QOD Cardiology
• You are treating a 4-month-old infant who
was born with tetralogy of Fallot. Her
mother brings her to the clinic because
she has had diarrhea and fever since the
previous evening. On physical
examination, the infant is irritable and has
cyanosis and a heart rate of 180
beats/min.
Of the following, the finding that is MOST
consistent with a tetralogy spell is
1.
2.
3.
4.
5.
clubbing of the digits
hepatomegaly
inability to hear a murmur
SaO2 of 75% in room air
S3 gallop rhythm
Answer C
•
Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart
disease, with an incidence of approximately 0.2 in 1,000 live births and accounting for
9% of all congenital heart disease. The four components of TOF are right ventricular
outflow/pulmonary stenosis, ventricular septal defect (VSD), overriding aorta, and
right ventricular hypertrophy. The primary lesion is underdevelopment of the
pulmonary infundibulum, which has led some to refer to this disease as "monology of
Fallot" because all aspects of the tetrad result from this lesion. The result of
underdevelopment of the pulmonary infundibulum is deviation of the infundibular
septum anteriorly and superiorly, bringing it into the right ventricular outflow tract.
This leads to obstructed right ventricular outflow and the commonly seen
underdevelopment of the pulmonary valve and pulmonary arteries caused by
diminished blood flow through these structures. The underdeveloped pulmonary
infundibulum also creates a VSD, which is almost universally large and of the
malalignment type. The defect resulting from anterior malalignment of the
infundibulum allows the aorta to "override" the ventricular septum. Finally, right
ventricular hypertrophy results from exposure to systemic pressures (large VSD and
pulmonary stenosis).
•
Most patients who have TOF do not present with cyanosis in the newborn period, but
rather come to medical attention because of a harsh systolic murmur. The murmur
results from infundibular stenosis and pulmonary stenosis, not from the VSD. The
second heart sound is single. Because the degree of pulmonary blood flow
obstruction can vary among patients, the degree of systemic oxygen desaturation
ranges from mild to severe. Children who have mild obstruction may appear "pink,"
and those who have severe pulmonary stenosis have significantly reduced pulmonary
blood flow and an increase in right-to-left shunting across the VSD into the aorta,
leading to more pronounced cyanosis. Furthermore, as pulmonary blood flow
decreases with tight pulmonary stenosis, pulmonary venous return to the left atrium
decreases, resulting in less highly saturated blood leaving the left ventricle and
entering the aorta. Conversely, mild pulmonary stenosis is associated with more
pulmonary blood flow, less right-to-left intracardiac shunting, and less systemic
desaturation. In the mildest cases, there is left-to-right shunting across the VSD and
near-normal or normal systemic saturation.
A decreased or absent murmur signifies diminished pulmonary blood flow, as occurs
in the cyanotic spell or tetralogy spell. Such spells are marked by distress, crying,
inconsolability, hyperpnea, and increasing cyanosis, as described for the infant in the
vignette. They frequently occur in the morning or at times of dehydration (eg, fever,
gastroenteritis). If not treated quickly, cyanotic spells can lead to serious morbidity
and even death.
•
Treatment of cyanotic spells centers on increasing pulmonary blood flow, which is
accomplished by several means. The first step is to alter the ratio of relative
resistance of pulmonary and systemic beds. Increasing the systemic vascular
resistance relative to the pulmonary vascular resistance decreases the right-to-left
shunt at the VSD and can be accomplished by placing the patient in a knee-to-chest
position or by squatting in older children. Pharmacologic augmentation of the
systemic vascular resistance can be achieved with intravenous phenylephrine.
Therapy also includes the use of sedation with morphine, which suppresses the
sensation of suffocation and can relieve the patient's fear. The use of high-flow
oxygen, which dilates pulmonary vasculature, constricts systemic vasculature and
increases PO2 of pulmonary venous return, and generous intravascular fluid
administration to increase preload are important therapies for the patient
experiencing a tetralogy spell.
Clubbing of the digits can be seen in cyanotic heart disease as well as a variety of
other entities, but it is not typical in patients younger than 1 year of age and its
presence is not associated with a tetralogy spell. Hepatomegaly is uncommon in the
infant who has TOF; its presence suggests right heart failure. Diminished oxygen
saturation is a component of a tetralogy spell, although the physical findings and
condition of the patient, not the oxygen saturation, define the spell. Finally, an S3
gallop rhythm can be heard in the patient who has myocardial failure but is not
expected in a patient who has TOF, particularly with the pronounced tachycardia
described for the patient in the vignette.
American Board of Pediatrics Content Specification:
Identify the clinical characteristics of a tetralogy spell
• You are working in an urgent care clinic
when an 18-year-old boy is brought in by
his mother because of slurred speech over
the past hour. She explains that he has
unrepaired cyanotic congenital heart
disease.
Of the following, the finding that is MOST likely to
be related to the symptoms reported for this
patient is
1.
2.
3.
4.
5.
hypoglycemia
hypothyroidism
iron deficiency
polycythemia
Wolff-Parkinson-White syndrome
Answer D
•
Cerebrovascular accidents can occur in patients affected by congenital heart disease
as a result of perioperative surgical complications, hemodynamic abnormalities,
intracranial abscess, or endocarditis. Patients who have chronic cyanotic heart
disease, such as the boy described in the vignette, are at additional risk for
cerebrovascular accident due to paradoxic emboli and a relative anemia.
Paradoxic emboli result from the right-to-left intracardiac shunting of blood such that
an embolus that originates in the systemic venous system avoids the filtering function
of the pulmonary vasculature and crosses from the right to the left side in the heart,
thereby gaining access to the systemic circulation, including the cerebral circulation.
Stroke from relative anemia may result from complex interactions of iron-deficient
blood in the cerebral circulation, including the decreased oxygen-carrying capacity of
iron-deficient blood. In addition, the microcytes formed under conditions of relative
anemia are less deformable than those formed in an iron-rich environment, and such
"structural" erythrocyte changes may be associated with an increased viscosity
despite the lower hemoglobin concentration. The higher viscosity leads to more
resistance to flow, and the altered flow in the cerebral microvasculature can result in
cerebrovascular accident.
Hypoglycemia might lead to abnormal speech, both in terms of content and patterns,
but this would not be expected to occur over the course of 1 hour in the absence of
other symptoms. Hypothyroidism would not be expected to present with slurring of
speech. Polycythemia can be associated with increased viscosity and, therefore,
decreased flow through small cerebral vessels, as mentioned previously. However,
iron deficiency in the presence of polycythemia poses a greater risk for stroke.
Finally, Wolff-Parkinson-White syndrome would be expected to present with
palpitations, diaphoresis, or chest pain, but not slurring of speech in isolation.
American Board of Pediatrics Content Specification:
Know that a relative anemia can be associated with a stroke in a patient with cyanotic
heart disease
• You are seeing a 2-week-old girl in your office
for a health supervision visit. Her parents report
that she is eating well and has good weight gain.
On physical examination, you note a strong right
brachial pulse, but you cannot feel pulses in the
right or left femoral region. As you explain the
diagnosis to the parents, they ask you about
long-term complications following repair of her
condition.
Of the following, the MOST likely long-term
complication for this child is
1.
2.
3.
4.
5.
frequent pulmonary infections
hypertension
neurodevelopmental delay
poor exercise performance
renal dysfunction
Answer B
•
The girl described in the vignette has the classic physical findings of coarctation of
the aorta: an easily palpable pulse in the right arm (blood flow origin proximal to the
obstruction) and an absent pulse in the lower extremities (blood flow origin distal to
the obstruction). Coarctation of the aorta refers to an anatomic obstruction or
narrowing in the aorta that can be localized as a ridge of tissue, formed as a discrete
ring of tissue, or collarlike with length forming a segment of aortic hypoplasia. Lessthan-normal blood flow through the aortic arch during fetal life may result in
hypoplasia of the arch and promote the likelihood of coarctation developing, which
forms the basis for the association between aortic stenosis (and other left heart
obstructions) and coarctation.
