A National Congenital Cardiac Surgery program was established in 2019 in the Republic of North Macedonia. To provide the highest standard of care, we have established a capacity-building program with the Joe DiMaggio Children's pediatric cardiac surgery unit. Through the program, our local staff receives remote and on-site training and is assured of expert assistance through video conferences and ad-hoc remote supervision by the medical team in Florida.
Treatment of large hemodynamically important VSD includes surgical closure of the defect or catheterisation closure. Surgical closure is the mainstay treatment for most VSDs. Muscular VSD is challenging to access without a left ventricular incision, in particular when the VSD is accompanied by a large left-to-right shunt, pulmonary hypertension, or interventricular septal hypertrophy [1, 4]. Postoperative AV block is also more common in such cases.
The indications for treatment of large VSD in small infants are still ill-defined and are mainly guided by the individual clinical characteristics. Failure to thrive, congestive heart failure, a refractory medical condition, worsening pulmonary hypertension are the most critical signs of large VSD and indicators for closure [2, 5]. The patient's age and weight should also be considered in the decision-making process.
In infants, large muscular VSD is challenging to close from the right ventricular side. Pulmonary artery banding initially to control CHF and reduce the pulmonary artery pressures is performed in young (up to three months of age) babies. Open surgical repair is associated with the risk of effects of cardiopulmonary bypass (CPB), the risk of left ventriculotomy in large mVSD because of an inadequate operative field of vision, and postoperative ventricular dysfunction and arrhythmias. The estimated mortality rate following open-heart surgery ranges between 3 - 8% 
Nevertheless, hybrid procedures, such as transthoracic device closures (TTDC) pose less risk than conventional surgical closure of the muscular VSD. Per-ventricular device closure of VSD with TEE guidance was first reported by Amin and colleagues . The method combines surgical technique and interventional closure and makes it possible to avoid possible complications. The so-called hybrid approach of device closure of muscular ventricular septal defect has been encouraging and has been used in a few centres. This novel approach can be used to avoid not only cardiopulmonary bypass but also vascular injures caused by interventional closure.
Accounting for the factors mentioned above, our patient's age, weight, clinical state, developing pulmonary hypertension despite previous pulmonary banding, the dimension of the VSD and localisation we opted for the TTDC approach. The anatomical aspect is crucial, but also our goal to avoid left ventriculotomy. Furthermore, TTDC proceeds without extracorporeal circulation and thus may lower the risk of postprocedural atrioventricular blocks (AVB).
A recent meta-analysis by Yang Zhou et al.,  supported the decision for TTDC. The analysis included a total of 5 randomised controlled trials, 7 cohort studies, 13 case-control studies, 129 case series and 13 case reports. The primary outcome of interest was the success rate; the proportion of patients with no residual shunts, intraoperative conversion to open-heart surgery and morbidity from perioperative complications, for example, arrhythmia, valve regurgitation (aorta, tricuspid valve), AVB, as well as duration of the procedure, intensive care stay, hospital stay, number of transfusions. According to this study, we do not find intraoperative arrhythmia, or new onset of aortic or tricuspid regurgitation, due to device proximity toward the valves. The authors concluded that there was a significant difference in the rates of residual shunts comparing TTDC and open-heart surgery. Risk factors associated with for postoperative AVB were the existence of large muscular VSD, female gender and the size of the occluder.
Despite the presence of several risk-factors, we observed an uncomplicated postoperative course in our first successful case of TTDC which was further characterised by fast extubation, same-day oral feeding, mother-daughter bonding and discharge within one week.
The duration of the treatment of 90 minutes (Figure 3) can be explained considering the precautious measures taken, among others, a median sternotomy was done in the case we had to convert to open-heart surgery. Additionally, we modified the 7F Cera introducer for this purpose, to allow better control and opening of the device. However, despite the relative longer procedure time, there was no bleeding, need for intraoperative transfusions, occluder fall, malposition or malalignment of the device towards the intraventricular septum.
This work describes an initial case report. The long-term prognosis should be carefully evaluated in light of the residual shunt. We successfully reduced the dimensions of VSD to a level that is acceptable for the age and weight and which should promote complete closure with time. However, on the first postoperative control one week after discharge, even though we observed a markedly improved clinical state, there was still a residual < 2 mm shunt. To this end, intensive follow up will be required and likely more aggressive medical therapy (diuretics, ACE blockers).