Ductus arteriosus aneurysm

Summary

An aneurysm of the ductus arteriosus is defined as a saccular or globular dilation originating from the ductal origin at the descending aorta. Once considered a rare entity with limited case reports, modern high-resolution echocardiography now detects these aneurysms more frequently. They are generally regarded as congenital anomalies arising from in utero processes, though they can also occur as complications following surgical or transcatheter patent ductus arteriosus closure or result from ductal endarteritis. Proposed developmental mechanisms include abnormal intimal cushion formation due to defective elastin expression, or poststenotic dilation resulting from intrinsic ductal narrowing or tortuosity. These aneurysms are occasionally associated with specific clinical contexts, such as trisomy 21 or connective tissue disorders like Marfan syndrome. Diagnosis can occur prenatally, typically during the third trimester, where the aneurysm is often associated with increased ductal flow velocity and right ventricular dominance. Postnatally, it is frequently an incidental finding on an echocardiogram, although it may be suspected if a chest radiograph reveals a mass in the left upper mediastinum.

On a high-parasternal short-axis view, the aneurysm appears as a prominent vascular structure to the left of the main pulmonary artery. If the ductus remains patent, color Doppler typically demonstrates a characteristic horizontal jet, which contrasts with the more vertical orientation seen in a standard patent ductus arteriosus. This horizontal orientation often precludes accurate velocity measurements necessary for estimating pressure gradients. Clinicians must also use ultrasound to monitor for thrombus formation within the aneurysm and ensure such thrombi do not migrate into the pulmonary arteries or descending aorta. The natural history and presentation of ductal aneurysms are categorized by the age of the patient and the patency of the ductal ends. The neonatal type, which is the most common, typically features a closed pulmonary arterial end and an open aortic end, while the type found in older children and adults often remains patent at both ends.

Most neonatal aneurysms have a benign course, resolving spontaneously within the first two months of life as the ductus undergoes its natural process of constriction and obliteration. In some instances, the aneurysm may disappear as quickly as one or two days after birth as the ductus completely closes. However, despite this typical regression, some cases are complicated by perinatal distress, pulmonary hypertension, or symptoms of structural compression such as stridor, dyspnea, and hoarseness. While many aneurysms resolve without intervention, they carry risks of serious complications including spontaneous rupture, dissection, thrombosis/embolization and infection. Thromboembolic events are a significant concern, as thrombus within the sac can lead to neonatal systemic or pulmonary embolization.

Surgical repair is generally considered for aneurysms that persist beyond the neonatal period, fail to involute, or show evidence of enlarging. Other indications for surgery include the migration of thrombus, evidence of thromboembolism, or the compromise of adjacent chest structures. Resection typically requires the use of cardiopulmonary bypass to ensure a safe and complete repair. Given the potential for rapid change or serious sequelae, all neonatal ductal aneurysms require close surveillance through serial echocardiographic examinations .

Echocardiography example

The echocardiogram example below demonstrates an aneurysmal arterial duct measuring 1.28 × 1 cm at its junction with the descending aorta, with swirling flow noted within the aneurysm but no evidence of thrombus. Additionally, a small patent ductus arteriosus measuring 0.11 cm is present at the pulmonary artery end, demonstrating bidirectional shunting.