Discussion

Our study shows that performing percutaneous interventions in small children with the use of the Glidesheath Slender is safe, feasible, and effective. It enables downsizing of the outer sheath diameter by one French, which is significant in this patient group. Therefore, with this approach, it is possible to extend percutaneous treatment possibilities.

The vessel diameter comprises a significant limitation for catheter interventions in small children with congenital heart disease. Large sheaths, which are required for implantation of some devices (stent, occluder) or balloons, proved to be, among others, a risk factor for vascular complications.^{Reference Vitiello, McCrindle, Nykanen, Freedom and Benson1} Although the range of various interventions performed via Glidesheath Slender among patients from our study group is very heterogeneous, no vascular complications were recorded in any patient.

In the past, when only the large size (8F or 9F) angioplasty catheters were available, the ileofemoral arterial complications rate in small children was very high.^{Reference Burrows, Benson and Williams2,Reference Burrows, Benson, Babyn and MacDonald4} Injury or occlusion of the access vessel is one of the possible complications after percutaneous interventions in paediatric patients. Among our patients, treatment of re-coarctation of the aorta was the most common procedure. Especially for these patients, the potential need for stent re-expansion limits the use of stent implantation,^{Reference Feltes, Bacha and Beekman5} because a larger sheath is needed for stents that can address the demands of a growing vessel. The Slender sheath offers the possibility to use an arterial 5F sheath even in patients with a median weight of 5.3 kg with less danger of vessel damage after the procedure.

For percutaneous ventricular septal defect occlusion, a weight of less than 5 kg was significantly correlated with procedure-related complications.^{Reference Holzer, Balzer and Cao6} Using the Slender sheath allows the introduction of a 6F guiding catheter into an arterial system in small children with an outer diameter of a 5F regular sheath, with the possibility to introduce larger devices from a retrograde access, thereby shortening and simplifying the procedure.

Although the venous system generally tolerates larger sheaths, pulmonary arterial interventions can be performed with the Slender sheath in smaller children with less risk of vessel compromise. Although even stents delivered through a 6F coronary guiding catheter may not be dilatable to adult size, they may be very well cracked later in life to achieve adult-sized vessel or valve dimensions.^{Reference Gendera, Ewert and Tanase7}

Arterial duct stenting aims to establish a reliable source of pulmonary blood flow. According to current indications for cardiac catheterisation in paediatric patients,^{Reference Feltes, Bacha and Beekman5} access vessel injury or obstruction is particularly mentioned as potential risks or complication of the procedure. As the procedure is performed mostly in newborns, the advantages of a smaller sized sheath are obvious.

We are convinced that downsizing the outer sheath French-size to the smallest commercially available values may result in significant decrement of the incidence of vascular complications in miscellaneous interventions like collateral vessel closure or Blalock–Taussig shunt stenting as it was shown in our patient group.

In our study group, an intravenous high-molecular-weight heparin infusion was applied due to weak peripheral pulses just after catheterization only in two patients. None of them required fibrinolytic therapy, which in our centre is initiated in patients in whom intravenous heparin infusion is not effective within the first 4 hours after cardiac catheterization.

The absence of peripheral pulses within the first 3–6 hours after arterial access for cardiac catheterization is a reliable predictor for arterial thrombosis.^{Reference Hurwitz, Franken, Girod, Smith and Smith8} After this time, the predictive value of peripheral pulse presence in paediatric patients is significantly decreased, due to the high incidence of false negative results due to early collateralization.^{Reference Flanigan, Keifer, Schuler, Ryan and Castronuovo9} Therefore, repeated pulse control within the first hours after cardiac catheterization was considered as a reliable tool to detect arterial thrombosis.

However, performing percutaneous interventions via Glidesheath Slender may be associated with some procedural limitations. The short length of the sheath does not enable angiography during device implantation (for example, in case of re-Coarctation of Aorta stenting), so reliable landmarks are needed, or a second catheter needs to be placed for angiographic depiction during device deployment. For the same reason, a stent cannot be advanced to the landing zone, protected by the sheath. Hence, it must be possible to deliver the stent in the correct position without stent dislodgement. Although the Glidesheath Slender enables device introduction and implantation, device retrieval may be difficult (snaring of embolised stents and removal through the sheath) due to significantly thinner walls of the sheath and, hence, less mechanical stability at withdrawal of embolised metallic material. Finally, due to the hydrophilic coating, the sheath has the tendency to dislodge during an intervention. We learnt to fix the sheath with strips to avoid this annoying feature.

The initial experience with Glidesheath Slender in adults with radial access is promising.^{Reference Aminian, Dolatabadi and Lefebvre3} So far, there is only one case report presenting results of Glidesheath Slender in small children.^{Reference Gendera, Cleuziou and Tanase10} In our experience with a larger cohort of patients, all patients showed vessel patency by clinical means, and hence, the results are very promising.