Ventricular recovery properties and QRST deflection area in cardiac electrograms

We measured QRST deflection areas in cardiac surface electrograms of dogs and determined their relation to changes of refractory period induced by localized myocardial warming. Refractory period changes and QRST deflection areas were highly correlated with an average correlation of 0.95 over multiple activation sequences. For a single activation sequence, refractory period change was also highly correlated with ST-T deflection area, but over multiple activation sequences this correlation was reduced and the pooled variance of ST-T deflection areas was over 18 times greater than that of QRST area. No relation between QRST deflection area and the absolute value of refractory period over various cardiac sites was evident. Findings suggest that a particular set of ventricular recovery properties cannot be defined on the basis of QRST deflection areas, but that changes of recovery properties can be recognized on that basis.