Transoesophageal aortic velography in man.

An ultrasonic probe placed in the oesophagus of anaesthetized patients was used to observe the velocity of the blood flow down the descending aorta. The operating principle of the technique was the Doppler shift of the reflection of a continuously emitted MHz beam of ultrasound. The human oesophagus took up to 15 minutes to accommodate to the presence of the probe in the oesophagus. Changes in the diastolic portion of the flow pattern were seen with small changes in peripheral resistance (produced by transiently obstructing a femoral popliteal by-pass graft) (Figure 1). Surgical stimuli also produced marked changes in the flow pattern (Figure 3) before arrhythmias occurred. Following a prolonged period of cardiac arrest the flow pattern was observed to return to normal very quickly (Figure 4). It is suggested that the ultrasonic trans-oesophageal probe could play a useful role in patient monitoring in anaesthesia.