The incidence of coarctation is approximately 1 in 2,300 live births, making it one of
the most common types of congenital heart disease encountered by the pediatrician.
It occurs with greater frequency in females who have Turner syndrome (45,X), in
whom the incidence may be as high as 15%. Patients who have coarctation have a
high incidence of associated congenital heart disease, the most common of which are
a patent ductus arteriosus, bicuspid aortic valve, and mitral valve abnormalities.
Physical examination in the patient who has coarctation usually reveals a discrepant
pulse quality between the right radial and the femoral or dorsalis pedis. Patients also
may come to attention with hypertension noted on examination. A systolic ejection
murmur of low intensity is audible at the base and axilla and left interscapular region
and usually is loudest over the back.
•
Neonates who have significant coarctation may present with signs and symptoms of
congestive heart failure and inadequate perfusion of the gut and lower body.
Ultimately, affected patients can present in cardiogenic shock because the left
ventricle is unable to pump against the afterload imposed by the coarctation.
Coarctation that presents in the symptomatic neonate should be repaired surgically.
However, even with aggressive and excellent surgical repair, recoarctation can occur
as the child grows. In addition, patients who undergo surgical repair of aortic
coarctation have a higher incidence of hypertension at long-term follow-up and should
be followed closely for this complication. In contrast to the long-term risk for
hypertension, patients who have undergone an uncomplicated neonatal repair of
aortic coarctation do not have an increased rate of pulmonary infections,
neurodevelopmental delay, or poor exercise performance. Although congenital heart
disease can be associated with renal abnormalities in some cases, routine
coarctation and its repair are not associated with the long-term complication of renal
dysfunction.
American Board of Pediatrics Content Specification:
Understand the immediate (eg, referral) and long-term (eg, frequent blood pressure
measurements) management in a patient with coarctation of the aorta
• You are evaluating a 12-year-old girl as part of a sports
screening program at the local school. She tells you that
she has trouble keeping up with her friends during gym
class and on the soccer field. On physical examination,
she appears well and is in no distress. Her precordial
examination demonstrates a mild lift. The first heart
sound is normal, and the second heart sound is
prominently split and does not vary with respiration.
There is a 3/6 systolic ejection murmur at the upper left
sternal border. Diastole is clear, and her pulses are
normal in all extremities.
Of the following, the MOST likely cause of this
patient's signs and symptoms is
1.
2.
3.
4.
5.
aortic stenosis
atrial septal defect
patent ductus arteriosus
pulmonary stenosis
ventricular septal defect
Answer B
•
Recognition of cardiac anomalies in pediatric patients requires a complete history and
physical examination. The timing and severity of the presentation often depends on
the severity of the underlying condition, such as the size of a ventricular septal defect,
the degree of semilunar valve stenosis, or the extent of obstruction to pulmonary
blood flow. Many of the congenital cardiac anomalies lead to turbulent blood flow
within the heart or great vessels, which produces a murmur. The loudness, timing,
location, radiation, and pitch of the murmur can suggest the cause of the anomaly.
The girl described in the vignette has the typical findings of an atrial septal defect.
When the left-to-right shunt at the atrial level is significant, the patient may report a
history of decreased exercise tolerance when compared with peers. Such decreased
tolerance likely is the result of the dilated right ventricle, which receives the normal
blood flow returning to the right atrium from the systemic veins as well as the
abnormal blood flow that results from the left-to-right shunt of the atrial septal defect.
The murmur in patients who have atrial septal defects is not from the blood flow
across the atrial septum because this flow usually is not turbulent and at low
pressure. Rather, the systolic murmur results from a relative pulmonary stenosis
because the left-to-right atrial shunt and the subsequent increased right ventricular
volume are required to cross the pulmonary valve. The valve annulus does not dilate
and, therefore, the amount of blood (stroke volume) crossing the valve is increased.
•
The increased flow across the valve per heart beat necessitates an increase in the
velocity of that blood flow, resulting in turbulence. It is this turbulence that creates the
murmur that is heard best at the upper left sternal border. Because there is no
structural abnormality of the pulmonary valve, no click is appreciated in patients who
have atrial septal defects. In large atrial septal defects, a murmur also may be noted
during diastole due to the increased amount of blood that must cross the tricuspid
valve during ventricular filling. Finally, patients who have atrial septal defects often
have a fixed and split second heart sound that most likely results from the relative
prolonged time required for the dilated ventricle to empty its contents during systole.
In contrast, in the healthy heart, the second heart sound splits variably with
respiration. The lack of variation of the split most likely is due to the free
communication between the two atria, which allows for equalization of the influence of
respiration on both the right and left ventricle.
The murmur of pulmonary stenosis often is associated with a systolic click that results
from the abnormal structure and function of the pulmonary valve itself. Although
patients who have pulmonic stenosis also have a prominently split S2, it varies with
respiration. The normal splitting of the second heart sound occurs because the
volume of right ventricular blood and its stroke volume generally are normal.
Similarly, aortic stenosis is associated with an ejection click that does not change with
position, and the accompanying murmur is heard best at the upper right sternal
boarder, with radiation into the neck. Affected patients usually have a normal second
heart sound. The patent ductus arteriosus typically produces a continuous murmur
that is characterized as having a "machinery" quality and usually is loudest at the left
infraclavicular area.
•
The murmur is continuous because the flow between the systemic and pulmonary
circulation is constant due to the higher systemic compared with pulmonary vascular
resistance throughout the cardiac cycle and the lack of a valve to separate the two in
the structure of the ductus.
The murmur of a ventricular septal defect typically is holosystolic because the left-toright shunt at the ventricular level begins with the onset of systole, even before the
aortic and pulmonary valves open. When the ventricular septal defect is small, it
produces a high-pitched murmur, heard along the sternal border, and the second
heart sound is normal, with no change in its normal physiologic splitting.
American Board of Pediatrics Content Specification:
Recognize the major clinical findings in patients with cardiac anomalies such as
ventricular septal defect, atrial septal defect, patent ductus arteriosus, aortic stenosis,
or pulmonic stenosis
• You are caring for a 2-year-old girl who has
cardiomyopathy and is awaiting cardiac
transplantation. She is receiving a continuous
infusion of milrinone at 0.5 mcg/kg per minute,
intravenous furosemide three times a day, and 2
L/min of oxygen administered via nasal cannula.
On physical examination, her temperature is
39.0°C, heart rate is 130 beats/min, respiratory
rate is 30 breaths/min, and blood pressure is
80/40 mm Hg. Her oxygen saturation is 92%. An
arterial blood gas shows a pH of 7.35, Paco2 of
40 mm Hg, and Pao2 of 50 mm Hg, with a
hemoglobin of 8 g/dL (80 g/L).
Of the following, the treatment that can BEST
increase her tissue oxygen delivery is
1.
2.
3.
4.
5.
administration of 10 mg/kg acetaminophen
increased furosemide administration to four times a day
increased oxygen flow to achieve an SaO2 of 95%
reduction of the milrinone infusion to 0.25 mcg/kg/min
transfusion with 15 mL/kg packed red blood cells
Answer E
•
Adequate tissue oxygenation requires a complex interaction between the pulmonary,
cardiovascular, and hematologic systems and can be disturbed by a variety of
disease processes. Continual supply of oxygen is imperative because cells lack the
ability to store oxygen. Imbalances between tissue demand and supply result in cell
injury and death.
