A Nurse Assessing an Infant Admitted With a Poor History of Feeding Hears a Continuous Murmer

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Introduction

Each year, approximately one percent of all babies born in the United States are diagnosed with congenital heart disease (CHD). As many as one-third of these babies will be critically ill and require care by cardiologists in the first days to weeks of life. Depending on the type of heart problem, initial signs and symptoms may include tachypnea, cyanosis, or a heart murmur. With severe forms of CHD, there may be marked cyanosis, respiratory distress, and rapid progression to advanced states of shock. Prompt, effective care of neonates with CHD can reduce secondary organ damage, improve short and long-term outcomes and reduce mortality (AMA, 2020).

Cardiovascular assessment of the newborn requires great skill with inspection, palpation, and auscultation techniques. Inspection of the general activity of the neonate, breathing patterns, presence or absence of cyanosis, and activity of the precordium are all important. Palpation of pulses, peripheral perfusion, and thrills are also imperative. Auscultation, however, is the main focus of the exam. This time is when the examiner assesses heart rate, rhythm, regularity, and heart sounds (especially murmurs). The dynamic properties of the newborn heart make this assessment more complicated than the cardiac assessment of an adult.

The cardiovascular exam constantly changes over the first few hours, days, and weeks of life as the neonate changes from fetal circulation with the placental circuitry to the newborn lung circuitry. Because changes in ductal flow, decreasing pulmonary vascular resistance, and increasing systemic vascular resistance occurs over the first few hours and days of life, cardiovascular assessments should be done shortly after birth, at six to twelve hours of age, and again at one to three days of life in addition to regular intervals after discharge (Mckee-Garret, 2019).

Fetal Circulation

Knowledge of the normal route of fetal blood flow is essential for understanding the circulatory changes at delivery. Fetal circulation is anatomically and physiologically different from adult circulation in several important ways. In the fetus, oxygenation of the blood and removal of carbon dioxide and wastes occurs in the placenta, a low-resistance circulatory pathway. Because placental oxygenation is not as efficient as pulmonary oxygenation, the fetus' arterial oxygen tension (PaO2) is approximately 20 to 30 torr.

Since fetal hemoglobin binds more tightly to oxygen, and the fetal oxyhemoglobin dissociation curve is located to the left of the adult curve, this oxygen tension corresponds to an arterial oxygen saturation of 60 to 70 percent. Fetal circulation involves three unique anatomic features not present in the adult other than the placenta and the umbilical vein and arteries. The ductus venosus permits most blood from the placenta to bypass the liver and enter the inferior vena cava. When this blood enters the right atrium, most of it is diverted toward the atrial septum. The foramen ovale is the opening in the interatrial septum that permits a portion of blood to flow from the right atrium directly to the left atrium. This blood then enters the left ventricle and aorta to perfuse the head and upper extremities of the fetus (Mayo Clinic, 2020).

Venous return from the head and upper extremities pass to the heart through the superior vena cava. Most of this blood flows through the right atrium into the right ventricle and enters the pulmonary artery. Since pulmonary vascular resistance is very high and systemic vascular resistance is low most of the blood in the main pulmonary artery flows through the ductus arteriosus and into the descending aorta to perfuse the trunk and lower extremities.

The patent ductus arteriosus (PDA) is a tubular communication between the pulmonary artery and the descending aorta that allows blood to flow between the pulmonary artery to the aorta, bypassing the fetal lungs. Only about eight percent of fetal cardiac output enters the lungs; 92 percent is diverted through the ductus arteriosus into the descending aorta. Fetal circulation can be described as two parallel circuits rather than the serial circuit present in extrauterine life.

Neonatal Circulation

The clamping of the umbilical cord and the subsequent removal of the placenta causes immediate circulatory changes in the neonate. With the first breath and occlusion of the umbilical cord, systemic resistance is elevated, which reduces blood flow through the ductus arteriosus. Cord occlusion causes a rapid rise in blood pressure and a corresponding stimulation of the aortic baroreceptors and the sympathetic nervous system. The onset of respirations and lung expansion causes a decrease in pulmonary vascular resistance secondary to the direct effect of oxygen and carbon dioxide on the blood vessels. Resistance decreases as arterial oxygen increases and arterial carbon dioxide decreases (AMA, 2020).

The major portion of the right ventricular output flows through the lungs and increases the pulmonary venous return to the left atrium. The increased amount of blood in the lungs and heat causes increased pressure in the left atrium. The increased pressure in the left atrium, combined with the increased systemic resistance, functionally closes the foramen ovale. In most individuals, the foramen ovale becomes sealed by fibrin and cell products deposit during the first months of life. This process is referred to as the anatomic closure of the foramen ovale.

However, in approximately 25 percent of the population, the foramen ovale is not anatomically sealed, so it remains probe-patent beyond adolescence. This finding means that a catheter can be passed from the right to the left atrium during cardiac catheterization or that probe can be passed through the foramen ovale during cardiovascular surgery.

Until the foramen ovale is anatomically sealed, anything that significantly increases right atrial pressure can reopen the foramen ovale, making it patent. Due to the opening structure, the shunt through the patent foramen ovale is primarily from the right to the left atrium. However, if both atria become much enlarged, the foramen ovale may become stretched open, permitting bi-directional shunting of blood at the atrial level.

The three major fetal shunts, the ductus venosus, the foramen ovale, and the patent ductus arteriosus, are normally eliminated within the first days of life. Following the closure of these shunts, postnatal circulation is established. Systemic venous blood enters the right atrium from the superior and inferior vena cavae. This poorly oxygenated blood enters the right ventricle and then passes through the pulmonary artery and into the pulmonary circulation, where it becomes oxygenated. The pulmonary venous blood returns to the left atrium through the pulmonary veins. This blood passes through the left heart and into the aorta to supply systematic circulation (AMA, 2020).

