56 LIGATURE OF THE CORONARY ARTERIES. 



only during the diastole or relaxation of the ventricle. To him it seemed that (a) 

 the diastolic filling of the coronary arteries would help to dilate the ventricles ; 

 (b) on the contrary, a systolic filling of these arteries would oppose the contraction, 

 because the systolic filling and expulsion of the blood from the coronary arteries 

 would ^diminish the force of the ventricular contraction. [To this supposed 

 arrangement Brucke gave the name " Selbststeuerung," which may be rendered as 

 above, or as " self-controlling " action of the heart by the aortic valves.] 



Arguments against Briicke's View. The following considerations militate against this 

 theory: (1) Filling the coronary vessels under a high pressure in a dead heart causes a 

 diminution of the ventricular cavity (v. Wittich). (2) The chief trunks of the coronary arteries 

 lie in loose sub-pericardial fatty tissue in the cardiac sulci, hence a dilatation of the ventricle 

 through this agency is most unlikely (Landois). (3) Experiments on animals have shown that 

 a coronary artery spouts, like all arteries, during the systole of the ventricle. Von Ziemssen 

 found that in the case of a woman who had a large part of the anterior wall of the thorax 

 removed by an operation, the heart being covered only by a thin membrane, the pulse in the 

 coronary arteries was synchronous with the pulse in the pulmonary artery. H. N. Martin and 

 Sedgwick placed a manometer in connection with the coronary artery, and another with the 

 carotid in a large dog, and they found that the pulsations occurred simultaneously. When 

 a coronary artery is divided, the blood Hows out continuously, but undergoes acceleration during 

 the systole of the ventricles (Endcmann, Perls). (4) If a strong intermittent current of water 

 be allowed to flow through a sufficiently wide tube into the left auricle of a fresh pig's heart, 

 so that the water passes into the aorta, and if the aorta be provided with a vertical tube, the 

 water flows continuously from the coronary arteries, and is accelerated during the systole. 

 (5) It is exceedingly improbable that the coronary arteries should be filled during the diastole, 

 while all the other arteries are filled during systole of the ventricle. (6) There is always a 

 sufficient quantity of blood in the sinus of Valsalva to fill the arteries during the first part of 

 the systole. (7) The valves, when raised, are not applied directly to the aortic wall [Bamberger, 

 lliidingcr) even by the most energetic pressure from the ventricle (Sandborg and Worm Milllcr). 

 (8) Observations on voluntary muscles have shown that the small arteries dilate during con- 

 traction of the muscle, and the blood -stream is accelerated. (9) By the systolic filling of the 

 aorta the arterial path is elongated this elastic distention is compensated before the diastole 

 occurs. By the recoil of the aortic walls the layer of blood in them is driven backwards and 

 doses the valves (Ccradini). According to Sandborg and Worm Midler, the semilunar valves 

 close just after the ventricles have begun to relax, which agrees with the curve obtained from 

 the cardiac impulse (fig. 39, A). 



During the systole, the small arterial trunks lying next the ventricular cavities 

 have to bear a higher pressure than that borne by the aorta, and their lumen must 

 be compressed during the systole so that their contents are propelled towards the 

 veins. 



Peculiarities of the Cardiac Blood- Vessels. The capillary vessels of the myocardium are 

 very numerous, corresponding to the energetic activity of the heart. Where they pass into 

 veins, several unite at once to form a wide venous trunk, whereby an easy passage is offered to 

 the blood. The veins are provided with valves so that (1) during systole of the right auricle 

 the venous stream is interrupted ; (2) during contraction of the ventricles, the blood in the 

 coronary veins is similarly accelerated as in the veins of muscles. The coronary arteries are 

 characterised by their very thick connective-tissue and elastic intima, which perhaps accounts 

 for the frequent occurrence of atheroma of these vessels {Henle). Some observers maintain that 

 the coronary arteries do not. anastomose, but this is denied by Langer and Krause. [West has 

 injected the one artery from the other.] Many of the small lower vertebrates have no blood- 

 vessels in their heart-muscle, e.g., frog (ffyrtl). 



Ligature of the Coronary Arteries. The phenomena produced by partial 

 obliteration or ligature of the coronary arteries are most important. In man 

 analogous conditions occur, as in atheroma or calcification of these arteries. See 

 and others have ligatured the coronary arteries in dogs, and found that after two 

 minutes the cardiac contractions gave place to twitchings of the muscular fibres, 

 and ultimately the heart ceased to beat. Ligature of the anterior coronary artery 

 alone, or of both its branches, is sufficient to produce this result. If the coronary 

 arteries be compressed or tied in a rabbit in the angle between the bulbus aortae 

 and the ventricle, the heart's action is soon weakened, owing to the sudden anaemia 

 and to the retention of the decomposition-products of the metabolism in the heart- 



