Successful transcatheter treatment of large right pulmonary artery to left atrial fistula: a case series and literature review.

Introduction: Cyanotic congenital heart diseases are among the most serious anomalies among newborns. A rare type of this condition is direct communication between the right pulmonary artery and left atrium, which presents mostly in adolescence and adulthood. Large shunts, however, should be corrected as soon as possible, considering their potential to cause congestive heart failure.

Case presentation: Two 2- and 13-year-old patients with this pathologic communication complained of exertional dyspnea and central cyanosis. Their physical exams were prominent, with a low oxygen saturation level. The diagnostic modalities used, electrocardiogram, chest X-ray, echocardiogram, CT scan, and selective angiography of the pulmonary arteries, showed right-to-left abnormal blood flow through the right pulmonary artery and left atrium shunt. Finally, both patients were treated successfully by a transcatheter occluder without any complications or follow-up complaints.

Discussion: The right pulmonary artery and left atrium abnormal congenital connections are rare causes of central cyanosis, mostly present with exertional dyspnea and cyanosis during adolescence or early adulthood. Transthoracic echocardiography, contrast-enhanced CT scans, and angiography of the pulmonary arteries make the diagnosis. The treatment has emerged during the last two decades, shifting from surgical treatment for severe cases to interventional percutaneous strategies, leaving the surgery for cases with no appropriate location for the application of interventional therapy.

Conclusion: Considering the potentially life-threatening complications of the untreated right pulmonary artery and left atrium fistulas, such as thromboembolic events, early diagnosis is crucial. However, treating these patients is not always straightforward, and strategies should be selected based on the connecting fistula's anatomical features, location, size, and tortuosity. Although endovascular treatment is the preferred option, some patients need to be treated with surgical procedures due to their structural characteristics.