The effects of acute oesophageal distension on arterial blood pressure, E.C.G. and respiration in dog.

Anginal pain is a common clinical finding during cardiospasm or during pneumatic dilatation of oesophagus to relieve cardiospasm. Thus the present work was taken up to find out any relationship between the oesophagus and the cardiovascular system during experimental distension of the oesophagus in dogs. Pneumatic distension of oesophagus was done in anaesthetised dogs and its effects on arterial blood pressure, E.C.G. and respiration were studied. A fall in arterial blood pressure was observed in almost all dogs during distension. E.C.G. changes like a reduction in the 'R' wave voltage, absence of 'R' wave and a shift in the isoelectric line were observed also during distension. Moreover, oesophageal distension produced a transient apnoea in almost all animals and they seemed to be in a respiratory distress. When the distension was continued, the arterial blood pressure instead of remaining low, came back to the control or even higher level inspite of the presence of distension. Bilateral vagotomy did not abolish the hypotensive effect and E.C.G. changes but abolished the increase of blood pressure during the later part of distension. The cardiovascular changes were considered to be of a reflex nature and besides the vagi, the sympathetics seem to play an important role in this.