The amount of oxygen transport in the blood is dependent on three factors:
hemoglobin concentration, cardiac output, and the amount of hemoglobin that is
saturated with oxygen. Although a small amount of oxygen is dissolved in blood, most
is carried by hemoglobin, as expressed in the equation for arterial oxygen content
(Cao2):
Cao2 (g O2/mL)= (hemoglobin x 1.34 x SaO2) + (0.003 x Pao2)
The tissue delivery of oxygen (DO2) is calculated using the cardiac output (CO) and
the Cao2 as follows:
DO2 = CO x Cao2
•
Oxygen delivery for the child described in the vignette can be improved most
appropriately by transfusion of packed red blood cells and correction of her anemia.
Other interventions may be beneficial but would not have the impact of transfusion.
Reducing her fever with acetaminophen would decrease tissue oxygen demand,
increasing the diuretic dose might increase cardiac output if her vascular volume is
elevated, and increasing oxygen flow would increase the arterial oxygen content. A
reduction in the milrinone dose would decrease cardiac output and reduce oxygen
delivery.
American Board of Pediatrics Content Specification:
Know how to manage the child with an hypoxic episode
• A 3-day-old infant who was born at 29
weeks' gestation and weighed 1,200
g has experienced respiratory
distress syndrome and is receiving
assisted ventilation. This morning,
you note a grade III/VI holosystolic
murmur, hyperdynamic precordium,
and widened pulse pressures.
Of the following, the MOST appropriate next step
is to
1.
2.
3.
4.
5.
administer ibuprofen treatment
administer indomethacin prophylaxis
increase maintenance fluids
obtain echocardiography
reduce the ventilator settings
Answer D
•
The 29-weeks' gestation very low-birthweight infant described in the vignette, who
has respiratory distress syndrome, is at risk for a persistent patent ductus arteriosus
(PDA). Closure of the ductus arteriosus often is delayed in such infants, but its
patency may be of variable hemodynamic or clinical significance. Symptoms or signs
resulting from a PDA typically appear between the third and seventh postnatal day,
although they can appear later.
The significance of the PDA for the infant in the vignette is suggested by the
presence of the murmur, a widened pulse pressure, and a hyperdynamic precordium.
Such findings are indicative of a left-to-right shunt of blood from the descending aorta
through the PDA into the pulmonary circulation. This condition may volume overload
the right heart, contributing to the hyperdynamic precordium. As the shunt continues,
pulse pressures widen and the overall adequacy of cardiac output to distal circulatory
beds may be jeopardized, resulting in systemic hypotension, metabolic acidemia,
oliguria, and potential gastrointestinal compromise. Untreated, the condition may
result in pulmonary congestion with reduced pulmonary compliance, congestive heart
failure, and hepatomegaly.
Diagnosis of a PDA is made both clinically and echocardiographically. The
hemodynamic significance of a PDA is determined echocardiographically by
assessing the size of the left atrium, the aortic outlet, the PDA, and the right ventricle
as well as the presence of reversed end-diastolic blood flow in the proximal aortic
arch. Judicious fluid management (<150 mL/kg per day) in the first week after birth
may reduce the likelihood of clinically significant PDA. However, once the PDA is
diagnosed, fluid restriction is a mainstay of treatment. The use of positive endexpiratory pressure (PEEP) also may help reduce pulmonary overcirculation in the
ventilated patient. Pharmacologic management consists of intravenous indomethacin
or ibuprofen-lysine, usually administered in three successive doses. If the PDA fails to
close with these pharmacologic measures, surgical ligation may be warranted.
•
Treatment with ibuprofen may follow confirmation of the PDA but should not be
initiated presumptively due to potential complications and adverse effects. A single
dose of intravenous indomethacin may be administered prophylactically in the first 12
to 24 hours after birth, but the window for prophylaxis has passed for the infant in the
vignette. Increasing fluids might worsen cardiopulmonary congestion in the setting of
a PDA. Reducing ventilator settings (PEEP, inspiratory time, or pressure) can result
in a reduction in mean airway pressure, which allows for an increase in left-to-right
shunting.
American Board of Pediatrics Content Specification:
Plan the initial management of a premature infant with patent ductus arteriosus
• You are evaluating a 2-month-old girl as part of a routine
health maintenance visit. Her mother tells you that she
has no trouble feeding and is gaining weight like her
previous children. Her precordial examination
demonstrates a mild lift. The first and second heart
sounds are normal. There is a systolic click at the upper
left sternal border as well as a 3/6 systolic ejection
murmur at the upper left sternal border with radiation to
the axillae. Diastole is clear, and her pulses are normal
in all extremities.
Of the following, the MOST likely cause of this
patient's signs and symptoms is
1.
2.
3.
4.
5.
aortic stenosis
atrial septal defect
patent ductus arteriosus
pulmonary stenosis
ventricular septal defect
Answer D
•
The infant described in the vignette has typical findings of pulmonary stenosis, which
often is associated with a systolic click resulting from the abnormal structure and
function of the pulmonary valve. The click is caused by the opening of the thickened
valve leaflets during systole. In contrast to the normal thin and flexible semilunar
valve leaflets, those of the stenotic pulmonary valve have an accentuated sound that
is referred to as an opening click. The murmur of pulmonary stenosis results from
systolic blood flow from the right ventricle across the abnormally narrowed orifice of
the pulmonary valve. The narrowing yields a diminished valve area through which the
stroke volume crosses, creating turbulence. Such turbulence is noted during
auscultation as a systolic ejection murmur and typically is heard best over the
pulmonary valve and main pulmonary artery. On the chest wall, these structures lie
beneath the left sternal border, with extension cephalad toward the left clavicle.
Frequently, the murmur radiates into the back and the axillae as the sound of
turbulence follows the course of the branch pulmonary arteries.
Aortic stenosis also is associated with a systolic ejection click that does not change
with position, but the accompanying murmur is heard best at the upper right sternal
border, with radiation into the neck. The murmur associated with an atrial septal
defect is not from the blood flow across the atrial septum, which usually is
nonturbulent and at low pressure. Rather, the systolic murmur created by an atrial
septal defect is the result of a relative pulmonary stenosis as the left-to-right atrial
shunt and resulting increased right ventricular volume must cross the pulmonary
valve. In contrast to pulmonary valve stenosis, there is no structural abnormality of
the pulmonary valve and, thus, no systolic click.
•
Patent ductus arteriosus typically produces a continuous murmur characterized as
having a "machinery" quality that is usually loudest at the left infraclavicular area. It is
continuous because of the constant flow between the systemic and pulmonary
circulation resulting from the higher systemic vascular resistance compared with the
pulmonary vascular resistance throughout the cardiac cycle and the lack of a valve to
separate the two circulations. The murmur of a ventricular septal defect typically is
holosystolic because the left-to-right shunt at the ventricular level begins with the
onset of systole, even before the aortic and pulmonary valves open. When the
ventricular septal defect is small, it produces a high-pitched murmur, heard along the
sternal border, and a normal second heart sound without a change in its normal
physiologic splitting.
American Board of Pediatrics Content Specification:
Recognize the major clinical findings in patients with cardiac anomalies such as
ventricular septal defect, atrial septal defect, patent ductus arteriosus, aortic stenosis,
or pulmonic stenosis
• You are evaluating a 15-year-old boy who will be
attending sports camp in the summer. He tells you that
he is very athletic, has no trouble keeping up with his
peers during physical activities, and, in fact, has less
fatigue with activities than most of his friends. On
physical examination, he is well-developed and
comfortable. The first and second heart sounds are
normal. There is a systolic click at the upper right sternal
border as well as a 3/6 systolic ejection murmur at the
upper right sternal border. There is a thrill in his
suprasternal notch. Diastole is clear, and his pulses are
normal in all extremities.
