Measurement of Human Heart Rate during Usual Activty.
A small, rugged, self-contained cumulative heart-beat counter has a transistorized amplifier, a watch movement made into a counter, and a battery. The counter is activated by each R-wave of the electrocardiographic complex obtained from newly designed precordial electrodes. Heart beats can be counted for as long as 24 hours.
Rowley
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Glagov
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Stoner
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