CARDIAC

The specialized tissue within the heart that initiates excitation impulses; an electronic device used to stimulate cardiac contraction when the electric conduction system of the heart is malfunctioning, especially in complete heart block. An electronic pacemaker consists of a battery-powered pulse generator and a wire that transmits the electric impulse to the ventricles.

That period in the cell-firing cycle at which it is possible but difficult to restimulate the cell to fire another impulse.

One of two arteries that carry deoxygenated blood from the right ventricle to the lungs.

The valve between the right ventricle and the pulmonary artery.

The first wave of the ECG complex, representing depolarization of the ventricles.

Restriction of cardiac contraction, failing cardiac output, and shock, caused by the accumulation of fluid or blood in the pericardium.

Widening of the bronchial tubes.

The period between the onset of one QRS complex and the onset of the next QRS complex.

The upper left chamber of the heart; receives blood from the pulmonary veins.

The hormone produced by the adrenal gland with alpha and beta sympathomimetic properties.

Death (necrosis) of a localized area of tissue caused by the cutting off of its blood supply.

Any one of the conductors, composed of two or more electrodes, in the ECG that shows the electrical conduction in the heart.

The effect on the rate of contraction of the heart.

The strength of heart muscle contractions.

The baseline of the ECG.

In references to blood vessels, an aneurysm, or bulge, formed by the separation of the layers of an arterial wall.

The early phase of cardiac repolarization, wherein the heart muscle cannot be stimulated to depolarize.

A partial disruption of the conduction of the depolarizing impulse from the atria to the ventricles, causing prolongation of the P-R interval.

Arising from a single site.

A subdivision of the autonomic nervous system that governs the body’s fight-or-flight reactions, stimulating cardiac activity.

The outer layer of tissue of a blood vessel wall, composed of elastic and fibrous connective tissue.

The upper right chamber of the heart; receives blood from the venae cavae and supplies blood to the right ventricle.

The period between the beginning of the P wave (atrial depolarization) and the onset of the QRS complex (ventricular depolarization), signifying the time required for atrial depolarization and passage of the excitation impulse through the atrioventricular junction.

The abnormal conduction of the electrical impulse through the heart.

The palpable beat of the apex of the heart against the chest wall during ventricular contraction; normally palpated in the fifth left intercostal space in the midclavicular line.

Angina pectoris characterized by periodic pain with a predictable pattern.

Very small veins.

A cardiac dysrhythmia seen just before the heart stops altogether; essentially asystole with occasional QRS complexes that are not associated with cardiac output.

The use of an unsynchronized direct current (DC) electric shock to terminate ventricular fibrillation.

The muscular, thick-walled blood vessels that carry blood away from the heart.

Protrusions of the myocardium into the ventricular cavities to which the chordae tendineae are attached.

The use of a synchronized direct current (DC) electric shock to convert tachyarrhythmias (such as atrial flutter) to normal sinus rhythm.

The process of discharging resting cardiac muscle fibers by an electric impulse that causes them to contract.

The withdrawal of blood from a vein.

A slight irregularity of the heart rate caused by changes in parasympathetic tone during breathing.

A short period immediately after depolarization in which the myocytes are not yet repolarized and are unable to fire or conduct an impulse.

A fall in blood pressure when changing to an erect position.

The thin membrane lining the outside of the heart.

The lower right chamber of the heart; receives blood from the right atrium and pumps blood out through the pulmonic valve into the pulmonary artery.

The blood vessels of the heart that supply blood to its walls.

A subdivision of the autonomic nervous system that is involved in control of involuntary, vegetative functions, mediated largely by the vagus nerve through the chemical acetylcholine.

A specialized structure located in the AV junction that slows conduction through the AV junction.

The flow of blood from the left ventricle through the aorta, to all of its branches and capillaries in the tissues, and back to the right atrium through the venules, veins, and venae cavae; also called the greater circulation.

The pressure exerted by the pulsatile flow of blood against the arterial walls.

