Abstract: A synthetic layered silicate material may be produced which exhibits tolerance to high levels of electrolytes and surfactants as measured by viscosity, hydration rate and clarity. The synthetic layered silicate material may produce similar or improved rheological properties when compared to natural hectorite at comparable or lower addition rates in select aqueous systems.

Abstract: The diagnostic unit 1 consists of a microprocessor-based control section 5, a data memory 6 and a pacemaker 7. The control section 5 monitors heart action using the intracardiac electrogram and a second signal representative of intracardiac pressure. It detects events of interest to clinicians including bradycardia, tachycardia, cardiac pauses, pressure pauses, interference and pacing pauses, and records the numbers of each type of event. Selective recordings of the waveforms of the sensed signals are made in memory within the unit whenever an event of interest is detected. The unit is worn by the patient for periods of up to three weeks, and the parameters of the events to be sensed can be programmed into the unit by the clinician using a computer 4. The same computer 4 is used to extract and display the recorded data.

Abstract: There is disclosed an event counting and reporting heart pacer which is useful for patients who suffer from bradycardia. The pacer operates in a demand mode with a 2.5-second escape interval. A count is maintained of the number of pauses each of which exceeds this escape interval. Four successive pauses, each of which exceeds 2.0 seconds but is less than 2.5 seconds, are treated as a single 2.5-second pause. Following the detection of each pause, the escape interval is reduced to 1.2 seconds and the counter is inhibited from further operation; the counter is enabled and the 2.5-second escape interval applies once again only after a spontaneous heartbeat is detected within 1.2 seconds of the preceding beat. When a maximum count of 128 pauses is reached, the system thereafter operates with fixed 1.2-second escape interval.