[Time domain and power spectrum of wide frequency band electrocardiogram in pigeons]

The wide frequency band ECG (WFB-ECG) was recorded in 33 (anesthetized) normal pigeons by the microprocessor ECG system (made in Nanjing University) with a wide-frequency response (0-1000 Hz), a high-speed sweep (up to 1401 mm/s) and a high sensitivity (up to 28 mm/mV). The recording methods for limb leads in the pigeon were the same as those in man, except that the needle electrodes (made by No.5 needles) were subcutaneously inserted in the bases of the wings and in the legs. We studied the features of time domain and power spectrum of pigeons WFB-ECG. It presents P, R, S and T waves, but no Q wave, basically similar to the results from Aves described by Sturkie. But there are still many characters that were not be recorded on the conventional ECG: (1) the main QRS complex is inverted and forms the type of rS or rSr , no Q wave in leads II, III, aVF, and the S-T segment is absent, which is different from that of humans. The T wave is upright in leads II, III, and aVF (except one), in agreement with that of man. But in lead aVR, the main QRS complex is upright and forms the type of Rs, and the T wave is inverted without any exception. There is a large notch on the upstroke of S wave without any exception. The amplitude of the notch is 0.413+/-0.133 mV and the duration is 9.733+/-1.291 ms in lead II. (2) The ratio of duration of P wave to P-R segment is about 0.8, lower than that of humans (1.0-1.6), but higher than that of mice (0.4). (3) The low frequency signals (0-80 Hz) are prominent. The relative power content of high frequency range of QRS in lead II is: 100-1000 Hz: (10.181+/-7.443)%; 80-300 Hz: (15.418+/-10.579)%. (4)The QRS vector loop in the frontal plane lies between -90 degrees and -180 degrees. The electrical axis of QRS complex averages -118 +/-10 (ranges from -96 degrees to -136 degrees). The reason that position of vector loop and the direction of main wave of QRS in the pigeon are different from human s and rodent s is probably that the Purkinje fibers cross the whole ventricular wall and terminate in the subepicardium in Aves including pigeons . After the impulses coming from the sinoatrial node reach the ventricular muscles, the subepicardium is depolarized before the endocardium. However in human s and rodent s, the Purkinje fibres only reach one-forth to one-second of the whole thickness from the endocardium to the epicardium, the subendocardium is depolarized before the subepicardium.