You can mark you interesting snippets of text that will be available through a unique link in your browser.


Pacemaker

Translation
Pacemaker
A system that sends electrical impulses to the heart in order to set the heart rhythm. The pacemaker can be the normal "natural" pacemaker of the heart or it can be an electronic device. The natural pacemaker of the heart is the sinus node, one of the major elements in the cardiac conduction system, the system that controls the heart rate. This stunningly designed system generates electrical impulses and conducts them throughout the muscle of the heart, stimulating the heart to contract and pump blood. The sinus node consists of a cluster of cells that are situated in the upper part of the wall of the right atrium (the right upper chamber of the heart). The electrical impulses are generated there. The sinus node is also called the sinoatrial node or, for short, the SA node. The electrical signal generated by the sinus node moves from cell to cell down through the heart until it reaches the atrioventricular node (AV node), a cluster of cells situated in the center of the heart between the atria and ventricles. The AV node serves as a gate that slows the electrical current before the signal is permitted to pass down through to the ventricles. This delay ensures that the atria have a chance to fully contract before the ventricles are stimulated. After passing the AV node, the electrical current travels to the ventricles along special fibers embedded in the walls of the lower part of the heart. Although there are different types of artificial pacemakers, all are designed to treat bradycardia, a heart rate that is too slow. Some pacemakers function continuously and stimulate the heart at a fixed rate or at an increased rate during exercise. A pacemaker can also be programmed to detect an overly long pause between
* * *
1. Biologically, any rhythmic center that establishes a pace of activity. 2. An artificial regulator of rate activity. 3. In chemistry, the substance of which the rate of reaction sets the pace for a series of chain reactions; the rate-limiting reaction itself; e.g., in a metabolic pathway, the enzyme catalyzing the slowest or rate-limiting reaction in that pathway. [L. passus, step, pace]
- artificial p. any device that substitutes for the normal p. and controls the rhythm of the organ; especially an electronic cardiac p., which may be implanted in the chest, with electrodes attached to the external cardiac surface, or passed through the venous circulation into the right side of the heart (pervenous p.).
- demand p. a form of artificial p. usually implanted into cardiac tissue because its output of electrical stimuli can be inhibited by endogenous cardiac electrical activity.
- diaphragmatic p. a device that paces the diaphragm, used in patients with chronic ventilatory insufficiency resulting from quadriplegia or certain types of phrenic nerve malfunction.
- ectopic p. any p. other than the sinus node.
- electric cardiac p. an electric device that can substitute for the normal cardiac p., controlling the heart's rhythm by artificial electric discharges. SYN: electronic p..
- electronic p. SYN: electric cardiac p..
- external p. an artificial cardiac p. of which the electrodes for delivering rhythmic electric stimuli to the heart are placed on the chest wall. SYN: transthoracic p..
- fixed-rate p. an artificial p. that emits electrical stimuli at a constant frequency.
- nuclear p. a nuclear-powered unit used to generate the electrical current for artificially pacing the heart; replaced by units using long-life nickel-cadmium and other power sources.
- pervenous p. an artificial p. passed through the venous circulation into the right side of the heart.
- runaway p. rapid heart rates over 140/min caused by electronic circuit instability in an implanted pulse generator.
- shifting p. SYN: wandering p..
- subsidiary atrial p. secondary source for rhythmic control of the heart, available for controlling cardiac activity if the sinoatrial p. fails; usually located within the crista terminalis and atrial free wall near the inferior vena cava.
- transthoracic p. SYN: external p..
- wandering p. a disturbance of the normal cardiac rhythm in which the site of the controlling p. shifts from beat to beat, usually between the sinus and AV nodes, often with gradual sequential changes in P waves between upright and inverted in a given ECG lead. SYN: shifting p..

Medical dictionary. 2011.

  
Share  

Look at other dictionaries:

  • Pacemaker — Entwickler Cluster Labs Aktuelle Version 1.0.10/ 1.1.4 (12.11.2010/ 20.10.2010) Betriebssystem Linux Programmier­sprache C u. a. Lizenz …   Deutsch Wikipedia

  • pacemaker — n. (Physiol. & Anat.) 1. a specialized bit of heart tissue that controls the heartbeat. Syn: cardiac pacemaker, sinoatrial node. [WordNet 1.5] 2. An implanted electronic device that takes over the function of the natural cardiac pacemaker[1];… …   The Collaborative International Dictionary of English

  • pacemaker — 1> лидер (в забегах) 2> задающий тон Ex: she is a pacemaker in fashions она задает тон в моде 3> мед. электрокардиостимулятор; электронный стимулятор сердца 4> мед. синусовый узел сердца 5> физиол. пейсмекер, водитель ритма, ритмоводитель;… …   Новый большой англо-русский словарь

  • pacemaker — m ingl электронный стимулятор сердца …   Большой итальяно-русский и русско-итальянский словарь

  • pacemaker — m ingl электронный стимулятор сердца …   Большой итальяно-русский и русско-итальянский словарь

  • pacemaker — pacemaking, n. /pays may keuhr/, n. 1. pacesetter. 2. Med. an electronic device implanted beneath the skin for providing a normal heartbeat by electrical stimulation of the heart muscle, used in certain heart conditions. 3. Anat., Physiol. any… …   Universalium

  • Pacemaker — Cette page d’homonymie répertorie les différents sujets et articles partageant un même nom. Sur les autres projets Wikimedia : « Pacemaker », sur le Wiktionnaire (dictionnaire universel) Le terme pacemaker a diverses… …   Wikipédia en Français

  • pacemaker — кардиостимулятор, мед. ритмоводитель implant a pacemaker лидер (в забегах) задающий тон she is a * in fashions она задает тон в моде (медицина) электрокардиостимулятор; …   Большой англо-русский и русско-английский словарь

  • pacemaker — noun Date: 1884 1. a. one that sets the pace for another b. one that takes the lead or sets an example 2. a. a group of cells or a body part (as the sinus node of the heart) that serves to establish and maintain a rhythmic activity b. an… …   New Collegiate Dictionary

  • Pacemaker — …   Большой немецко-русский и русско-немецкий словарь