Congestive Heart Failure MUHAMMAD ALI Cardiology Division Department of Child Health University of Sumatera Utara

Definition 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 venous return adequately, or a combination of the two. Cause CHF may result from congenital or acquired heart diseases with volume and/or pressure overload or from myocardial insufficiency.

CONGENITAL HEART DISEASE CHD with volume or pressure overload is the most common cause of CHF in the pediatric age group. Volume overload lesions, such as VSD, PDA and ECD, are the most common causes of CHF in the first 6 months of life. The time of onset of CHF varies predictably with the type of defect. Children with TOF) do not develop CHF unless they have received a large aorta—to—pulmonary artery (PA) shunt procedure (such as the Waterston or Potts operation), which is no longer performed.

ASD rarely causes CHF in the pediatric age group, although it causes CHF in adulthood. Large L-R shunt lesions, such as VSD and PDA, do not cause CHF before 6 to 8 weeks of age because the PVR does not fall low enough to cause a large left-to- right shunt until this age. The onset of CHF resulting from L-R shunt lesions may be earlier in premature infants (within the first month) because of an earlier fall in the PVR in these infants.

ACQUIRED HEART DISEASE Acquired heart disease of various causes can lead to CHF. With acquired heart disease, the age at onset of CHF is not as predictable as with congenital heart disease, but the following generalities apply: Metabolic abnormalities (severe hypoxia and acidosis, as well as hypoglycemia and hypocalcemia) can cause CHF in newborns. Endocardial fibroelastosis, a rare primary myocardial disease, causes CHF in infancy; 90% of cases occur in the first 8 months of life. Viral myocarditis tends to be more common in small children older than 1 year. It occurs occasionally in the newborn period, with a fulminating clinical course. Acute rheumatic carditis is an occasional cause of CHF that occurs primarily in schoolchildren.

Rheumatic valvular heart diseases, usually volume overload lesions such as MR or AR, cause CHF in older children and adults. These diseases are uncommon in industrialized countries. Dilated cardiomyopathy of the idiopathic type may cause CHF at any age during childhood and adolescence. Cardiomyopathies associated with muscular dystrophy and Friedreich's ataxia may cause CHF in older children and adolescents. Doxorubicin cardiomyopathy may manifest months to years after the completion of chemotherapy for malignancies in children.

MISCELLANEOUS CAUSES Miscellaneous causes include the following: Supraventricular tachycardia (SVT) causes CHF in early infancy. Complete heart block associated with structural heart defects causes CHF in the newborn period or early infancy. Severe anemia may be a cause of CHF at any age, hydrops fetalis may be a cause in the newborn period, and severe sicklemia may be a cause at a latter age. Acute hypertension, as seen in acute postinfectious glomerulonephritis, causes CHF in school-age children. Fluid retention with poor renal function is important as the cause of hypertension in this condition. Bronchopulmonary dysplasia seen in premature infants causes predominantly right-sided heart failure in the first few months of life. Acute cor pulmonale caused by acute airway obstruction (such as seen with large tonsils) can cause CHF at any age but most commonly during early childhood.

Clinical Manifestations The diagnosis of CHF relies on several sources of clinical findings, including history, physical examination, and chest-x-ray films. In addition to the physical findings discussed here, cardiomegaly on a chest film is nearly a prerequisite sign of CHF; an ECG is perhaps the least important test for the diagnosis of CHF. No single test is specific for CHF; the diagnosis is based on several clinical findings. History Poor feeding of recent onset, tachypnea that worsens during feeding, poor weight gain, and cold sweat on the forehead suggest CHF in infants. Older children may complain of shortness of breath, especially with activities, easy fatigability, puffy eyelids, or swollen feet.

Physical Examination Physical findings of CHF may be classified as follows, depending on their pathophysiologic mechanisms. The more common findings are in italics. The following are compensatory responses to impaired cardiac function: –Tachycardia, gallop rhythm, and weak and thready pulse –Cardiomegaly is almost always present. –There are signs of increased sympathetic discharges (e.g., growth failure; perspiration; cold, wet skin). Pulmonary venous congestion (left-sided failure) results in the following: –Tachypnea is common. –Dyspnea on exertion (poor feeding in small infants) is common. –Orthopnea may be seen in older children. –Wheezing and pulmonary crackles may be audible.

Systemic venous congestion (right-sided failure) results in the following: Hepatomegaly is common, but it is not always indicative of CHF. A large liver may be palpable in the absence of CHF. Conversely, the absence of hepatomegaly does not rule out CHF; hepatomegaly may be absent in (early) left-sided failure. Puffy eyelids are common in infants. Distended neck veins and ankle edema, which are common in adults, are not seen in infants. Splenomegaly is not indicative of chronic CHF; it usually indicates infection.

X-ray Studies The presence of cardiomegaly should be demonstrated by chest x-ray films. The absence of cardiomegaly almost rules out the diagnosis of CHF. However, the presence of cardiomegaly per se does not mean that CHF is present, because some children with large left-to-right shunt lesions have cardiomegaly without heart failure. Electrocardiography ECGs help determine the type of defect but are not helpful in deciding whether CHF is present. Echocardiography Echo may confirm an enlarged chamber or impaired left ventricle (LV) function (decreased fractional shortening or ejection fraction, increased left preejection period/left ventricular ejection time). A more important role of echo may be its ability to determine the cause of CHF. Echo is also useful in serial evaluation of the efficacy of therapy.

Management The treatment of CHF consists of (1) elimination of the underlying causes (2) elimination of the precipitating or contributing causes (e.g., infection, anemia, arrhythmias, fever) (3) control of heart failure state by the use of multiple drugs, usually inotropic agents, diuretics, and afterload-reducing agents, along with general supportive measures. Eliminating the underlying causes is the most desirable approach whenever possible. Surgical correction of CHDs is such an approach. Every patient with CHF should receive maximal medical treatment, but continuing with long-term anticongestive measures is unwise when the heart defect can be safely repaired through surgery.

GENERAL MEASURES A “cardiac chair” or “infant seat” is used to relieve respiratory distress. Oxygen (40% to 50%) with humidity is administered to infants with respiratory distress. Sedation with morphine sulfate (0.1 to 0.2 mg/kg per dose subcutaneously every 4 hours as needed) or phenobarbital (2 to 3 mg/kg per dose by mouth or intramuscularly every 8 hours as necessary) for 1 to 2 days occasionally is indicated. Salt restriction in the form of a low-salt formula and severe fluid restriction are not indicated in infants. Use of diuretics has replaced these measures. In older children, salt restriction (<0.5 g/day) and avoidance of salty snacks (chips, pretzels) and table salt are recommended. Daily weight measurement is essential in hospitalized patients. Predisposing factors, such as fever, anemia, and infection, are eliminated. For anemia, packed cell transfusions are given to raise the hematocrit to 35% or higher. Underlying causes such as hypertension, arrhythmias, and thyrotoxicosis are treated.

DRUG THERAPY Three major classes of drugs are used in the treatment of CHF in children: inotropic agents, diuretics, and afterload-reducing agents. Rapidly acting inotropic agents (dopamine, dobutamine) are used in critically or acutely ill infants and children. Digoxin is used in all noncritically ill patients. The use of digoxin is contraindicated in hypertrophic cardiomyopathy, complete heart block, or cardiac tamponade. Diuretics are almost always used with inotropic agents. Afterload-reducing agents have gained popularity because they can increase cardiac output without increasing myocardial oxygen consumption.

THANK YOU