cardiac impulse

impulse /im·pulse/ (im´puls)

1. a sudden pushing force.

2. a sudden uncontrollable determination to act.

3. nerve i.

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cardiac impulse  movement of the chest wall caused by the heart beat.

ectopic impulse 

1. the impulse that causes an ectopic beat.

2. a pathologic nerve impulse that begins in the middle of an axon and proceeds simultaneously towards the cell body and the periphery.

nerve impulse  the electrochemical process propagated along nerve fibers.

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cardiac impulse

Etymology: Gk, kardia + L, impellere, to set in motion

1 the mechanical movement of the thorax caused by the beating of the heart. It is readily palpable and easily recorded. See also point of maximum impulse.

2 the electrical stimulus generated by the heart for pacing purposes.

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cardiac

1. pertaining to the heart. See also heart.

2. pertaining to the gastric cardia.

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cardiac afterload

the impedance to ventricular emptying presented by aortic pressure.

cardiac area

see precordium.

cardiac biopsy

an uncommon clinical procedure. May be performed via thoracotomy or with a biopsy catheter introduced intravenously.

cardiac catheterization

the insertion of a catheter into a vein or artery and guiding it into the interior of the heart for purposes of measuring cardiac output, determining the oxygen content of blood in the heart chambers, and evaluating the structural components of the heart.

cardiac compensation

in cardiac disease the compensation for the inefficiency of the heart's pump action by enlisting the various reserves of the heart such as hypertrophy, enlargement, increase in rate, so as to maintain circulatory equilibrium and prevent the appearance of signs of congestive heart failure.

cardiac compression

an emergency measure to empty the ventricles of the heart in an effort to circulate the blood, and also to stimulate the heart so that it will resume its pumping action. Involves the application of pressure through the thoracic wall. More commonly used in animals than other forms of cardiac massage.

cardiac conducting cells

specialized cardiac fibers modified to conduct impulses from the A-V node via the septum to the ventricles. Called also Purkinje fibers.

cardiac conducting system

the cardiac tissue responsible for electrical conduction, made up of the sinoatrial node, the atrioventricular node, and the atrioventricular bundle and cardiac conducting fibers.

cardiac depressor nerve

a branch of the vagus nerve composed of afferent nerve fibers which arise around the base of the heart; called also aortic nerve.

cardiac dilatation

the heart volume is increased but the effective mass of cardiac muscle is not. A dilated heart has lost some of its reserve.

cardiac dullness

the area of the chest wall over which a dull sound, indicating the position of the heart, can be elicited by percussion.

cardiac failure

see heart failure.

cardiac fibrillation

see ventricular fibrillation.

cardiac fibrosis

see cardiac cirrhosis.

cardiac flow load

the work required of the heart can be increased by a need for an increased flow rate of blood, e.g. when there is an anastomosis, congenital arteriovenous defect, portosystemic shunt.

cardiac function curves

statistical curves used in modeling the cardiovascular functions, relating e.g. venous return to cardiac output.

cardiac glands

in the cardiac region of the gastric wall; branched, tubular, coiled, mucus-secreting.

cardiac glycosides

the glycosides of Digitalis purpurea (digitoxin, gitalin and gitoxin) and digoxin (from D. lanata). Strophanthin and ouabain are glycosides found in Strophanthus spp. Other cardiac glycosides are present in the skin of toads (Bufo maritimus, B. vulgaris), but are of toxicological rather than therapeutic interest.

cardiac horse sickness

see african horse sickness.

cardiac hypertrophy

enlargement of the heart coincident with an increase in muscle mass; an indication of response to an increase in load which may or may not be associated with disease. It is an expression of cardiac compensation but some of the cardiac reserve has been lost.

cardiac impulse

see cardiac impulse. Called also apex beat.

cardiac index

cardiac output divided by the animal's body surface area in m². The normal range for dogs is 1.8-3.5 l/m².

left-sided cardiac enlargement

may involve either the left ventricle or atrium, or both, and can be demonstrated on radiographs and electrocardiography. Seen most commonly in mitral valvular disease in dogs.

cardiac massage

manual massage of the heart or stimulation with an electrical current through an open thoracic wall. The term is sometimes used interchangeably with cardiac compression.

cardiac mucosa

the most cranial of the gastric mucosae; secretes only mucus, except in pigs, in which the area covered by this mucosa is much larger than in the other species and bicarbonate is also secreted.

cardiac murmur

see heart murmur.

cardiac output

the volume of blood pumped per unit of time. May be calculated by oxygen consumption measurement or determined by dilution of indocyanine green or cold saline, using catheters with thermistors placed intravenously (thermodilution method). It can be estimated clinically by measuring heart rate, pulse quality or pressure, and assessment of tissue perfusion, e.g. capillary refill time.

cardiac pacing

employing cardiac pacemakers to control heart rate.

cardiac preload

ventricular end-diastolic volume.

cardiac pressure load

the stress of working against an elevated blood pressure in the arterial circuit; one of the two major groups of causes of heart disease; the other is flow load.

cardiac racing syndrome

a disease of companion birds manifested by a sudden increase in heart rate, up to 1000/min, in the period immediately after being restrained. Death occurs within a few seconds.

cardiac reserve

the reserve mechanisms in the heart to compensate for defects which could make the heart's pumping action ineffective. The reserve mechanisms include hypertrophy, enlargement, increase in heart rate and an increase in stroke volume, a result of the increase in muscle mass and the enlargement of the ventricles.

right-sided cardiac enlargement

may involve either the right ventricle or atrium. Occurs in heartworm disease in dogs.

cardiac rupture

penetration of the myocardium by a reticular foreign body in cows, or rupture of a patch of chronic fibrotic myocarditis in horses, causes cardiac tamponade and sudden death.

cardiac size

may increase as a result of hypertrophy, dilatation or a combination of the two. A common belief with some scientific support is that performance of horses in sprint races is closely related to heart size.

cardiac stroke volume

the amount of blood ejected with each systole.

cardiac thrill

see thrill.

cardiac valve fenestration

the valve surface is incomplete, creating a lattice effect; mostly congenital defects in foals.

cardiac valve hematocysts

congenital, blood-filled cysts on the atrioventricular valves considered to be of no pathogenic significance.

cardiac valve laceration

tearing of the valve tissue or attachment to myocardium may occur spontaneously or as a sequel to endocarditis; adds a significant additional flow load to the heart.

cardiac valve rupture

see cardiac valve laceration (above).

cardiac valves

heart valves formed by evaginations of the cardiac and vascular endothelium supported by connective tissue; includes atrioventricular and semilunar valves on both sides of the heart.

cardiac valvular disease

see valvular disease.

cardiac vascular shunts

includes patent foramen ovale, ventricular septal defect, tetralogy of Fallot, patent ductus arteriosus.

cardiac work

includes effective work—that needed for the onward propulsion of blood through the correct channels against arterial pressure, total work—includes all of the work performed by the heart including some involved in moving blood in the wrong direction.

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impulse

1. a sudden pushing force.

2. a sudden uncontrollable act.

3. a nerve impulse.

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cardiac impulse

movement of the chest wall caused by the heartbeat. Called also apex beat.

nerve impulse

the electrochemical process propagated along nerve fibers.