HISTORICAL DEVELOPMENT OF CARDIOVASCULAR PHYSIOLOGY 



17 



compatible bloods. Successful transfusion, now so 

 standard a procedure in surgery, had to wait until 

 Karl Landsteiner (1868-1943) showed iso-agglutinins 

 in human blood in 1900, an observation which gradu- 

 ally led to practical blood grouping and blood banks. 

 The seventeenth century efforts at transfusion, 

 however, had one practical result which Harvey 

 foresaw: Sigmund Elsholtz (1623-1688) showed that 

 drugs could be directly injected into the blood stream 

 to produce the effects desired. This observation also 

 waited nearly two centuries before being used in 

 medical practice. 



One of the staunch scientific supporters of Harvey's 

 work was Jean Pecquet (1622-1674). In his anatomi- 

 cal studies at Paris he described the thoracic duct, the 

 receptacuhim chyli, and the connections to the venous 

 system. This obser\ation began the clarification of the 

 relation of the lymphatic system to the general circu- 

 latory system. Appearing in 1651, this report must 

 have been singularly gratifying to Harvey as an ex- 

 ample of the scientific stimulus afforded by his efforts. 



Although Harvey's conclusions implied the muscu- 

 lar activity of the heart in its contractions, the 

 anatomical recognition of the muscular character of 

 the heart was detailed by the Danish priest-scientist, 

 Niels Stensen (1638-1686). Leeuwenhoeck correctly 

 pictured the peculiarities of cardiac muscle, but with- 

 out appreciating their significance. Giorgio Baglivi 

 (1668-1706) of Rome differentiated smooth from 

 striated muscle, but the correct interpretation of the 

 branched muscle layers of the heart, with their stria- 

 tions, had to wait for the keen mind of Albert von 

 Kolliker (181 7-1905) of Zurich and \Vurzburg. This 

 was further well elucidated by Franklin P. Mall 

 (1862-1917), of the Johns Hopkins Medical School, 

 Baltimore, who demonstrated the scroll-like arrange- 

 ment of the ventricular musculature. He showed the 

 presence o*" two spiral bands, one going from the 

 tricuspid or sinus part of the heart to the apex of the 

 right ventricle, and the other going from the aortic 

 and mitral region to the apex of the left \'cntricle. 

 These spiral bands, in contracting, produce the char- 

 acteristic motion of the heart, which Harvey had so 

 well described. 



Two scientifically oriented Cornishmen, Richard 

 Lower (1631-1691) and John Mayow (1643-1679), 

 began the train of studies which led to our under- 

 standing of the respiratory function of the blood and 

 circulation. Lower found in animals that dark venous 

 blood injected into an insufflated lung becomes bright 

 red, and concluded the blood absorbs something 

 from the air in the change. Mayow noted that this 



occurs wlien venous blood is shaken with a gas ob- 

 tained from niter. This gas we now call oxygen. Lower 

 also studied cardiac mechanics and realized the 

 muscular character of cardiac contraction. He found 

 anastomoses between coronary arteries by injection, 

 and he illustrated his famed Tractatus de corde (London, 

 i66g) with superimposable flaps to show the arrange- 

 ment of heart valves. Mayow recognized heat pro- 

 duction in muscle contraction. He also noted 

 dilatation of the right ventricle in mitral stenosis. 

 This was a start in (he understanding of the conse- 

 quences of cardiac malfunction. 



The great Dutch biologist, Jan Swammerdam 

 (1637-1680), clinched the Harveian problem of 

 anastomoses between arteries and veins by hot wax 

 injections. He also tried to measure the movements of 

 muscles and the heart by simple plethysmographic 

 methods. He found that muscles do not increase their 

 volume in contraction, and thus refuted the belief of 

 Giovanni Borelli (1608-1679) of Pisa that a supposed 

 nerve fluid enters a muscle to swell it in contraction. 

 Swammerdam noted (confirming Harvey) that the 

 heart is smaller in systole than in diastole, in propor- 

 tion to the blood ejected. 



At the beginning of the eighteenth century, 

 Raymond Vieussens (i 641-17 15) of Montpellier 

 correctly described the course of the coronary vessels 

 in relation to the structure of the heart, and noted the 

 valve in the large coronary vein as well as coronary 

 sinus. This is basic to an appreciation of coronary 

 factors in cardiac malfunction. Vieussens also dis- 

 cussed the back-pressure symptoms in mitral stenosis. 

 \n his comments on cyanosis, he observed that it 

 might occur when there is no mixture of arterial and 

 venous blood, and thus suggested our concept of 

 anoxia. 



The first really significant advance in our knowl- 

 edge of the circulation occurred more than a century 

 after Harvey's demonstration. In 1733, the Reverend 

 Stephen Hales (1677-1761), conventional vicar of 

 Teddington, reported on his amazing direct measure- 

 ment of blood pressures in a variety of animals 

 including horses. How he managed to handle the 

 animals is a mystery, but he succeeded admirably, 

 and established the significance of the pressure rela- 

 tions in arteries and veins. However, it was almost 

 another century before Jean L. M. Poiseuille (1799- 

 1869) made an effective follow-up in 1828 with his 

 hemodynamometer showing blood pressure changes in 

 relation to respiration and the extent of arterial 

 dilation with each heart beat. 



The real scientific significance of Hales's work is in 