When the lungs expand and become air-filled, the fetal lung fluid is primarily absorbed into the pulmonary capillaries. Since the lungs provide more efficient oxygenation of the blood than does the placenta, the neonate's arterial oxygen tension rises, this rise is thought to be the most potent stimulus to constriction of the ductus arteriosus. The increase in the oxygen tension of the blood bathing the ductus may also contribute to ductal constriction. Acidosis and a fall in endogenous prostaglandin levels also promote ductal closure.

If the infant has a congenital heart defect producing increased pulmonary blood flow, such as a patent ductus arteriosus or a ventricular septal defect, pulmonary vascular resistance will not normally fall after birth. Such neonates demonstrate a delayed and less marked drop in pulmonary vascular resistance during the first four to twelve weeks of life (this drop may occur over a shorter period in the premature neonate). Because of this delay, a fall in pulmonary vascular blood flow often fails to become apparent until the child is four to twelve weeks of age. These symptoms may develop earlier if the infant is premature.

Cardiac Assessment

A review of the maternal, fetal, and neonatal history is helpful in the cardiac evaluation of the newborn (Geggel, 2019). The following is a list of hereditary diseases in which congenital heart disease (CHD) is a frequent finding (Pierpoint et al., 2018):

Hereditary	Common Cardiac Disease	Important Features
Apert's Syndrome	VSD	Irregular craniosynostosis with particular head and facial appearances Syndactyly of digits and toes
Crouszon's disease (craniofacial dysostosis)	PDA, COA	Ptosis with shallow orbits Craniosynostosis, maxillary hypoplasia
Down's Syndrome	AV defect, VSD, PDA
Di George	Truncus, TET
Ehler-Danlos syndrome	Aneurysm of aorta and carotids	Hyperextensive joints, hyperelasticity, fragility, and bruisability of skin
Ellis-van Creveld syndrome (chondroectodermal dysplasia)	Single atrium	Neonatal teeth, short distal limbs, polydactyly, nail hypoplasia
Friedreich's ataxia	Cardiomyopathy	Late-onset ataxia, skeletal deformities
Glycogen storage disease II (Pompe's disease)	Cardiomyopathy	Large tongue and flabby muscles, cardiomegaly; ECD: LVH and short PR; normal FBS and GTT
Holt-Oram syndrome (cardiac-limb)	ASD, VSD	Defects or absence of thumb or radius
Idiopathic hypertrophic subaortic stenosis (IHSS)	Muscular subaortic stenosis
Leopard syndrome	PS, cardiomyopathy	Legitinous skin lesion, ECG abnormalities, Ocular hypertelorism, Pulmonary stenosis, Abnormal genitalia, retarded growth, deafness
Long QT syndrome: Jervell and Lange-Nielsen, and Romano-Ward	Long QT interval, Ventricular tachyarrhythmias	Congenital deafness (not in Romano-Ward), syncope due to ventricular arrhythmias; family history of sudden death
Marfan's syndrome	Aortic aneurysm, aortic regurgitation, and/or mitral regurgitation	Arachnodactyly, subluxation of the lens
Mitral valve prolapse syndrome (primary)	Mitral regurgitation Dysrhythmias	Thoracic skeletal anomalies (80%)
Mucopolysaccharidosis Hurler's (type I) Hunter's (type II) Morquio's (type IV)	Aortic regurgitation/mitral regurgitation, coronary artery disease	Coarse features, large tongue, depressed nasal bridge, kyphosis, retarded growth, hepatomegaly, corneal opacity (not in Hunter's), mental retardation
Muscular dystrophy	Cardiomyopathy	Waddling gait, "pseudohypertrophy" of the calf muscle
Neurofibromatosis (von Recklinghausen's disease)	PS, COA	Café au lait spots, acoustic neuroma, variety of bone lesions
Noonan's syndrome	PS (dystrophic pulmonary valve)	Similar to Turner's syndrome but may occur in phenotypic male and without a chromosomal abnormality
Rendu-Osler-Weber syndrome	Pulmonary AV fistulas	Hepatic involvement; telangiectases, hemangiomas or fibrosis
Trisomy 13	VSD
Trisomy 18	VSD, PDA, DORV
Tuberous sclerosis	Rhabdomoyoma	Adenoma sebaceum (2-5 years of age), convulsions mental defect
Turner syndrome	COA, PS
VATER	VSD, TET
William's syndrome (surpavalvular aortic stenosis)	Surpavalvular aortic stenosis, PA stenosis	Mental retardation, peculiar "elfin" facies, hypercalcemia of infancy

A history that may be associated with congenital heart defects:

• Maternal infections, especially viral and protozoal infections, early in pregnancy
• Maternal use of tobacco, alcohol, or drugs. Maternal drugs are known to cause congenital heart defects:

Drug	Defect
Diphenylhydanten Fetal hydantoin syndrome	PS, AS
Trimethadoine	VSD, TET
Thalidomide	TET, Trunctus
Lithium	Epstein's anomaly
Alcohol Fetal alcohol syndrome	VSD, ASD

Neonatal history that indicates possible cardia disease includes:

• Cyanosis
• Tachypnea without pulmonary disease
• Sweating
• Poor feeding
• Edema

Physical Assessment

Inspection

As part of the inspection, the nurse should evaluate the newborn's activity: sleeping or awake, alert or lethargic, anxious, or relaxed. The nurse should also check respiratory effort, including signs of respiratory distress such as nasal flaring, expiratory grunting, stridor, retractions, or paradoxical respirations. Next, the nurse should note the skin color in a well-lit room. (Assess mucous membranes in dark-skinned neonates).

