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Biomedical subjects

M Schaldach

Publications and source records attributed to M Schaldach.

At least 109 records · Page 6Linked to original sources
PubMed1990

A physiological approach to different concepts of rate adaptive cardiac pacing.

Physiological aspects of rate adaptive pacing are dealt with in the context of the cardiovascular control loop with the cardiac output as the controlling quantity and mean arterial blood pressure as the controlled quantity. Different methods proposed or clinically investigated are analyzed with respect to cardiovascular control mechanisms. To qualify as physiologic, the sensor-driven pacing rate must respond to disturbance variables similarly as the sinus node. To achieve this, the feedback signals, which control the cardiac output and are summarized as the sympathetic and parasympathetic innervation of the heart, are prime candidates as input signals for rate control in the presence of chronotropic insufficiency. Since only sympathetic tone can serve to increase contractility and thereby stroke volume and cardiac output in the absence of rate support, its meaningful measurement is the key for physiological sensor-driven rate control. PEP clinically has proved to be a measure of contractility, which represents sympathetic tone as it affects central hemodynamics. PEP-controlled pacing rate adaptation therefore enables restoration of a closed-loop pacing system utilizing those components of the physiological system that are still functioning.

Adaptation, Physiological↗
PubMed1987

Present state and future trends in electrical heart stimulation.

Examples of electrical heart stimulation techniques are presented to illustrate for the physician and biomedical engineer the technical feasibility of realizing many therapeutic concepts by means of microelectronics. Because of the life-supporting applications, extremely high system reliabilty must be guaranteed. The usual methods of enhancing safety by providing redundancy cannot be used, and the service life requirements can be met only by appropriate adaptation of the current consumption due to the limited battery capacity. Based on the practical experience gained in the manufacture of more than 100,000 implantable devices, it can be reported that by rigid application of, and adherence to, quality assurance measures reliability values can be achieved of lambda = 10(-7)h-1 at a confidence level of 90% for the hybrid components and of lambda = 10(-9)h-1 for integrated circuits and passive components. The requirement for technical reliability of the implantable device for patient safety requires a thorough understanding of all technical and medical details of the therapeutic device. The success of future developments (e.g. the automatically-controlled systems which are meant to substitute for the multiprogrammable pacemakers) will not only require utilization of currently available technologies but also will depend to a great extent on active participation of the physicians in the development process itself.

Cardiography, Impedance↗