Of the following, the MOST likely cause of this
patient's signs and symptoms is
1.
2.
3.
4.
5.
aortic stenosis
atrial septal defect
patent ductus arteriosus
pulmonary stenosis
ventricular septal defect
Answer A
•
The patient described in the vignette has the typical findings of aortic stenosis, which
often is associated with a systolic click that results from the abnormal structure and
function of the valve. The click occurs with opening of the thickened semilunar valve
leaflets during systole. In contrast to the normal thin and flexible valve leaflets, those
of the stenotic aortic valve have an accentuated sound that is referred to as an
opening click. The murmur of aortic stenosis results from systolic blood flow from the
left ventricle across the abnormally narrowed orifice of the aortic valve. The narrowing
yields a diminished valve area through which the stroke volume crosses, creating
turbulence that is noted during auscultation as a systolic ejection murmur and
typically is heard best over the aortic valve and ascending aorta. On the chest wall,
these structures lie beneath the right sternal border, with extension up toward the
right clavicle. The murmur often radiates into the neck. A thrill may be appreciated in
the suprasternal notch, with the turbulent blood flow in the transverse aortic arch
being palpable in some patients.
Pulmonary stenosis is associated with a systolic ejection click that does not change
with position, but the accompanying murmur is heard best at the upper left sternal
border, with radiation into the back and axillae. The murmur associated with an atrial
septal defect is not from the blood flow across the atrial septum, which usually is not
turbulent and at low pressure. Rather, the systolic murmur created by an atrial septal
defect is caused by a relative pulmonary stenosis because the left-to-right atrial shunt
and resulting increased right ventricular volume must cross the pulmonary valve. In
contrast to pulmonary valve stenosis, there is no structural abnormality of the
pulmonary valve and, thus, no systolic click.
A patent ductus arteriosus typically produces a continuous murmur that is
characterized as having a "machinery" quality and usually is loudest at the left
infraclavicular area. It is continuous because of the constant flow between the
systemic and pulmonary circulation, with the higher systemic than pulmonary
vascular resistance throughout the cardiac cycle and no valve to separate the two in
the structure of the ductus. The murmur of a ventricular septal defect is typically
holosystolic because the left-to-right shunt at the ventricular level begins with the
onset of systole, even before the aortic and pulmonary valves open. When the
ventricular septal defect is small, it produces a high-pitched murmur, heard along the
sternal border, and the second heart sound is normal, with no change in its normal
physiologic splitting.
American Board of Pediatrics Content Specification:
Recognize the major clinical findings in patients with cardiac anomalies such as
ventricular septal defect, atrial septal defect, patent ductus arteriosus, aortic stenosis,
or pulmonic stenosis
A 16-year-old girl who is new to your practice comes to the
clinic for a physical examination prior to enrollment in a
summer volleyball camp. She is generally healthy, and
she does well academically. On physical examination,
you note that she is unusually tall and slender, and she
appears to have long fingers and toes. You are
concerned that she could have Marfan syndrome, and
you refer her for a clinical genetics evaluation.
Of the following, the additional finding that would
MOST strongly suggest the diagnosis of Marfan
syndrome for this girl is
1.
2.
3.
4.
5.
high myopia
long, narrow face
mitral valve prolapse
narrow palatal contour
spontaneous pneumothorax
Answer E
•
Marfan syndrome (MS) is an autosomal dominant connective tissue disorder that has a
prevalence of 1 in 10,000 and usually is caused by alterations in the fibrillin 1 (FBN1) gene. MS
primarily involves the skeletal, cardiovascular, and ocular systems. Skeletal features include
pectus carinatum, pectus excavatum, reduced upper-to-lower segment ratio, scoliosis of greater
than 20 degrees or spondylotlisthesis, reduced elbow extension, joint hypermobility, and others.
Major cardiovascular features are dilation or dissection of the ascending aorta, and minor features
include mitral valve prolapse, dilation of the main pulmonary artery, and calcification of the mitral
annulus. Ocular features include ectopia lentis, flat cornea, hypoplastic iris, and increased axial
length of the globe. Although high myopia; long, narrow face; mitral valve prolapse; and narrow
palatal contour all are associated with MS, they are also relatively common findings in other
syndromes and in the general population. Spontaneous pneumothorax occurring in a teenager,
however, is unusual and is one of the minor criteria for the diagnosis of MS. Therefore, the history
of spontaneous pneumothorax associated with this girl's physical features should increase the
pediatrician's suspicion for MS.
Due to the risks for aortic root dilatation and dissection associated with MS, affected individuals
are asked not to participate in contact or competitive sports or isometric exercise. In addition, they
should avoid activities placing them at increased risk for joint injury or pain.
•
•
American Board of Pediatrics Content Specification(s):
Recognize the physical findings of Marfan syndrome
Recognize that patients with Marfan syndrome may have associated cardiac disease that
precludes participation in sports
• A 14-year-old boy loses consciousness while playing
basketball. He regains consciousness in 30 seconds and
is transported to a pediatric emergency department.
Results of head computed tomography scan,
electroencephalography, and echocardiography are
within normal limits. Electrocardiography results are
interpreted as abnormal, with a heart rate of 90
beats/min, PR interval of 150 msec, and QTc interval of
550
Of the following, the MOST likely explanation for
this patient's syncopal episode is
1.
2.
3.
4.
5.
complete atrioventricular block
first-degree atrioventricular block
hypertrophic cardiomyopathy
long QT syndrome
SVT due to Wolff-Parkinson-White
Answer D
•
The young child or adolescent who experiences an episode of syncope
must undergo 12-lead electrocardiography (ECG) as a part of his or her
evaluation. Findings on ECG may indicate the possibility of a rhythm
disturbance or conduction disorder. However, the corrected QT interval
must be measured to assess for the possible diagnosis of long QT
syndrome. Findings on ECG almost always are abnormal in the patient who
has symptomatic long QT syndrome. In addition to a prolonged corrected
QT interval, there may be bizarre or notched T waves and prominent U
waves, as shown for the boy in the vignette. Exercise testing may elicit
abnormalities not seen on resting ECG. Patients who have long QT
syndrome are at risk for life-threatening ventricular tachycardia, torsades de
pointes, and ventricular fibrillation. The syndrome may have an autosomal
dominant or autosomal recessive inheritance pattern or may be a new
mutation. Many of the mutations causing long QT syndrome demonstrate
ion channel abnormalities. Clinical laboratory testing is available.
Pharmacologic therapy and implantation of automatic cardiovertordefibrillators are the currently employed treatment modalities. Affected
patients may present with cardiac arrest, syncope, seizures, or palpitations.
Any patient who presents with suspicious symptoms in whom ECG
identifies a corrected QT interval greater than 450 msec warrants specialty
evaluation.
Answer D
•
Patients who have complete atrioventricular block also may present with
syncope. However, the teenager who has complete atrioventricular block
would have a resting heart rate dramatically lower than 70 beats/min
(typically in the range of 40 to 60 beats/min), and the ECG would
demonstrate a profound conduction disturbance characterized by a lack of
relationship between the atrial and ventricular rates. It is atypical for firstdegree atrioventricular block to result in syncope. In addition, first-degree
block is identified easily on baseline ECG by the PR interval exceeding
approximately 180 msec.
Hypertrophic cardiomyopathy can present with syncope due to either
obstruction of left ventricular outflow and resultant hypotension or
ventricular arrhythmias caused by the disturbance to repolarization.
