System and method for controlling the stimulation frequency of heart pacemakers

US4870968A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Alexander Wiertzfeld · Thanning, DE
• Roland Heinze · Munich, DE

Key dates

• Filing date: Apr 2, 1987
• Grant date: Oct 3, 1989
• Expiry date: Apr 2, 2007

Classification

• Technology area (CPC A): Human Necessities
• CPC primary: A61N1/36557
• WIPO field: Medical technology
• WIPO sector: Instruments

Abstract

A follower control matches the stimulation frequency of a heart pacemaker to patient load condition by obtaining measurement values S.sub.02 corresponding to the central venous blood oxygen saturation in the heart according to the principle of reflection oximetry, by forming control values B.sub.S1 according to the quotient .DELTA.S.sub.02 /.DELTA.S.sub.02max where the numerator is the difference between the current measurement value and a stored reference value (e.g. S.sub.02max or S.sub.02min) and the denominator serves to standardize the control value based on the maximum change of the measurement value over a relatively long time interval, and by changing the stimulation frequency by an amount dependent on the magnitude of the control value. Preferably, the stimulation frequency f.sub.p is set directly as a function of the control value B.sub.S1 and most preferably according to the function ##EQU1## where f.sub.min is a prescribed minimum frequency, .DELTA.f.sub.max is the maximum frequency difference, c.sub.w is a programmable constant and .DELTA.f.sub.opt is a frequency change introduced by a concurrently operating optimizing control. Artifacts are avoided by obtaining measur…