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Cardiac
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cardiovascular disease  (CVD)


disease affecting the heart peripheral blood vessels or both


coroary heart disease  (CHD)


a type of CVD; the single largest killer of americans


anastomosis


communication between two or more vessels


Poiseyille's law


a law of physiology stating that blood flow through a vessel is directly proportional to the radius of the vessel to the fourth power


cardiac cycle


the period of time from the end of one cardiac contraction to the end of the next


diastole


the period of time when the myocardium is relaxed and cardiac filling and coronary perfusion occur


systole


the period of the cardiac cycle when the myocardium is contracting


ejection fraction


ratio of blood pumped from the ventricle to the amount remaining at the end of diastole


stroke volume


the amount of blood ejected by the heart in one cardiaccontraction


preload


the pressure within the ventricles at the end of diastole; commonly called the end-diastolic volume


Starling's law of the heart


law of physiology stating that the more the myocardium is stretched, up to a certain amount, the more forceful the subsequent contraction will be


cardiac output


the amount of blood pumped by the heart in 1 minute


afterload


the resistance against which the heart must pump


chronotropy


pertaining to the heart


inotropy


pertaining to cardiac contractile force


dromotropy


pertaining to the speed of impulse transmission


intercalated discs


specialized bands of tissue inserted between myocardial cells that increase the rate in which the action potential is spread from cell to cell


syncytium


group of cardiac muscle cells that physiologicaly function as a unit


cardiac depolarization


a reversal of charges at a cell membrane so that the inside of the cell becomes positive in relation to the outside; the opposite of the cell's resting state in which the inside of the cell is negative in relation to the outside


resting potential


the normal electrical state of cardiac cells


action potential


the stimulation of myocardial cells, as evidenced by a change in the membrane electrical charge, that subsequently spread across the myocardium


repolarization


return of a muscle cell to its preexcitation resting state


excitablility


ability of the cells to respond to an electrical stimulus


conductivity


ability of the cells to propagate the electrical implulse from one cell to another


automaticity


pacemaker cells' capability of self-depolarization


contractility


ability of muscle cells to contract, or shorten


rhythm strip


electrocardiogram printout


electrocardiogram (ECG)


the graphic recording of the heart's electrical activity.  It may be displayed either on paper or on an oscilloscope


artifact


deflection on the ECG produced by factors other than the heart's electrical activity


bipolar limb leads


electrocardiogram leads applied to the arms and legs that contain two electrodes of opposite (positive and negative) polarity; leads I, II, and III.


Einthoven's triangle


the triangle around the heart formed by the bipolar limb leads


augmented limb leads


another term for unipolar limb leads (see the following definition), reflecting the fact that the ground lead is disconnected, which increases the ampliude of deflection on the ECG tracing


unipolar limb leads


elerocardiogram leads applied to the arms and legs, consisting of one polarized (positive) electrode and a nonpolarized referenced point that is created by the ECG machine combining two additional electrodes; also called augmented limg leads; lead aVR, aVL, and aVF


precordial (chest) leads


electrocardiogram leads applied to the chest in a pattern that permits a view of the horizontal plane of the hert; leads V1, V2, V3, V4, V5, and V6


QT interval


period from the beginning of the QRS to the end of the T wave


corrected QT (QTc)


The QT interval divided by the square root of the R-R interval


prolonged QT interval


QT interval greater than 0.44 sec.


refractory period


the period of time when myocardial cells have not yet completely reploarized an cannot be stimulated again


absolute refractory period


the period of the cardiac cyle when stimulation will not produce any depoloarization whatever


relative refractory period


the period of the cardiac cycle when a suffiiently strong stimulus may produce depolarization


tachycardia


a heart rate greater than 100 beats per minute


bradycardia


a heart rate less than 60 beats per minute


normal sinus rhythm


the normal heart rhythm


dysrhythmia


any deviation from the normal electrical rhythm of the heart


arrhythmia


the absence of cardiac electrical activity; often used interchangeable with dysrhythmia


ectopic focus


nonpacemaker heart cell that automatically depolarizes (plural: ectopic foci)


ectopic beat


cardiac depolarization resulting from depolarization of ectopic focus


noncompensatory pause


pause following an ectopic beat where the SA node is depoloarized and the underlyin cadence of the heart is interrupted


bruit


the sound of turbulent blood flow through a vessel; usually associated with atherosclerotic disease


compensatory pause


the pause following anectopic beat where the SA node is unaffected and the cadence of the heart is uninterrupted


interpolated beat


a PVC that falls between two sinus beats without effectively interrupting this rhythm


coupling interval


distance between the preceding beat and the PVC


aberrant conduction


conduction of the electrical impulse through the heart's conductive system in an abnormal fashion


bundle branch block


a knd of interventricular heart block in which conduction through either the right or left bundle branches is blocked or delayed


bundle of Kent


an accessory AV conduction pathway that is thought to be responsible for the ECG findings of preexcitation syndrome


defibrillation


the process of passng an elctrical current through a fibrillating heart to depolarize a critical mass of myocardial cells.  This allows them to repolarize uniformly, resulting in an organized rhythm


synchronized cardioversion


the passage of an electric current through the beart during a specific part of the cardiac cycle to terminate certain kinds of dysrhythmias


acute coronry syndrome (ACS)


a spectrum of coronary artery disease processes from myocardial ischemia and myocardial injury to myocardial infarction and includes the clinical entities of stable and unstable angina and acute myocardial infarction


angina pectoris


cheat pain that results when the heart's oxygen requirements exceed oxygen supply available from blood


