Background: Ventricular septal defects (VSDs) are one of the most prevalent congenital heart defects, and their closure is often indicated to prevent left heart volume overload, pulmonary hypertension, recurrent infections, or failure to thrive. While surgical closure remains a standard treatment, the last two decades have witnessed significant advances in transcatheter closure (TCC) techniques. However, the widespread adoption of TCC for perimembranous and intraconal VSDs has been tempered by concerns about procedural complexity, especially in small children, and by the historical need for arterial access and arteriovenous loop (AVL) formation.

A significant shift has been enabled by the use of upfront transvenous antegrade cannulation from the right ventricle (RV), which allows the entire procedure to be completed via venous access. This strategy simplifies closure, particularly in infants and children with small femoral arteries. Central to the success of this approach is the selection of appropriate devices. In this context, Amplatzer Duct Occluder (ADO) devices have become mainstays due to their low profile, soft construction, and ease of deployment via small sheaths. Objectives: The study aimed to evaluate the safety, feasibility, and efficacy of TCC for perimembranous, intraconal, and residual VSDs using upfront antegrade transvenous cannulation. A particular focus was placed on the usage patterns, procedural outcomes, and advantages associated with specific devices in this context. Methods: A retrospective analysis was performed of 163 patients who underwent transcatheter closure of VSDs at a single tertiary care centre between January 2019 and December 2023. Patients who underwent TCC using upfront transvenous antegrade cannulation formed the primary study group (n = 116), while those treated using AVL constituted the comparison cohort (n = 31). Elective retrograde closures were excluded.

All patients underwent transthoracic echocardiography (TTE)-guided closure. The procedure involved advancing a Judkins right catheter into the RV via femoral venous access, aiming toward the interventricular septum under fluoroscopic and pressure waveform guidance. Successful crossing into the left ventricle allowed for device delivery without arterial access. Echocardiography, rather than angiography or balloon sizing, guided defect measurements and device selection. The type of device was chosen based on septal anatomy, defect type, and patient size. Outcomes were measured in terms of procedural success, complication rates, valvular interference, conduction disturbances, and follow-up findings. Results: Patient Characteristics and Indications. The median age of patients undergoing upfront antegrade cannulation was 55 months (IQR: 17.8–120.8), and the median weight was 15.8 kg (IQR: 9.6–29.8). Notably, 68.9% of patients had pulmonary arterial hypertension (PAH), and nearly one-third were significantly underweight. The indexed VSD size to body surface area was larger in this group compared to AVL controls, supporting the need for early closure.

The most common indications were clinical symptoms of heart failure, such as poor weight gain and recurrent respiratory infections (61.2%), or evidence of left heart dilation. Aortic valve prolapse was present in 17 patients, though limited to mild or trivial regurgitation. Types C and D perimembranous VSDs predominated, with a smaller representation of intraconal and post-surgical residual defects.

Device Selection. In the antegrade group, 118 devices were deployed across 116 patients. ADO-II was the most frequently used occluder, selected as the initial device in 54 cases (45.8%) and ultimately retained as the final device in 48 cases (40.7%). Duct occluder devices including ADO-I were the next most common, used in 42 patients (35.6%) as the first attempt and 40 cases (33.9%) as the final implant.

The preference for ADO-II in cases with aneurysmal tissue or multiple septal fenestrations stemmed from its dual-disk, soft-mesh design that conforms well to irregular anatomy and causes minimal interference with valvular structures. Duct occluder devices, with their tapered cylindrical body and robust waist, were typically reserved for defects with a firm, central orifice and adequate rims. Other devices, such as the Konar-MFO and muscular VSD occluders, were used more selectively, often when ADO sizing was unsuitable or embolization occurred. Procedural Success and Efficiency. Antegrade cannulation was successful in 83.6% of attempted cases (97 of 116). Overall procedural success, defined as complete and stable device deployment without significant complications, was achieved in 99.1% of the study group. Procedural efficiency was markedly improved with this approach. The median procedural time was 45 minutes compared to 65 minutes in the AVL group. Fluoroscopy time was similarly reduced (median 13.3 vs. 21.9 minutes), as was radiation exposure.

