f 



Abnormal Left Coronary Artery of Ox Heart 57 



The only related case on record was described by Mr H. Blakeway in 

 the Journal of Anatomy, vol. lii, p. 354. The heart in this case — a child which 

 lived 36 hours — had amongst other abnormalities no direct communication 

 betAveen the left ventricle and the aorta, but an indirect one by means of the 

 anterior interventricular branch of the left coronary artery. Mr Blakeway 

 considered the question of the possibility of the origin of the abnormal com- 

 munication between the aorta and the left ventricle as being due to some 

 developmental peculiarity of the bulbus cordis. He, however, rejected this 

 consideration. 



The actual course taken by the blood in the abnormal ox heart forms an 

 interesting speculation. Before the heart went into rigor, the left ventricle 

 was artificially compressed above the apex to imitate systole, and at the same 

 time a stream of fluid under pressure was directed against the pseudo-valvular 

 opening by means of a tube introduced through the aorta past the aortic 

 valves. Practically no fluid escaped into the dilated part. Again, fluid was 

 allowed to run into the aorta. The aortic valve being competent, most of the 

 fluid passed along the abnormal channel. The fluid entered the cavity of the 

 left ventricle (the left ventricle being empty) through the pseudo-valvular 

 opening, if the left ventricle was not compressed. 



It would appear that during the greater part of systole leakage took place 

 directly from the left ventricle to the dilatation at the apex. In all probability, 

 the opening between the left ventricle and the dilated portion would not be 

 closed by ventricular contraction except towards the end of systole. During 

 diastole, unless the pseudo-valvular structvire acted as an efficient valve, there 

 must have been free communication between the aorta and the interior of 

 the left ventricle, and the diastolic pressure in the abnormal vessel and in the 

 interior of the left ventricle must have been equal to the pressure in the aorta. 

 After the wall of the distended part at the apex of the left ventricle was laid 

 open, a strong stream of fluid was directed against the valve-like structure. 

 It appeared to act as an efficient valve except when the left ventricle was 

 distended or relaxed. 



As bearing on the accepted relation between increased diastolic intraven- 

 tricular pressure and dilatation and the striking development of dilatation and 

 hypertrophy in aortic regurgitation in man, it is noteworthy that in this ox 

 regurgitation into the left ventricle with its concomitant high diastolic 

 pressure was not associated with appreciable dilatation or hypertrophy. 



The following notes give a brief account of the microscopical appearance 

 of the parts of which sections were made : 



(1) Ventricle {MVj. 



Muscle, healthy. Nothing abnormal noted. 



(2) Innominate artery. 

 Intima, healthy. 



Media, towards inner part of media regularly arranged bundles of plain 