Normal findings:

• Acrocyanosis – peripheral cyanosis or bluish discoloration of hands and feet not involving the mucous membranes. It often resolves by 48 hours or with stabilization of the infant.
• Circumoral cyanosis – bluish discoloration around the mouth which is associated with nipple or breastfeeding and should resolve following the feeding.

Abnormal findings:

Central cyanosis – bluish discoloration of the tongue and mucous membranes caused by desaturation of arterial blood, indicating cardiac or respiratory dysfunction. Cyanosis may be visible with reduced hemoglobin 3 to 5 gm/dL. Infants with polycythemia (Hgb > 20 gm) may appear cyanotic even when adequately oxygenated. Infants with anemia (Hgb < 10 gm) may not appear cyanotic even when adequately hypoxemic. Pallor may indicate vasoconstriction. Physiologic jaundice may be prolonged. If cyanosis is present, one must differentiate between peripheral and central cyanosis and whether it improves with crying, does not change, or becomes worse with crying.

While performing inspection, the nurse should also check for the presence of sweating. Assess for precordial bulging or precordial activity without bulging. Check for pectus excavatum, which may cause a pulmonary systolic ejection murmur or large cardiac silhouette on an anteroposterior chest radiograph because of the decreased anteroposterior chest diameter. Check skin perfusion – normal capillary refill time is ≤ 3 seconds. Signs of shock can be observed with abnormal skin perfusion when the capillary refill is > 3 seconds, prolonged in the lower body compared with the upper body, and mottling associated with other symptoms.

Palpation

During palpation, the nurse should note any hyperactivity. There are two classes of heart disease in which the pericardium appears quite active. This situation can be seen in cases of volume overload present in CHD with large left-to-right shunts, such as PDA or VSD. This finding can also be seen in cases of severe valvular insufficiency, such as aortic or mitral insufficiency.

The nurse should check for a thrill. A thrill is a fine vibration felt by the hand and corresponds to the sound of a murmur. Thrills are best detected with the palm rather than the fingertips, although the fingertips are needed to feel a thrill in the suprasternal notch or over the carotid arteries.

The nurse should also determine the point of maximal impulse (PMI). This finding will aid in determining whether the right or left ventricle is dominant. The impulse is maximal at the lower left sternal border if the right ventricle is dominant. If the left ventricle is dominant, the impulse is at the apex. Count the peripheral pulse rate, noting any irregularities or inequalities of rate or volume. Evaluate the carotid, brachial, femoral, and pedal pulses to detect differences between sides and upper and lower extremities. If pulses are unequal, obtain four extremity blood pressures. The coarctation of the aorta may cause a marked difference. Cuff size is critical. A too narrow cuff gives falsely high readings, and too large a cuff may yield low readings. Assess for bounding pulses. Palpate the abdomen to determine the liver and spleen's size, consistency, and location.

Auscultation

Expert auscultation of the neonatal heart requires much practice over time. The neonatal heart should be auscultated with the infant inactive and quiet. A pediatric or neonatal stethoscope with a diaphragm and bell is very helpful when auscultating. The pediatric stethoscope has a smaller chest piece than the adult model, and a stethoscope with an even smaller chest piece is used for examining premature infants. The tubing is usually longer to reach inside an isolette. They both have two types of chest pieces.

The open bell conducts sound with no distortion, but it makes all sounds loud and may be difficult to maintain an airtight seal. Since low-frequency sounds are hard to hear, the bell is well suited for them. If properly sized, the diaphragm maintains its seal and is useful for high-pitched sounds. The closed diaphragm has a larger diameter than the bell. It is important to note that the bell piece functions as a diaphragm chest piece when applied too tightly to the skin. The skin acts as a diaphragm, and low-frequency sounds are not as easy to discern. The binaurals should fit comfortably. The ear tubes must be inclined anteriorly to conform to the direction of the normal ear canal. Proper positioning may be difficult to achieve if the chest piece is too large, resulting in a harsh noise by intermittent contact of skin with the diaphragm. The harsh noise sounds like a pericardial friction rub.

At a minimum, the four traditional auscultatory areas should be examined. These are the aortic area (second intercostals space, right sternal angle), pulmonic area (second intercostals space, left sternal angle), tricuspid area (fourth intercostals space, left sternal angle), and mitral area (fourth intercostals space, left midclavicular line). A more thorough examination is recommended. There are six anterior areas and three posterior areas for auscultation.

Anterior

Left Ventricular Area – centered around the apex of the heart. It extends laterally to the anterior axillary line. The following heart sounds are best heard in this area:

• Mitral insufficiency murmur
• Summation gallops
• Subaortic stenosis murmur
• Aortic insufficiency murmur
• Aortic ejection click in aortic stenosis
• Click and late systolic murmur in mitral valve prolapse
• Mitral stenosis murmur

Right, Ventricular Area – encompasses the lower part of the sternum and the third and fourth intercostal spaces on both sides of the sternum. The following are heart sounds best heard in the right ventricular area:

• Summation gallop
• Pulmonary insufficiency murmur
• Ventricular septal defect murmur
• Aortic insufficiency murmur
• Tricuspid stenosis murmur

Left Atrial Area – murmurs associated with the left atrium are best heard at the apex:

• Mitral insufficiency

Right, Atrial Area – extends 1–2 cm to the right of the sternum in the fourth and fifth intercostal spaces. The murmur of tricuspid insufficiency is best heard here.