However, the corrected QT interval is not markedly prolonged. In addition,
the findings of hypertrophic cardiomyopathy are readily discerned by
echocardiography. Supraventricular tachycardia due to Wolff-ParkinsonWhite syndrome can result in syncope because patients are at risk for
degeneration of their arrhythmia to atrial and subsequently ventricular
fibrillation. However, baseline ECG should demonstrate the classic features
of a short PR interval and a delta wave.
•
American Board of Pediatrics Content Specification(s):
Recognize the cardiac causes of syncope
• At 60 minutes of age, a term 3.3-kg female infant
appears cyanotic but is otherwise well. Her
oxygen saturation is 79%, she has widespread
cyanosis, and you can hear a faint low-pitched
murmur diffusely across the chest. The
remainder of findings on her physical
examination are within normal limits. After
placing her on nasal cannula oxygen at 2 L/min,
you note no change in saturation.
Of the following, the MOST likely cause of this
child's findings is
1.
2.
3.
4.
5.
anemia
hypoplastic left heart syndrome
neonatal sepsis
retained fetal lung liquid syndrome
tracheoesophageal fistula
Answer B
•
Hypoplastic left heart syndrome (HLHS) occurs in approximately 2 of every 1,000 live
births and represents approximately 3% of congenital heart diseases. The spectrum
of HLHS ranges from hypoplasia of the mitral or aortic valves to valvar atresia. In
addition, there is virtually always coarctation of the aorta, and the left ventricle is
markedly hypoplastic and dysfunctional. Although HLHS often can be detected
prenatally via fetal echocardiography, most cases are unsuspected at birth. Affected
infants may appear initially well prior to ductal closure, and the only clinical finding
may be cyanosis in the initial hours after birth. There may be a soft murmur, as
described for the infant in the vignette, or no murmur because the blood flow typically
is not turbulent. Spontaneous closing of the ductus arteriosus results in tachypnea,
respiratory distress, mottling, pallor, hypotension, weak pulses, cool extremities, and
eventually acidosis and shock due to systemic hypoperfusion. Management of shock
due to cyanotic congenital heart disease consists of the administration of
prostaglandin E1 to maintain patency of the ductus arteriosus.
Other causes of cyanotic congenital heart disease include complete transposition of
the great arteries, single ventricle lesions such as tricuspid atresia, pulmonary
atresia, severe tetralogy of Fallot, truncus arteriosus, interrupted aortic arch, and total
anomalous pulmonary venous return. All of these manifest only a minimal or no
response to oxygen administration.
Answer B
•
The "hyperoxia test" has been used for decades to help determine if a neonate who
has cyanosis is likely to have a cyanotic congenital cardiac defect. An FiO2 is
delivered via head hood, and a "preductal" right radial arterial blood gas is obtained.
PaO2 values in excess of 150 mm Hg during a hyperoxia test are not consistent with
the diagnosis of cyanotic congenital heart disease. Pulmonary disease and primary
pulmonary hypertension (if not sufficiently severe to be unresponsive to oxygen) are
more likely in this scenario. PaO2 values less than 150 mm Hg may indicate the
presence of cyanotic congenital heart disease. Patients who have complete
transposition of the great arteries have the lowest PaO2 findings, with typical values
of 30 to 60 mm Hg. The patient who has HLHS usually has a PaO2 in the range of 50
to 120 mm Hg, with the severity dependent upon the degree of obstruction across the
mitral and aortic valves as well as the presence or absence of obstruction to left-toright shunting across the patent foramen ovale.
The neonate who has severe anemia can manifest cyanosis, but the hyperoxia test
should elicit a dramatic improvement in PaO2 and oxygen saturation. The same holds
true for the neonate who has sepsis, retained fetal lung fluid syndrome, and
tracheoesophageal fistula. All of these conditions may have associated pulmonary
parenchymal disease but should respond to administered oxygen.
•
American Board of Pediatrics Content Specification(s):
Know the cardiac causes of cyanosis in the newborn infant
• A 3-year-old girl presents for a health
supervision visit. At birth, she was
diagnosed with hypoplastic left heart
syndrome and underwent uncomplicated
staged surgical palliation. Today her
mother asks you if her daughter's heart
disease could affect her development.
Of the following, you are MOST likely to advise the
mother that
1. a small percentage of children who undergo neonatal
heart surgery may develop transient motor delay
2. cognitive problems are rare with neonatal heart
surgery
3. evaluation for developmental delay should wait until
after kindergarten
4. speech and behavioral disorders are common among
those who undergo neonatal heart surgery
5. the only children who suffer developmental delay after
neonatal heart surgery are those who have pre- or
postoperative complications
Answer D
•
Over the past decade, outcomes associated with neonatal cardiovascular surgery
have improved dramatically. The expectation is that overall survival for pediatric open
heart surgery will exceed 96%. The arterial switch procedure performed for
transposition of the great arteries (TGA) is expected to achieve survival of 95% or
greater, and the Norwood operation for hypoplastic left heart syndrome (HLHS)
should maintain mortality at less than 15%. However, morbidity associated with these
procedures continues to exist. End-organ complications may result from associated
congenital anomalies, cardiovascular collapse in the patient who presents for care at
the time of ductal closure, and complications at the time of surgery or postoperatively
(eg, embolic phenomena).
Clinicians are just beginning to understand the neurodevelopmental impact on the
child who has cyanotic heart disease. A wide range of outcomes exists in this
population, and screening programs only recently have been established. The
screening is modeled on that performed in the long-term neonatology follow-up clinics
that have been developed for preterm infants. The most robust programs include
expertise in assessing motor milestone attainment, physical and occupational
therapy, neurocognitive evaluation and management, psychological testing, and
educational assessment.
Answer D
•
The data surrounding outcomes in the population of patients who have cyanotic congenital heart
disease are raising concerns about various areas of development. The mean full-scale intelligence
quotient (IQ) score has been shown to be 93 in patients who have TGA and have undergone
arterial switch operations. A number of studies have shown that the population of patients who
have undergone Norwood procedures for HLHS have IQ scores between 71 and 90. Overall
outcomes for the arterial switch operation demonstrate that 55% of patients have some degree of
impaired cognitive, behavioral, motor, or speech function. A Children's Hospital of Philadelphia
study showed that 69% of patients who had HLHS had attention-deficit disorder, but only one
patient was receiving medication. This highlights the poor recognition of impairment. Among
patients who have cyanotic heart disease and have undergone staged "single ventricle" palliation,
45% have required speech therapy, 40% have required physical therapy, 40% have required
special education, and 30% have been followed by a neurologist. Accordingly, the mother in the
vignette should be told that speech and behavioral disorders are common among those who
undergo neonatal heart surgery.
Most patients who undergo neonatal heart surgery experience transient motor delay as they
recover from the stress of intervention and stabilize their hemodynamics. However, only a small
number have long-standing profound gross or fine motor dysfunction unless there is associated
brain injury.
It is important to initiate neurodevelopmental evaluation early for these children. For those in
whom assessment is delayed until the school years, institution of therapy specific to their needs is
less successful, and academic milestones are more difficult to achieve. Assessment should begin
during the toddler years to allow directed therapy. The issues of risk of neurodevelopmental and
physical deficits should be addressed thoroughly as a part of ongoing and early discussions with
families. The discussion should delineate a strategy for obtaining screening assessments at
specific time intervals throughout childhood. Of course, the child who has more obvious deficits
should be referred for consultation with the appropriate specialist at the first sign of limitations.
