Heart Failure
Heart failure occurs when the heart cannot deliver adequate cardiac output to meet the
metabolic needs of the body. In the early stages of heart failure, various compensatory
mechanisms are evoked to maintain normal metabolic function. When these mechanisms
become ineffective, increasingly severe clinical manifestations result.
CLINICAL MANIFESTATIONS.
The clinical manifestations of heart failure depend on the degree of the child's cardiac
reserve. A critically ill infant or child who has exhausted the compensatory mechanisms
to the point that cardiac output is no longer sufficient to meet the basal metabolic needs
of the body will be symptomatic at rest. Other patients may be comfortable when quiet
but are incapable of increasing cardiac output in response to even mild activity without
experiencing significant symptoms. Conversely, it may take rather vigorous exercise to
compromise cardiac function in children who have less severe heart disease. A thorough
history is extremely important in making the diagnosis of heart failure and in evaluating
the possible causes. Parents who observe their child on a daily basis may not recognize
subtle changes that have occurred in the course of days or weeks. Gradually worsening
perfusion or increasing cyanosis may not be recognized as an abnormal finding. Edema
may be passed off as normal weight gain, and exercise intolerance as lack of interest in
an activity. The history of a young infant should also focus on feeding. An infant with
heart failure often takes less volume per feeding, becomes dyspneic while sucking, and
may perspire profusely. Eliciting a history of fatigue in an older child requires detailed
questions about activity level and its course over several months.
In children, the signs and symptoms of heart failure may be similar to those in adults and
include fatigue, effort intolerance, anorexia, abdominal pain, dyspnea, and cough. Many
children, however, especially adolescents, may have primarily abdominal symptoms and
a surprising lack of respiratory complaints. Attention to the cardiovascular system may
come only after an abdominal roentgenogram unexpectedly shows the lower end of an
enlarged heart. The elevation in systemic venous pressure may be gauged by clinical
assessment of jugular venous pressure and liver enlargement. Orthopnea and basilar rales
are variably present; edema is usually discernible in dependent portions of the body, or
anasarca may be present. Cardiomegaly is invariably noted. A gallop rhythm is common;
when ventricular dilatation is advanced, the holosystolic murmur of mitral or tricuspid
valve regurgitation may be heard.
In infants, heart failure may be difficult to identify. Prominent manifestations include
tachypnea, feeding difficulties, poor weight gain, excessive perspiration, irritability, weak
cry, and noisy, labored respirations with intercostal and subcostal retractions, as well as
flaring of the alae nasi. The signs of cardiac-induced pulmonary congestion may be
indistinguishable from those of bronchiolitis; wheezing is prominent. Pneumonitis with
or without atelectasis is common, especially in the right middle and lower lobes; it is due
to bronchial compression by the enlarged heart. Hepatomegaly usually occurs, and
cardiomegaly is invariably present. In spite of pronounced tachycardia, a gallop rhythm
can frequently be recognized. The other auscultatory signs are those produced by the
underlying cardiac lesion. Clinical assessment of jugular venous pressure in infants may
be difficult because of the shortness of the neck and the difficulty of observing a relaxed
state. Edema may be generalized and usually involves the eyelids as well as the sacrum
and less often the legs and feet. The differential diagnosis is age dependent
-- Etiology of Heart Failure
FETAL
Severe anemia (hemolysis, fetal-maternal transfusion, parvovirus B19–induced
anemia, hypoplastic anemia)
Supraventricular tachycardia
Ventricular tachycardia
Complete heart block
Severe Ebstein anomaly or other severe right-sided lesions
Myocarditis
PREMATURE NEONATE
Fluid overload
Patent ductus arteriosus
Ventricular septal defect
Cor pulmonale (bronchopulmonary dysplasia)
Hypertension
Myocarditis
Genetic cardiomyopathy
FULL-TERM NEONATE
Asphyxial cardiomyopathy
Arteriovenous malformation (vein of Galen, hepatic)
Left-sided obstructive lesions (coarctation of aorta, hypoplastic left heart
syndrome)
Large mixing cardiac defects (single ventricle, truncus arteriosus)
Myocarditis
Genetic cardiomyopathy
INFANT-TODDLER
Left-to-right cardiac shunts (ventricular septal defect)
Hemangioma (arteriovenous malformation)
Anomalous left coronary artery
Genetic or metabolic cardiomyopathy
Acute hypertension (hemolytic-uremic syndrome)
Supraventricular tachycardia
Kawasaki disease
Myocarditis
CHILD-ADOLESCENT
Rheumatic fever
Acute hypertension (glomerulonephritis)
Myocarditis
Thyrotoxicosis
Hemochromatosis-hemosiderosis
Cancer therapy (radiation, doxorubicin)
Sickle cell anemia
Endocarditis
Cor pulmonale (cystic fibrosis)
Genetic or metabolic cardiomyopathy (hypertrophic, dilated)
DIAGNOSIS.
