Pediatric Annals

CME 

An Unusual Cause of Respiratory Distress in an Infant

Colleen H. Rusciolelli, MD; Joseph R. Hageman, MD; Abraham Groner, MD

Abstract

Partial anomalous venous connection (PAPVC) is a congenital cardiovascular defect where one or more (but not all) of the pulmonary veins return anomalously back to the right atrium, either via a direct or indirect connection. It often occurs with other cardiac defects, most commonly a secundum atrial septal defect. Individuals with a large degree of shunting will present with dyspnea, fatigue, and, in some cases, heart failure. Clinical associations and variants of PAPVC include scimitar syndrome, pseudo-scimitar or meandering right pulmonary vein, sinous venosus defects, malposition of the septum primum, and Turner syndrome.

The patient in this case, a previously healthy, 6-month-old, full-term male, presented to the emergency department for evaluation of respiratory distress and wheezing. The infant was first seen in his pediatrician’s office, where he was noted to be tachypneic and wheezing. He was feeding without difficulty, voiding well, and was active and playful. The patient had passed critical congenital heart disease screening after his birth and prior to discharge, and the family history was negative for any respiratory or cardiac conditions.

Cardiac magnetic resonance imaging is becoming the mode of choice for diagnosis of PAPVC. The definitive treatment is surgical correction, but surgery is not indicated in all cases, especially if the patient is asymptomatic and the degree of shunting is small. Patients with isolated PAPVC who undergo surgical correction have good long-term outcomes.

In this case, the patient underwent the Warden procedure, which causes an increased risk of superior vena cava stenosis or obstruction to the right atrium. This patient will require lifelong follow-up to assess for new onset pulmonary venous obstruction.


Abstract

Partial anomalous venous connection (PAPVC) is a congenital cardiovascular defect where one or more (but not all) of the pulmonary veins return anomalously back to the right atrium, either via a direct or indirect connection. It often occurs with other cardiac defects, most commonly a secundum atrial septal defect. Individuals with a large degree of shunting will present with dyspnea, fatigue, and, in some cases, heart failure. Clinical associations and variants of PAPVC include scimitar syndrome, pseudo-scimitar or meandering right pulmonary vein, sinous venosus defects, malposition of the septum primum, and Turner syndrome.

The patient in this case, a previously healthy, 6-month-old, full-term male, presented to the emergency department for evaluation of respiratory distress and wheezing. The infant was first seen in his pediatrician’s office, where he was noted to be tachypneic and wheezing. He was feeding without difficulty, voiding well, and was active and playful. The patient had passed critical congenital heart disease screening after his birth and prior to discharge, and the family history was negative for any respiratory or cardiac conditions.

Cardiac magnetic resonance imaging is becoming the mode of choice for diagnosis of PAPVC. The definitive treatment is surgical correction, but surgery is not indicated in all cases, especially if the patient is asymptomatic and the degree of shunting is small. Patients with isolated PAPVC who undergo surgical correction have good long-term outcomes.

In this case, the patient underwent the Warden procedure, which causes an increased risk of superior vena cava stenosis or obstruction to the right atrium. This patient will require lifelong follow-up to assess for new onset pulmonary venous obstruction.


A previously healthy, 6-month-old, full-term male presented to the emergency department (ED) for evaluation of respiratory distress and wheezing. Parents reported initial symptoms started 24 hours prior to presentation and consisted of labored breathing and occasional wheezing. Humidified air at home provided minimal improvement, and no other therapies were attempted. They denied any fever, cough, rhinorrhea, choking episodes, travel history, or sick contacts. He was feeding without difficulty, voiding well, and was active and playful. The infant was seen in his primary pediatrician’s office, where he was noted to be tachypneic, wheezing, and had an oxygen saturation (SaO2) of 91% to 94% in room air. He was sent to the ED for further evaluation.

The birth history was unremarkable, as he was born full-term without complications. The newborn screen was normal, and the infant passed critical congenital heart disease (CCHD) screening and hearing tests prior to discharge. His past medical history was only notable for frenulectomy performed at 2 months of age. The family history was negative for any respiratory or cardiac conditions.

