Dr.S.Venkatesan MD

The cell of origin of ventricular tachycardia is rarely discussed at bedside. It is still in research labs !

                                    Ventricles are not made up off entirely myocytes. Apart from myocytes it contains specialised  purkinje cells , fibrocytes, interstitial cells and  some times primitive mesenchymal cells. Ventricular tachycardia can arise either in purkinje cells, the myocytes  or even the fibrocytes. The myocyte  VT  classically occur during ACS or post infarct VTs.They are  more often hemodynamically unstable and quickly degenerate into ventricular fibrillation. Myocardial VT is likely to be pulseless and require DC cardiversion frequently. Purkinje VTs are relatively less unstable. If VT arise proximally in the septum near the distal his, or in bundle branches (BBR) the VT is more stable.They  are likely to respond to be medical management.

What is the therapeutic implication of knowing  myocardial VT ?

                               In fact  ,simply knowing the cell of origin of VT is not suffice .The ionic currents inside the cell that trigger and sustain the VT is more important. There are few ionic circuits responsible for VT. Sodium , Intra cellular calcium, potassium , beta receptor mediated calcium current.If we know the individual ionic culpirit we can block that specifically  . Now we have multi purpose ion blockers  like amiodarone which acts like a broad spectrum antibiotic and terminates a VT.

                              So as of now there is no real purpose of breaking our head  in locating the cell  of origin  and the ions responsible for VT  at  the bed side ,( Researchers will do that for us !).  We have only few  antiarrhythmic drugs available in our crash cart  .Our job is to choose the optimal  drug  which will fit in for our patient. In electro physiology labs, radio frequency ablation is done .This is  nothing but shooting down the abnormal electrical  focus (Cluster of cells or a samll segment of myocardium).  In future,  a single abnormal  cell could be selectively neutralised with cell based therapy assisted by  nanopore robots !