Roentgenograms of the chest show cardiac enlargement. Pulmonary vascularity is
variable and depends on the cause of the heart failure. Infants and children with large leftto-right shunts have exaggeration of the pulmonary arterial vessels to the periphery of the
lung fields, whereas patients with cardiomyopathy may have a relatively normal
pulmonary vascular bed early in the course of disease. Fluffy perihilar pulmonary
markings suggestive of venous congestion and acute pulmonary edema are seen only with
more severe degrees of heart failure. Cardiac enlargement is often noted as an unexpected
finding on a chest roentgenogram performed to evaluate for a possible pulmonary
infection, bronchiolitis, or asthma.
Chamber hypertrophy noted by electrocardiography may be helpful in assessing the cause
of heart failure but does not establish the diagnosis. In cardiomyopathies, left or right
ventricular ischemic changes may correlate well with clinical and other noninvasive
parameters of ventricular function. Low-voltage QRS morphologic characteristics with
ST-T wave abnormalities may also suggest myocardial inflammatory disease but can be
seen with pericarditis as well. The electrocardiogram is the best tool for evaluating
rhythm disorders as a potential cause of heart failure.
Echocardiographic techniques are most useful in assessing ventricular function. The
most commonly used parameter in children is fractional shortening (a single dimensional
variable), determined as the difference between end-systolic and end-diastolic diameter
divided by end-diastolic diameter. Normal fractional shortening is between 28% and
40%. In adults, the most commonly used parameter is ejection fraction (which uses twodimensional data to calculate a three-dimensional volume) and the normal range is 55–
65%. In children with right ventricular enlargement or other cardiac pathology resulting
in flattening of the interventricular septum, ejection fraction is used since fractional
shortening will not be accurate. Doppler studies can be used to estimate cardiac output.
Magnetic resonance angiography (MRA) can be useful in quantifying left and right
ventricular function and mass. If valvar regurgitation is present, MRA can quantify the
regurgitant fraction.
TREATMENT.
The underlying cause of cardiac failure must be removed or alleviated if possible
General Measures.
Strict bed rest is rarely necessary except in extreme cases, but it is important that the
child be allowed to rest during the day as needed and sleep adequately at night. Some
older patients feel better sleeping in a semi-upright position, using several pillows
(orthopnea).
Diet.
Infants with heart failure may fail to thrive because of increased metabolic requirements
and decreased caloric intake. Increasing daily calories is an important aspect of their
management. Increasing the number of calories per ounce of infant formula (or
supplementing breast-feeding) may be beneficial. Many infants do not tolerate an
increase beyond 24 calories/oz because of diarrhea or because these formulas provide too
large a solute load for compromised kidneys
Digitalis.
