Basic EKG Cardiology Flashcards
(26 cards)
ECG (EKG)
Electocardiogram, the test used to identify electrical conduction of the heart
Lead
the electrical view of the heart obtained from any combination of electrodes
Wave
positive or negative deflection from baseline that indicates a specific electrical event
Interval
time between two specific ECG events
Segment
length between two specific points on an ECG that should be at baseline without a positive or negative deflection
Complex
multiple waves grouped together
Intrinsic/inherent
natural or native to the heart
Foci/Focus
Excitable group of cells that occur outside normal pacemakers.
Premature Beat
a beat that comes before the next expected beat, an early beat. Sometimes called ectopy.
Escape Beat
a beat generated from source other than SA node, when the SA node fails to initiate an impulse, a late beat.
Unifocal
premature beats originating from one location/focus, which means all premature beats will have the same appearance.
Multifocal
premature beats originating from more than one location/focus, beats will have varying appearances, more serious than unifocalss indicates more irritation in area.
Automaticity
Ability of pacemaker cells to initiate an electrical impulse without being stimulated from another source.
A property of all cells of the heart.
Normal concentrations of K+, Na+, and Ca++ are important in maintaining automaticity.
Increased blood concentrations of these electrolytes decreases automaticity.
Decreased concentrations of K+ and Ca++ in the blood increase automaticity.
Excitability
Ability of cardiac muscle cells to respond to an outside stimulus. Also called irritability.
The property that allows pacemakers to work.
The heart’s normal pacemaker usually prevents other area of the heart from assuming this function.
Conductivity
Ability of a cardiac cell to receive an electrical stimulus and conduct that impulse to an adjacent cardiac cell.
Contractility
Ability of cardiac cells to shorten, causing cardiac muscle contraction.
Cannot occur without automaticity, excitability, and conductivity.
Inotropes
affect the force of contractility
Chronotropes
affect the heart rate
Dromotropes
affect the speed of conductivity in the AV node
Conduction system
Sinoatrial (SA) node
Primary pacemaker.
Inherent rate = 60 to 100 bpm
Impulses from the SA node stimulate atrial contraction and create a P wave on the ECG.
Atrioventricular (AV) node
Secondary pacemaker.
Inherent rate = 40 to 60 bpm.
Creates a normal and intentional electrical delay, acting as a “speed bump,” to keep ventricles from contracting too quickly, allowing for adequate ventricular filling.
Can act as a “gatekeeper” to the ventricles, adjusting the number of atrial impulses conducted to the ventricles during rapid atrial beat generation.
Bundle of His
Primarily functions to transmit impulses into the ventricles.
Receives impulses from AV node, then passes those impulses down to the right and left bundle branches.
The Bundle of HIs together with the AV node is referred to as the AV Junction.
Bundle branches
Located in the ventricular septum; there is a left and a right bundle branch.
NOT pacemakers; receive impulses from the Bundle of His and transmit these impulses to the Purkinje fibers.
A bundle branch block (or intraventricular conduction delay) is the result if impulses failing to navigate properly through one or both of these “power lines”.
