The construction of endocardial balloon arrays for cardiac mapping

The advent of multichannel recording systems has enabled clinical mapping to be performed on a beat-by-beat basis using multi-electrode arrays. Surgical ablation of ventricular arrhythmias generally requires endocardial mapping. Clinical usage has indicated that an inflatable balloon array is the most practical design and can obviate the need for ventriculotomy by a transatrial introduction in the deflated state. Successful experience with the left ventricular balloon led to the development of a right ventricular balloon array suitably configured to extend into the outflow tract. Custom moulds are used to create an appropriate balloon from liquid latex. Nylon cloth is cut from a cardboard pattern to fashion a stretchable sock to envelope the balloon. Electrodes are formed by stitching 2-mm silver beads to the balloon sock in a preconfigured pattern. Teflon-coated 31 G multi-strand stainless-steel wires 130 mm in length connect the electrode beads by solder to the multipin connectors for easy hookup to the amplifier inputs. Tygon tubing 0.53 cm in diameter fitted to the balloon allows inflation and pressure monitoring. This basic design has been successfully implemented for the last 6 years.