A syndrome characterized by short P-R intervals, delta waves, nonspecific ST-T wave changes, and paroxysmal episodes of tachycardia caused by the presence of an accessory pathway.

A large vessel in the posterior part of the coronary sulcus into which the coronary veins empty.

Congestion of the pulmonary air spaces with exudate and foam, often secondary to left heart failure.

The death of tissue, usually caused by a cessation of its blood supply.

The number of heart contractions per minute.

The slurring of the upstroke of the first part of the QRS complex that occurs in Wolff-Parkinson-White syndrome.

Extremely narrow blood vessels composed of a single layer of cells through which oxygen and nutrients pass to the tissues. Capillaries form a network between arterioles and venules.

The largest artery in the body, originating from the left ventricle.

A parasympathetic blocker; opposes the action of acetylcholine on the heart and elsewhere, thereby allowing the body’s natural sympathetic system to speed up the heart rate.

Angina pectoris characterized by a changing, unpredictable pattern of pain, which may signal an impending acute myocardial infarction.

A disturbance in electric conduction through the right or left bundle branch from the bundle of His.

The period of ventricular relaxation during which the ventricles passively fill with blood.

Arising from or pertaining to many foci or locations.

Term used to describe any group of clinical symptoms consistent with acute myocardial ischemia.

One of the two branches of the left main coronary artery.

A thick wall that separates the right and left ventricles.

A system of fibers in the ventricles that conducts the excitation impulse from the bundle branches to the myocardium.

The middle and thickest layer of tissue of a blood vessel wall, composed of elastic tissue and smooth muscle cells that allow the vessel to expand or contract in response to changes in blood pressure and tissue demand.

Forced exhalation against a closed glottis, the effect of which is to stimulate the vagus nerve and, thereby, slow the heart rate.

Spontaneous initiation of depolarizing electric impulses by pacemaker sites within the electric conduction system of the heart.

The inside diameter of an artery or other hollow structure.

The period during which the ventricles contract.

An artificial product; in cardiology, is used to refer to noise or interference in an ECG tracing.

The valve between the right atrium and right ventricle of the heart.

The valve located between the left atrium and the left ventricle of the heart.

The mesh of arteries and capillaries that furnishes blood to a segment of tissue whose original arterial supply has been obstructed.

The normal rhythm of the heart, wherein the excitation impulse arises in the SA node, travels through the internodal pathways to the atrioventricular junction, down the bundle of His, through the bundle branches, and into the Purkinje network without interference.

The largest veins of the body; they return blood to the right atrium.

A chemical mediator of the parasympathetic nervous system.

A naturally occurring clot-dissolving enzyme, usually present in the body in its inactive form, plasminogen.

Fibrous strands shaped like umbrella stays that attach the free edges of the leaflets, or cusps, of the atrioventricular valves to the papillary muscles.

The drugs used in the treatment of congestive heart failure and certain atrial arrhythmias.

A small blood vessel that carries oxygenated blood, branching into yet smaller vessels called capillaries.

Specialized areas in tissues that initiate certain actions after specific stimulation.

The atrioventricular junction; the portion of the electric conduction system of the heart located in the upper part of the interventricular septum that conducts the excitation impulse from the atria to the bundle of His.

An arrhythmia arising from ectopic foci in the area of the atrioventricular junction; often shows an absence of the P wave, a short P-R interval, or a P wave appearing after the QRS complex.

An excessive amount of potassium in the blood.

The dominant pacemaker of the heart, located at the junction of the superior vena cava and the right atrium.

The sudden and often unexpected cessation of adequate cardiac output.

In the heart, the specialized cardiac tissue that initiates and conducts electric impulses. The system includes the SA node, internodal atrial conduction pathways, atrioventricular junction, atrioventricular node, bundle of His, and the Purkinje network.

A condition present when a period of cardiac ischemia caused by sudden narrowing or complete occlusion of a coronary artery leads to death (necrosis) of myocardial tissue.

The resistance against which the ventricle contracts.

