Volume 4, Case 3
James J. Matsuda MD, PhD
Kapiolani Medical Center For Women And Children
University of Hawaiʻi John A. Burns School of Medicine
This is 2-month old male who presents to the emergency department with a five day history of funny breathing. He was well until 5 days prior when his mother noted noisy, rapid breathing and a tactile temperature. Four days prior, he was taken to his private physician and was started on amoxicillin for otitis media. His lung exam at that time was normal.
Two days prior he was taken to the emergency department and was noted to be wheezing. He was given an albuterol aerosol and was discharged on oral albuterol. He continued to have breathing problems at home and now returns to the emergency department since his condition has not improved.
His birth history is unremarkable, and he has shown adequate weight gain since birth. There are no reported feeding problems according to his mother. His family history is significant for two siblings with asthma.
Exam: T36.9, P168, BP 98/60. His respiratory rate varies between 60 and 80 per minute. His oxygen saturation is 97% in room air. His oxygen saturation improves to 100% on oxygen by nasal cannula at 2 liters per minute. He is a fussy infant with modest tachypnea. Despite this, he does not appear to be in significant distress. He is not toxic. He is noted to have mild retractions when crying, with bilaterally coarse breath sounds without wheezes. Heart regular without murmurs or gallops. Abdomen: Liver edge palpable 3 cm below the right costal margin.
A chest X-ray is obtained.
View CXR: AP view.
View CXR: Lateral view.
Do you think this represents a pneumonia? The emergency department physician reads this as mild perihilar infiltrates. A diagnostic impression of a viral pneumonia is made, and the infant is hospitalized because of his young age and persistent tachypnea.
The following morning, the radiologist reads the chest radiograph as showing borderline cardiomegaly with prominence of the right atrium and increased pulmonary vascularity. The right heart border appears to be prominent, but this initially was thought to be due to rotational artifact. The diffuse reticular markings fanning out from the hilum suggest pulmonary venous congestion but are difficult to distinguish from perihilar infiltrates. These findings are suggestive of congenital heart disease. This radiographic information prompts a cardiac work-up. The most important point here is to realize that a cardiac defect may be responsible for the infant's respiratory symptoms. Scrutinizing the chest radiograph for subtle signs of cardiac disease is important since, once cardiac disease is suspected, it is a simple matter of obtaining an echocardiogram.
After admission to the wards, the infant develops worsening respiratory distress. A blood gas is obtained. On room air, an arterial blood gas shows pH 7.27, pCO2 35, pO2 76, HCO3 of 16. With 100% O2, the pO2 increases to 138. An EKG shows right atrial enlargement with right axis deviation and right ventricular hypertrophy. An echocardiogram shows a membranous structure in the left atrium, a high atrial septal defect, and dilation of the right atrium and right ventricle. The right ventricular systolic pressure is elevated to 103 mm Hg. The diagnosis of cor triatriatum with secondary congestive heart failure is made, and the infant is started on digoxin and diuretics. He is referred to a cardiac surgeon for corrective surgery and does well postoperatively.
A follow up chest radiograph taken a few months later shows a decrease in heart size and decreased pulmonary congestion.
View follow-up CXR.
Also present are surgical wires and metal clips in the area of the left atrium. There is some residual prominence of the pulmonary vasculature.
Cor triatriatum is a rare congenital cardiac anomaly where the pulmonary veins enter an accessory chamber that joins the left atrium through a narrow opening. This accessory chamber may also directly communicate with the right atrium. In classical cor triatriatum, a membranous partition exists in the left atrium in the shape of a wind sock.
View Cor Triatriatum diagram.
The upper chamber (XC) of this partition receives blood from the pulmonary veins, and the distal chamber communicates with the mitral valve. The orifice diameter of the windsock ranges from less than 3 mm to about 1 cm. In a minority of cases, a patent foramen ovale or an atrial septal defect allows communication with the right atrium. Right ventricular hypertrophy and dilation are almost always present, and right atrial dilation occurs 25% of the time. Current theories suggest that the defect occurs because the common pulmonary vein fails to incorporate into the left atrium during cardiac embryogenesis.
The clinical features of this anomaly are related to the pulmonary congestion and hypertension created by the membranous left atrial structure. When pulmonary venous blood flow becomes obstructed, the lungs reflect varying degrees of pulmonary edema and intraalveolar hemorrhage. Patients usually present within the first few years of life with a history of shortness of breath and frequent pulmonary infections and audible rales. Signs of pulmonary hypertension, including a loud pulmonic component of the second heart sound, right ventricular heave and pulmonary systolic ejection clicks are often present. The usual heart murmur is a soft, blowing, systolic murmur heard best at the left sternal border. The EKG usually reveals signs of right-sided heart overload such as right ventricular hypertrophy and right atrial enlargement.
The chest radiograph often reveals pulmonary venous obstruction. Diffuse reticular pulmonary markings fan out from the hilum to involve the lower lung fields. Kerley B lines may also be present. The right heart border may reveal a double density suggestive of left atrial enlargement. Other findings include enlargement of the main pulmonary artery and right ventricular hypertrophy.
Treatment of this disease involves management of congestive heart failure. Once patients reach this stage, they usually deteriorate fairly quickly despite medical management. Surgical intervention should be planned as soon as possible in symptomatic patients once the diagnosis is made. The operation of choice is usually correction under direct vision with cardiopulmonary bypass. The prognosis of cor triatriatum is related to the size of the orifice in the obstructing membrane. Without surgical correction, the average survival is about 3 months when the opening is less than 3 mm, and 16 years when the opening is greater than 3 mm. In those patients surviving operative correction, the prognosis is excellent.
References