MEDICINE 395 



If now we see the muscle of which the heart is composed as 

 the prairie we are able to understand the abnormal rhythm. 

 Sir Thomas likens the fire to the increase of excitability of the 

 muscle which occurs an instant of time before the muscle con- 

 tracts, and which, for all ordinary purposes, may be looked on as 

 a part of the contraction. That portion of the muscle which 

 has just contracted is therefore the burnt-out area. This 

 portion will not contract again until the muscle has rested — 

 until, that is, the " grass has had time to grow." 



Now, in the case of the fire, if a ring of grass is made and a 

 light applied to it at any given point of its circumference, the 

 flames will travel in both directions round the ring till they meet. 

 If, however, the flame be allowed to travel only in one direction, 

 and if the grass should be able to grow again almost at once 

 after it has been burned, the flame would travel round and 

 round the ring continuously. There would always be a gap of 

 unburnt, new-grown grass in front of it. Thus we should have 

 a " circus movement." 



Such a circus movement can be induced experimentally in 

 rings cut from the hearts of reptiles. Sir Thomas Lewis has 

 applied this experimental finding to the heart of man, and has 

 shown that when a heterogeneous rhythm occurs a " circus 

 movement " has been set up in a portion of the heart muscle. 

 The " flame " goes round and round, finding always in front of 

 it a fresh gap of muscle ready to " burn " or contract. 



His explanation led to the idea that if the " gap " of " un- 

 burnt " muscle could be got rid of the circus movement would, 

 automatically, come to an end. That is to say, the abnormal 

 rhythm would come to an end. 



More recently he has published some results achieved with 

 a drug called " quinidine," a quinine compound which appears 

 to have the effect of closing the gap and stopping the circus 

 movement. In some 50 per cent, of cases the drug has, when 

 administered to patients with auricular fibrillation, brought 

 the fibrillation of the auricle to an end, and set the normal 

 rhythm going again. 



Sir Thomas Lewis does not suggest that the time for a 

 general exhibition of the drug in practice has arrived. It is still 

 in the experimental stage. Moreover, Sir James Mackenzie 

 has pointed out that clots are apt to form in the auricular 

 appendages during fibrillation, and are thus apt to be dislodged 

 when the normal rhythm returns. This very real danger has 

 been emphasised by other workers. Yet the value of the 

 research as a whole will not be disputed. It has been recognised 

 throughout the whole medical world. 



On November i three London hospitals, the London, St. 

 Thomas's, the Royal Free, and the Hampstead General Hospital, 