•
American Board of Pediatrics Content Specification(s):
Understand the prognosis for cognitive development in patients with cyanotic congenital heart
disease
• You are monitoring a 4-week-old male infant
who has a large ventricular septal defect. He is
developing tachypnea but is not yet receiving
medications. The surgeon has informed the
family that surgery should occur at
approximately 6 months of age. The pediatric
resident asks you about expected symptoms
over the next several months until scheduled
surgery.
Of the following, the MOST appropriate information
to share with her is that
1. diuretic therapy may help to relieve tachypnea and
diaphoresis but will not improve weight gain
2. even with successful surgery, symptoms of
congestive heart failure are likely to persist until 18 to
24 months of age
3. feeding difficulties and problems with poor weight
gain are rare
4. most affected children do not develop pulmonary
overcirculation
5. symptoms of congestive heart failure likely will
develop over the next several weeks
Answer E
•
The natural history of a ventricular septal defect depends on the magnitude of the left-to-right
shunt. Smaller defects are restrictive, resulting in a high-grade murmur due to the pressure
gradient between the normal systemic blood pressure of the left ventricle and the much lower
pulmonary artery pressure of the right ventricle. For these patients, the magnitude of the left-toright shunt is minimal and, therefore, pulmonary overcirculation and associated congestive heart
failure do not occur. However, moderate-to-large ventricular septal defects, as described for the
infant in the vignette, are associated with a lower-grade murmur due to the lack of a pressure
gradient between the two ventricles. In this case, there is systemic pressure in the right ventricle,
and assuming that there is no obstruction to pulmonary outflow (ie, pulmonary stenosis or
infundibular muscular obstruction of the right ventricular outflow tract, as is present in tetralogy of
Fallot), the pulmonary artery pressure will be at systemic levels. Therefore, congestive heart failure
evolves over the first 1 to 2 postnatal months, as the pulmonary vascular resistance naturally falls.
Symptoms of congestive heart failure include tachypnea, poor feeding, diaphoresis, and poor
energy. Affected children grow poorly due to reduced caloric intake associated with their lack of
energy and resultant poor intake and unmet increases in metabolic requirements. A combination of
pharmacologic and nutritional interventions often is required. The standard pharmacologic regimen
includes diuretics and digoxin. Diuretics reduce the volume of shunting to the lung bed, thereby
reducing dilation of the left atrium and left ventricle. The left heart dilation results from inefficient
left-to-right shunting in which previously oxygenated blood from the left heart is shunted again
through the ventricular septal defect back out to the pulmonary circulation. Many infants receive
human milk or formula fortified to achieve a caloric density of 22 to 30 kcal/oz, depending on
caloric needs. Medications and calories are titrated to achieve a weight gain of between 10 and 30
g/day.
Answer E
•
Occasionally, an infant who has a large, unrestricted ventricular septal defect will not manifest
symptoms of pulmonary overcirculation and congestive heart failure because the normal decrease
in pulmonary vascular resistance does not occur. This prevents the development of a large left-toright shunt. Such babies are at risk for the eventual development of Eisenmenger syndrome and
irreversible pulmonary vascular changes. If they undergo surgery before such vascular changes
develop, successful surgical intervention is possible and can mitigate further trauma to the
pulmonary vasculature. The vessel wall abnormalities subsequently regress over time.
Surgical intervention typically is performed at 4 to 6 months of age. However, the child who is in
uncompensated congestive heart failure such that he or she is too tachypneic to feed, thus
requiring tube feeding; who is not growing adequately; or who is in respiratory distress may
require earlier surgical intervention. In prior eras, these children may have been candidates for
staged surgical intervention, with the initial placement of a pulmonary artery band (thereby
avoiding neonatal cardiopulmonary bypass) and subsequent pulmonary artery band removal and
ventricular septal defect patch repair. However, the current approach is to perform the complete
repair either at the "standard" timeframe of 4 to 6 months or when intractable symptoms are
present. The survival from surgical intervention for an isolated perimembranous ventricular septal
defect (the most common location for such a lesion requiring surgery) is more than 98%. Almost
all patients experience brief, uncomplicated postoperative recoveries. Residual symptoms of
congestive heart failure are rare after successful repair, and most children are weaned from all
cardiac medications by 4 to 8 weeks after surgery. These children do well long term, but they
warrant routine follow-up evaluations. Rare complications include rhythm disturbances, ventricular
dysfunction, or valve dysfunction.
•
American Board of Pediatrics Content Specification(s):
Know the expected natural history of ventricular septal defect
• You have been following a healthy 5-year-old
boy since birth. You noted a heart murmur at his
6-month health supervision visit, and you have
heard it intermittently at subsequent evaluations.
You are seeing the boy today because of a viral
upper respiratory tract infection associated with
2 days of fever. On physical examination, the
murmur sounds particularly prominent.
Of the following, the finding that MOST strongly
suggests that this murmur is benign is
1. a decrease in murmur intensity when moving from
supine to upright position
2. a higher blood pressure in the arms than legs
3. its continuous “machinery” quality in the left
infraclavicular position
4. its diastolic nature
5. the harsh, high-pitched auscultatory features heard
best on the lateral neck
Answer A
•
•
•
•
•
•
•
•
Cardiac murmurs are the result of turbulent flow through the cardiac valves,
chambers, and arteries. With auscultation of any cardiac murmur, the clinician can
identify and characterize the following qualities of the sound:
Loudness, graded on a scale of 1 through 6
Timing within the cardiac cycle: systolic, diastolic, continuous
Location (or its greatest intensity) on the chest wall
Radiation, which often indicates the direction of the turbulent blood flow
Pitch, which results from the degree of pressure difference between the flow before
and after the source of turbulence
Such qualities and characteristics of the murmur help the examiner to determine
whether the turbulent blood flow results from intrinsic cardiovascular pathology or
normal flow through a normal cardiovascular system. The latter condition is
considered an innocent murmur, also referred to as a functional, benign, or normal
murmur, and may be transient during childhood. Such murmurs may be accentuated
during high-output states (eg, fever, infection, anemia).
Physical examination begins with the patient in the supine position, using both the
bell and the diaphragm components of the stethoscope. The entire precordium,
axillae, abdomen, anterior fontanelle, and neck are evaluated. The examination is
repeated with the patient in a sitting position. Finally, the patient’s back is auscultated.
•
•
•
Innocent murmurs are typically relatively quiet (grades 1 or 2), systolic, located over
the left sternal border, possibly radiating to the upper left or right sternal border, lowpitched, vibratory, and typically decreasing in intensity when the patient transitions
from a supine to a sitting position.
The history of onset in infancy, intermittent nature, and lack of other signs and
symptoms of congenital heart disease for the child described in the vignette are
suggestive of a benign murmur. The decrease in murmur intensity when he is
repositioned from a lying to a sitting position is also consistent with a functional
(benign) murmur. The murmur is more prominent at his current visit for a respiratory
illness due to the increased cardiac output associated with infection and fever.
Because the history and examination findings are consistent with a benign flow
murmur, no additional testing or follow-up evaluation is required.
A higher blood pressure in the arms than in the legs suggests the possibility of
coarctation of the aorta, which is not a benign condition. A continuous “machinery”
murmur at the infraclavicular region is suggestive of a patent ductus arteriosus.
Diastolic murmurs are rarely benign and may result from aortic or pulmonary
insufficiency or inflow obstruction across the tricuspid or mitral valves. A high-pitched
systolic murmur heard over the neck is typical of aortic stenosis. It is often
accompanied by a systolic click and may be accentuated when the patient moves
from a sitting to a lying position.
• A 15-year-old girl is brought to your office after “passing
out” while she was participating in a band program
outside on an 80.0°F day. She recalls feeling
lightheaded, then awakening surrounded by her
bandmates. The reported duration of the episode was 1
minute. She has had one similar episode in the past.
