87 



readings from diflFerent limbs, depending on local causes — 

 the presence or absence of strong contraction in the large 

 arteries of the respective limbs. Actual rises of general 

 arterial pressure involve cardiac changes in addition to 

 vascular constriction, etc. It is evident that disturbances 

 of this kind may be influential with regard to the onset of 

 anginal attacks or of sudden death in subjects where a 

 special predisposition exists. 



The Question of Coronary Sjxism. 



With regard to sudden interference with coronary blood 

 supply, apart from the rare accident of embolism and the 

 less rare occurrence of thrombosis, there arises the question 

 of spasmodic contraction — an old hypothesis as applied to 

 the explanation of anginal attacks. The obscure cardio- 

 vascular disturbances already referred to might be invoked 

 to account for the onset of some anginal attacks during 

 rest ; the attack might be determined by antecedent unrecog- 

 nized changes in blood pressure and heart action. But 

 there are on record cases in which such attacks during a 

 period of rest are found to be unattended by elevation of 

 the blood pressure or recognizable changes in the heart's 

 action. Again, there are instances among anginal subjects 

 who have varying periods of relatively low and high 

 pressures, where no greater tendency to angina has been 

 found in the phases of high pressure; a notable example of 

 this has been recorded by Sir James Mackenzie. In such 

 cases the idea of coronary spasm has commended itself to 

 many observers, supported by such analogies as the extreme 

 arterial constriction of Raynaud's disease, the thickening 

 and narrowing of the temporal artery on the same side as 

 the pain in migraine and the occasional association of Ray- 

 naud's disease and migraine, the occurrence (sometimes in 

 relatively youthful subjects) of transitory aphasias, hemi- 

 plegias, etc., attributed to an acute temporary anaemia or 

 ischaemia from extreme constriction of a cerebral artery, 

 and sometimes associated with migraine. Again, there is 

 the so-called " abdominal angina," which has been cor- 

 related with spasmodic contraction of sclerosed mesenteric 

 arteries. Sir William Osler,^* referring to arteries in 

 general, states that in a certain stage of sclerosis arteries 

 are very prone to spasm — a view repeatedly urged by Pro- 

 fessor W. RusselP' and supported by PaP" and many others. 



It is evident that a temporarily excessive contraction of 

 some part of the coronary system (especially in cases where 

 the blood supply is already reduced or minimal) would 

 induce an ischaemic condition which might be responsible 

 for the onset of fibrillation or of an anginal attack; in this 

 way an apparently unprovoked paroxysm of pain during 

 rest might be accounted for and also its equally unexplained 

 passing off after variable periods. It might also be sur- 

 mised that amyl nitrite may relax a constricted coronary 

 as part of its general vascular effect, with relief of pain 



