-
cardiac rhythm
- pattern (or pace) of the heartbeat produces a rhythmic
- pattern which greatly influences the heart's ability to pump blood effectively
-
-
dysrhythmias
originating in the atria
- sinus bradycardia, sinus tachycardia, premature atrial contractions,
- supraventricular tachycardia, and atrial fibrillation
-
sinus
bradycardia
- dysrhythmia
- that proceeds normally through the conduction pathway but at a slower than usual
- rate (<60 beats/minute). The danger is the slow rate may be insufficient to
- maintain cardiac output. Tx is atropine sulfate (a cholinergic blocking agent)
-
sinus
tachycardia
- faster
- than normal heart rate that proceeds normally through conduction system (100 -
- 150 beats/min.) It occurs in pt's with healthy hearts as a physiologic response
- to strenuous exercise, anxiety and fear, pain, fever, hyperthyroidism,
- hemorrhage, shock, or hypoxemia
-
premature
atrial contractions
- - early electrical impulse initiated by neural tissue. Is
- identified by an irregularity in the underlying rhythm. The P wave may differ
- slightly because it is initiated somewhere in the atria other than the SA node.
- Causes: caffeine, nicotine or other sympathetic nervous system stimulants
-
ectopic
site
- one
- that initiates an electrical impulse independently of the SA node, can lead to
- more serious dysrhythmias such as supraventricular tachycardia
-
supraventricular
tachycardia
- heart rate has a consistent rhythm, but beats at a dangerously
- high rate (>150 beats/min). Diastole is shortened, cardiac output drops
- dangerously low and heart failure can occur. SIGNS/SYMPTOMS: tachycardia,
- angina, hypotension, syncope, and reduced renal output. TX: Digitalis,
- Adrenergics, and calcium channel blockers (all used to slow HR)
-
atrial
flutter
- a single atrial impulse outside the SA node causes the atria
- to contract at an exceedingly rapid rate (200 - 400/min). See a characteristic
- sawtooth pattern
-
atrial
fibrillation
- several areas in the right atrium initiate impulses
- resulting in disorganized, rapid activity. The atria quiver rather than
- contract. TX: chemical cardioversion drugs, antidysrhythmics, heparin,
- coumadin, Maze procedure
-
Maze
procedure
- the surgeon makes a new conduction pathway (used when pt's
- fail to respond to cardioversion)
-
heart
block
- dysrhythmia
- originating in the AV node, is a interference with transmission of impulses.
- Are three types (first, second, third
-
first
and second degree heart block
-
3rd
degree heart block
- also called complete heart block, the atrial impulse never
- gets through and the ventricular rate is slow (30-40 beats/min).
- TX: pacemaker insertion
-
ventricular
dysrhythmias
- premature ventricular contractions, ventricular
- tachycardias, and ventricular fibrillation
-
premature
ventricular contractions
- a ventricular contraction that occurs early and
- independently in the cardiac cycle before the SA node initiates an electrical
- impulse. SYMPTOMS: flutter, pallor, nervousness
- * PVC's are precursors of lethal dysrhythmias
-
ventricular
tachycardia
- caused by a single, irritable focus in the ventricle that
- initiates and then continues the same repetitive pattern. The ventricles beat
- very fast (150-250) and cardiac output is decreased. May lose consciousness and
- become pulseless, often requires defibrillation and may progress to ventricular
- fibrillation
-
ventricular
fibrillation
- rhythm of a dying heart. PVC's or ventricular tachycardia
- can precipitate it. The ventricles do not contract effectively and there is no
- cardiac output. CPR and immediate defibrillation necessary
-
AICD automatic
implanted cardiac defibrillator
- internal electrical device used for recurrent serious
- tachydysrhythmias
-
pacemakers
- provides an electrical stimulus to the heart muscle to treat an ineffective
- bradydysrhythmia(slow abnormal rhythm)
-
two
modes that pacemakers function in
demand(synchronous) or fixed-rate(asynchronous)
-
demand
mode pacemakers(synchronous)
- self-activate
- when the pt's pulse falls below a certain level
-
fixed-rate
pacemaker(asynchronous)
- produce an electrical stimulus at a preset rate (usually
- 72-80beats/min) despite the pt's natural rhythm
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