She has no underlying medical problems, and there is no
family history of seizures or heart disease. Currently, her
temperature is 37.3°C, heart rate is 84 beats/min,
respiratory rate is 18 breaths/min, and blood pressure is
98/64 mm Hg. The remainder of her findings, including
those of cardiovascular and neurologic examinations,
are normal.
Of the following, the MOST appropriate next step
in her evaluation is
1.
2.
3.
4.
5.
cardiac event monitoring
CT scan of the brain
electrocardiography
electroencephalography
tilt table testing
Answer C
•
•
Syncope, as experienced by the girl in the vignette, is defined as the transient loss of
consciousness and postural tone associated with an acute disruption in cerebral
perfusion. It is a common pediatric problem, occurring at least once in 20% or more
of all persons before age 20, according to one survey. Because it has a wide variety
of underlying causes, some of which are life-threatening, a number of tests may be
considered to evaluate this phenomenon. In most patients, the cause is benign, and
the evaluation should be based primarily on history and physical examination
findings. Despite its frequency, there is not yet a standardized approach to the
evaluation of children and adolescents who experience syncope. Although the data
are limited, most authors agree that electrocardiography (ECG) may be the only test
required for patients who have a typical history and normal physical examination
findings, such as the girl described in the vignette.
The underlying cause for syncope can be cardiac, neurologic, psychological, or
metabolic, but in most studies, about 75% of cases are diagnosed as
neurocardiogenic (also known as simple faint or vasovagal or neurally mediated
syncope). Neurally mediated syncope (NMS) can be further divided into central (eg,
pain- or emotion-induced), postural (associated with prolonged standing or sitting),
and situational (eg, micturition, coughing, hair grooming-induced). The exact
mechanisms causing NMS are unclear but involve complex interactions of
parasympathetic, sympathetic, and cardiac reflexes that can result in hypotension or
bradycardia. An interesting recent study suggests a higher prevalence of iron
deficiency with or without anemia in patients who have NMS, so testing for this
possibility (eg, with a ferritin measurement) might be considered in some patients.
•
•
Typically, the patient has been standing, usually for at least several minutes to
sometimes hours, often in a warm environment. There is a distinct prodromal phase
of seconds to a few minutes of nausea, clamminess, pallor, dizziness, visual and
hearing changes, and weakness. This is followed by loss of consciousness and
collapse. Recovery is usually quick, in 1 to 2 minutes, with no subsequent symptoms
besides fatigue or a feeling of shakiness. Alternatively, the patient or observers may
describe inciting events such as blood draws, injections, or hair grooming.
Perhaps the most concerning potential etiologic category for syncope is cardiac, with
conditions ranging from arrhythmias (especially prolonged QT syndrome) to
pulmonary hypertension to cardiomyopathy. Studies indicate that a cardiac diagnosis
can be found in 2% to 3% of children who have syncope. The history in such patients
differs from that of children who have NMS and may direct the clinician to the cause.
The child may have a past history of congenital heart disease; syncope may occur
during exercise or suddenly without prodrome; there may be a family history of
cardiomyopathy, sudden death, or deafness; or the child may experience atypical
precordial pain or a sensation of palpitations. A personal or family history of recurrent
syncope also may suggest an underlying cardiac cause. Although a normal ECG in
the presence of the usual history of NMS syncope reassures the examiner of a low
likelihood of an arrhythmia, if the history suggests a cardiac diagnosis, further testing
may be warranted. In that case, echocardiography may detect structural
abnormalities, and a cardiac event monitor or tilt table test may reveal an arrhythmia
not present on ECG. However, in one study, echocardiography accounted for 14% of
the costs of testing children who had syncope and did not reveal a single abnormality
not already detected by history, physical examination, and ECG.
•
•
Despite its utility in adults who have syncope, cardiac event monitoring has not
yielded substantial benefit in children, possibly because of the lower incidence of
heart disease. Tilt table testing has shown a high yield of diagnoses, but there is
concern about low specificity of the test, and it is not necessary with a typical history
and physical examination findings associated with NMS.
Other causes of transient loss of consciousness in one study of children included
seizures (1.9%), migraines (0.2%), conversion reactions (1.4%), hypoglycemia
(0.4%), severe anemia (0.2%), and hyperventilation (0.2%). In this study, cranial
imaging was not found to be helpful in diagnosing a single case.
Electroencephalography was diagnostic in 39% of patients, but all of the children had
history or examination findings indicative of underlying neurologic disease. History
and physical examination findings also typically led to the appropriate diagnosis of
hypoglycemia and anemia.
• A 6-year-old previously healthy boy presents with the
recent development of nocturnal dyspnea. On
questioning of his parents, you discover that the child
has experienced exercise intolerance, two episodes of
syncope while running, poor appetite, and a cough
without congestion over the past year. His physical
examination reveals a heart rate of 120 beats/min,
respiratory rate of 26 breaths/min, gallop rhythm, III/VI
high-pitched blowing systolic murmur at the apex,
hepatomegaly, and diminished pulses. Chest
radiography documents an enlarged cardiac silhouette
with pulmonary vascular congestion, and
echocardiography demonstrates a regurgitant mitral
valve with a dilated left ventricle and markedly reduced
systolic contractility.
Of the following, the MOST likely cause for this
child’s dilated cardiomyopathy is
1.
2.
3.
4.
5.
a congenital mitral valve abnormality
Duchenne muscular dystrophy
Friedreich ataxia
rheumatic heart disease
sickle cell disease
Answer A
•
•
The causes of a dilated cardiomyopathy are diverse and include viral myocarditis,
arrhythmias, metabolic conditions, muscle disorders, drug toxicities, and congenital
cardiac lesions. Among the mitral valve disorders are abnormalities of the valve
leaflets or chordal apparatus, which result in either acute neonatal symptoms or
chronic, indolent findings that eventually degenerate. Mitral valve disorders can occur
in isolation or as a part of a complex of left heart pathology that may include
abnormalities of the aortic valve (eg, bicuspid aortic valve with stenosis or
regurgitation), aortic arch (coarctation of the aorta), and left ventricle (hypoplastic left
heart syndrome). Mitral valve disease can result in either stenosis or regurgitation.
Both can be tolerated by the child for long periods of time, but eventually they worsen
and result in left atrial dilation, left ventricular dilation, and elevated pressure back into
the lungs (pulmonary hypertension). As the left ventricle continues to dilate, efficiency
of contractility is reduced because fiber cross-linking exceeds the most optimal
portion of the Starling curve, and eventually a dilated cardiomyopathy results.
Accordingly, the boy in the vignette most likely has a congenital mitral valve
abnormality and congestive heart failure (CHF).
Symptoms of CHF in older children include exercise intolerance, fatigue, dizziness or
syncope, shortness of breath, palpitations, diaphoresis, abdominal discomfort, and
anorexia. Among the signs are tachycardia, rales, poor tissue perfusion,
hepatomegaly, and a gallop rhythm. Auscultation may identify a blowing systolic
ejection murmur at the apex with radiation to the back from mitral regurgitation. Even
in the absence of an intrinsic mitral valve disorder, mitral regurgitation can develop
when left ventricular dilation causes a change in geometry that results in poor leaflet
coaptation.
•
•
Echocardiography is the gold standard for diagnosing both mitral valve disorders and
a cardiomyopathic process. In children, the mitral valve can be seen in exquisite
detail, allowing identification of pathologic features, as described for this boy. Color
Doppler interrogation assists with determination of mitral regurgitation or stenosis.
The left ventricular cavity can be assessed for chamber dilation, and quantitative
determination of contractility is the routine part of echocardiographic assessment.
