Atrial Septal Puncture
Interatrial septa isolated from 36 porcine hearts were immersed in a
room temperature bath of 0.9% sodium chloride solution and positioned
on a cork sample holder to normalize force applied during puncture
(Figure 2A). RF energy was delivered using the RF wire and electrified
guidewires under each power setting. Additional energy applications were
delivered until the tip of the wire perforated the septum, or up to a
maximum of 8 attempts. Failure to puncture was defined as the inability
to perforate the septum after 8 RF applications. To model a range of
conditions in clinical practice, multiple distances from the distal wire
to the dilator tip were tested; 1mm (i.e. underexposure of wire tip),
3mm (i.e. ideal wire tip exposure) and 5mm (i.e. over-exposure of wire).
The number of RF applications required to perforate the septum was
recorded for each treatment condition. Each treatment condition was
repeated at least six times. Inspection of puncture sites was performed
immediately post-puncture under 30-50X magnification using an optical
microscope (VHX-5000, Keyence, Osaka, Japan) to confirm TSP success and
qualitatively assess the defect site.