Aortic area – corresponds to the aortic root region and part of the ascending aorta. It begins at the third left intercostal space and extends across the manubrium to the first, second, and third right inter-spaces. The aortic area includes the suprasternal notch and the head of the right clavicle. The following heart sounds are best heard in the aortic area:

• Aortic stenosis murmur
• Aortic stenosis murmur
• Aortic insufficiency murmur
• Sounds caused by increased aortic flow or dilation of the ascending aorta
• Sounds produced by abnormalities of the carotid and subclavian arteries
• The aortic component of the second heart sound

Pulmonary Area – encompasses the second and third left interspaces close to the sternum. The following sounds are best heard over the pulmonary area:

• Pulmonary stenosis murmur
• Pulmonary insufficiency murmur
• Murmurs are caused by an increased flow of the pulmonary artery
• Pulmonary ejection click
• The pulmonary component of the second heart sound
• A murmur of patent ductus arteriosus

Posterior

Left Atrial Area – overlies the fifth, sixth, seventh, and eighth posterior interspaces. It is especially good for hearing the mitral insufficiency murmur.

Aortic Area – overlies the fourth to eighth thoracic vertebral bodies to the left of the midline. The following murmurs are heard in the aortic area:

• Aortic stenosis murmur
• Aortic insufficiency
• Coarctation of the aorta

Pulmonic area – overlies the fourth and fifth thoracic vertebrae and the corresponding interspaces to the left and right of the spine. The murmurs heard there are:

• Pulmonary stenosis murmur
• Pulmonary insufficiency murmur
• Atrial septal defect

Identification of Heart Sounds

There are four individual heart sounds: S1, S2, S3, and S4. S3 and S4 are rarely heard in the newborn. S1 is the sound resulting from the closure of the mitral and tricuspid valves after atrial systole. It is best heard at the apex or lower left sternal border. S1 is the beginning of ventricular systole. Splitting of S1 is infrequently noted in newborns. Wide splitting of S1 is heard in a newborn with the right bundle branch block or Epstein's anomaly.

S2 is the sound created by the closure of the aortic and pulmonary valves, which marks the end of systole and the beginning of ventricular diastole. It is best heard in the upper left sternal border or pulmonic area. Evaluation of the splitting of S2 is important diagnostically. The timing of the closure of the aortic and pulmonary valves is determined by the volume of blood ejected from the aorta and pulmonary artery and the resistance against which the ventricles must pump.

In the immediate newborn period, there may be no appreciable splitting of SV. Because the right and left ventricles pump similar quantities of blood and the pulmonary pressure is close to the aortic pressure, these valves close almost simultaneously. Thus, S2 is heard as a single sound. As the pulmonary vascular resistance falls, the pulmonary resistance decreases and becomes lower than the aortic pressure, causing a splitting of S2 as the valve leaflets on the left side of the heart (aortic valve) close before those on the right (pulmonary valve).

By 72 hours of life, S2 should be split. The absence of a split S2 or a widely split S2 usually indicates an abnormality. A fixed, widely split S2 occurs in conditions that prolong right ventricular ejection time or shorten left ventricular ejection time. A narrowly split S2 occurs in conditions where there is the early closure of the pulmonary valve (pulmonary hypertension) or a delay in aortic closure. A single S2 is significant because it could represent the presence of only one semilunar valve (aortic or pulmonary atresia, truncus arteriosus).

The relative intensity of the aortic and pulmonary components of S2 must be assessed. The aortic component is usually louder than the pulmonary component in the pulmonary area. Compared with the aortic component, increased intensity of the pulmonary component occurs with pulmonary hypertension. Conditions that cause decreased diastolic pressure of the pulmonary artery (critical pulmonary stenosis, tetralogy of Fallot (TOF), tricuspid atresia) may cause the decreased intensity of the pulmonary component. Since S3 and S4 are rarely heard in the neonatal period, their presence denotes a pathologic process. Likewise, a gallop rhythm, the result of a loud S3 and S4, and tachycardia are abnormal.

After evaluating the individual heart sounds, the systolic and diastolic sounds are evaluated. The ejection sound or click occurs after S1 and may sound like a splitting of S1. The ejection click is best heard at the upper left or right sternal border or base. The pulmonary click can best be heard at the second or third left intercostals space and is louder with expiration. The aortic click best heard at the second right intercostal space does not change in intensity with a change in respiration.

Murmurs

Cardiac murmurs should be evaluated as to intensity (grades 1 to 6), timing (systolic or diastolic), location, transmission, and quality (musical, vibratory, or blowing):

• Grade 1: barely audible
• Grade 2: soft but easily audible
• Grade 3: moderately loud; no thrill
• Grade 4: loud; thrill present
• Grade 5: loud; audible with stethoscope barely on chest
• Grade 6: loud; audible with stethoscope not touching the chest

The murmur grade is recorded as 1/6, and so on. The next step in evaluating a murmur is its classification in relation to S1and S2. The three types of murmurs are systolic, diastolic, and continuous. An infant with no murmur may still have significant cardiac disease.

Systolic Murmurs

Most heart murmurs are systolic, occurring between S1 and S2. Systolic murmurs are either ejection or regurgitation murmurs. They are a normal finding during the routine physical exam of a healthy infant. Studies have shown that as many as 90% of healthy children have a benign murmur at some time.

