Cardiac pacemaker electrodes

Jaron D, BrUler A, Schwan HP, Geselowitz DB. 1969. Nonlinearity of cardiac pacemaker electrodes. IEEE Trans Biomed Eng 16,132-138. 

Keitel O, Kruger E, Ponitz M. Selective parylene coating for cardiac pacemaker electrodes. US Patent 8355 802, assigned to Heraeus Precious Metals GmbH Co. KG, Hanau, DE 2013. 

Smith CW, Messenger JC, Schanner SP, et al. Cardiac pacemaker electrodes improved methods of extraction. Work in progress. Radiology 1994 193 739. 

Rowley, B. A., 1963, Electrolysis—A factor in cardiac pacemaker electrode failure, Trans. IEEE,PGBMEA0(4) 76. 

A more general formulation by Jaron et al. (1967, 1969), specifically for cardiac pacemaker electrodes, but of general applicability, gives... 

Jaron, D., Schwan, H. P., and Geselowitz, D. B., 1967, A mathematical model for the polarization impedance of cardiac pacemaker electrodes, Proc. 20th ACEMB, Boston, p. 15.2. 

Electrical Stimulation Devices. Bioelectrodes that transmit electrical signals into the body are generally known as electrical stimulation devices, examples of which include cardiac pacemakers, transcutaneous electronic nerve stimulators (TENs) for pain suppression, and neural prostheses such as auditory stimulation systems for the deaf and phrenic nerve stimulators for artificial respiratory control. In these, and other similar devices, electrodes transmit current to appropriate areas of the body for direct control of, or indirect influence over, target cells. 

At the end of this chapter, some readers may wonder why we did not present one of the three most famous and beneficial neural prostheses that are in clinical use since several years the cardiac pacemaker, the cochlea implant and the urinary bladder stimulator of Brindley. In our view, the devices may not be considered microsystems. Only the electronic parts are built of monolithic integrated circuitry in silicon technology. The electrodes are still manufactured in a conventional way not reaching miniaturization levels that were presented here. 

In addition to the EP study and ablation therapy internal electrodes are the primary form of signal recording for both the cardiac pacemaker and implantable defibrillator. These devices both sense cardiac activation from permanent indwelling catheters and deliver energy to the heart through them. In the... 

Yamamoto and Yamamoto (1981) studied human skin tissue and found the limit current of linearity to be about 10 pA/cm at a frequency of 10 Hz. Grimnes (1983b) studied electro-osmosis in human skin in vivo and found a strong polarity-dependent nonlinearity. The effect was stronger the lower the frequency, Figure 10.17 shows the dramatic effect with 20 V and 0.2 Hz, soon leading to skin breakdown. Nonlinearity of cardiac pacemaker CC electrodes made of noble metals and intended for use with pulses has been extensively studied (Jaron et al. 1969). 

Small area contacts occur, for example, with pacemaker electrodes, catheter electrodes, and CC fluid-fiUed cardiac catheters. Small area contact implies a monopolar system with possible high local current densities but low current levels in the external circuit. This is called a microshock situation. The 50/60 Hz safe current hmit for a small area contact with the heart is 10 i,A in normal modes. The dilfer-ence between macro- and microshock dangerous current levels is, therefore, more than three orders of magnitude. 

Implantable stimulation systems use an encapsulated pulse generator that is surgically implanted and has subcutaneous leads that terminate at electrodes on or near the desired nerves. In low power consumption applications such as the cardiac pacemaker, a primary battery power source is included in the pulse generator case. When the battery is close to depletion, the pulse generator has to be surgically... 

The use of electrosurgery on patients with metallic implants or cardiac pacemakers may pose problems. Metallic implants are usually considered not to be a problem if the form is round and not pointed, Etter et al. (1947). The pacemaker electrode tip is a small area electrode, where relative small currents may coagulate endocardial tissue. The pacemaker catheter positioning should therefore not be parallel with the electrosurgery current density lines. This is illustrated in Figure 10.22 for a heart pacemaker implant. 

A cross section of a Li/l2 prismatic cardiac pacemaker cell is shown in Fig. 11.5. In this design, a lithium sheet is placed between two I2-P2VP electrodes. Energy densities oxU 2 cells are 210-280 Wh kg and 810-1,030 Wh dm [14]. 

Kemp A, Johansen JK, Kjaergaard E. Malplacement of endocardial pacemaker electrodes in the middle cardiac vein. Acta Med Scand 1976 199 7-11. 

Imparato A, Kim GE. Electrode complications in patients with permanent cardiac pacemakers. Arch Surg 1972 105 705-710. 

Dohhna ML, et al. Myocardial stimulation threshold in patients with cardiac pacemakers effect of physiologic variables, pharmacologic agents, and lead electrodes. Cardiol Clin 1985 3 527. 

Waller D, Calhes E, Langenfeld H. Adverse effects of direct current cardioversion on cardiac pacemakers and electrodes. Is external cardioversion contraindicated in patients with permanent pacing systems Europace 2004 6 165-168. 

Achenbach S, Moshage W, Diem B, Bieberle T, Schibqilla V, Bachmann K. Effects of magnetic resonance imaging on cardiac pacemakers and electrodes. Am Heart J 1991-,13A-.A61-413. 

Cochlear Implants. Cochlear implants (Cl), by fer the most successful sensory neural prostheses to date, have penetrated the mainstream therapeutic arsenal. Their popularity is rivaled only by the cardiac pacemakers and deep brain stimulation (DBS) systems. Implanted in patients with sensorineural deafness, these devices process sounds electronically and transmit stimuli to the cochlea. A Cl includes several components a microphone, a small speech processor that transforms sounds into a signal suitable for auditory neurons, a transmitter to relay the signal to the cochlea, a receiver that picks up the transmitted signal, and an electrode array implanted in the cochlea. Individual results vary, but achieving a high degree of accuracy in speech perception is possible, as is the development of language skills. 

Batteries require the transfer of ions from one electrode to another. Originally in battery technology, the electrolyte was a fluid. However, batteries for uses in space craft and medical apphcations, such as cardiac pacemakers, require that the electrolyte should be a permeable sohd. The original pacemaker batteries used a mixture of poly(N-vinylpyrrohdone) mixed with a low molar mass plasticiser and doped with a high concentration of a salt. 

The first lithium/iodine cardiac pacemaker battery was implanted in 1972. This type of battery proved to be very successful in this field and for other applications, too. The special features of this solid state battery are explained with its technique, which is limited with its extremely high energy density and reliability, especially for low rate applications. This technique is based firstly on the electrode couple of lithium and iodine with its high energy content - the OCV of the lithium/iodine cell is 2.80 V -and secondly on the favorable fact that the product of the cell reaction, the lithium iodide (LiJ), forms very tight and continuous layers between the active material of the electrodes, which are acceptable ionic conductors with negligible electronic... 

The simplest example is Lil, which shows not an excellent, but still considerable con-ductivity of 5 x 10 S cm at room temperature, while other lithium halides are almost insulators, probably because of the less polarizable nature of their halogen ions. It is notewortlty that Lil was the first practical solid electrolyte used in a Li/Ij-complex cell in 1972, in which a layer of Lil was formed by contact of the negative and the positive electrodes. The layer was so thin that the resistance was small enough for low current uses, such as in a cardiac pacemaker. 

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