| 摘要 |
A cardiac pacemaker improves battery longevity by automatically providing optimized threshold amplitude and pulse width values. During capture verification and threshold searching, the pacemaker delivers a pacing pulse and a rapid, maximum amplitude backup pulse in case the pacing pulse fails to capture a patient's heart. Unlike the prior art, the backup pulse is delivered before a predefined Vulnerable Period (during which time pacing might lead to re-entrant tachycardia or fibrillation.) This results in threshold searching which is quick, accurate and with smaller rate drops during loss of capture. In another aspect of the present invention, a diagnostic strength-duration curve is approximated by first setting the pulse width to a maximum value and determining the amplitude threshold (rheobase), and then by doubling the amplitude and determining the pulse width threshold (chronaxie).
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