Duchenne muscular dystrophy often leads to the development of a dilated
cardiomyopathy due to the adverse effect of the dystrophin mutation on the
cardiomyocyte. However, the child in the vignette is younger than the typical child
who develops left ventricular dysfunction (unusual before 10 years of age). In
addition, most boys who have Duchenne muscular dystrophy and develop a dilated
cardiomyopathy already manifest skeletal muscle involvement. Friedreich ataxia is
associated with the development of a cardiomyopathy, but it is a hypertrophic rather
than a dilated cardiomyopathy. In addition, a child who has Friedreich ataxia and
advanced cardiac findings invariably exhibits ataxia. Mitral valve (as well as aortic
valve) thickening and dysfunction are found in rheumatic heart disease. However, this
child has none of the other cardinal features of acute rheumatic fever (dermatologic,
infectious, neurologic, or joint). Sickle cell disease can result in high-output heart
failure due to anemia, but this child does not have the features of a chronic disease
state, which very likely would have developed by the age of 6 years.
• You are seeing a 4-week-old previously healthy infant in
your office because of concern about poor feeding. On
questioning, the parents report that the child has
developed grunting respirations associated with
feedings, diaphoresis, pallor, and prolonged periods of
sleep. On physical examination, the boy’s heart rate is
160 beats/min, respiratory rate is 55 breaths/min, blood
pressure in the right arm is 75/48 mm Hg, blood
pressure in the left leg is 88/55 mm Hg, and oxygen
saturation is 95%. He exhibits tachypnea, rales and
retractions, a II/VI low-pitched holosystolic murmur
across the precordium, and a palpable liver 2 cm below
the right costal margin.
Of the following, the MOST likely explanation for
the child’s findings of congestive heart failure is
1.
2.
3.
4.
5.
aortic valve stenosis
coarctation of the aorta
tetralogy of Fallot
transposition of the great arteries
ventricular septal defect
Answer E
•
•
The natural history of a ventricular septal defect (VSD) depends on the magnitude of
the left-to-right shunt. A moderate-to-large VSD is associated with a lower-grade
murmur, as described for the infant in the vignette, due to the lack of a pressure
gradient between the two ventricles. In this case, there is systemic pressure in the
right ventricle, and assuming that there is no obstruction to pulmonary outflow (eg,
pulmonary stenosis or infundibular muscular obstruction of the right ventricular
outflow tract, as is present in tetralogy of Fallot), the pulmonary artery pressure also
is at systemic levels. Congestive heart failure (CHF) evolves over the first 1 to 2
postnatal months as the pulmonary vascular resistance naturally falls. In contrast,
smaller defects are restrictive, resulting in a louder and higher-pitched murmur due to
the pressure gradient between the normal systemic pressure of the left ventricle and
the much lower pulmonary artery pressure of the right ventricle. In these patients, the
magnitude of the left-to-right shunt is minimal and, therefore, pulmonary
overcirculation and associated CHF do not occur. Other causes of neonatal and
infant CHF include any congenital heart lesion that results in either a large left-to-right
shunt (eg, atrioventricular canal defect or patent ductus arteriosus) or pulmonary
hypertension (eg, mitral valve disorders), myocarditis, severe anemia, drug toxicity, or
metabolic/mitochondrial disorders.
Symptoms of CHF include tachypnea, poor feeding, diaphoresis, and poor energy.
Affected children grow poorly due to reduced caloric intake from their lack of energy
and resultant poor intake and an unmet increase in metabolic requirements. A
combination of pharmacologic and nutritional interventions is often required. The
standard pharmacologic regimen includes diuretics, digoxin, and afterload-reducing
agents such as captopril.
•
•
Diuretics reduce the volume of shunting to the lung bed, thereby reducing dilation of
the left atrium and left ventricle. Such left heart dilation is a result of the inefficient leftto-right shunt in which previously oxygenated blood from the left heart is again
shunted through the VSD back out to the pulmonary circulation. Many children
receive human milk or formula fortified to achieve a caloric density between 22 and
30 kcal/oz, depending upon caloric needs. Medication and calories are titrated to
achieve a weight gain of 15 to 30 g/day.
Obstructive left heart lesions (such as coarctation of the aorta and aortic stenosis)
can result in CHF if the obstructive process is severe, but neither would result in the
murmur described in the vignette. Tetralogy of Fallot more commonly produces
cyanosis due to reduced pulmonary circulation rather than CHF due to pulmonary
overcirculation. Similarly, transposition of the great arteries is associated with
neonatal cyanosis and does not cause the signs and symptoms of CHF.
• You are called to the emergency department to assess a
7-day-old infant who has presented with poor perfusion
and respiratory collapse. He has been well-appearing
but slightly dusky since birth. Pulse oximetry reveals an
oxygen saturation of 90% in the right arm but 55% in the
left leg. His blood pressures are symmetric but diffusely
reduced. Although he has no obvious cardiac murmur,
he does exhibit a gallop rhythm, his liver is enlarged, and
his extremities are cool, with reduced pulses.
Of the following, the MOST likely diagnosis for this
infant is
1.
2.
3.
4.
5.
coarctation of the aorta
dilated cardiomyopathy due to viral myocarditis
hypertrophic cardiomyopathy due to gestational diabetes
hypoplastic left heart syndrome
transposition of the great arteries
Answer
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D
Hypoplastic left heart syndrome (HLHS) occurs in approximately 2 in 1,000 live births
and represents approximately 3% of congenital heart disease. The spectrum of HLHS
ranges from hypoplasia of the mitral or aortic valves to valvar atresia. In addition,
there is virtually always coarctation of the aorta, and the left ventricle is markedly
hypoplastic and dysfunctional. Although HLHS can often be detected prenatally
through fetal echocardiography, most cases are still unsuspected at birth. Affected
infants may initially appear well; the only clinical finding may be cyanosis, which may
be overlooked. There may be a soft murmur or absence of a murmur because the
blood flow typically is not turbulent. When the ductus arteriosus begins to close
spontaneously, tachypnea and respiratory distress develop, with mottling, pallor,
hypotension, weak pulses, cool extremities, and eventually acidosis and shock due to
systemic hypoperfusion, as described for the infant in the vignette. Because the
ductus arteriosus must supply circulation to the area distal to the area of aortic arch
hypoplasia, the oxygen saturation is reduced in the lower body due to the obligate
ductal right-to-left shunt of desaturated right heart blood. Management of the neonate
suspected of having shock due to cyanotic congenital heart disease consists of the
administration of prostaglandin E1 to maintain patency of the ductus arteriosus. Other
congenital heart lesions that can produce neonatal shock include aortic stenosis and
coarctation of the aorta. Neonatal cardiomyopathy also can manifest as shock, as
can sepsis, catastrophic blood loss, and respiratory failure.
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As noted, coarctation of the aorta can result in neonatal shock, but the absence of a
blood pressure discrepancy in the child described in the vignette makes this
diagnosis highly unlikely. Similarly, dilated cardiomyopathy due to viral myocarditis
can produce shock. However, this neonate is described as having been wellappearing since birth and has highly discrepant oxygen saturations between the arm
and leg, findings that point toward a ductal-dependent lesion. Hypertrophic
cardiomyopathy can cause neonatal shock due to the presence of obstructive left
ventricular outflow tract obstruction. This condition is characterized by a high-pitched
murmur but no oxygen saturation disparity between arm and leg. Although
transposition of the great vessels is a ductal-dependent lesion, it involves the left
heart supplying well-saturated blood flow to the pulmonary artery, ductus arteriosus,
and lower body, while the desaturated blood from the right heart travels to the aorta
and upper body, thus resulting in lower saturation in the upper extremities compared
to the lower extremities.