An Interactive Computer System for Guiding the Surgical Treatment of Life-Threatening Ventricular Tachycardias

Ventricular tachycardias that are medically refractory can be treated surgically by resection of the area that generates the arrhythmia. The origin of a tachycardia can be determined during operation by recording endocardial electrograms. Tachycardias occurring spontaneously, or induced during the operative procedure, often last for only a few cycles and require the simultaneous recording of endocardial signals from numerous sites (mapping). The conventional technique of sequential mapping by using a roving probe cannot be applied in such cases. We, therefore, developed a flexible computerized system which enables us to record simultaneously from a multiple of 16 electrode terminals. The basic concept can accommodate 64 channels. A multielectrode array consisting of an inflatable balloon, uniformly covered with electrode terminals, is used to map the whole endocardial surface simultaneously. A rectangular grid covered with electrode terminals is used for refined resolution. Optically isolated amplifiers are used, providing ohmic isolation between the patient and the support electronics. After amplification and filtering, the endocardial signals are collected in groups of 16 and transferred to data acquisition units. Each unit contains a 16-channel multiplexing A/D converter and a 16K circular buffer. An LSI-11 based minicomputer controls the acquisition units and accounts for the transition of data to disk. Preselection of data is carried out during acquisition in order to reduce operation time. After acquisition, hard copies of the signals are made on a 16-channel chart recorder.