Complexity Diagnostics in Cardiology: Methods

In living organisms, there is a general principle that governs behaviors and reactions; they are designed to optimize "survival." In higher organisms this self-preservation aspect is maintained by a plethora of specialized sensors, which monitor essential functions, note potentially troublesome deviations from the normal state, transmit this information, and initiate suitahle control mechanisms to compensate for this, if necessary. In the cardiovascular system, relevant properties that are monitored continnously are the arterial hlood pressure, the oxygen content, the pH value of the blood, the atrial wall tension, etc. These properties are continuous variahles, the corresponding "signals" can be regarded as amplitude modulated analog signals. The sensor responsible for monitoring these properties passes the information on to the central nervous system (CNS). It is ahle to do so mainly in a "frequency modulated" form via afferent nerve fibers of the autonomic nervous system. (The integrals of the neural action potentials carry some information, too.) This implies an analog-to-digital (AD) conversion. In the CNS the incoming information from many such sensors is processed and some "reaction" is arrived at. The details of this particular process are not well understood yet. For our purposes it is sufficient to regard the CNS as a "hlack hox," whose function is to assemble incoming information, process it. and produce new instructions, which are then transmitted in digital form through efferent fibers of the autonomic nervous system to their destination—the "effectors" in the periphery.