The thick-walled, muscular, lower left chamber of the heart; receives blood from the left atrium and pumps it out through the aorta into the systemic arteries.

The interval between the end of the QRS complex and the beginning of the T wave; often elevated or depressed with respect to the isoelectric line when there is significant myocardial ischemia.

The valve between the left ventricle and the aorta.

A weakening or loss of a palpable pulse during inhalation, characteristic of cardiac tamponade and severe asthma.

The two valves, the aortic and pulmonic, that divide the heart from the aorta and pulmonary arteries.

The pressure under which the ventricle fills.

High blood pressure, usually a diastolic pressure greater than 90 mm Hg.

A subdivision of the nervous system that controls primarily involuntary body functions. It comprises the sympathetic and parasympathetic nervous systems.

Abnormal whooshing sounds indicating turbulent blood flow within a blood vessel.

A low level of calcium in the blood.

A pathologic process caused by atherosclerosis that leads to progressive narrowing and eventual obstruction of the coronary arteries.

Two premature ventricular contractions occurring sequentially.

Amount of blood pumped by the heart per minute, calculated by multiplying the stroke volume by the heart rate per minute.

Inflammation of the wall of a vein, sometimes caused by an IV line, manifested by tenderness, redness, and slight edema along part of the length of the vein.

Severe shortness of breath occurring at night after several hours of recumbency, during which fluid pools in the lungs; the person is forced to sit up to breathe. PND is caused by left heart failure or decompensation of chronic obstructive pulmonary disease.

A premature complex in every third heartbeat.

The period from one cardiac contraction to the next. Each cardiac cycle consists of ventricular contraction (systole) and relaxation ( diastole).

The therapy that uses medications that act to dissolve blood clots.

The vessels that carry oxygenated blood from the lungs to the left atrium.

Severe dyspnea experienced when lying down and relieved by sitting up.

The 10th cranial nerve, the chief mediator of the parasympathetic nervous system.

A condition present when a period of cardiac ischemia caused by sudden narrowing or complete occlusion of a coronary artery leads to death (necrosis) of myocardial tissue.

Fainting; brief loss of consciousness caused by transiently inadequate blood flow to the brain.

The opening up of new channels through a blocked artery.

A neurotransmitter and drug sometimes used in the treatment of shock; produces vasoconstriction through its alpha stimulator properties.

The blood vessels of the heart that supply blood to its walls.

A sac or bulge resulting from the weakening of the wall of a blood vessel or ventricle.

A pathologic condition in which the arterial walls become thickened and inelastic.

The hormone produced by the adrenal gland with alpha and beta sympathomimetic properties.

In cardiology, the white to yellow lesion found in atherosclerosis that is made up of lipids, cell debris, and smooth muscles cells; in older people, may also include calcium.

The inside diameter of an artery or other hollow structure.

Tissue anoxia from diminished blood flow to tissue, usually caused by narrowing or occlusion of the artery.

One of the two branches of the left main coronary artery.

The double-layered sac containing the heart and the origins of the superior vena cava, inferior vena cava, and pulmonary artery.

The addition to ventricular volume contributed by contraction of the atria.

A sensation felt under the left breast of the heart “skipping a beat,” usually caused by a premature ventricular contraction.

The portion of the electric conduction system in the interventricular septum that conducts the depolarizing impulse from the atrioventricular junction to the right and left bundle branches.

The volume of blood pumped forward with each ventricular contraction.

The groove along the exterior surface of the heart that separates the atria from the ventricles.

The resumption of blood flow through an artery.

The effect on the velocity of conduction.

The flow of blood from the right ventricle through the pulmonary arteries and all of their branches and capillaries in the lungs and back to the left atrium through the venules and pulmonary veins; also called the lesser circulation.

A common type of arteriosclerosis affecting the coronary and cerebral arteries.

The thin membrane lining the inside of the heart.

Situated or occurring behind the sternum.

A large vessel in the posterior part of the coronary sulcus into which the coronary veins empty.