His physical examination was notable for tachypnea (respiratory rate 50), intermittent subcostal retractions with good aeration throughout all lung fields; no wheezing was noted at the time of exam (after administration of albuterol). Cardiac exam revealed mild tachycardia, +S3, 2/6 blowing holosystolic murmur at the left main stem bronchus (LMSB), right ventricular heave (RVH), and displaced point of maximal impact (PMI). The liver edge was palpable 2 cm below the right costal margin. No clubbing or peripheral edema was noted in the extremities.

Evaluation and Initial Management

The infant had a chest radiograph taken (Figure 1) that revealed cardiomegaly and central pulmonary vascularity, suggesting increased cardiac output. An electrocardiogram (Figure 2) revealed sinus rhythm, right superior axis deviation, right atrial enlargement, and RVH. A stat echocardiogram (Figures 34) was performed and the pediatric cardiologist was consulted. The echocardiogram demonstrated small secundum atrial septal defect (ASD), possible sinus venosus septal defect, severely dilated right ventricle, moderately dilated right atrium, and dilated pulmonary valve and pulmonary arteries. The left pulmonary veins drained into the left atrium (LA). The right pulmonary veins drainage pattern was not definitively seen. In addition, the left ventricular size and function were normal, with a shortening fraction of 40% (normal, 28% to 44%).

Chest radiograph with cardiomegaly and central pulmonary vascularity, suggesting increased cardiac output.Images courtesy of Colleen H. Rusciolelli, MD.

Figure 1.

Chest radiograph with cardiomegaly and central pulmonary vascularity, suggesting increased cardiac output.

Images courtesy of Colleen H. Rusciolelli, MD.

Electrocardiogram demonstrating sinus tachycardia, right superior axis (axis >180°), and right ventricular hypertrophy.

Figure 2.

Electrocardiogram demonstrating sinus tachycardia, right superior axis (axis >180°), and right ventricular hypertrophy.

Echocardiogram: Apical four-chamber view demonstrating moderate right atrial enlargement and right ventricular dilation.

Figure 3.

Echocardiogram: Apical four-chamber view demonstrating moderate right atrial enlargement and right ventricular dilation.

Echocardiogram: Parasternal short-axis view demonstrating dilated right ventricle overlying a normal left ventricle.

Figure 4.

Echocardiogram: Parasternal short-axis view demonstrating dilated right ventricle overlying a normal left ventricle.

After seeing the infant and reviewing the echocardiogram, the pediatric cardiologist was concerned that the magnitude of RV dilation could not be attributed to the secundum ASD alone. There was concern for another source of left-to-right shunting not seen on the echocardiogram. The infant was given a dose of furosemide in the ED for treatment of right heart failure. He was then transferred to the pediatric intensive care unit (PICU) of a tertiary care children’s hospital for further evaluation.

There, a CT angiogram of the head and chest (Figures 56) revealed two large, right-sided pulmonary veins connecting and draining into the superior vena cava (SVC) without connection to the left atrium. There was an additional smaller right-sided pulmonary vein seen draining and connecting to the left atrium. The infant was noted to have clinical improvement after diuresis with furosemide and was discharged home on continued daily furosemide. Nevertheless, further follow-up as an outpatient revealed mild respiratory distress and difficulty tolerating his furosemide secondary to emesis. In an attempt to better evaluate his underlying hemodynamics, a sedated cardiac MRI (CMR) was scheduled. The CMR revealed identical anatomy as shown on the CT with the additional information of a Qp:Qs ratio of 3.8:1. Based on these findings and his continued mild right heart failure, he was scheduled for elective surgical repair. He subsequently underwent a successful baffling of all anomalously draining right-sided pulmonary veins to the LA via a Warden procedure. His postoperative course was uneventful, and he is currently thriving without any cardiac medications.

Computed tomography image coronal view demonstrating right upper and lower pulmonary veins entering into the superior vena cava (arrow).

Figure 5.

Computed tomography image coronal view demonstrating right upper and lower pulmonary veins entering into the superior vena cava (arrow).

Computed tomography image transverse view with arrows demonstrating two right-sided pulmonary veins entering the superior vena cava.

Figure 6.

Computed tomography image transverse view with arrows demonstrating two right-sided pulmonary veins entering the superior vena cava.