The blood flow causes ejection murmurs through stenotic or deformed valves or increased flow through normal valves. Regurgitant systolic murmurs begin with S1, with no interval between S1 and the beginning of the murmur. Regurgitation murmurs generally continue throughout systole. Regurgitation systolic murmurs are caused by blood flow from a chamber at a higher pressure throughout the systole than in the receiving chamber. Regurgitation systolic murmurs are associated with only three conditions:

• ventricular septal defects (VSDs)
• mitral regurgitation
• tricuspid regurgitation

Diastolic Murmurs

Diastolic murmurs are classified according to their timing in relation to heart sounds as early diastolic, mid-diastolic, or pre-systolic. They are usually pathologic. They result from aortic regurgitation and pulmonary insufficiency. With aortic regurgitation, the murmur is high-pitched and blowing. It begins with the second heart sound and is loudest in early diastole. It may be missed because it is often very soft or may be mistaken for breath sounds because of its high pitch. Bounding pulses are present.

The murmur of pulmonary insufficiency is a distinctive diastolic murmur. It is low-pitched, early in onset, and of short duration. It ends well before the first heart sound. It occurs with postoperative TOF, pulmonary hypertension, postoperative pulmonary valvotomy for pulmonary stenosis, or other deformities of the pulmonary valve.

Mid-diastolic murmur results from abnormal ventricular filling. Due to stenosis, the murmur results from turbulent flow through the tricuspid or mitral valve. They are associated with mitral stenosis or large left-to-right shunt VSD or PDA, producing relative mitral stenosis secondary to increased flow across the normal-sized mitral valve. It is seen in the atrial septal defect (ASD), total or partial anomalous pulmonary venous return (TAPVR, PAPVR), endocardial cushion defects, or abnormal stenosis of the tricuspid valve.

Continuous Murmurs

Most continuous murmurs are not audible throughout the cardiac cycle. They begin in systole and extend into diastole. They are a pathologic finding. They can be produced in rapid blood flow, high-to-low pressure shunting, and localized arterial obstruction.

The most significant is the PDA high-to-low shunting. The patency of the ductus is normal in the first 24 hours of life, but a few weeks later, a patent ductus is abnormal. It is more common in girls (sex ratio of 3:2), tends to affect siblings, and may be a complication of maternal rubella. It is six times more common in infants born at high altitudes and more common in premature infants. There may be a vigorous pericardial activity, a systolic thrill, and bounding pulses if the ductus is large. There may be symptoms of congestive heart failure (CHF).

Congenital Heart Defects

Cardiac development occurs during the first seven weeks of gestation. Causes are classified as chromosomal (ten to twelve percent), genetic (one to two percent), maternal or environmental (one to two percent), or multifactorial (85 percent). The vast majority are considered to be of multifactorial origin. These defects are probably the result of an interaction effect of the other causes. The following diagram of a normal heart is supplied for reference when reading the descriptions of abnormalities (Yun, 2011).

Acyanotic Heart Defects

Acyanotic heart defects are those that produce a left-to-right shunt. Typically, these defects do not produce cyanosis because sufficient oxygenated blood is in circulation. The left-to-right or right-to-left shunts increase pulmonary blood flow and workload on the heart (AHA, 2020b).

Patent Ductus Arteriosus (PDA)

PDA is the failure of the ductus to close in response to increased arterial oxygen concentrations after the initiation of pulmonary function. The persistence of the ductus arteriosus is beyond 24 hours. A systolic murmur is heard. Bounding peripheral pulses help differentiate a PDA from a Ventricular Septal Defect (VSD). The precordium is usually active. Some infants will have widened pulse pressures. Infants weighing <1,000 grams are likely to have reduced systolic and diastolic pressures. The volume overload of blood in the left atrium and left ventricle lead to increased pulmonary venous engorgement. In addition to the systolic murmur and bounding pulses, CHF symptoms are tachypnea, dyspnea, hoarse cry, frequent lower respiratory tract infections and coughing, and poor weight gain. The timing of PDA treatment is controversial with three broad approaches to timing:

• Treating when the PDA becomes clinically symptomatic
• Targeted presymptomatic treatment
• Prophylactic treatment

None of these approaches has shown clear benefits in short and long-range outcomes. It is important to note that the prophylactic approach to PDA treatment is the only strategy that has been shown to have benefits of any sort. Medical management includes prophylactic antibiotics against bacterial endocarditis and prostaglandin inhibitors. Prostaglandins prevent the ductus from closing. The definitive treatment is surgical ligation.

Ventricular Septal Defect (VSD)

VSD can occur anywhere in the ventricular septum. The size of the defect and the degree of pulmonary vascular resistance are more important to severity than location. X-ray is normal. There is usually a loud, harsh pansystolic murmur. Symptoms depend on the severity and range from asymptomatic to poor exertional tolerance, recurrent pulmonary infections, and symptoms of CHF. With severe VSD, there may be pulmonary hypertension and cyanosis.

Management of VSD includes monitoring for CHF and treatment with diuretics and digitalis. Unless there is pulmonary hypertension, there is no activity restriction. Prophylaxis against bacterial endocarditis may be implemented prior to surgical closure of the VSD.

Atrial Septal Defect (ASD)

ASD is a communication between the right and left atria. There is increased blood flow to the right ventricle through the pulmonary valve. This malformation creates the typical ejection murmur, usually grade II/VI. The infant is usually asymptomatic unless the murmur is present. The X-ray may show enlargement and an increase in pulmonary vascularity. Untreated ASD can lead to CHF, pulmonary hypertension, and atrial arrhythmias.

Spontaneous closure of ASDs occurs in the first five years of age in up to 40 percent of children, and medical management includes prevention and treatment of CHF. Activity is not restricted. Surgical correction is accomplished by a simple patch or with direct closure.

