Embryology/Clinic
Name one of the factors contributing to ductal patency in the fetus
The two prostaglandins produced in the ductus are prostaglandin E2 (PGE2) and prostacyclin (PGI2). Circulating PGE2 in fetal blood probably plays the larger role in maintaining patency of the ductus arteriosus in normal fetal circulation. Following birth, there is a rapid decrease in the concentration of PGE2, which, along with an increase in blood oxygen concentration, contributes to functional closure of the ductus arteriosus
One significant factor contributing to ductal patency in the fetus is the low dissolved oxygen concentration (pO2) supplied to the ductus.
A 5-day-old neonate who was born at home is brought to the emergency department. The infant is noted to have cataracts and microcephaly. Scattered petechiae are noted across chest, back, and face. Hepatosplenomegaly is discovered on abdominal examination. On further history, the mother tells you she has never had any vaccines “except DTAP and influenza.” You are called to the ED to perform a transthoracic echocardiogram. The congenital heart abnormality most commonly associated with this infectious syndrome is:
A. Patent ductus arteriosus
B. Tetralogy of Fallot
C. Hypoplastic left heart syndrome
D. Pulmonary atresia
E. Transposition of the great arteries
(A) This infant seems to be presenting with congenital rubella syndrome which may include cataracts, “blueberry muffin rash” secondary to petechiae or purpura, and hepatosplenomegaly. While postnatal rubella is usually a mild illness, congenital rubella syndrome (secondary to maternal infection during the first trimester) often has devastating consequences. Patent ductus arteriosus and peripheral pulmonary artery stenosis are the most common congenital heart deficits associated with the syndrome.
A 28-week preemie develops persistent abdominal distention, increasing residuals before feedings, blood in the stools, and decreasing bowel sounds. Abdominal x-ray reveals evidence of intramural air in the right lower quadrant. The patient has bounding pulses, and an echocardiogram confirms the presence of a hemodynamically significant patent ductus arteriosus (PDA). What is the best next step in management?
A. Referral to surgery for immediate surgical closure
B. Percutaneous closure of PDA with occluding coil
C. Trial of indomethacin
D. Trial of ibuprofen
E. Do nothing
(A) When signs of necrotizing enterocolitis develop in an infant with significant left-to-right shunting through a PDA, early surgical closure of the ductus arteriosus has significantly reduced mortality. Therefore, if abdominal distention is persistent, increasing residuals before feedings, blood in the stools or gastric aspirate, decreasing bowel sounds, and, particularly, intramural air occurs in association with a significant left-to-right shunt through a PDA, immediate surgical closure is recommended.
A 25 year old is referred for evaluation of a murmur that was recently heard during a general physical. On examination, there is a regular rate and rhythm. No lift or thrill. First heart sound is normal in intensity. Second heart sound is hard to distinguish. There is a 3/6 continuous murmur, heard best at the left sternal border. It peaks around the second heart sound. No third or fourth heart sounds. No rubs. Right radial, right carotid, and femoral pulses are all easily palpable. Blood pressure is 120/40 mm Hg in both the right and left arms. Which test is most likely to define the source of the murmur?
A. ECG
B. Transesophageal echocardiogram
C. Transthoracic echocardiogram
D. Exercise ECG
E. Dobutamine stress echocardiogram
(C) The murmur described in the examination is continuous and it peaks around the second heart sound—typical of a PDA. An audible PDA usually can be visualized with transthoracic echocardiography. If that imaging is suboptimal, CT or MRI of the chest may be helpful. If the PDA is audible, especially in a patient with a wide pulse pressure, one would expect left ventricular and left atrial enlargement. This patient should undergo closure of the PDA, usually via a transcatheter procedure.
Which of the following patients does not require bacterial endocarditis prophylaxis?
A. 2 year old female who had transcatheter PDA closure 4 months ago
B. 17 year old with history of bacterial endocarditis
C. 3 year old with PDA which has not been closed
D. 20 year old with PDA and resultant cyanosis
E. 18 month old who underwent transcatheter PDA closure 8 months ago with tiny residual shunt
C
Current recommendations, however, exclude most PDAs from antibiotic prophylaxis. Exceptions for which endarteritis prophylaxis is indicated include patients within the first 6 months after device or coil occlusion of PDA, patients who have a persistent shunt around a device or coil, and patients with a personal history of endarteritis. Because endarteritis prophylaxis is recommended for patients with unrepaired cyanotic heart disease, one could infer that it may also be warranted for individuals with PDA and Eisenmenger syndrome, although such a recommendation is not explicitly given
The angiogram shown in Figure 4.9 is obtained in an otherwise healthy, asymptomatic 8-month-old girl with an enlarged cardiac silhouette on chest x-ray. Based on these findings, which of the following is recommended for the patient?
