. Even if physicians cannot find a specific cause of chest pain, it is relatively easy to rule out cardiac causes of chest pain.

1. History of present illness. The initial history is directed at determining whether the pain is likely of cardiac origin. One asks about the nature of the pain, in terms of its association with exertion or physical activities, the intensity, character, frequency, duration, and points of radiation. A typical anginal pain is located in the precordial or substernal area and radiates to the neck, jaw, either or both arms, back, or abdomen. Exercise, heavy physical activities, or emotional stress typically precipitate the pain. It is not a sharp pain. The patient describes the pain as a deep, heavy pressure; the feeling of choking; or a squeezing sensation. Nonexertional sharp pain of short duration is usually not of cardiac origin. Associated symptoms such as syncope, dizziness, or palpitation with chest pain suggest potential cardiac origin of the pain. Pain that changes with position of the body may suggest pleural pain. The following are some examples of questions used in determining the nature of chest pain.

a. What seems to bring on the pain (e.g., exercise, eating, trauma, emotional stress)?

b. Do you get the same type of pain while you watch TV or sit in class?

c. What is the pain like (e.g., sharp, pressure sensation, squeezing)?

d. What are the location (e.g., specific point, localized, or diffuse), severity, radiation, and duration (seconds, minutes) of the pain?

e. Does the pain get worse with deep breathing? (If so, the pain may be caused by pleural irritation or chest wall pathology.) Does the pain improve with certain body positions? (This is sometimes seen with pericarditis.)

f. Does the pain have any relationship with your meals?

g. How often and how long have you had similar pain (frequency and chronicity)?

h. Have you been hurt while playing, or have you used your arms excessively for any reason?

i. Are there any associated symptoms, such as presyncope, syncope, dizziness, palpitation?

j. Have you been coughing a lot lately?

2. Past and family histories

a. Past history of congenital or acquired heart disease, cardiac surgery, infection, asthma, or Kawasaki disease

b. Medications, such as asthma medicines or birth control pills

c. Family history of recent chest pain or a cardiac death

d. Family history of long QT syndrome, cardiomyopathies, or unexpected sudden death

e. History of exposure to drugs (cocaine) or cigarettes

3. Physical examination

a. The chest should be carefully inspected for trauma or asymmetry. The chest wall should be palpated for signs of tenderness or subcutaneous air. Special attention should be paid to the possibility of costochondritis as the cause of chest pain. Physicians should use the soft part of the terminal phalanx of a middle finger to palpate each costochondral and chondrosternal junction, not the palm of a hand. Pectoralis muscles and shoulder muscles should be examined for tenderness.

b. The skin and extremities should be examined for trauma or chronic disease.

c. The abdomen should be carefully examined because it may be the source of pain referred to the chest.

d. The heart and lungs should be auscultated for arrhythmias, heart murmurs, rubs, muffled heart sounds, gallop rhythm, crackles, wheezes, or decreased breath sounds. One must be careful not to interpret commonly occurring innocent murmurs as pathologic.

4. Other investigations. CXR films (for pulmonary pathology, cardiac size and silhouette, and pulmonary vascularity) and an ECG (for arrhythmias, hypertrophy, conduction disturbances, Wolff-Parkinson-White [WPW] preexcitation, and prolonged QT intervals) may be obtained. Drug screening is ordered when cocaine-induced chest pain is suspected. Clinical findings of cardiac causes of chest pain are summarized in Table 6-7.

5. Tentative diagnosis of noncardiac chest pain

a. The chest pain is likely of noncardiac origin if the following are true.

(1) It is nonexertional, occurring while watching TV or sitting in class; sharp pain; or of chronic nature (many cases of costochondritis have a chronic history of pain, having been there for weeks or months).

(2) The family history is negative for hereditary heart disease (such as long QT syndrome, cardiomyopathies, unexpected sudden death).

(3) The past history is negative for heart disease or Kawasaki disease.

(4) The cardiac examination is unremarkable.

(5) The ECG and CXR films are normal.

b. At this point, the clinician can reassure the patient and family of the probable benign nature of the chest pain. Simple follow-up may clarify the cause or the pain may subside without recurrence. The physician should then consider a condition in other systems, such as gastrointestinal, respiratory systems, or psychogenic origin. Drug screening for cocaine may be worthwhile in adolescents who have acute, severe chest pain and distress with an unclear cause. Appropriate referral to a specialist may be considered at this time.

6. Referral to cardiologists. The following are some indications for referral to a cardiologist for cardiac evaluation of chest pain.

a. When chest pain is triggered or worsened by physical activities or chest pain is accompanied by other symptoms such as palpitation, dizziness, or syncope

b. When there are abnormal findings in the cardiac examination or when abnormalities occur in the CXR films or ECG

c. When there is a family history of cardiomyopathy, long QT syndrome, sudden unexpected death, or other hereditary diseases commonly associated with cardiac abnormalities

d. When there are high levels of anxiety in the family and patient and the pain is of a chronic, recurring nature

D. TREATMENT

When a specific cause of chest pain is identified, treatment is directed at correcting or alleviating the cause.

1. Costochondritis can be treated by reassurance and occasionally by nonsteroidal antiinflammatory agents (such as ibuprofen) or acetaminophen. Ibuprofen is a better choice because it is an antiinflammatory as well as analgesic agent.

2. Most musculoskeletal and nonorganic causes of chest pain can be treated with rest, acetaminophen, or nonsteroidal antiinflammatory agents.

3. Exercise-induced asthma is most effectively prevented by inhalation of a β2-agonist immediately before exercise. Inhaled albuterol usually affords protection for 4 hours.

