In order to record the fetal electrocardiogram of cattle under clinical conditions, an adaptor unit which makes a connection with the routine electrocardiograph was tentatively manufactured. A preamplifier (Fig.1) and a fetal lead selector for four electrodes (Fig. 2) were put together in a unit box, which weighed 800 g and was 20×15×6 cm in size (Fig.3). The preamplifier had the following characteristics: input inpedance, 5MΩ×2; maximum sensitivity, 50μv/mV at the time constant 0.01 sec; S/N, 90 db; calibration, 50 uV; current consumption, 4mA; frequency characteristic, 0.5-70Hz±3 db; and battery, 5.2 V Mallory H4D×2 (±10.4 V). The output from the unit joined the external input of the routine elctrocardiograph. The fetal electrodes made a connection with the input terminals of the unit. Attenaution of the output was controlled by an attenuator in the electrocardiograph.
Ten pregnant cows of the Japanese Black breed at 172-294 days of pregnancy were examined in a small barn of the respective owner. In all of them, except cow No. 2, low noise fetal electrocardiograms with an enough amplitude were obtained (Figs.5 & 6). They were of the same pattern as the fetal electrocardiograms of dairy cows. No fetal heart rate showed any remarkable change with the advance in fetal age.
In cow No. 10, which was quite near to the parturition, the P, QRS, and T waves of the fetal electrocardiogram could be observed with a high amplitude by recording at the time constant 0.01 and 0.3 sec (Fig.7). In this cow, labor attacks were seen frequently for recording. Fetal bradycardia of short duration was observed before, during, and after each attack (Fig. 8). In the intermittent stage between labor attacks, fetal arrhythmia was also seen. When recorded 30 hours and 30 days after parturition, the electrocardiograms of the calf presented a normal heart rhythm and a normal pattern. Therefore, fetal arrhythmia appearing near birth was considered to be a physiological reaction to the labor of the fetus.

View full abstract

As part of the work to develop and improve small-sized swine as experimental animals, electrocardiographic and anatomical studies were performed on the cardiac position in the thorax.
There was little change in the waveforms of the electrocardiogram with the advance in body growth.
The waveform intervals and durations, however, were extended with the advance in age and reached a plateau at 4 months of age.
The relative anatomical position of the cardiac axis was constant for all ages.
The basic pattern of the waveform of the electrocardiogram hardly underwent changes. There were height correlations for each measurement.
Therefore, it was concluded that the heart grows without changing the position of its axis and the relationship between the right and left ventricles.

View full abstract

Electrocardiograms were recorded and hemodynamical measurements made in fifteen adult mongrel dogs with the main bundle branches blocked experimentally.
The electrocardiographical characteristics of the bundle branch blocks on both sides were the same in dogs as in man.
There was no difference im any hemodynamical measurement in the right bundle branch between the value before blocking and that after blocking. In the left bundle branch block, however, there was a decrease in the left intraventricular pressure, the systemic blood pressure, and the blood stream velocity in the peripheral artery. On the contrary, the right intraventricular pressure increased in this block. It was assumed that circulatory disturbances might have appeared in both systemic and pulmonary circulatory systems of the block continued chronically. From the alterations in the right intraventricular pressure curve in the left bundle branch block, it was presumed that the ventricular septum might have played an important role in the right ventricular output formation.

View full abstract