Accelerated ventricular escapes induced in the intact dog by barium, strontium and calcium

Accellerated ventricular escapes (AVE) were produced with infusion of BaCl2, SrCl2 and CaCl2. AVE demonstrated overdrive acceleration rather than overdrive suppression, i.e., faster pacing rates caused shorter escape intervals. BaCl2 (mean 20.2 mumol/kg) produced AVE in 18 of 23 dogs and a decrease in mean serum potassium (K+). SrCl2 alone (mean 2494 mumol/kg) did not produce AVE in 5 dogs and K+ was unchanged. When insulin and glucose were infused to lower K+ and SrCl2 was infused 30 minutes later, AVE was demonstrated in 7 of 10 dogs. CaCl2 alone (mean 1628 mumol/kg) produced AVE in 3 of 5 dogs and CaCl2 (mean 1733 mumol/kg) infused 30 minutes after insulin and glucose produced AVE in 4 of 4 dogs. This study demonstrates that AVE previously produced with cardiac glycosides can also be induced by infusion of barium, strontium and calcium.