The Utility of the Parallax Principle in Subclavian Stick for Permanent Pacemakers Implantation

Aims: The subclavian stick is a routine procedure in electrophysiology (EP), representing a serious risk of pneumothorax.

The Parallax principle is based on the angular deviation of the apparent position of an object according to the position of the observer. In this study we report the usefulness of this method for decreasing the incidence of pneumothorax during pacemaker implantation.

Methods and results: We compared the annual incidence of pneumothorax in 1,128 patients who underwent permanent pacemaker implantation between 2008 and 2015. Those implanted between 2008-2011 (n = 649) were the control group (A), while those implanted since 2012, group B, (n = 479). Fluoroscopy was used to guide the stick with postero-anterior projections (PA) in group A, and PA combined with 30-50º caudal angulation for patients of group B. The first projection guides the clinician cranio-caudal direction, to direct the needle towards the clavicle’s head. The caudal angulation allows to evaluate the depth of the puncture. This is extremely useful to keep the needle in the extra-thoracic space, between the clavicle and the first rib.

Continuous variables were evaluated with student t-test and nominal ones with Chi² test, considering an alpha <= 0.05.

Both groups were comparable in mean age and gender. A total of 1,718 subclavian punctures were performed.

In group B, less attempts were required to achieve the venous access (P <0.02) and the incidence of pneumothorax was significantly lower, reducing the annual incidence from 2.4 in group A to 1.6 in group B (p = 0.04).

Conclusions: Radiographic localization using the "Parallax" principle is simple and its implementation in EP requires no special equipment beside the fluoroscope.

During the implantation of a permanent pacemaker, this technique is useful in reducing the incidence of pneumothorax and the number of attempts to stick the vein.