Endocardial Cushion Defects

Endocardial cushion defects are lesions that produce abnormalities of the atrial septum, ventricular septum, and AV valves. Symptoms result from increased pulmonary blood flow caused by the abnormal connection between ventricles and the atria. The infant may present with respiratory distress, signs of CHF, tachycardia, and a murmur. The mitral regurgitation may be heard as a grade III holosystolic murmur transmits to the back. A chest x-ray reveals generalized cardiomegaly and increased pulmonary vascularity. The infant has recurrent respiratory infections and failure to thrive.

Management is aimed at preventing or treating CHF and bacterial endocarditis. Surgical closure of ASD and VSD with the reconstruction of the AV valves is required. In some cases, pulmonary artery banding may be performed as a palliative procedure if there is no significant mitral regurgitation. Surgery is indicated when CHF is unresponsive to medical therapy, recurrent pneumonia, failure to thrive, or a large shunt with the development of pulmonary hypertension and increased pulmonary vascular resistance.

Aortic Stenosis

Aortic stenosis is one of a group of defects that produce obstruction to ventricular outflow. There is narrowing or thickening of the aortic valvular region. Symptoms depend on severity. Mild stenosis can be asymptomatic. More severe stenosis can cause activity intolerance, chest pain, and CHF. There may be narrow pulse pressure and higher systolic pressure in the right arm. Cardiomegaly is present with CHF.

Management of aortic stenosis includes preventing and treating CHF with fluid restriction, diuretics, and digitalis. Some activity restrictions may be required to prevent increased demand on the heart in moderate to severe cases. Balloon valvuloplasty may be performed during cardiac catheterization to improve circulation. In critical cases, maintenance of the patency of the ductus arteriosus with prostaglandin E1 to prevent hypoxia may be needed. The type and timing of surgical correction depend on the exact location and severity of the defect.

Cyanotic Heart Defects

Cyanotic heart defects are right-to-left shunts with either reduced or increased pulmonary blood flow (Geggel, 2020).

Tetralogy of Fallot (TOF)

TOF is composed of the following abnormalities:

1. Ventricular septal defect
2. Pulmonic outflow obstruction
3. Aorta overriding right and left ventricles
4. Right ventricular hypertrophy

In cases of TOF, blood is shunted right to the left through the VSD and the overriding aorta. The murmur of TOF is loudest along the left sternal border between the third and fourth interspaces. A thrill will be present if the murmur is at least a grade III. There is usually a single-second heart sound. Cyanosis depends on the varying degrees of pulmonary outflow obstruction. The chest x-ray demonstrates an enlargement of the right ventricle, small main pulmonary artery, and a normal left atrium and left ventricle. It has been called a "boot-shaped" heart. The EKG would show right ventricular hypertrophy.

Cardinal signs include cyanosis, hypoxia, and dyspnea. Severe decompensation or "tet" spells are common in infants or children but can occur in neonates. Children instinctively assume a squatting position, which traps venous blood in the legs and decreases systemic venous return to the heart. Chronic arterial desaturation stimulates erythropoiesis, causing polycythemia that may lead to increased blood viscosity, microcytic anemia, and cerebrovascular accident.

Definitive therapy for TOF is surgical repair. Medical management includes the prevention and treatment of hypoxemia, polycythemia, infection, and microcytic hypochromic anemia. It is important to avoid dehydration to prevent an increased risk of cerebral infarcts because of hemoconcentration. Surgical management may be either palliative or corrective, with palliative procedures undertaken to improve pulmonary blood flow by creating a pathway between systemic and pulmonary circulation.

Coarctation of the Aorta

The coarctation of the aorta obstructs flow from the proximal portion of the aorta to its distal portion. If it is proximal to the insertion of the ductus arteriosus, the lower half of the body will be supplied by the right ventricle through the ductus and should be cyanotic. The upper half of the body will be supplied by the left ventricle and should be oxygenated. Collateral circulation will not be stimulated during fetal life. After birth, the circuitry persists. On chest x-ray, cardiomegaly is evident. The EKG will consistently show right ventricular hypertrophy. Hypertension in the upper extremities and lower pressure in the lower extremities can be expected. Femoral pulses will be present but weaker.

Typically no murmur is present. The second sound will be closely split. If the coarctation is distal to the insertion of the ductus arteriosus, collateral circulation will be established during fetal life to permit perfusion to the lower half of the body. This x-ray shows an indentation of the aorta that resembles the number 3. The infant will present with CHF, absent, weak, or delayed pulses in the lower extremities, and bounding pulses in the upper extremities. There may be a systolic thrill felt at the suprasternal notch.

Surgery is performed at three to five years of age if signs and symptoms can be medically controlled. Surgery is performed earlier if medical management fails to provide adequate oxygenation, prevent CHF, and avoid sub-acute bacterial endocarditis. Prostaglandin E1 may be needed to maintain ductal patency if the constricted segment is at the level of the ductus arteriosus.

Pulmonary Atresia

Pulmonary atresia results in the absence of communication between the right ventricle and the pulmonary artery. The right ventricle is usually hypoplastic, with thick ventricular walls. The presence of a PDA, ASD, or patent foramen ovale to allow blood mixing is crucial for survival. Cyanosis and tachypnea are present without other signs of obvious respiratory distress. A soft systolic murmur is heard at the upper left sternal border. Heart size may be normal or enlarged. There are decreased pulmonary vascular markings.

Prostaglandins are used to maintain ductal patency until balloon atrial septostomy can promote the mixing of systemic and pulmonary venous blood in the atria. Surgical correction is performed by creating a systemic-pulmonary artery shunt between the left subclavian artery and the left pulmonary artery.