Prinzmetal's angina


variant of angina pectoris caused by vasospasm of the coronary arteries, not blockage per se; also called vasospastic angina or atypical angna


reperufsion


restoring blood flow to ischemic tissue


myocardial infarction (MI)


death and subequent necrosis of the heart muscle caused by inadequate blood supply; also acute myocardial infarction (AMI)


transmural infarction


myocardia infarction that affects the full thickness of the myocardium and almost always results in a pathological Q wave in the affected leads


ST-segment elevation myocardial infarction (STEMI)


a transmural (Q wave) myocardial infarction in which Q waves may appear fairly late in the infarction, but ST segment elevation occurs almost immediately; usually caused by complete obstruction of a coronary artery, involving the full thickness of the heart wall


subendocardial infarction


myocardial infarcton that affects only the deeper levels of the myocardium; also called non-Q wave infarction because it typically does not result in a significant Q wave in the affected lead


non-ST-segment elevation myocardial infarction (NSTEMI)


a subendocardial myocardial infarction that typically presents with normal or depressed ST segments and no Q wave development; usually caused by partial obstruction of a coronary artery and involving less than the full thickness of the heart wall


percutaneous coronary intervention (PCI)


placement of a catheter into an artery and its advancement to the heart to aid in visualizing the coronary arteries


coronary arteriogram/coronary angiogram


administration of a radiographic contrast dye into the coronary arteries via a catheter advanced from a remove artery to permit radiographic visualization of the coronary arteries and any possible obstructions or lesions to these arteries


percutaneious transluminal coronary angioplasty (PTCA)


insertion and inflation of a balloon into an artery to dilate an obstructed artery


primary coronary stenting


insertion of a wire mesh scaffold to prop open an artery recently cleared by angioplasty


coronary artery bypass grafting (CABG)


a surgical procedure in which the saphenous vein from one leg or an internal mammary artery is harvested and used to construct a bypass around the bloacked area of an artery that is not amenable to clearing by PCI techniques.  Also called aortocoronary grafting


heart failure


clinical syndrome in which the heart's mechanical performance is compromised so that cardiac output cannot meet the body's needs


pulmonary embolism (PE)


blood clot in one of the pulmonary arteries


congestive heart failure (CHF)


condition in which the heart's reduced stroke volume causes an overload of fluid in the body's other tissues


paroxysmal nocturnal dyspnea (PNA)


a sudden episode of difficult breathing that occurs after lying down; most commonly caused by left-heart failure


cardiac tamponade


accumulation of excess fluid inside the pericardium


hypertensive emergency


an acute elevation of blood pressure that requires the blood pressure to be lowered within 1 hour; characterized by end-organ changes such as hypertensive encephalopathy, renal failure or blindness


hypertensive encephalopathy


a cerebral disorder of hypertension indicated by severe headache, nausea, vomiting, and altered mental status.  Neurologic symptoms may include blindness, muscle twitches, inability to speak, weakness, and paralysis


cardiac shock


the inability of the heart to meet the metabolic needs of the body, resulting in inaduquate tissue perfusion


cardiac arrest


the absence of ventricular contraction


sudden death


death within 1 hour after the onset of symptoms


dowtime


duration from the beginning of the cardiac arrest until effective CPR is established


total downtime


duration from the beginning of the arrest until the patient's delivery to the emergency department


resuscitation


provision of efforts to return a spontaneous pulse and breathing


return of psontaneous circulation (ROSC)


resuscitation results in the patient's having a spontaneous pulse


survival


when a patient is resuscitated and survives to be discharged from the hospital


atheroscleross


a progressive, degenerative disease of the midsize and large arteries


arteriosclerosis


a thickening, loss of elastivity, and hardening of the walls of the arteries from calcium deposits


claudication


severe pain in the calf muscle due to inadequate bood supply.  It typically occurs with exertion and subsides with rest


aneurysm


the ballooning of an arterial wall, resulting from a defect or weakness in the wall


dissecting aortic aneurysm


aneurysm caused when blood gets between and separates the layers of the aortic wall


cystic medial necrosis


a death or degeneration of a part of an artery wall


acute pulmonary embolism


blockage that occurs when a blood clot or other particle lodges in a pulmonary artery


acute arterial occlusion


the sudden occlusion of arterial blood flow


vasculitis


inflammation of blood vessels


peripheral arterial atherosclerotic diease


a progressive degenerative disease of the midsize and large arteries


deep venous thrombosis


a blood clot in a vein


varicose veins


dilated superficial veins, usually in the lower extremity


vector


a force that has both magnitude and direction


QRS axis


reduction of all the heart's electrical forces to a single vector represented by an arrow moving in a single plane


right axis deviation


a calculated axis of the heart's electrical energy that equals or exceeds +105o (or in a simplified formula, from +90 to +180o)


left axis


a calculated axis of the heart's electrical energy that equals or exceeds -30o (or in a simplified formula, from 0 to -90o)


indeterminate axis


a calculated axis of the heart's electrical energy from -90o to -180o. (Indeterminate exis is often considered to be extreme right axis deviation.)


myocardial ischemia


deprivation of oxygen and other nutrients to the myocardium (heart muscle), typically causing abnormalities in repolarization


myocardial injury


injury to the myocardium (heart muscle), typically following myocardial ischemia that results from loss of blood and oxygen supply to the tissue.  The injured myocardium tends to be partially or completely depolarized


current of injury (injury current)


the flow of current between the pathologically depolarized area of myocardial injury and the normally depolarized areas of the myocardium


reciprocal


a morror image seen typically on the opposite wall of the injured area


hypertrophy


stretching; enlargement without any additional cells