A. No further cardiology follow-up is necessary
B. Repeat catheterization in 6 to12 months
C. Transcatheter intervention
D. Oral diuretic therapy
E. Surgical referral for operative management
(C) The angiogram is a lateral projection demonstrating retrograde access for a left heart catheterization with an angiogram performed in the proximal descending aorta. There is left-to-right shunting through a patent ductus arteriosus to the left pulmonary artery. All symptomatic PDAs with left-to-right shunting and asymptomatic PDAs with LA or LV enlargement should be closed, regardless of age. In the current era, transcatheter device closure is the standard of care.
What is the theoretical benefit of ibuprofen over indomethacin for closure of PDA in premature infants?
A. Decreased risk of intraventricular hemorrhage
B. Decreased risk of pulmonary hypertension
C. Decreased risk of gastrointestinal bleeding
D. Greater rate of ductal closure
E. Less effect on cerebral blood flow
(E) Ibuprofen has been evaluated as a possible alternative to indomethacin in preterm infants. Studies have shown a similar rate of ductal closure after ibuprofen treatment with fewer negative effects on renal function, cerebral vasculature, and cerebral blood flow than indomethacin. The risk of intraventricular hemorrhage is equivocal. Of note, using ibuprofen for prophylaxis is associated with increased risk of pulmonary hypertension.
An 18 year old with unrepaired pulmonary valve atresia/VSD (PA/VSD) comes to clinic for an annual evaluation. On examination, the patient has upper and lower extremity clubbing. There is a regular rate and rhythm. A parasternal lift is present but no thrill. First heart sound is normal. Second heart sound is single. There is a 3/6 continuous murmur which is heard best at the right scapula. No third or fourth heart sounds. Blood pressure is 120/40 mm Hg in both the right and left arms. The origin of the murmur is most likely:
A. Right coronary artery fistula
B. Aortic valve regurgitation
C. Mitral valve stenosis
D. Patent ductus arteriosus
E. Pulmonary valve regurgitation
(D) The continuous murmur is typical of a PDA or systemic arterial to pulmonary artery collateral vessels (common in patients with pulmonary atresia). Patients with PA/VSD frequently have a right-sided aortic arch and the PDA may be best heard over the right back. A right coronary fistula may produce a continuous murmur but is unlikely to be heard best in the back. The other choices do not generate continuous murmurs.
Which branchial arch does the ductus arterioles develop from?
A. 3rd
B. 4th
C. 5th
D. 6th
The ductus arteriosus is a normal fetal structure that develops from the sixth branchial arch by the sixth week of gestation and allows communication between the aorta and pulmonary arteries (PAs)
PICUTRE
Which of the following defects best explains the clinical and hemodynamic findings?
A. Primary (idiopathic) pulmonary hypertension
B. Anomalous pulmonary venous connections
C. Ventricular septal defect
D. Patent ductus arteriosus
E. Anomalous right pulmonary artery from the ascending aorta
(D) This patient has severe pulmonary hypertension both clinically and hemodynamically. While there is a small atrial level shunt (demonstrated echocardiographically and by a small “step-down” in saturation from pulmonary vein to left atrium and left ventricle), the striking hemodynamic abnormalities are suprasystemic pulmonary artery pressure and a significant “step-down” in saturation from ascending aorta to descending aorta. The most likely explanation for this finding is a right-to-left shunt between the ascending and descending aorta, such as a PDA or aortopulmonary window. Primary (idiopathic) pulmonary hypertension would be a consideration in the absence of a significant shunt lesion. The saturation step-down occurs at the level of the great arteries, making anomalous pulmonary veins (an “atrial” level shunt) and ventricular septal defect less likely. Anomalous origin of the right pulmonary artery from the aorta (so-called “hemitruncus”) can result in pulmonary hypertension/Eisenmenger syndrome, but invasive hemodynamics would demonstrate right pulmonary artery saturation equal to aortic, and a lower left pulmonary artery saturation.