Notably, antegrade cannulation success was highest in younger and lighter patients with proportionally large defects. Multivariate analysis showed that smaller body weight and higher indexed VSD size-to-weight ratio were significant independent predictors of cannulation success. In infants below 1 year, success was universal. Complications and Device-Related Events: Device embolization occurred in five patients in the antegrade group. In all but one case, the embolized device was retrieved and replaced successfully with an upsized occluder. One embolization associated with tricuspid chordal rupture necessitated surgical intervention. The embolizations were attributed to under sizing or challenging anatomy rather than intrinsic device failure.

Valvular complications were minimal. Four patients developed mild new-onset aortic regurgitation, and two had moderate tricuspid regurgitation, all managed conservatively. There were no instances of severe valve dysfunction.

Conduction disturbances occurred transiently in a few patients. Complete heart block and left bundle branch block were seen intra-procedurally in three cases and resolved after releasing cable tension or administering steroids. No patient required pacemaker implantation. New-onset bundle branch block was observed in four patients (3.4%), a rate comparable to existing literature on VSD closures.

Follow-Up Outcomes. At a median follow-up of 25 months, the outcomes were favourable. Residual shunts were noted in 26.1% immediately post-procedure, though most resolved or became trivial by follow-up. Only two patients required reintervention with additional devices. Left ventricular end-diastolic diameter (LVEDD) decreased significantly (Z-score reduced from +0.79 to −0.45). Weight gain occurred in most underweight children, and no progression of valvular regurgitation was observed.

Discussion: This study demonstrates that upfront transvenous antegrade VSD closure is a safe, efficient, and highly effective technique, particularly in younger patients or those with borderline vascular access. The approach obviates the need for arterial catheterization, which is especially beneficial in infants prone to vascular complications, and reduces procedural time, radiation exposure, and patient discomfort.

Among occluder options, Amplatzer Duct Occluder devices—both ADO-I and ADO-II—emerged as the workhorses of transvenous VSD closure. ADO-II was especially favored in aneurysmal or multiple-exit defects due to its soft profile and double-disk design. Duct occluder devices retained value in central defects with firm rims. The soft structure of both devices likely contributed to the low incidence of conduction issues and valvular interference, in contrast to earlier-generation asymmetric perimembranous occluders.

These results align with previous reports supporting the use of ADO-II for off-label VSD closure, especially in infants and those with complex morphologies. While the use of muscular occluders remains important for defects with deficient margins or large tunnels, the versatility, safety, and deployability of ADO-I and II make them the preferred choices in the majority of cases managed via antegrade access.

Limitations: The number of attempts required to cross the defect was not evaluated as the study was performed in an academic institution where trainees started most procedures. However, the median fluoroscopic time was 13.3 min. The study compared the antegrade cannulation approach with a retrospective control group after AVL but was not randomized with a chance of selection bias. Even though antegrade cannulation seemed attractive, aneurysmal defects with multiple small exits especially in large patients might pose challenges for this approach. Conclusions: Upfront transvenous cannulation and device closure of perimembranous, intraconal, and post-surgical residual VSDs were feasible in most patients with shorter procedural and fluoroscopy times compared to conventional AVL strategy. Small patients with relatively large defects were best suited for this technique. Avoiding arterial sheaths and AVL was advantageous in infants. Transient conduction abnormalities following the procedure were clinically insignificant and were similar to the conventional technique. Within this approach, Amplatzer Duct Occluder I and II devices were the most frequently used, providing optimal performance in terms of safety, ease of delivery, and long-term outcomes. Their soft, adaptable profiles and small sheath compatibility make them the preferred devices minimally invasive VSD intervention strategies.

ETHICS DECLARATIONS

Conflict of Interest: The authors declare they do not have any conflict of interests.

Ethical Approval: Not applicable.

Consent for Publication: Not applicable.