Accurate guidance for percutaneous access to a specific target in soft tissues: Preclinical study of computer-assisted pericardiocentesis

In the field of percutaneous access to soft tissues, our project was to imp rove classical pericardiocentesis by performing accurate guidance to a sele cted target, according to a model of the pericardial effusion acquired thro ugh three-dimensional (3D) data recording. Required hardware is an echocard iographic device and a needle, both linked to a 3D localizer, and a compute r. After acquiring echographic data, a modeling procedure allows definition of the optimal puncture strategy, taking into consideration the mobility o f the heart, by determining a stable region, whatever the period of the car diac cycle. A passive guidance system is then used to reach the planned tar get accurately, generally a site in the middle of the stable region. After validation on a dynamic phantom and a feasibility study in dogs, an accurac y and reliability analysis protocol was realized on pigs with experimental pericardial effusion. Ten consecutive successful punctures using various tr ajectories were performed on eight pigs. Nonbloody liquid was collected fro m pericardial effusions in the stable region (5 to 9 mm wide) within 10 to 15 minutes from echographic acquisition to drainage. Accuracy of at least 2 .5 mm was demonstrated. This study demonstrates the feasibility of computer -assisted pericardiocentesis. Beyond the simple improvement of the current technique, this method could be a new way to reach the heart or a new tool for percutaneous access and image-guided puncture of soft tissues. Further investigation will be necessary before routine human application.