4. If gastritis, gastroesophageal reflux, or peptic ulcer disease is suspected, trials of antacids, hydrogen ion blockers, or prokinetic agents ( such as metoclopramide [Reglan]) are helpful therapeutically (as well as diagnostically).

5. If organic causes of chest pain are not found and psychogenic etiology is suspected, psychological consultation may be considered.

6. The correct therapy for acute cocaine toxicity has not been established. Calcium channel blockers (nifedipine, nitrendipine), β-adrenergic blockers, nitrates, and thrombolytic agents have resulted in varying levels of success. The use of β-blockers is controversial; they may worsen coronary blood flow.

III. SYNCOPE

A. PREVALENCE

As many as 15% of children and adolescents are estimated to have a syncopal event between the ages of 8 and 18 years.

B. DEFINITION

Syncope is a transient loss of consciousness and muscle tone that results from inadequate cerebral perfusion. Presyncope is the feeling that one is about to pass out while remaining conscious with a transient loss of postural tone. The most common prodromal symptom is dizziness.

C. CAUSES

The normal function of the brain depends on a constant supply of oxygen and glucose. Significant alterations in the supply of oxygen and glucose may result in a transient loss or near loss of consciousness. Syncope may be due to noncardiac causes (usually autonomic dysfunction), cardiac conditions, neuropsychiatric, and metabolic disorders. Box 6-5 lists possible causes of syncope.

BOX 6-5 CAUSES OF SYNCOPE

AUTONOMIC (NONCARDIAC)

Orthostatic intolerance group

Vasovagal syncope (also known as simple, neurocardiogenic, or neurally mediated syncope)

Orthostatic (postural) hypotension (dysautonomia)

Postural orthostatic tachycardia syndrome (POTS)

Situational syncope

Breath holding; cough, micturition; defecation, etc.

Carotid sinus hypersensitivity

Excess vagal tone

CARDIAC

Arrhythmias

Tachycardias: SVT, atrial flutter/fibrillation, ventricular tachycardia (seen with long QT syndrome, arrhythmogenic RV dysplasia)

Bradycardias: sinus bradycardia, asystole, complete heart block, pacemaker malfunction

Obstructive lesions

Outflow obstruction: AS, PS, hypertrophic cardiomyopathy, pulmonary hypertension;

Inflow obstruction: MS, tamponade, constrictive pericarditis, atrial myxoma

Myocardial: coronary artery anomalies, hypertrophic cardiomyopathy, dilated cardiomyopathy, MVP, arrhythmogenic RV dysplasia

NEUROPSYCHIATRIC

METABOLIC

Hypoglycemia

Electrolyte disorders

Anorexia nervosa

Drugs/toxins

In adults, most cases of syncope are caused by cardiac problems. In children and adolescents, however, most incidents of syncope are benign, resulting from vasovagal episodes (probably the most common cause), other orthostatic intolerance entities, hyperventilation, and breath holding. Before age 6 years, syncope is likely caused by a seizure disorder, breath holding, or cardiac arrhythmias. Only circulatory causes of syncope will be discussed in some detail.

1. Noncardiac causes of syncope

a. Orthostatic intolerance. Three easily definable entities of orthostatic intolerance are vasovagal syncope, orthostatic hypotension, and postural orthostatic tachycardia syndrome (POTS).

(1) Vasovagal syncope

(a) Vasovagal syncope (also called simple fainting or neurocardiogenic syncope) is the most common type of syncope in otherwise healthy children and adolescents. This syncope is uncommon before 10 to 12 years of age but quite prevalent in adolescents, especially girls. It is characterized by a prodrome lasting a few seconds to a minute; the prodrome may include dizziness, nausea, pallor, diaphoresis, palpitation, blurred vision, headache, and/or hyperventilation. The prodrome is followed by the loss of consciousness and muscle tone with a fall. The unconsciousness does not last more than a minute. The syncope may occur after rising in the morning or in association with prolonged standing, anxiety or fright, pain, blood drawing or the sight of blood, fasting, hot and humid conditions, or crowded places.

(b) The normal responses to the assumption of an upright posture are a reduced cardiac output, an increase in heart rate, and an unchanged or slightly diminished systolic pressure (Fig. 6-2) with about 6% decrease in cerebral blood flow. Pathophysiology of vasovagal syncope is not completely understood, but one theory is as follows: In susceptible individuals, a sudden decrease in venous return to the ventricle produces a large increase in the force of ventricular contraction, which causes activation of the left ventricular mechanoreceptors. A sudden increase in neural traffic to the brainstem somehow mimics the conditions seen in hypertension and thereby produces a paradoxical withdrawal of sympathetic activity, resulting in a peripheral vasodilation, hypotension, bradycardia, and subsequent decrease in cerebral perfusion (Fig. 6-2).

(c) History is most important in establishing the diagnosis of vasovagal syncope. Tilt testing of various protocols is useful in diagnosing vasovagal syncope, but its specificity and reproducibility are questionable.

(2) Orthostatic hypotension (dysautonomia)

(a) The normal response to standing is reflex arterial and venous constriction and a slight increase in heart rate. In orthostatic hypotension the normal adrenergic vasoconstriction of the arterioles and veins in the upright position is absent or inadequate, resulting in hypotension without a reflex increase in heart rate (Fig. 6-2). Unlike the prodrome seen with vasovagal syncope, in orthostatic hypotension, patients experience only light-headedness. They do not display the autonomic nervous system signs seen with vasovagal syncope, such as pallor, diaphoresis, and hyperventilation. Prolonged bed rest, prolonged standing, dehydration, drugs that interfere with the sympathetic vasomotor response (e.g., calcium channel blockers, antihypertensive drugs, vasodilators, phenothiazines), and diuretics may exacerbate orthostatic hypotension.