Clinical Presentation of Congenital Heart
Disease by Nancy Braudis. My name is Nancy Braudis, and I am a clinical
nurse specialist in the cardiac ICU at Children’s Hospital Boston. Introduction. Children with congenital heart disease often
present in one of three pathophysiological states. Low cardiac output. This occurs when there’s a heart defect that
obstructs the flow of blood from the heart, or when the heart muscle is unable to pump
effectively. Congestive heart failure. This often occurs when there is a heart defect
that causes an increase in blood flow to the lungs. Cyanosis. This occurs when there is a heart defect that
causes a decrease in blood flow to the lungs. Cardiac Assessment. On admission, a full cardiac assessment should
be completed. This includes a comprehensive history that
should identify if there was a prenatal diagnosis or any significant birth and genetic history. A complete set of vital signs should be done
as a baseline, and a set of blood pressures in all four extremities should be done to
evaluate for any gradient within the aorta. The physical exam includes evaluation of general
color, body temperature, evaluation of heart sounds, and the presence of any murmurs, assessment
of the liver will indicate if there is an overload of fluid on the right side of the
heart, and the quality and strength of pulses. Diagnostic tests should include a chest radiograph,
an electrocardiogram. Other tests may include an echocardiogram
or a cardiac catheterization. Low Cardiac Output. Signs of low cardiac output in infants and
children include pale or mottled skin color, irritability, cool and clammy skin, or decreased
level of consciousness, decreased urine output, capillary refill greater than three seconds,
metabolic acidosis, hypoglycemia, and increased serum lactate. Other signs include weak pulses, temperature
instability, or apnea. There may also be evidence of organ dysfunction
such as kidney or liver failure. Late signs include hypotension, cyanosis,
anuria, and altered mental status. Interventions to improve low cardiac output
include correcting the heart rate and restoring normal conduction within the heart, administration
of fluids, correcting acid-base imbalance and electrolyte abnormalities, and using medications
to improve the function of the heart and to reduce the stress on the body. Congestive Heart Failure. Congestive heart failure occurs when the heart
cannot deliver enough blood to meet the demands of the body. The heart attempts to compensate by increasing
the heart rate, thickening the walls of the heart to contract more effectively, or dilating
the heart to increase the volume of blood within the heart to improve cardiac output. Congestive heart failure occurs in 30% of
infants and children with congenital heart disease and occurs in over 75% of children
with complex heart disease. The causes of congestive heart failure include
volume overload of the heart, pressure overload of the heart, and a heart muscle dysfunction. Some of the clinical signs of congestive heart
failure include tachypnea, retractions, nasal flaring, diaphoresis, pulmonary edema, irritability,
change in responsiveness, fatigue, poor feeding, failure to thrive, tachycardia, cool skin,
decreased urine output, an enlarged liver, periorbital edema, pulmonary effusions, and
ascites. Interventions for congestive heart failure
include medications, such as diuretics to eliminate excess fluid, limiting fluid administration,
and improved nutrition to maximize calories. Other interventions include respiratory support
to reduce the work of breathing and temperature control. Cyanosis. Cyanosis occurs when neonates are unable to
tolerate the changes that occur when the blood flow within the heart changes after birth. Cyanosis may also occur in infants and children
with congenital heart defects that cause a decrease in blood flow to the lungs. Cyanosis: respiratory or cardiac? When cyanosis occurs with respiratory disease,
the cyanosis usually decreases with crying, improves with oxygen administration, and there
are usually signs of respiratory distress. When cyanosis occurs with cardiac disease,
the cyanosis usually increases with crying because the demand of oxygen increases, but
the body is unable to deliver sufficient oxygen. Cyanosis with cardiac disease does not usually
improve significantly with the administration of supplemental oxygen, and the infants usually
breathe fast but do not have evidence of respiratory distress. Tests that can help in the diagnosis of respiratory
or cardiac disease include a 12-lead electrocardiogram, a chest radiograph, and a hyperoxia test that
involves evaluating the oxygen content of the blood with and without supplemental oxygen. Point of clarification. Hyperoxia test. The basic physiology of the hyperoxia test
is that you are going to use supplemental oxygen to distinguish between cardiac and
pulmonary causes of cyanosis. Specifically, the way that the test is done
is that you obtain a preductal arterial blood gas in the cyanotic patient. So that is typically a radial arterial blood
gas to measure the oxygen tension in arterial blood on room air. You then place the patient in an oxygen-rich
environment. So that’s at 100% oxygen for 10 minutes. That can be either via ventilator or via an
oxy hood. After 10 minutes of breathing in oxygen-rich
environment, you repeat the blood gas preductally– so the radial arterial blood gas– and remeasure
the partial pressure of oxygen in arterial blood. Typically, the cutoffs that we use here at
Children’s Hospital Boston is a PaO2, in your arterial blood of greater than 150 indicates
a high likelihood of a known cardiac cause of cyanosis, such as pulmonary venous desaturation. A PaO2 of less than 150 is very suspicious
for a cardiac cause of cyanosis as a right-to-left shunt cannot be overcome by the provision
of supplemental oxygen. Degraded further, we consider a PaO2 of less
than 100 very suspicious for cyanotic congenital heart disease, and this should trigger cardiac
consultation. Signs of cyanosis with congenital heart disease
include bluish discoloration of skin and mucous membranes, increased respiratory rate and
effort, irritability, or lethargy. Other signs include decreased blood flow to
the body, decreased urine output, and metabolic acidosis. Long-term effects of chronic cyanosis include
an increased hematocrit, thickening of the blood, increased risk of clot formation, clubbing
of fingers, and an increase in the release of oxygen to the tissues. Interventions to reduce cyanosis include maintaining
a high hematocrit to maximize oxygen-carrying capacity and fluid administration to reduce
the thickness of the blood. Other interventions include the administration
of supplemental oxygen– close monitoring for air in intravenous infusion lines is essential
to reduce the risk of air traveling to the brain in an infant or child with cyanotic
heart disease– and using alprostodil in neonates to keep the ductus arteriosus open to allow
mixing of blood within the heart. Please help us improve the content by providing
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