Cardio

9/10/99

EKG handout

• Straight line
• Above the line is positive
• Electrical signal is heading toward that electrode when the line is going up
• Below the line is negative
• Electrical signal is heading away from that electrode
• SA node controls the rate—upper right hand area
• Circuit—Bachmans bundle carries the signal from the R atrium to L atrium
• P wave is atrial depolarization
• Pause after the P wave—atrium have received their signal
• P mitrale—prolonged P wave b/w L atrium is enlarged from mitral valve stenosis
• Wandering pacemaker—can see the P wave inverted
• Alternating P wave above and below the line
• Electrode I is on the left side of the heart
• Signals traditionally go from R®L
• The inverted P wave says the signal is going L®R
• Pt has developed other pacemakers in different places in the heart
• This is not a good condition
• Ectopic node (away from the site)
• What are pacemakers?
• Are they nerve fibers—no
• Muscle cells that has the innate capability to discharge on its own
• Other cells have the ability to become a pacemaker
• Neurochemical that may help is NE
• NE comes from sympathetics
• Give b blockers—block ectopic sites to NE
• Standard Limb Leads—3 leads—every signal should be predominantly positive
• SA block—artia are not contracting
• Signal for ventricles to fire comes from the AV node
• If AV doesn't work, then the common bundle can serve
• #1 cause of AV node not to fire,
• vagus is parasympathetic to heart and depresses the SA node—vagotonia