Direct-current potentials created by arcing during monopolar radiofrequency electrosurgery.

Muscle and nerve stimulation during radiofrequency electrosurgery has been a well-known phenomenon for over 50 years. However, as electrosurgery expands into new procedures, such as tissue ablation in the heart, the mechanism of the potentially deleterious stimulation becomes more important. This article presents data showing that large DC currents are generated during electrosurgery and that these potentials increase with increasing sparking at the active electrode. The data also show DC potentials generated by various generators, different operation modes (cut, coagulation, fulguration), and operations on tissues of various impedances.

A simple and inexpensive method for measuring electrosurgical variables.

A simple circuit that demodulates the high-frequency output of an electrosurgical generator to proportional DC values can be employed to monitor generator voltage and electrosurgical current. An example of the use of the circuit in a urologic application is given. Employing this monitoring circuit, quantitative comparisons of electrosurgical equipment and performances can be made.

Twenty-four hour left ventricular bypass with a centrifugal blood pump.

A new centrifugal blood pump system has been developed for left ventricular bypass by the addition of non-thrombogenic blood surface materials and an ultrathin-walled cannula for the retrograde cannulation of the left ventricle. Partial LV bypass at 3 to 6 L/min was undertaken in 55 calves without thoracotomy. In 20 it was continued for 24 hours, with 13 survivors who were eventually sacrificed. Eleven of the last 14 experiments were completed without mishap. Heparin was employed only during pump insertion. Hematologic changes were limited to moderate platelet depression, and tolerable hemolysis (average serum level 21 mg% in the last 13 experiments). Normal clotting parameters and the absence of significant fibrin split product formation correlated with the absence of gross thrombosis and few minor renal emboli observed at autopsy. This pump system appears to have several advantages over previously described equipment for LV bypass.