Electrolyte imbalances is one of the chief reasons for acquired recollective QT syndrome ( LQTS ) . First will talk about the electropathophysiology of the heart very just because this will help you to sympathise clearly how the electrolytes imbalances causes QT continuation .
What Electrolyte Imbalances Cause Long QT Syndrome?
The electrolyte imbalances get long QT syndrome are :
Hypokalemia
Hypokalemiareduces potassium levels ( electrolyte imbalance ) causing retentive QT syndrome . The proposed cellular mechanism is inhibition of the rapid delay rectifier K+ channels , leading to supernumerary Na influx or a decreased potassium efflux . This supererogatory positive ions causes an extensive repolarization resulting in a prolong QTc separation .
Causes
Hypocalcemia
Reduce Ca levels ( electrolyte imbalance ) causes ’ long QT syndrome . low-spirited Ca level protract the tableland form . This causes calcium ion channels to be opened for a long metre , allowing more calcium to influx to the cell , causing an extended repolarization resulting in a prolong QTc interval .
Hypomagnesemia
Reduce magnesium level ( electrolyte dissymmetry ) make the electric cell unable to retain potassium differences , intracellular and extracellular space and results in depletion of K inside the cadre . This do changes in the action voltage and make QTc prolongation . Hypomagnesemia also cause hypocalcemia . Both mechanisms give to QTc prolongation . It is shown that patients with long QT syndrome better with magnesium therapy .
What is the Action Potential?
Action potentiality is the alteration in electrical potential along the membrane of a brawn cubicle or nerve cell by the change of electric impetus . In the nerves this create the brass urge , in brawniness this will contract the muscle required to bring forth movement .
The transmembrane potential ( TMP ) is the electric possible difference ( voltage ) between the interior and the exterior of a mobile phone . When there is a nett movement of + ve ion into a cell , the TMP becomes more + ve , and when there is a final movement of + ve ion out of a jail cell , TMP becomes more – ve .
Action Potential Of The Heart
sum is also a heftiness ; the natural process potential of the heart is unlike from the skeletal muscles . There are 5 phases in the activeness potency of the heart ( Phase 0 - 4 )
Phase 0 – Depolarization
Phase 1- Depolarization
Phase 2 – Plateau Phase
Phase 3 – Repolarization
Phase 4 – Resting Phase
The electrolyte unbalance causing farseeing QT syndrome are hypokalemia , hypocalcemia and hypomagnesemia . Hypokalemia causes inhibition of the rapid delayed rectifier K+ channels , lead to excess sodium influx or a lessen atomic number 19 effluence . This supernumerary positively charged ion stimulate an extended repolarization result in a prolong QTc separation . . Low atomic number 20 levels prolong the plateau form . This causes calcium ion canal to be open for a long time , allowing more calcium to influx to the cell , stimulate an extended repolarization resulting in a prolong QTc interval . Hypomagnesemia causes hypokalemia and hypocalcaemia which results in prolong QTc .
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