Biomedical Engineering Reference
In-Depth Information
4
Biomaterials for pacemakers, defibrillators and
neurostimulators
M . J . E B E R T , Medtronic Cardiac Rhythm Disease Management,
USA, S - P . L Y U , Medtronic Strategy and Scientific Operations,
USA, M . T . R I S E , Medtronic Neuromodulation, USA and
M . F . WO L F , Medtronic Strategy and Scientific Operations, USA
Abstract: This chapter discusses the materials used to make functional
electrical stimulation devices, including implantable pacemakers,
defibrillators, and neurostimulators. It focuses on the use of the materials in
terms of structures, functions, and biological responses of these devices, and
engineering principles to solve problems related to material biocompatibility,
biostability, and unmet needs.
Key words: functional electrical stimulation, implantable electrical
stimulation devices, pulse generator, leads, cardiac stimulation,
neuromodulation, implantable biomaterials.
4.1 Introduction
4.1.1 Overview of electrical stimulation devices
Artificial cardiac pacing is a therapy to restore the rhythm functions of a
diseased heart through electrical stimulation. This therapy is generated and
delivered to the heart by a cardiac pacemaker. A pacemaker has two com-
ponents: a pulse generator, or `can', that produces electric pulses (therapy) after
analyzing the signals that it senses from the diseased heart; and one or more
leads that deliver the therapy. In their initial clinical applications, pacing
therapies focused on the treatment of slow heart rate problems (bradycardia).
Gradually, pacemakers evolved to treat fast rate problems (tachycardia), irre-
gular beating problems (arrhythmia/fibrillation), and neurological disorders.
Today, electrical stimulation is established as a unique, safe, and effective
therapy and is becoming a competitive alternative to pharmaceutical therapies
for many chronic diseases. The therapies are different for different diseases, but
the stimulation devices are similar; they have similar structures, functions, and
biological requirements. The materials used to make these devices are similar as
well. This chapter focuses on the materials for cardiac pacemakers,
defibrillators, and neural stimulators.
