Subaortic ventricular septal defects (VSDs) resemble perimembranous VSDs anatomically, but physiologically, they have a higher tendency for right coronary cusp prolapse, which can lead to aortic valve insufficiency (1). Closing a subaortic VSD poses unique challenges due to its proximity to the aortic valve (2). Surgical closure remains the standard treatment for subaortic VSD closure, but it is associated with notable morbidity, as patients often require intensive care unit (ICU) admission and blood transfusions (1, 2). Additionally, smaller infants face an increased risk of atrioventricular (AV) block (3). A meta-analysis involving over 6,300 patients undergoing transcatheter VSD closure reported a rate of complete AV block (cAVB) comparable to surgical outcomes, at 1.1% (4).

Percutaneous closure of subaortic ventricular septal defects (VSDs) in infants weighing less than 10 kg is challenging (3), with a higher risk of procedural failure, device-related complications, and adverse events, often requiring extended fluoroscopy times (5). Small infants are particularly susceptible to the harmful stochastic and deterministic effects of radiation. To address these risks, various strategies have been developed to reduce radiation and contrast exposure, including zero-fluoroscopy or radiation-free techniques (6, 7). Despite these advancements, the procedure remains technically demanding in low-weight infants due to their smaller femoral vessels, with arteriovenous loop formation potentially causing rhythm disturbances and hemodynamic instability (3). This study aims to assess the efficacy and safety of percutaneous subaortic VSD closure in infants under 10 kg, utilizing transthoracic echocardiography (TTE)-only guidance.

A one-year-old female infant, weighing 8.9 kg, was scheduled for ventricular septal defect (VSD) closure. She had no history of feeding difficulties, recurrent respiratory tract infections, or febrile episodes. However, her parents reported concerns about failure to thrive. A heart murmur was first detected during a physical examination at three days of age. The patient was born at 38 weeks of gestation via cesarean section due to maternal pre-eclampsia, with a birth weight of 3,790 g. There was no family history of congenital heart disease. On examination, the patient was alert with a heart rate of 112 beats per minute, a respiratory rate of 26 breaths per minute, a temperature of 36.8°C, and oxygen saturation of 98%. Cardiac auscultation revealed normal S1 and S2 heart sounds, accompanied by a grade III/VI pansystolic murmur at the left lower sternal border. No gallop rhythms were detected. She had been previously prescribed captopril 6.25 mg three times daily.

The patient underwent the procedure under sedation. Preprocedural apical 5-chamber view revealed a subaortic ventricular septal defect (VSD) with a membranous septal aneurysm (MSA), left-to-right shunt, with VSD exit diameter of 3.8 mm, and an inlet diameter of 6–7 mm (Figure 1a). There was an adequate distance between the VSD and the tricuspid and aortic valves. Mild mitral regurgitation was noted without evidence of aortic regurgitation. Based on these findings, percutaneous VSD closure was planned using a retrograde transarterial approach with TTE-only guidance.

Aseptic and antisepsis were prepared in the left and right femoral regions. The right femoral artery was punctured, and a 4/5F slender sheath was inserted. Heparin (800 IU) was administered intra-arterially. A 3.5/5F JR guiding catheter was advanced via the descending aorta, aortic arch, and ascending aorta into the left ventricle using the subxiphoid 12 o'clock view (Figure 1b), suprasternal short axis view (Figure 1c), parasternal long axis view in which the catheter was positioned just above the aortic valve (Figure 1d) and pressure monitoring, with the assistance of a 0.035” Terumo soft hydrophilic wire. The guiding catheter was used to cross the VSD from LV to RV using parasternal long axis view (Figure 1e) and parasternal short axis view (Figure 1f). Hemodynamic measurements showed left ventricular pressure of 80/16 mmHg, right ventricular pressure of 20/6 mmHg, and descending aortic pressure of 71/37 mmHg (mean 49 mmHg). Left ventricular oxygen saturation was 98%. Prophylactic intravenous cefuroxime (400 mg) was administered.

A 5F delivery cable and a Konar-MF VSD Occluder (Lifetech) size 7/5 mm were introduced through the guiding catheter and positioned within the defect. The low-pressure disc was deployed in the right ventricle as shown in inverted apical 5 chamber view (Figure 1g) followed by deployment of the high-pressure disc in the left ventricle as shown in parasternal short axis view (Figure 1h).

The total procedural time was 46 min. Postprocedural descending aortic pressure was 73/38 mmHg (mean 51 mmHg) with peripheral oxygen saturation of 100%. No complications were observed. Post procedure, the patient was prescribed captopril 6.25 mg three times daily, aspirin 45 mg once daily, and bisoprolol fumarate 0.125 mg once daily, and cefuroxime 500 mg once daily. At six-month follow-up, TTE showed a well-seated device without residual shunt, and good left and right ventricular function (LVEF 68% and TAPSE 1.5 cm).

Our case demonstrates that percutaneous subaortic VSD closure can be successfully performed under TTE guidance in infants without significant complications. Larger, controlled studies are needed to assess the feasibility and long-term outcomes of this approach.