ECG I & II Terminology Flashcards
Aberrancy/Aberrant conduction
abnormal pathyway of an impulse traveling through the heart’s conduction system
Arrhythmia
disturbance of the normal cardiac rhythm from the abnormal origin, discharge, or conduction of electrical impulses
automaticity
ability of cardiac cell to initiate an impulse on its own
Biphasic
Having an electrical impulse that is shown as deflections above and below the isoelectric line
bradycardia (sinus bradycardia)
a sinus beat below 60 bpm and a regular rhythm
chronotropy
neural, chemical, or physical factor that influences heart rate; referring to rate or time, such as the rate of cardiac contraction
positive chronotropic agent
increase heart rate
negative chronotropic agent
decrease heart rate
conductivity
ability of one cardiac cell to transmit and electrical impulse to another cell; the reciprocal of resistivity
depolarization
response of a myocardial cell to an electrical impulse that causes movement of ions across the cell membrane, which triggers myocardial contraction; the process or act of reversing the resting potential in excitable cell membranes when stimulated
deviation
major direction of the overall electrical activity of the heart. It can be normal, leftward (left axis deviation, or LAD), rightward (right axis deviation; RAD) or indeterminate (northwest axis). The QRS is the most important to determine; however, the P wave or T wave axis can also be measured
dromotropy
agent the affects the conduction speed of the AV node and subsequently the rate of electrical impulse; referring to the conductivity of a nerve fiber, such as the ability to conduct through the AV node
positive dromotropic agent
increase velocity
negative dromotropic agent
decrease velocity
escape rhythm
a self-generated electrical dishcarge initiated by, and causing contraction of, the ventricles of the heart; this beat usually follows a long pause in ventricular rhythm and acts to prevent cardiac arrest
excitability
ability of a cardiac cell to respond to an electrical stimulus
hypertrophy
growth to an organ or tissue due to an increase in the size of the cell
infarction
tissue death due to inadequate blood supply to the tissue
inotropy
chemicals that influence contractility of the heart
positive inotropic agents
increase contractility
negative inotropic agents
decrease cotractility
intrinsic/inherent
naturally occurring electrical stimulus from within the heart’s conduction system
interval
duration of time that includes one segment and one or more waves
ischemia
local decrease in blood supply
monomorphic
form of ventricular tachycardia in which the QRS complexes have a uniform appearance from beat to beat
multifocal/multiform
type of premature ventricular contractions that have differing QRS configurations as a result of their originating from different irritable site in the ventricle
paroxysmal
episode of an arrhythmia that starts and stops suddenly
polymorphic
type of ventricular tachycardia in which the QRS complexes change from beat to beat
reciprocal leads
leads that take a view of an infarcted area of the heart opposite that taken by indicative leads
pre-excitation
an abnormal heart rhythm in which the ventricles of the heart become depolarized too early, which leads to their partial premature contraction
refractory period
brief period during which excitability in a myocardial cell is depressed
repolarization
recovery of the myocardial cells after depolarization during which the cell membrane returns to its resting potential; the return of cell membrane potential to the resting state
tachycardia (aka sinus tachycardia)
a sinus rate of more than 100 bpm. The rate rarely exceeds 160 bpm except during exercise
Threshold
the minimum level to which a membrane potential must be depolarized to initiate an action potential
segment
part of the ECG between the QRS complex and the T wave
