Figure 1

Electrical recording on an isolated guinea-pig heart placed in a Langendorff setup. (a) Electrocardiogram showing the P-wave, the QRS-complex and the T-wave. Electrographic intervals RR and QT are depicted with arrows. (b) Power spectral density of the electrocardiogram of a single heartbeat lasting approximately 0.25 s (RR = 247 ms corresponding to 243 bpm).