ABSTRACT
Background: Cor triatriatum sinistra (CTS) is a rare condition where the left atrium (LA) is divided by a thin membrane into an upper and lower chamber. Incidentally, the diagnosis is made in late adulthood, usually because of a favourable variant such as in our patient who presented with partial CTS. Case summary: We present the case of a 62-year-old female who presented with COVID-19. She was known for longstanding symptoms of dyspnoea on exertion as well as a minor stroke several years ago. Computed tomography on admission suggested there was a mass in the LA but transthoracic echocardiography and cardiac magnetic resonance imaging revealed the diagnosis of partial CTS in which the superior compartment received pulmonary venous drainage from the right lung and the left-sided pulmonary veins drained into the inferior chamber. Since there were signs of chronic pulmonary oedema she successfully underwent balloon dilatation of the membrane resulting in remission of symptoms and normalization of the pressure in the accessory chamber. Discussion: Partial CTS is a rare variant of CTS. Since part of the pulmonary veins drains in the lower chamber of the LA (and thereby unload the right ventricle), it is a favourable variant and patients may present later in life when membrane orifices calcify or it may be discovered as an incidental finding. In some patients requiring intervention, balloon dilatation of the membrane may be considered as an alternative to surgical removal of the membrane by thoracotomy.
ABSTRACT
INTRODUCTION: A patient with presumed status asthmaticus, treated with beta-agonist and fluid resuscitation, developed flash pulmonary edema and respiratory failure in the setting of undiagnosed cor triatriatum. DESCRIPTION: A teen male with history of asthma developed dyspnea and chest pain at work. At a local emergency room (ER), he received albuterol, steroid, magnesium sulfate, and 2 liters (L) of fluid. Chest X-ray (CXR) and computed tomography of the chest were normal. He was transferred with a diagnosis of status asthmaticus. On exam in the pediatric ER, he had tachycardia, tachypnea and diffuse wheezing. He received albuterol 20mg/hour and 3L of fluid boluses over several hours. Despite improvement in wheezing, the patient had ongoing tachycardia and chest pain. He was placed on oxygen by high-flow nasal cannula. Repeat CXR exhibited new diffuse airspace opacities, and a focused cardiac ultrasound showed a hyperdynamic left ventricle (LV) with normal function. The patient began to expectorate pink frothy fluid, with hypoxemia, requiring intubation. Covid-19 PCR, Troponin-I and B-Type Natriuretic peptide were negative. An echocardiogram revealed a dilated left atrium (LA) with an echogenic membrane within the LA, separating the pulmonary venous chamber from the LA and restricting blood flow into the LV. The LV was small in size with normal function. The right heart was normal. These findings were consistent with diagnosis of cor triatriatum sinister, whereby the LA is divided into two compartments by a membrane that can variably obstruct flow into the LV. For this patient, treatment with beta-agonist caused tachycardia and decreased LV filling. Fluid resuscitation increased intravascular volume. This combination worsened obstruction of blood flow from the LA to the LV, leading to flash pulmonary edema, respiratory failure, and shock. In the ICU, the patient underwent diuresis, and the cor triatarium membrane was later surgically resected. DISCUSSION: Asthma is encountered commonly in children. Patients not responsive to treatment for respiratory distress should have alternative diagnoses considered. Multiple cognitive biases led to delayed recognition of cardiac etiology as the cause for this patient's respiratory failure, including anchoring bias with premature closure.