A 5-day-old infant is brought to the emergency room with excessive lethargy and poor oral intake. The oxygen saturation on the right arm is 98% but the one on the foot is not reading. On examination, he has cold lower extremities with barely palpable pulses. A ductal-dependent lesion was assumed and prostaglandin infusion was started at a high dose. An echocardiogram was performed that confirmed the diagnosis of severe, discrete juxtaductal coarctation of the aorta with a mean Doppler gradient of 38 mm Hg. No patent ductus arteriosus was seen despite the child being on prostaglandin for over an hour. The left ventricular function was mildly decreased with a calculated ejection fraction of 50%. A bicuspid aortic valve with no stenosis or regurgitation was noted. A cardiac surgeon will not be available for several hours. What is the next best management step for this patient?
A. Call for ECMO support
B. Transcatheter ductal stent placement
C. Start furosemide infusion
D. Start epinephrine infusion
E. Give oral digoxin
(D) If the ductus arteriosus does not open after prostaglandin infusion in severe coarctation of the aorta, inotropic support should be used to improve left ventricular function and augment flow across the coarctation. Neonatal coarctation should not be managed with ductal stent. Diuretics and digoxin do not help in this situation and the patient should be kept NPO
While undergoing a predischarge examination in the newborn nursery, a 2-day-old term infant is noted to have poor femoral pulses. She also fails the congenital heart disease saturation screening. Electrocardiogram shows sinus tachycardia. Echocardiogram shows an interrupted aortic arch (IAA) with an intact ventricular septum. Which of the following associated findings should be looked for on the echocardiogram?
A. Secundum ASD
B. Left superior vena cava (SVC) to coronary sinus
C. Atrioventricular canal defect
D. Aortopulmonary window
E. Cor triatriatum
(D) In the setting of IAA without a VSD, an aortopulmonary window can be associated and needs to be ruled out. The others are not common associations that are significant.
(PICTURE)
Char syndrome is an autosomal dominant “heart-hand” syndrome associated with PDA. Typical facial features include short philtrum, prominent lips (sometimes referred to as “duck-billed”), flattened nasal bridge with upturned nose, and abnormalities of the fifth finger (often absence or hypoplasia of the phalanges). The eyes are wide-set with droopy eyelids. A missense mutation in the TFAP2B gene on chromosome 6p has been shown to cause Char syndrome
You are assessing a 5-year-old girl for possible PDA closure. Echocardiogram shows a large PDA with bidirectional shunting. There is no murmur on examination. Her echo is otherwise normal with no tricuspid regurgitation and no chamber enlargement. Her parents report she is a quiet child but does not seem to be limited in any way. What is the next best step?
A. Surgical closure of her PDA
B. Transcatheter closure of her PDA
C. Return in 3 years for follow-up echo evaluation
D. Return in 6 to 12 months for follow-up echo
E. Hemodynamic cardiac catheterization
(E) AHA Pediatric Catheterization Guidelines—In patients with a large PDA and bidirectional flow due to pulmonary vascular disease, occlusion may be beneficial only if the pulmonary lung bed shows some reactivity to pulmonary vasodilator therapy. These patients should undergo hemodynamic assessment and pulmonary vasoreactivity testing before consideration for ductal occlusion. However, data on this group of patients are scant, and long-term follow-up data are unknown. Should pulmonary vascular disease continue to progress, the ductus will no longer be available to prevent the RV pressures from becoming supersystemic. Class III transcatheter PDA occlusion should not be attempted in a patient with a PDA with severe pulmonary hypertension associated with bidirectional or right-to-left shunting that is unresponsive to pulmonary vasodilator therapy (level of evidence: C).
A neonate is found to have d-transposition of the great arteries with a large ventricular septal defect (VSD), a large atrial septal defect, and severe left ventricular outflow tract (LVOT) obstruction. The patient’s oxygen saturation is 68% on room air. Which of the following is the most appropriate initial intervention for this patient?
A. Arterial switch operation
B. Blalock–Hanlon septostomy
C. Pulmonary balloon valvuloplasty
D. Balloon atrial septostomy
E. PDA stent implantation
(E) This patient’s anatomy consists of a subpulmonary left ventricle with obstruction. This manifests clinically as severe hypoxemia due to inadequate pulmonary blood flow. The best intervention in this neonate to increase pulmonary blood flow is to stent the ductus arteriosus or place a modified BT shunt. This child is likely to not be a candidate for a traditional arterial switch operation due to the LVOT obstruction. The Blalock–Hanlon septostomy is an open surgical atrial septostomy that is no longer performed. Because LVOT obstruction is most often complex and not isolated to pulmonary valve stenosis, balloon valvuloplasty is unlikely to provide improvement in pulmonary blood flow. With a large ASD, the patient’s cyanosis is not a result of inadequate atrial shunting/mixing, so septostomy is not likely to provide improvement in oxygenation.