Pulmonary Stenosis

Pulmonary stenosis is when narrowing the pulmonary valve causes the right ventricle to pump harder to get blood past the blockage. Cyanosis depends on the severity of the stenosis. Valvuloplasty may be done during cardiac catheterization to stretch the valve. Moderate stenosis may cause easy tiring. Severe or critical pulmonary stenosis will cause CHF. A pulmonary systolic ejection click at the upper left sternal border and widely split S2 or systolic ejection murmur (grade 2 to 5/6) at the upper left sternal border and transmits across the back.

Surgical correction is performed in children when the right ventricular pressure measures 80 to 100 mm Hg, and balloon valvuloplasty is unsuccessful. Infants with critical pulmonary stenosis and CHF require prostaglandin infusion to maintain ductal patency until surgery.

Truncus Arteriosus

Truncus Arteriosus results from the inadequate division of the common great vessel into a separate aorta and pulmonary artery. Cyanosis may be present, depending on the amount of pulmonary blood flow. A systolic click and harsh VSD murmur may be present. On x-ray, the heart size is increased. CHF, bounding arterial pulses, and widened pulse pressures are present. If truncus arteriosus is not detected in the newborn period, the infant will feed poorly, fail to thrive, have frequent respiratory infections, and worsening CHF.

Treatment involves control of CHF and prophylaxis with antimicrobial agents. Pulmonary artery banding is a palliative measure in small infants with increased pulmonary blood flow and CHF that does not respond to medical management. The definitive surgical correction is performed during infancy.

Transposition of the Great Arteries (TGA)

TGA is the result of inappropriate septation and migration of truncus. The aorta receives unoxygenated blood and returns it to the systemic circuit. There are two separate parallel circulations. Marked cyanosis is present, as well as signs of CHF. There will be a loud, harsh systolic murmur. Hypoglycemia, hypocalcemia, and metabolic acidosis are frequently present. On x-ray, the heart is enlarged and has a narrow base. It is described as egg-shaped.

TGA is a cardiac emergency. Immediate management includes the correction of acidosis, hypoglycemia, and hypocalcemia. Oxygen and prostaglandins are administered. Cardiac catheterization with balloon atrial septostomy is done. The prognosis for TGA without surgical intervention is poor. Definitive surgical correction is done by switching the right and left-sided structures at the ventricular, artery, or atrial levels.

Tricuspid Atresia

There is no tricuspid valve in this condition, so that no blood can flow from the right atrium to the right ventricle. The right ventricle is small, and survival depends on an ASD or VSD. Most poorly oxygenated blood goes from the left ventricle into the aorta and onto the body. The rest of the blood flows through the VSD to the small right ventricle to the pulmonary artery and back to the lungs. The infant is cyanotic.

Total Anomalous Pulmonary Venous Return

The pulmonary veins drain into the right atrium (rather than the left atrium). There is no direct connection between the pulmonary veins and the left atrium. Cyanosis is present, as is respiratory distress. Feeding is associated with increased cyanosis, the infant tires easily and has progressive growth failure. Increased cyanosis associated with feeding is secondary to the compression of the common pulmonary vein by the filled esophagus. A grade II to III systolic ejection murmur is heard at the left sternal border. A precordial bulge and hyperactive right ventricular impulse may be seen. The PMI is at the xiphoid process or lower left sternal border. The pulmonic sound may be pronounced. A quadruple or quintuple gallop rhythm is heard. X-ray findings include mild to moderate cardiomegaly and increased pulmonary markings. The characteristic "snowman sign" occurs because of the anatomic appearance of the left superior vena cava, the left innominate vein, and the right superior vena cava.

Treatment is focused on preventing CHF and hypoxemia. Diuretics may be administered to decrease pulmonary edema, and balloon atrial septostomy performed to enlarge the interatrial communication to promote better blood mixing. Surgery is delayed until infancy if medical management is successful.

Hypoplastic Left Heart Syndrome (HLHS)

HLHS consists of a group of defects, including a small aorta, aortic and mitral valve stenosis, and a small left atrium and ventricle. The infant presents with progressive cyanosis, pallor, and mottling. Tachycardia, tachypnea, dyspnea, and pulmonary rales are present. The second heart sound is loud and single. Poor peripheral pulses and vasoconstriction of the extremities are noted on the exam. On x-ray, mild to moderate heart enlargement and pulmonary venous congestion is seen.

Management is aimed at the prevention of hypoxemia and correction of metabolic acidosis. Prostaglandins are administered to maintain ductal patency. Balloon atrial septostomy is done to decompress the left atrium. Surgical correction of HLHS is experimental and has a high mortality. Transplantation is a more common option for these infants, who typically have 100 percent mortality.

Drug Treatment of Congenital Heart Defects

Diuretics

Diuretics are used in the treatment of CHF to decrease fluid overload and fluid retention:

• Furosemide (Lasix®) – 1 mg/kg/dose IV
• Spironolactone (Aldactone®) – 1.5 – 3.0 mg/kg/day PO
• Chlorothiazide (Diuril®) – 20 – 40 mg/kg/day PO

Inotropic Agents

These are used to increase myocardial performance by increasing the strength of contraction of the heart muscle. There is often a concomitant increase in heart rate during the administration of these agents. It is also used to increase renal perfusion and heart rate, increase venous return to the heart, and decrease pulmonary vascular resistance. They have a short half-life and must be infused continuously. The major complications are tachyarrhythmias and tissue necrosis following extravasation.

