Tachycardia and hyperkalemia. What will happen after therapy with 1 gram of Ca gluconate and some bicarbonate?

A 20-something type, 1 diabetic presented by EMS with altered mental status.  Blood pressure was 117/80, pulse 161, Resp 45, SpO2 100 on oxygen.Here is the 12-lead ECG:Wide complex tachycardiaWhat do you think?The providers thought that this wide QRS was purely due to (severe) hyperkalemia.  They treated with 4 ampules (200 mL) of bicarb and 1 gram of calcium gluconate. Note: 1 g of calcium gluconate is insufficient. 1 g of calcium chloride has 3x as much calcium and is indeed a good start.His pulse on the monitor suddenly went down to 140 and another 12-lead ECG was recorded:Sinus tachycardia at a rate of 143There are peaked T-waves typical of hyperkalemiaThe K returned at 6.9 mEq/L.What do YOU think happened here?  What is the diagnosis on the top ECG?  Do you think that this was simply hyperkalemia with a wide complex that resolved with bicarb and calcium?That top ECG with a wide complex tachycardia has all the features of ventricular tachycardia (VT): slow onset of the QRS, absence of P-waves, very wide, absence of any LBBB or RBBB morphology.  It is VT until proven otherwise and electrical cardioversion is indicated.  When I was told that this was hyperkalemia that resolved with bicarb and calcium, I told them that,no,this is VT induced by hyperkalemia and that it just happened to coincidentally spontaneously convert at the same time as the administration of (inadequate) hyperkalemia  medicines.How do I know that it is VT...
Source: Dr. Smith's ECG Blog - Category: Cardiology Authors: Source Type: blogs