PA-PSRS has received a report of a patient experiencing premature ventricular contractions (PVCs) during a procedure involving an intracorporeal electrohydraulic lithotripter (EHL). According to the hospital, a PVC occurred each time the EHL was activated.

The lithotripter electrode is inserted through the urethra using a cystoscope to remove stones from the bladder or nephroscope to remove stones from the kidney. With saline used for irrigation and the electrode placed near the bladder or kidney stone, the lithotripter is activated, generating a series of high-voltage sparks at the electrode tip. Sparks in the liquid medium generate a series of hydraulic shock waves, causing the stone to fracture.

Cardiac arrhythmias, though rare, can occur during EHL procedures. A review of FDA’s Manufacturer and User Facility Device Experience (MAUDE) database, from 1992 to the present, revealed three reports of patients’ experiencing abnormal cardiac rhythms during activation of the EHL generator. In two reports, patients experienced asystole. The rhythm returned to normal sinus rhythm when the EHL device was turned off. In the third report, the patient’s heart rate decreased, and the procedure was aborted with no reported injury to the patient.

Respective EHL device manufacturers’ responses in the MAUDE reports did not include definitive causes, but did suggest possible causes for the abnormalities in two of the three reports. One report in which the patient experienced asystole included a potential cause: that the patient was electrically grounded through the anesthesiologist, who may have been in physical contact with the patient during activation of the device. In the report concerning the patient’s decreased heart rate, the suggested cause was that the patient may have been electrically grounded through the patient electrodes and lead wires to the physiologic monitoring system used to monitor the patient’s vital signs during the procedure.

A review of MAUDE, also from 1992 to the present, revealed approximately 25 reports of electrical shocks experienced by the patient, anesthesiologist, surgeon, or a combination of individuals during EHL device activation.

In 1982, ECRI published a Hazard Report concerning anesthetists receiving electrical shocks during EHL bladder stone removal procedures.¹ Based on the hospital reports, ECRI conducted experiments with several EHL device models. They determined that the magnitude of the electric current was sufficient to be perceived by a locally anesthetized patient or a clinician who becomes part of the current’s path to ground. The 1982 reports also described the possible occurrence of an electrical path to ground for stray lithotripter current from an intracardiac catheter or electrode. ECRI stated that the occurrence was rare, but potentially hazardous. With the use of an intracardiac or pacemaker catheter, the electrical pathway for current would be directed through cardiac tissue, possibly resulting in cardiac arrhythmias.

• Methods that can help to mitigate the problem of electrical shocks or arrhythmias include:
• Informing surgical staff of the possibility of shocks or cardiac arrhythmias occurring during EHL procedures.
• Avoiding physical contact as much as possible between surgical staff and patients during activation of the EHL device.
• Minimizing patient contact with grounded metal surfaces during procedures.
• Avoiding EHL device use on patients who have externally connected intracardiac catheters.

Note

1. ECRI. Electrohydraulic Lithotripters [Hazard Report]. Health Devices 1982 Dec;
   12(2):46-7.