Digoxin, once the mainstay of heart failure management in both children and adults, is
currently used less, as a result of the introduction of newer therapies and the recognition
Digoxin should be discontinued if a new rhythm disturbance is noted. Prolongation of the P-R
interval is not necessarily an indication to withhold digitalis, but a delay in administering the
next dose or a reduction in the dosage should be considered, depending on the patient's clinical
status. Serum digoxin determination is helpful when digitalis toxicity is suspected, although it
may be less reliable in infants. ST segment or T-wave changes are commonly noted with digitalis
administration and should not affect the digitalization regimen. Baseline serum electrolyte levels
should be measured before and after digitalization. Hypokalemia and hypercalcemia exacerbate
digitalis toxicity. Because hypokalemia is relatively common in patients receiving diuretics,
potassium levels should be monitored closely in those receiving a potassium-wasting diuretic
(e.g., furosemide) in combination with digitalis. In patients with active myocarditis, some
cardiologists recommend avoiding digitalization altogether and starting maintenance digitalis at
half the normal dose due to the increased risk of arrhythmia in these patients.of its potential
toxicities
Diuretics
Furosemide is the most commonly used diuretic in patients with heart failure. It inhibits the
reabsorption of sodium and chloride in the distal tubules and the loop of Henle. Patients
requiring acute diuresis should be given intravenous or intramuscular furosemide at an initial
dose of 1–2 mg/kg, which usually results in rapid diuresis and prompt improvement in clinical
Spironolactone is an inhibitor of aldosterone and enhances potassium retention, often
eliminating the need for oral potassium supplementation, which is frequently poorly tolerated.
This drug is usually given orally in two to three divided doses of 2–3 mg/kg/24 hr.status.
Chlorothiazide is used occasionally for diuresis in children with less severe chronic heart failure.
It is less immediate in action and less potent than furosemide
Afterload-Reducing Agents and ACE Inhibitors.
This group of drugs reduces ventricular afterload by decreasing peripheral vascular
resistance and thereby improving myocardial performance. Some of these agents also
decrease systemic venous tone, which significantly reduces preload. Afterload reducers
are especially useful in children with heart failure secondary to cardiomyopathy and in
patients with severe mitral or aortic insufficiency.Intravenously administered agents
such as nitroprusside should be administered only in an intensive care setting.The orally
active ACE inhibitor captopril produces arterial dilatation by blocking the production of
angiotensin II, thereby resulting in significant afterload reduction.
α- and β-Adrenergic Agonists.
Dopamine is a predominantly β-adrenergic receptor agonist, but it has α-adrenergic effects at
higher doses. Dopamine has less chronotropic and arrhythmogenic effect than the pure βagonist isoproterenol does. In addition, it results in selective renal vasodilation because of its
interaction with renal dopamine receptors, which is particularly useful in patients with the
compromised kidney function that is often associated with low cardiac output. At a dose of 2–10
μg/kg/min, dopamine results in increased contractility with little peripheral vasoconstrictive
effect. If the dose is increased beyond 15 μg/kg/min, Dobutamine, a derivative of dopamine, is
useful in treating low cardiac output. It causes direct inotropic effects with a moderate
reduction in peripheral vascular resistance. Dobutamine can be used as an adjunct to dopamine
therapy to avoid the vasoconstrictive effects of high-dose dopamine. Dobutamine is also less
likely to cause cardiac rhythm disturbances than isoproterenol is. The usual dose is 2–20
μg/kg/min.Isoproterenol is a pure β-adrenergic agonist that has a marked chronotropic effect; it
is most effective in patients with slow heart rates and should be used with caution in those who
already have significant tachycardia..Epinephrine is a mixed α- and β-adrenergic receptor
agonist that is usually reserved for patients with cardiogenic shock and low arterial blood
pressure. Although epinephrine can raise blood pressure effectively, it also increases systemic
vascular resistance and therefore increases the afterload against which the heart has to work.
Phosphodiesterase Inhibitors.
Milrinone is useful in treating patients with low cardiac output who are refractory to
standard therapy and has been shown to be highly effective in managing low-output state
in children after open heart surgery. It works by inhibition of phosphodiesterase, which
prevents the degradation of intracellular cyclic adenosine monophosphate. Milrinone has
both positive inotropic effects on the heart and significant peripheral vasodilatory effects
and has generally been used as an adjunct to dopamine or dobutamine therapy in the
intensive care unit.. A major side effect is hypotension secondary to peripheral
vasodilation, especially when a loading dose is used.
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