k. MEDICAL ELECTRONICS EQUIPMENT This section of the report briefly discusses some published work on the effects of electromagnetic interference on medical electronic devices and examines the possibility that solar power satellites could interfere adversely with the devices. The term "Medical Electronic Device" as used here implies individual cardiac pacemakers and those primarily health-oriented electrical devices (diagnostic and therapeutic) found in hospitals, clinics, physicians’ offices, and in emergency vehicles. Taken as a group, there are in excess of 5000 medical electronic devices available today (Jenkins and Woody, 1978). Because of this great number, it is impractical to study them individually. It is best to broadly group them, establish priorities for study, and identify some relevant trends. To assess the possibility of adverse SPS electromagnetic interference with medical electronic devices, an exhaustive literature search was conducted and many people were contacted for information and assistance. Those contacted were engineers or others involved in the maintenance, manufacture, or sale of medical electronic devices; researchers who test them; or government officials directly concerned with establishing EMC standards. 4.1 Cardiac Pacemakers and EMI It is apparent, after discussions with workers in the medical electronics industry and a survey of pertinent literature, that cardiac pacemakers are prime subjects for a study of compatibility with the SPS power beam. This stems from their immediate importance to cardiac patients, the large numbers now in use, and the fact that many interference related failures have been observed. Four basic types of pacemakers are in use today. Probably the simplest and least likely to be affected by interference is the asynchronous or fixed rate pacemaker, as shown in Figure 4(a). This unit stimulates the heart at a fixed rate that is usually around 70 beats per minute. The second type is the p-wave synchronous as shown in Figure 4(b). These units sense the electrical activity in the atrium and provide a stimulation pulse to the ventricle after a delay of approximately 120 milliseconds. The third type is the R-wave synchronous as shown in Figure 4(c) . A unit of this type is essentially the same as a p-wave synchronous except it senses and stimulates the ventricle without any time delay between sense and stimulation. The fourth type which is also described by Figure 4(c) is the demand or R-wave inhibited pacemaker. This unit also senses the ventricle activity, but unlike the others remains inactive until the rate falls below a predetermined
RkJQdWJsaXNoZXIy MTU5NjU0Mg==