Diagnosis:

Partial Anomalous Pulmonary Venous Connection

Discussion

Partial anomalous venous connection (PAPVC) is a congenital cardiovascular defect where one or more (but not all) of the pulmonary veins return(s) anomalously back to the right atrium, either via a direct or indirect connection. It can occur in isolation but often occurs with other cardiac defects, most commonly a secundum ASD. Additional associations are discussed below. The incidence is considered to be rare, but post-mortem anatomic studies have shown an incidence as high as 0.7% of the population.1 This discrepancy is likely secondary to the fact that many patients with this defect are clinically asymptomatic, especially those with a single anomalously draining vein. The most common defect is one or more of the right-sided pulmonary veins connected to the SVC.

Physiology

PAPVC is an obligate left-to-right shunt in which already-oxygenated blood in the pulmonary vein(s) is recirculated back to the right atrium and is hemodynamically similar to an atrial septal defect. The degree of shunting is determined by the number of veins involved, the pulmonary segments they drain, the resistance of the all of the pulmonary veins, and the compliance of the right and left atria. The clinical symptoms and hemodynamic significance is determined by the number of veins involved and the amount of blood they carry. Patients with only one vein involved are usually asymptomatic. Individuals with two or more veins are more likely to develop symptoms, but this may not occur until adulthood.2

Clinical Symptoms and Findings

Clinical manifestations depend on the magnitude of the shunt, as well as whether there are any additional cardiac or pulmonary abnormalities. Individuals with a large degree of shunting will present with dyspnea, fatigue, and, in some cases, heart failure.

Cardiac physical exam findings may include precordial bulge, fixed-split S2, systolic ejection murmur at left sternal border (caused by increased flow across the pulmonary valve), and tricuspid regurgitation also causing a systolic murmur. All of these findings may not be present and are not required for the diagnosis.

A chest radiograph may demonstrate cardiomegaly with right atrial prominence, RV enlargement (demonstrated by retrosternal fullness on a lateral view), and increased pulmonary vascular markings. These findings suggest significant left-to-right shunting.3

Clinical Associations and Variants of PAPVC

Scimitar syndrome is a rare variant of PAPVC in which a portion or, in some cases, the entire right lung is drained by the right pulmonary veins connected via an anomalous vein(s) (scimitar vein[s]) to the inferior vena cava (IVC). Often, the affected lung parenchyma and airways are hypoplastic. Sequestration of the involved lung tissue and/or aortopulmonary collateral vessels to the affected right lung are often seen as well. The name of this syndrome is derived from the fact that on chest radiograph the anomalous veins, which course from the diaphragm toward the IVC, cast a shadow resembling that of a scimitar sword.4 Clinical symptoms include tachypnea, poor feeding, failure to thrive, cyanosis, and lethargy. About one-half of older patients who are diagnosed after the first year of age remain asymptomatic and are typically identified by an incidental finding on chest radiograph. In other patients, there is a range of symptoms that include fatigue, dyspnea, and recurrent pneumonia.5

Pseudo-scimitar or meandering right pulmonary vein cases have been reported in which, on chest x-ray (CXR), there is the appearance of a “scimitar sign” due to an anomalous right pulmonary vein taking a circuitous route to the left atrium. These cases often do not have the associated cardio-pulmonary complications described in classic scimitar syndrome. Therefore a “scimitar sign” on CXR is suggestive but not diagnostic of scimitar syndrome, and further cardio-pulmonary imaging is indicated before scimitar syndrome can be diagnosed.6

Sinous venosus defects occur when the common wall that normally separates the vena cava from the pulmonary veins is absent. Superior sinus venosus defects between the right-upper pulmonary vein and SVC are much more common than their inferior counterpart. These defects display partial anomalous pulmonary venous drainage (PAPVD) but with normal connections, as the affected vein still inserts into the left atrium. The blood flow preferentially drains into the SVC and right atrium, as with most atrial-level shunts.7

Malposition of the septum primum occurs when the atrial septum primum has leftward attachment in the left atrium. With significant leftward displacement of the septum, the right pulmonary veins (and, in extreme cases, all pulmonary veins) will drain into the right atrium rather than the left atrium, resulting in partial anomalous drainage. This condition is almost always associated with the heterotaxy syndrome.8

