Artificial cardiac pacemakers

Isoproterenol (ISUPREL, others) may be used in emergencies to stimulate heart rate in patients with bradycardia or heart block, particularly in anticipation of inserting ait artificial cardiac pacemaker or in patients with the ventricular arrhythmia torsades de pointes. In asthma and shock isoproterenol largely has been replaced by other sympathomimetic drugs (set below and Chapter 27). 

As with the normal cardiac conducting system and its propagation of impulses through the His Purkinje network, electrostimulation by an artificial cardiac pacemaker depends on the depolarization of a single or a group of myocyte cell membranes which can then act as pacemaker cells. In order for these cells to depolarize, the electric field of the applied artificial pacemaker stimulus must exceed a threshold voltage. This initiates a complex cascade of ionic currents both in and out of the cell membrane referred to as the action potential. The impulse or wave of depolarization then propagates away from the site of stimulation from cell to cell across gap junctions or intercalated disks, which with normal cells provide very low resistance to depolarization. 

Schecter DC. Modem era of artificial cardiac pacemakers. In Schecter DC. Electrical cardiac stimulation. Minneapolis Medtronic, 1983 110-134. 

Funnan S, Parker B, Krauthammer J, Esher DJ. The influence of electromagnetic environment on the performance of artificial cardiac pacemakers. Am Thorac Surg 1968 6 90. 

Polymers are a fundamental part of the modem world, showing up in everything from coffee cups to cars to clothing. In medicine, too, their importance is growing for purposes as diverse as cardiac pacemakers, artificial heart valves, and biodegradable sutures. 

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. 

Canadian John Hopps invents the first cardiac pacemaker The synthetic fabric, polyester, is invented The first kidney dialysis machine is developed Polyurethanes are synthesized by Otto Baeyer The first plastic artificial eye is developed in the US Percy Spencer creates the first microwave oven... 

The presence of a foreign body in an infected site markedly rednces the likelihood for snccess-ful antibiotic therapy. Prosthetics such as cardiac valves, artificial joints, pacemakers, vascnlar grafts, and various shunts promote the formation of a bacterial biofilm that impairs phagocytosis within the film, the slower growth of bacteria may also reduce antibiotic activity and favor bacterial persistence. Infections associated with foreign bodies thus are characterized by frequent relapses and failure, even with long-term antibiotic therapy. Successful therapy usually requires removal of the foreign material. 

Many devices for medical stimulation have now come into routine use over long periods of time, for example, cardiac pacemakers. Large currents ( shocks ) of artificial origin also are used to terminate action potentials in some cases, for example, cardiac defibrillators. The transmembrane potential changes induced by such shocks now have been measured in considerable detail [e.g., Zhou et al., 1996 fdeker et al, 2000]. 

Several actinide nuclides have found other applications. Heat sources made from kilogram amounts of Pu have been used to drive thermoelectric power units in space vehicles. In medicine, Pu was applied as a long-lived compact power unit to provide energy for cardiac pacemakers and artificial organs. Am has been used in neutron sources of various sizes on the basis of the (a,n) reaction on beryllium. The monoenergetic 59-keV y radiation of Am is used in a multitude of density and thickness determinations and in ionization smoke detectors. Cf decays by both a emission and spontaneous fission. One gram of Cf emits 2.4 10 neutrons per second. "Cf thus provides an intense and compact neutron source. Neutron sources based on Cf are applied in nuclear reactor start-up operations and in neutron activation analysis. 

Other uses are as superconductive materials of TiNb, the shape memory alloy of Ti-Ni, the hydrogen occlusion alloy of Ti—Fe, and in computer equipment as nonmagnetic substance, artificial bones, dental roots, cardiac valves and cardiac pacemakers as nontoxic and biocompatible materials [3,5]. 

DNLM 1. Electrocardiography, Ambulatory—methods. 2. Cardiac Pacing, Artificial. 3. Pacemaker, Artificial. WG 140 H587sm 2004] I. 

According to heart specialists, four distinct types of medical devices can be used to treat cardiac diseases, namely pacemakers, cardioverters, defibrillators, and left-ventricular assist devices. In addition, the total artificial or mechanical heart needs to be powered by batteries with an emphasis on reliability, safety, and OCV with no electrical surges and voltage fluctuations. Generally, cardiac pacemakers are prescribed by heart specialists when the cardiac rhythm is too slow or when the patient has an abnormal heart beat. This device is implanted in the patient s chest. The implanted pacemaker detects the slow heart rate and sends electrical impulses to stimulate the heart muscle. An electrical signal from the muscle is fed back to the device to make appropriate corrections in the stimulation parameters, which will normalize the heart rate within a hundred microseconds or so. 

Problem area Examples Replacement of diseased or damaged part Artificial hip joint, kidney dialysis machine Assist in healing Sutures, bone plates, and screws Improve function Cardiac pacemaker, intraocular lens Correct functional abnormality Cardiac pacemaker Correct cosmetic problem Augmentation mammoplasty, chin augmentation Aid to diagnosis Probes and catheters Aid to treatment Catheters, drains ... 

Heart Cardiac pacemaker, artificial heart valve, total artificial heart... 

An implantable medical device (IMD) operates inside the body to monitor certain physiological parameters. Based on the power requirements of the device, IMDs are divided into two categories (i) active (the devices that need power) and (ii) passive (those that do not require power). Examples of passive IMDs are artificial joints and vascular grafts, whereas active IMDs may include cardiac defibrillators, cardiac pacemakers, neurostimulators, drug pumps, cochlear implants, and retinal implants. The need to broaden the assortment of effectively active IMDs is constantly increasing. 

Most of the implantable cardiac pacemakers need to be replaced because of the battery exhaustion within 5-8 years. The longevity of the IMDs is determined by the battery life. When the service life of the battery ends, it needs to be replaced, causing the patient to undergo painful surgery and incur enormous expenses. In contrast, the main advantage of fuel cells for IMD is its theoretical potential to function as long as the individual is alive. The devices can use substrates that already exist in the body— no artificial fuel and oxidants are required. 

This approach is called the close loop. Examples of well-established intelligent devices in the medical area are the cardiac pacemakers. Through a set of electrodes, the pacemaker is able to detect abnormalities in the heart electrical signal and artificially stimulate the heart to suppress such anomalies. Another example, not yet fully realized, is the implantable insnlin pnmp (Spaan et al., 2014). 

Examples of self-sustained oscillatory systems are electronic circuits used for the generation of radio-frequency power, lasers, Belousov-Zhabotinsky and other oscillatory chemical reactions, pacemakers (sinoatrial nodes) of human hearts or artificial pacemakers that are used in cardiac pathologies, and many other natural and artificial systems. An outstanding common feature of such systems is their ability to be synchronized. 

The Dow Chemical Company does not recommend Pellethane elastomers for long-term medical implant applications in humans (more than 30 days). Nor do they recommend the use of Pellethane elastomers for cardiac prosthetic devices regardless of the time period that the device will be wholly or partially implanted in the body. Such applications include, but are not limited to, pacemaker leads and devices, cardiac prosthetic devices such as artificial hearts, heart valves, intra-aortic balloon and control systems, and ventricular bypass assist devices. The company does not recommend any non-medical resin (or film) product for use in any human implant applications. 

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