MS CARDIOVASCULAR

acute coronary syndrome

a constellation of signs and symptoms due to the rupture of atherosclerotic plaque and resultant partial or complete thrombosis within a diseased coronary artery

AFTERLOAD

the amount of resistance to ejection of blood from the ventricle

APICAL IMPULSE

impulse normally palpated at the fifth intercostal space, left midclavicular line; caused by contraction of the left ventricle (synonym: point of maximal impulse)

ATRIOVENTRICULAR (AV) NODE

secondary pacemaker of the heart, located in the right atrial wall near the tricuspid valve

BARORECEPTOR

nerve fibers located in the aortic arch and carotid arteries that are responsible for control of the blood pressure

CARDIAC CATHETERIZATIONS

an invasive procedure used to measure cardiac chamber pressures and assess patency of the coronary arteries

CARDIAC CONDUCTION SYSTEM

specialized heart cells strategically located throughout the heart that are responsible for methodically generating and coordinating the transmission of electrical impulses to the myocardial cells

CARDIAC OUTPUT

amount of blood pumped by each ventricle in liters per minute

CARDIAC STRESS TEST

a test used to evaluate the functioning of the heart during a period of increased oxygen demand; test may be initiated by exercise or medications

CONTRACTILITY

ability of the cardiac muscle to shorten in response to an electrical impulse

DEPOLARIZATION

electrical activation of a cell caused by the influx of sodium into the cell while potassium exits the cell

DIASTOLE

period of ventricular relaxation resulting in ventricular filling

EJECTION FRACTION

percentage of the end-diastolic blood volume ejected from the ventricle with each heartbeat

HEMODYNAMIC MONITORING

the use of pressure monitoring devices to directly measure cardiovascular function

HYPERTENSION

blood pressure that is persistently greater than 130/80 mm Hg

HYPOTENSION

a decrease in blood pressure to less than 90/60 mm Hg that compromises systemic perfusion

MURMUR

sounds created by abnormal, turbulent flow of blood in the heart

MYOCARDIAL ISCHEMIA

condition in which heart muscle cells receive less oxygen than needed

MYOCARDIUM

muscle layer of the heart responsible for the pumping action of the heart

NORMAL HEART SOUNDS

sounds produced when the valves close; normal heart sounds are S1 (atrioventricular valves) and S2 (semilunar valves)

OPENING SNAPS

abnormal diastolic sounds generated during opening of rigid atrioventricular valve leaflets

ORTHOSTATIC HYPOTENSION

a significant drop in blood pressure (20 mm Hg systolic or more or 10 mm Hg diastolic or more) after an upright posture is assumed

PRELOAD

degree of stretch of the cardiac muscle fibers at the end of diastole

PULMONARY VASCULAR RESISTANCE

resistance to blood flow out of the right ventricle created by the pulmonary circulatory system

PULSE DEFICIT

the difference between the apical and radial pulse rates

RADIOISOTOPES

unstable atoms that give off small amounts of energy in the form of gamma rays as they decay; used in cardiac nuclear medicine studies

REPOLARIZATION

return of the cell to resting state, caused by reentry of potassium into the cell while sodium exits the cell

S1

the first heart sound produced by closure of the atrioventricular (mitral and tricuspid) valves

S2

the second heart sound produced by closure of the semilunar (aortic and pulmonic) valves

S3

an abnormal heart sound detected early in diastole as resistance is met to blood entering either ventricle; most often due to volume overload associated with heart failure

S4

an abnormal heart sound detected late in diastole as resistance is met to blood entering either ventricle during atrial contraction; most often caused by hypertrophy of the ventricle

SINOATRIAL (SA) NODE

primary pacemaker of the heart, located in the right atrium

STROKE VOLUME

amount of blood ejected from one of the ventricles per heartbeat

SUMMATION GALLOP

abnormal sounds created by the presence of an S3 and S4 during periods of tachycardia

SYSTEMIC VASCULAR RESISTANCE

resistance to blood flow out of the left ventricle created by the systemic circulatory system

SYSTOLE

period of ventricular contraction resulting in ejection of blood from the ventricles into the pulmonary artery and aorta

SYSTOLIC CLICK

abnormal systolic sound created by the opening of a calcified aortic or pulmonic valve during ventricular contraction

TELEMETRY

the process of continuous electrocardiographic monitoring by the transmission of radio waves from a battery-operated transmitter worn by the patient