Multiple muscular Ventricular Septal Defects (VSDs) are defined as the presence of more than one VSD in the muscular septum, with or without other VSD located in the peri-membranous or outlet septum, with or without associated intra-cardiac or extra-cardiac malformations (3).

Conventional surgical repair of multiple muscular VSDs is generally accompanied by substantial early and late mortality and morbidity (1, 2, 4–21).

The hospital mortality with conventional repair has been reported in the literature to be between 0 and 14.2% (1, 2, 4–21). In the 192 patients reported in the Congenital Database of the European Association of Cardio-Thoracic Surgery the hospital mortality was 8.5%¹.

In the previous decade an alternative approach with intra-operative device closure reported unsatisfactory initial overall results due to elevated mortality (14–25%) and high failure rates (20–40%) (22–25). More recently institutions with advanced facilities for hybrid techniques have reported encouraging outcomes in selected series of multiple VDSs closure (26–30).

A palliative approach with conventional pulmonary artery banding (PAB) is a common surgical option, particularly in smaller infants and/or in the presence of associated anomalies, instead of primary repair (1, 2, 4–10, 15, 16, 18–21, 31). However the conventional PAB carries a high mortality. The hospital mortality in the 739 patients reported in the Congenital Database of the European Association of Cardio-Thoracic Surgery (see text footnote 1) was 8.9%. In addition, indication for conventional PAB is limited by a series of drawbacks, particularly due to the difficulty in determining the optimal tightening with a stable and satisfactory balance between systemic and pulmonary circulation to promote adequate growth (1, 2, 4–10, 15, 16, 18–21, 30–37).

After prolonged experimental studies (32) we introduced the telemetrically adjustable FloWatch-PAB^® (Leman Medical Technologies, Lausanne, Switzerland) in the clinical practice in 2003. We and other institutions have since reported favorable clinical results with its utilization in various congenital heart defects (33–40).

This multicenter prospective study was conducted to evaluate a new strategy to treat infants with multiple VSDs with FloWatch-PAB^®.

From 2004 to 2012 17 consecutive children (3 premature, 14 infants), mean age 3.2 months (range 9 days–9 months), mean body weight 4.2 kg (range 3.1–6.1 kg), with multiple VSDs underwent PAB with an adjustable FloWatch-PAB^®.

Criteria for inclusion in this prospective study were infants with the presence of multiple muscular apical VSDs (Swiss cheese type), with or without associated congenital heart defects, including the presence of other restrictive or unrestrictive VSD, either of peri-membranous or inlet type. In the study period no one infant with these characteristics underwent primary repair.

All patients presented with multiple muscular apical VSDs, associated with an additional large mid-muscular VSD in three patients, a large peri-membranous VSD in two and a large inlet VSD in one patient.

The diagnosis was established by echocardiography in all infants, and 9/17 (53%) patients also underwent cardiac catheterization and angiography.

The other associated cardiac anomalies are listed in Table 1.

Two infants had undergone previous cardiac surgery, one for closure of patent ductus arterious and the other for closure of patent ductus arterious with aortic coarctectomy, while one infant had undergone interventional closure of patent ductus arteriosus in cardiac catheterization laboratory.

One infant with Down syndrome had previously undergone non-cardiac surgery (colostomy) for an associated gastro-intestinal malformation.

Five infants (5/17 = 29.4%) required pre-operative mechanical ventilation, with a mean duration of 64 days (range 7–240 days), mostly due to the late referral for surgery from other institutions or to the presence of recurrent respiratory infections.

The structural characteristics of the FloWatch-PAB^® device, mechanism of functioning, surgical technique of implantation, and the procedures for post-operative percutaneous adjustments, have all been previously reported (32, 33, 36, 37).

At the moment of the beginning of this prospective study the device had already obtained the C.E. mark (equivalent in Europe to the FDA approval for USA), after a multicenter prospective study conducted through hospitals in different European countries (33). Furthermore the FloWatch-PAB^® had been successfully implanted by the same surgical team in other congenital heart defects, and therefore there was no need for approval by the institutional ethical committee.

As for any other surgical procedure in the pediatric cardiac service, written informed consent was obtained from the parents or the legal guardian of all patients.

In all the patients described in this study the device was implanted through a median sternotomy.

Nine patients underwent closure of an associated patent ductus arteriosus at time of PAB.

Cardiopulmonary bypass was required in 3/17 (18%) infants, in two for aortic arch reconstruction, and one for repair of cor triatriatum and closure of a large associated peri-membranous VSD.

In order to analyze the results of the study, the following data were prospectively collected with a database prepared before the beginning of the study and continuously updated: (a)

survival

For all patients the follow-up was censored at the last clinical observation before December 2012.

There were no early or late deaths during a mean follow-up of 48 months, with a range from 7 to 98 months.

The mean duration of post-operative mechanical ventilation was 2.4 days, with a range from 0 to 6 days.

The mean ICU and hospital stay were 5.6 (range 1–30 days) and 16.8 days (range 7–58 days) respectively.

The relatively long interval (average 3.2 days) between the end of the mechanical ventilation and the discharge from ICU was due to the fact that in both institutions an intermediate step unit between ICU and regular ward (High Dependency Unit) was not available.

The only re-operation required after FloWatch-PAB^® implantation was drainage of a pericardial effusion through a sub-xiphoid approach in an infant who developed a pericardial effusion on the eighth post-operative day after device implantation without associated procedure.

All patients required percutaneous adjustments of the device FloWatch-PAB^®, with a mean of 4.8 times/patient (range from 2 to 9 times) to tighten the banding, and a mean of 1.1 times/patient (range from 0 to 3 times) to lose the banding with the patient’s growth. The decision to adjust the banding was in the immediate post-operative period generally taken with progressive increase of the tightening until reaching the wanted pressure gradient, measured with Doppler echocardiography, providing normal distal pulmonary artery pressure with oxygen saturation>90% on room air at pulse oximeter. In the late follow-up, with interval evaluations dictated by the clinical conditions, adjustments of the banding were required to lose the banding because of the patient growth, with or without concomitant size reduction of the multiple muscular VSDs.

After a mean interval of 29 months, with a range 8–69 months, 10 patients (10/17 = 59%) underwent re-operation for FloWatch-PAB^® removal: (a)

seven patients underwent associated procedures: closure of a remaining VSD in six: peri-membranous in three patients, mid-muscular in two, and inlet in one Damus–Kaye–Stansel, bi-directional Glenn, and atrial septectomy in one

Pulmonary artery reconstruction was not required in 9/10 (90%) patients, even with an interval between FloWatch-PAB^® implantation and removal up to 98 months. In only one patient at the time of the FloWatch-PAB^® removal the surgeon decided to perform a patch enlargement of the main pulmonary artery because of a residual velocity of 3.2 m/s through the main pulmonary artery on intra-operative echocardiographic Doppler.

In five (5/7) of the remaining patients with FloWatch-PAB^® still in situ, at the last clinical observation with echocardiography all the muscular VSDs had spontaneously closed. There are residual muscular VSDs, however significantly reduced in size, still present in the two patients both of whom have the shortest follow-up, of 7 and 25 months respectively.

Overall, including the patients with the FloWatch-PAB^® still in situ, the multiple muscular VSDs had closed in 15/17 (88.2%).

All devices were functioning at the moment of removal, proven by the complete release of the banding before the surgical procedure, as well as at the last follow-up, with device testing under control by Doppler echocardiography.

This reproducible new strategy with adjustable FloWatch-PAB^® simplifies the management of infants with multiple muscular VSDs and provides the following advantages: (a)

good results (0% mortality)

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.