Which of the following measurements has the best potential to distinguish a large AVM from a large PDA in a young infant?
A. Pulse pressure as determined by sphygmomanometry
B. Cardiothoracic ratio on plain chest x-ray
C. Systemic vein oxygen saturation measurements obtained during cardiac catheterization
D. QRS axis on electrocardiogram
E. Liver span by physical examination
(C) Large AVMs and large patent ductus arteriosus have similar hemodynamic effects (large extracardiac left-to-right shunts) and thus are indistinguishable in terms of pulse pressure, liver span, cardiothoracic ratio on chest x-ray, and QRS axis on ECG. Diagnostic cardiac catheterization is usually unnecessary, as the diagnosis is suspected by clinical examination and confirmed by noninvasive imaging. When performed, catheterization demonstrates high cardiac output, elevated atrial and ventricular end-diastolic pressures, a widened systemic arterial pulse pressure, and a large difference in the oxygen saturation between the superior and inferior vena cava (higher saturation from the involved area).
Which of the following events is most responsible for early, functional closure of the ductus arteriosus?
A. Hemorrhage and necrosis in the subintimal region
B. Medial smooth muscle cell migration in the wall of the ductus
C. Equalization of pulmonary and systemic vascular resistance
D. Infolding of the endothelium
E. Thinning of the intimal layer
(B) Postnatal closure of the ductus arteriosus occurs in two phases. The first phase, “functional closure,” occurs within 12 hours after birth. There is contraction and cellular migration of the medial smooth muscle in the wall of the ductus arteriosus that causes the vessel walls to become thick and protrude into the vessel lumen.
The second stage usually is completed by 2 to 3 weeks and results from infolding of the endothelium, disruption and fragmentation of the internal elastic lamina, proliferation of the subintimal layers, and hemorrhage and necrosis in the subintimal region. There is connective tissue formation and replacement of muscle fibers with fibrosis with subsequent permanent sealing of the lumen, thus forming the ligamentum arteriosum.
A newborn female born at 38-week gestation had mild–moderate respiratory distress at birth requiring continuous positive airway pressure (CPAP). She has lower extremity cyanosis with saturations of 80% in the right lower extremity and 95% in the right upper extremity due to which an echocardiogram was obtained. Figure 5.3 shows the pulsed-wave spectral Doppler pattern obtained within the patent ductus arteriosus. Which of the following is the most likely diagnosis?
A. Transposition of the great arteries with coarctation of the aorta
B. Persistent pulmonary hypertension
C. Tausig–Bing anomaly
D. Tricuspid atresia with transposed great arteries
E. None of the above
(B) Newborn baby is demonstrating persistent pulmonary hypertension evident by the bidirectional flow at the level of patent ductus arteriosus (PDA) demonstrated by the spectral Doppler pattern in the PDA. There is >10% split between pre- and postductal oxygen saturation with lower postductal saturation due to the right-to-left shunting at the level of PDA. However, in patients with transposition of great arteries and coarctation of the aorta, a reverse differential cyanosis is seen with lower preductal and higher postductal oxygen saturation due to the shunting of oxygenated blood from the pulmonary artery to the aorta.
A neonate fails their pulse oximetry screen with saturation of 89% in the right arm. Saturation is 94% in the right leg. CXR shows a narrow mediastinum and no significant pulmonary edema. Cardiac examination is notable for a prominent S2, no murmur, and good distal pulses. Echocardiogram shows d-transposition of the great arteries. What other finding must also be present?
A. Wide open PDA with pulmonary hypertension
B. Wide open PDA with dropping pulmonary vascular resistance (PVR)
C. Intact atrial septum
D. Aberrant right subclavian artery
E. VSD
(A) There is a finding of differential cyanosis and in order for that to exist, there must be a PDA with right-to-left shunting. Choice B would have left-to-right shunting. Choices C and E would not cause differential cyanosis. Choice D would not show differential cyanosis due to the aberrant subclavian artery often coming off distal to the PDA.