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Clinical presentation of ventricular tachycardias : How outflow tract VTs are different form other VTs ?

Posted Feb 03 2009 12:09am

Ventricular  tachycardia (VT)  is one  of  the   dangerous form of  cardiac arrhythmias.When it occurs , it may present  in  many ways

  • Cardiac arrest with immediate degeneration into ventricular fibrillation. 
  • Pulseless VT in a  conscious patient but in  in shock.
  • With pulse, realatively stable , not much fall in blood pressure.
  • Incidentally detected.*(Rare)

This , gives us  an idea  that VT  as an electrical abnormality has wide clincal presentations , life threatening  at one end and pateint walking into the hospital with minimal palpitation !

The management issues

  • In patients with hemodynamic instability , decision making is easy as there is only option of DC shock.
  • In patients with stable VT, it is natural for the physicians to get tentative or even confused.This is because , dangers of shocking a stable patient has to be weighed against the currently available excellent antiarrhytmic drugs( Amiodarone, Ibutilide etc) .

 

The major issue here is  in  ruling out underlying structural heart disease.

Never shock a stable VT, without knowing the myocardial and valvular function.There has been many occasions underlying  severe LV dysfunction is missed   and they may go for asystole.

VT in the setting of cardiomyopathy, Post MI(Scar mediated) are often refractory even to DC shocks.It is the drugs that will  ultimately control the arrhythmia.DC shock is just used to terminate the VT.

VT  structurally normal heart , especially arising the outflow tracts of LV or RV  behave very differently (Fortunately they are more benign)

  • Have less hemodynamic  impact as it involves the outflow tract and  not over the  the pumping  zone of LV as in conventional ischemic myocardial VT .
  • They  respond to calcium blockers  verapamil to be precise (As they share properties of SVTs)
  • Sensitivity to verapamil by no way convey a meaning of Amiodarone resistance.Out flow tract VTs will also respond to Amiodarone many times.
  • Degeneration into VF is rare.

 

Also  read  Therapeutic issues in stable ventricular tachycardia

Presented and published in Indian heart journal

vtvt-therapeutic-issues1

Click  on link download PPT ventricular tachycardia

 

Related topics

Why some ventricular tachycardias are resistant , even to multiple DC shocks ?

      
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