• Dopamine – 2 - 20 μg/kg/min IV continuous infusion
• Dobutamine – 2-10 μg/kg/min IV continuous infusion
• Isoproterenol – 0.05-0.5 mg/kg/min
• Amrinone – 0.75 – 3 mg loading dose over three minutes, a maintenance infusion of 5 μg/kg/min

Prostaglandin

Prostaglandin is indicated to maintain patency of the ductus arteriosus to provide adequate systemic or pulmonary blood flow in infants with specific heart defects. It directly relaxes smooth muscles in arteriolar and venous walls; increases cardiac output if the decrease is secondary to myocardial dysfunction (Akkinapally et al., 2018).

Prior to initiation of therapy, other causes of hypoxia should be excluded. Prostaglandin E1 may precipitate respiratory depression or systemic hypotension in neonates with RDS, pulmonary disease, sepsis, or intracerebral hemorrhage. It has a rapid onset of action. It produces vasodilatation, smooth muscle relaxation of ductus arteriosus, and pulmonary and systematic circulations. There is increased arterial saturation by 25 to 100 percent. It is important to monitor B/P. Vasopressors may be required. Apnea, flush, fever, seizure-like activity, and decreased heart rate are common side effects.

• PGE1 – 0.05-0.1 mg/kg/min IV continuous infusion

Prostaglandin Synthetase Inhibitors

This inhibitor is indicated for the pharmacologic closure of the patent ductus arteriosus (PDA). During gestation, the patency of the ductus is maintained by the production of prostaglandins. It promotes ductal closure by inhibition of prostaglandins in the wall of the ductus.

Failure of the ductus to close postnatally often complicates recovery from respiratory distress syndrome (RDS) in premature infants. Despite initial improvement in the RDS with a subsequent decrease in pulmonary vascular resistance, the infant's condition worsens due to a large left-to-right shunt through the ductus. This shunt often increases supplemental oxygen requirements, ventilator dependence, and CHF.

Indomethacin is a nonsteroidal anti-inflammatory drug that inhibits prostaglandin production by blocking the action of cyclooxygenase on arachidonic acid, thus accelerating ductal closure. Its onset is 12 to 24 hours. It is essential to monitor renal function, bilirubin, electrolytes, glucose, platelets, and bleeding. Repeat dosing in premature infants may be required. Failure to close the ductus after three courses of Indocin may require surgical closure.

• Indomethacin (Indocin) – 0.2 mg/kg IV q 24 hr

Summary

Meticulous attention to every aspect of care is essential to providing a positive outcome and quality of life to these infants. The neonatal nurse and the pediatric nurse have a vital role in recognizing, preoperative management, and postoperative management of the approximately 40,000 babies born annually diagnosed with congenital heart disease.

Case Study

A repeat cesarean section delivered a 38-week gestation infant. The neonate had respiratory distress in the delivery room, requiring intubation. Normal blood pressures in all four extremities were documented on admission to the NICU. Femoral pulses were normal. A pulse oximeter probe placed on the right upper limb was 95-98% with a 21-25% oxygen requirement. This infant's first chest X-ray demonstrated bilateral hazy lung fields. Within 24 hours, the baby was extubated, and a subsequent chest X-ray showed marked improvement. She was discharged home in room air with a 98-100% pulse oximeter reading in the right upper limb.

Two weeks after discharge, she came to the pediatrician's office for a routine visit and was noted to have absent femoral pulses. An echocardiogram demonstrated an interrupted aortic arch with an aberrant left subclavian artery arising from the patent ductus arteriosus – PDA. The right common carotid artery, right subclavian, and left common carotid artery came off the proximal part of the aortic arch prior to the interruption. The infant underwent corrective surgery and was discharged home at four weeks of life.

Given the fact that the pulmonary artery supplied the left upper extremity and the lower half of the body through the ductus, it is likely that SpO2 obtained from the left upper limb or any lower limb would have demonstrated a lower SpO2 compared to the right hand, therefore a CCHD screen would likely have been negative because CCHD screening uses the right hand (Mania et al., 2014).

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References

• Akkinapally S, Hundalani SG, Kulkarni M, et al. Prostaglandin E1 for maintaining ductal patency in neonates with ductal-dependent cardiac lesions. Cochrane Database Syst Rev 2018; 2:CD011417.
• American Heart Association. Fetal Circulation. Accessed January 28, 2020. Visit Source.
• American Heart Association. Common Types of Heart Defects. Accessed January 28, 2020b. Visit Source.
• Geggel, RL. Diagnosis and initial management of cyanotic heart disease in the newborn. UpToDate. Updated November 6, 2019. Accessed January 28, 2020. Visit Source.
• Geggel RL. Cardiac causes of cyanosis in the newborn. UpToDate. Updated May 30, 2018. Accessed January 28, 2020. Visit Source.
• Manja V, Mathew B, Carrion V, Lakshminrusimha S. Critical congenital heart disease screening by pulse oximetry in a neonatal intensive care unit. Journal of Perinatology. 2014;35(1):67-71. doi:10.1038/jp.2014.135.
• Mayo Clinic. Patent foramen ovale. Published March 8, 2018. Accessed January 28, 2020. Visit Source.
• Mckee-Garret, TM. Overview of the routine management of the healthy newborn. Updated July 12, 2019. Accessed January 28, 2020. Visit Source.
• Pierpont ME, Brueckner M, Chung WK, et al., Genetic Basis for Congenital Heart Disease: Revisited. American Heart Association. Published September 27, 2018. Accessed January 28, 2020. Visit Source.
• Yun SW. Congenital heart disease in the newborn requiring early intervention. Korean J Pediatr. 2011;54(5):183–191. doi:10.3345/kjp.2011.54.5.183.

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