| cardiac muscle | <anatomy> Tissue specialised for contraction. See twitch muscle, catch muscle: Cardiac muscle (heart muscle) is a striated but involuntary muscle responsible for the pumping activity of the vertebrate heart. The individual muscle cells are joined through a junctional complex known as the intercalated disc and are not fused together into multinucleate structures as they are in skeletal muscle. Skeletal muscle is a rather non-specific term usually applied to the striated muscle of vertebrates that is under voluntary control. The muscle fibres are syncytial and contain myofibrils, tandem arrays of sarcomeres. Smooth muscle is muscle tissue in vertebrates made up from long tapering cells that may be anything from 20-500m long. Smooth muscle is generally involuntary and differs from striated muscle in the much higher actin/myosin ratio, the absence of conspicuous sarcomeres and the ability to contract to a much smaller fraction of its resting length. Smooth muscle cells are found particularly in blood vessel walls, surrounding the intestine (especially the gizzard in birds) and in the uterus. The contractile system and its control resemble those of motile tissue cells (for example fibroblasts, leucocytes) and antibodies against smooth muscle myosin will cross react with myosin from tissue cells, whereas antibodies against skeletal muscle myosin will not. See: dense bodies. (18 Nov 1997) |
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| cardiac muscle tissue | See: cardiac muscle. (05 Mar 2000) |
| cardiac muscle wrap | An operation that uses stimulated latissimus dorsi muscle (skeletal muscle ventricle) to assist cardiac function. The latissimus dorsi muscle is mobilised from the chest wall and moved into the thorax through the bed of the resected 2nd or 3rd rib. The muscle is then wrapped around the left and right ventricles and stimulated to contract during cardiac systole by means of an implanted burst-stimulator. (12 Dec 1998) |
| cardiac neurosis | Anxiety concerning the state of the heart, as a result of palpitation, chest pain, or other symptoms not due to heart disease; a form of hypochondriasis. See: neurocirculatory asthenia. Synonym: cardioneurosis. (05 Mar 2000) |
| cardiac notch | A deep notch between the oesophagus and fundus of the stomach. Synonym: incisura cardiaca. (05 Mar 2000) |
| cardiac notch of left lung | The notch in the anterior border of the superior lobe of the left lung which accommodates the pericardium. Synonym: incisura cardiaca pulmonis sinistri. (05 Mar 2000) |
| cardiac oedema | Oedema resulting from congestive heart failure. (05 Mar 2000) |
| cardiac opening | The trumpet-shaped opening of the oesophagus into the stomach. Synonym: ostium cardiacum, cardiac opening, oesophagogastric orifice. (05 Mar 2000) |
| cardiac orifice | The trumpet-shaped opening of the oesophagus into the stomach. Synonym: ostium cardiacum, cardiac opening, oesophagogastric orifice. (05 Mar 2000) |
| cardiac output | A measurement of the blood flow through the heart to the systemic (and pulmonary) circulation. Cardiac output is expressed as volume of blood per unit time or litres/minute. Cardiac output can be calculated using the Fick method (oxygen consumption divided by arteriovenous oxygen difference) or by the thermodilution technique, using a Swan-Ganz catheter. (27 Sep 1997) |
| cardiac output, high | A state of elevated cardiac output. Conditions that lower peripheral vascular resistance, such as anaemia, arteriovenous fistulas, thyrotoxicosis, and pregnancy, are among the most important factors augmenting the venous return and therefore elevating cardiac output. Increased cardiac output also occurs in muscular exercise, fever, and severe anoxia. (12 Dec 1998) |
| cardiac output, low | A state of subnormal or depressed cardiac output, usually seen in patients with heart failure secondary to coronary artery, hypertensive, primary myocardial, valvular, or pericardial disease. (12 Dec 1998) |
| cardiac pacemaker | An electrical device which delivers a small stimulant shock to the heart to effect cardiac contraction at a pre-determined rate. Many of today's pacemakers have two main components: the electrodes and the transducer (pulse generator). The electrodes are wires which are placed into the circulatory system and make physical contact with the heart muscle. A small electrical discharge from the pacemaker electrode stimulates the muscular wall of the heart to contract, thus pumping blood in an organised fashion. The transducer is a small device, usually implanted under the skin, that generates the electrical discharge at a pre-determined frequency. Transducers can monitor your heart's rate of contraction and deliver an electrical shock only when the heart is going too slow. (27 Sep 1997) |
| cardiac pacing, artificial | Regulation of the rate of contraction of the heart muscles by an artificial pacemaker. (12 Dec 1998) |
| cardiac part of stomach | The area of the stomach close to the oesophageal opening (cardiac orifice or cardia) which contains the cardiac glands. Synonym: pars cardiaca gastris, pars cardiaca ventriculi, cardia, gastric cardia. (05 Mar 2000) |