Children with Turner syndrome are at increased risk for underlying congenital cardiovascular abnormalities. Coarctation of the aorta in Turner syndrome is documented as occurring most frequently. However, multiple studies have stated the prevalence of PAPVC in patients with Turner syndrome may be as high as 13% to 18% and cannot always be detected on echocardiogram, emphasizing the need to obtain additional screening imaging in these patients.9,10

Diagnosis of PAPVC

Echocardiogram may be used initially to evaluate for PAPVC; however, due to acoustic window limitations from surrounding structures (airways and lung), it can be difficult to provide a definitive diagnosis. Usually, another imaging modality is employed to confirm the diagnosis and further elucidate the vascular anatomy. CMR is one option that is becoming the mode of choice because, in addition to detailed images and no radiation for the child, it can also perform phase velocity testing. Phase velocity testing can quantify and compare the blood flow to the lungs versus the systemic circulation. This is known as the Qp:Qs ratio. Patients with a Qp:Qs ratio greater than 2:1 are recommended to undergo surgical intervention.11–14 Cardiac CT scan is also often used, as it is more widely available and can be performed faster than CMR. This may avoid the need for sedation in very young or anxious patients receiving CMR but has the drawback of radiation exposure and the inability to measure flow and resultant Qp:Qs.15

Management of PAPVC

Definitive treatment is surgical correction. However, surgery is not indicated in all cases, especially if the patient is asymptomatic and the degree of shunting is small.2,3 Some studies recommend surgical intervention if any of the following conditions are present: a hemodynamically significant left-to-right shunt (Qp:Qs ratio > 2:1); recurrent pulmonary infections (often seen in patients with scimitar syndrome or pulmonary sequestration); compression and/or obstruction of surrounding structures secondary to the anomalous vein; and if a surgical repair is occurring for other cardiac lesions, so long as this repair does not put the patient at increased risk.2

Outcomes of PAPVC

In general, patients with isolated PAPVC who undergo surgical correction have good long-term outcomes. In a case series of 306 children who underwent surgery for PAPVC, follow-up at 15 years demonstrated no deaths and limited significant morbidity.17 However, children with multiple cardiac abnormalities or associated conditions (pulmonary hypertension, sequestration, and hypoplasia) were at higher risk for poor outcomes and significant morbidity and mortality.5,16 In our patient who underwent the Warden procedure (division of the SVC with baffling of the pulmonary veins and now disconnected SVC to the LA), there is an increased risk of SVC stenosis or obstruction to the right atrium. These patients require lifelong follow-up to assess for new onset pulmonary venous obstruction as well.

Conclusion

In conclusion, this case reminds all pediatric care providers that the causes of respiratory distress are quite variable. A thorough history and physical examination are essential to picking up on less common but more serious etiologies for respiratory distress. It further underscores the importance of obtaining a chest radiograph in “first-time wheezers,” especially those in whom the history and/or physical exam is not consistent with bronchospasm, and whose symptoms are not responsive to bronchodilators. A CXR can evaluate for additional structural clues that could indicate the etiology of their distress is not pulmonary in origin. Finally, it is also important to remember that the CCHD screening that occurs in nurseries nationwide is only designed to detect severe structural lesions that would result in a difference in pre- and post-ductal oxygen saturation. Other structural lesions would not be detected; thus, one could be falsely reassured and exclude cardiac conditions from their differential diagnosis despite an infant passing CCHD screening.

References

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Authors

Colleen H. Rusciolelli, MD, is an Attending Pediatric Hospitalist, Department of Pediatrics, NorthShore University HealthSystem, and a Clinical Educator, Pritzker School of Medicine, University of Chicago. Joseph R. Hageman, MD, is Senior Clinician Educator, Pritzker School of Medicine, University of Chicago, and Emeritus Attending Pediatrician, NorthShore University HealthSystem. Abraham Groner, MD, is Assistant Professor of Pediatrics, Department of Pediatrics, Section of Pediatric Cardiology, Pritzker School of Medicine, University of Chicago.

Address correspondence to: Colleen H. Rusciolelli, MD, 2650 Ridge Avenue, Evanston, IL 60201; email: chdroste@gmail.com.

Disclosure: The authors have no relevant financial relationships to disclose.

10.3928/00904481-20140417-11

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