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Old 03-30-2016
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Default ventricular tachycardia

why exatly do ventricular tachycardias have long qrs segments? I know the reason is because it takes longer time to depolarize if the startpoint is of ventricular origin but why exactly does it take longer?
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why exatly do ventricular tachycardias have long qrs segments? I know the reason is because it takes longer time to depolarize if the startpoint is of ventricular origin but why exactly does it take longer?
this forum is turned into garbage you cant discuss serious things anymore.
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Originally Posted by jojooo View Post
why exatly do ventricular tachycardias have long qrs segments? I know the reason is because it takes longer time to depolarize if the startpoint is of ventricular origin but why exactly does it take longer?
This is my understanding:

VT is usually a consequence of ischaemia. Lack of oxygen and ATP disrupts the ion pumps across the membrane and interferes with the membrane potential. This leads to reduced upstroke velocity, amplitude, increase in the refractory period and ultimately prolongation of action potential. And that would be why administrating lidocaine is a good idea since it reduced action potential duration.
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why exatly do ventricular tachycardias have long qrs segments? I know the reason is because it takes longer time to depolarize if the startpoint is of ventricular origin but why exactly does it take longer?
I'll give it a shot....

Normal electrical conduction to the ventricles is propagated from the AV node to the bundle of His to the respective Purkinje fibers. This is the fastest route and it results in a narrow QRS interval.

With ventricular tachycardias, however, electrical conduction begins somewhere in the ventricle as opposed to in the AV node. This means that the electrical impulse must go from one side of the heart to the opposite, as opposed to from the middle and then simultaneously to the sides. This increases the length of time needed for ventricular depolarization, and thus widens the QRS interval.
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Last edited by Kruno; 03-31-2016 at 12:45 PM. Reason: spelling error
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I'll give it a shot....

Normal electrical conduction to the ventricles is propagated from the AV node to the bundle of His to the respective Purkinje fibers. This is the fastest route and it results in a narrow QRS interval.

With ventricular tachycardias, however, electrical conduction begins somewhere in the ventricle as opposed to in the AV node. This means that the electrical impulse most go from one side of the heart to the opposite, as opposed to from the middle and then simultaneously to the sides. This increases the length of time needed for ventricular depolarization, and thus widens the QRS interval.
Ok. But if the impulse begins from one side and then travels to the other wouldnt this mean that the 2 ventricels would then also depolaraze not in synchrone with each other?
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Ok. But if the impulse begins from one side and then travels to the other wouldnt this mean that the 2 ventricels would then also depolaraze not in synchrone with each other?

yes, that is the case
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yes, that is the case
makes sense. thnx
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makes sense. thnx
no problem
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