Terminology for Electrocardiography Part I & Part II Flashcards
Aberrancy/Aberrant conduction
abnormal pathway 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
complex containing both an upward and a downward deflection; usually seen when the electrical current is perpendicular to the observed lead
Bradycardia (aka sinus bradycardia)
a sinus beat below 60 bpm and a regular rhythm
Chronotropy
neural, chemical, or physical factors that influences heart rate; positive chronotropic factors increase HR, while negative chronotropic factors decrease HR (refer to Marieb A&P book for further info)
Conductivity
ability of one cardiac cell to transmit an electrical impulse to another cell
Depolarization
response of a myocardial cell to an electrical impulse that causes movement of ions across the cell membrane, which triggers myocardial contraction
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, or 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 that affects the conduction speed of the AV node and subsequently the rate of electrical impulse; positive dromotropic agent increases velocity while a negative dromotropic agent decreases velocity
Escape rhythm
a self-generated electrical discharge 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
Ectopic beat
contraction that occurs as a result of an impulse generated from a site other than the sinoatrial node
Excitability
ability of a cardiac cell to respond to an electrical stimulus
Hypertrophy
growth to an organ or tissue due to increase in the size of the cells
Infarction
tissue death due to inadequate blood supply to the tissue
Inotropy
chemicals that influence contractility of the heart; positive inotropic agents increase contractility while negative inotropic agents decrease contractility (refer to Marieb A&P book for further info)
Interval
duration of time that includes one segment and one or more waves
Intrinsic/inherent
naturally occurring electrical stimulus from within the heart’s conduction system
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 sites 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
Pre-excitation
an abnormal heart rhythm in which the ventricles of the heart become depolarized too early, which leads to their partial premature contraction
Reciprocal leads
leads that take a view of an infarcted area of the heart opposite that taken by indicative leads
Re-entry mechanism
failure of a cardiac impulse to follow the normal conduction pathway; instead it follows a circular path
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
Segment
the part of the ECG between the QRS segment and the T wave
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 and action potential
