Elecrolytes & EKG

Elecrolytes & EKG 

hyperkalemia

the more rapid repolarization = peaked T wave

dashed line = hyperkalemia action potrntial


hypokalemia - more common

gi loss
diuretics
alkalosis
hypokalemic periodic paralysis

enhabced automaticity
most arythmogenic electrolyte disturbance
prolonged QE
U WAVE

Changes in the serum concentration of ions, particularly potassium, can cause changes in SA nodal firing rate.  Hyperkalemia induces bradycardia or can even stop SA nodal firing.  Hypokalemia increases the rate of phase 4 depolarization and causes tachycardia.  It apparently does this by decreasing gK during phase 4.   http://www.cvphysiology.com/Arrhythmias/A005.htm



hypomagnesia similar to hypokalcemia


hypercalcemia  seen in metastatic bone disease


hypocalcemia  
prolonged ST segment


ischemia


slows conduction - PR interval

ST elevated = ischemic = reversible
ST depressed = infarcted = irreversible

Q wave in lead that normally has no Q wave = infarction 
must be 40 msec wide and 20 % of R wave
tachycardia after MI due to pain, fear SNS activated

ischemia produces arrythmias - typical cause of death = VF


chronic CAD



hypothermia

accidental
therapeutic

J wave at J point - dispersion of depolarization in phase 1 between epi and endo cardium.