BLOOD SUPPLY TO THE HEART 



1573 



mental fact that handling the heart raises the ventricu- 

 lar fibrillation threshold. Some may be improved by 

 procedures such as de-epicardialization which could 

 obliterate the afferent pathways for pain. However, 

 results of the sham operation of Adams (1) and 

 Dimond (85), involving only a skin incision, strongly 

 suggest that much of the positive benefit is on a 

 psychogenic basis. 



Coronary endarterectomy which has been applied 

 to man is on a sound physiological basis and its 

 purpose is entirely different from the preceding. The 

 surgeon directly reestablishes coronary flow through 

 the original coronary artery by removing its athero- 

 sclerotic plug. It does not require collateral develop- 

 ment and should be effective provided there exists a 

 gross coronary insufficiency of blood beyond the 

 obstruction, provided the vessel remains patent and 

 thrombi do not form, and provided there are no 

 sizeable atherosclerotic lesions beyond the region of 

 the occluded coronary artery. It is quite doubtful 

 that these criteria can be met (182). Preliminary 

 experiments with the use of endarterectomy for 

 coronary occlusion were apparently initially favorable 

 to the patients, relieving their angina, and improving 

 their electrocardiograms and work tolerance (241, 

 326). However, most of these patients have died, and 

 no evidence is available that at autopsy the endarter- 

 ectomized artery has remained patent. Many more 

 operations will have to be performed to establish the 

 possible merit of this procedure in humans. 



Finally, bypass of a length of an occluded coronary- 

 artery by anastomosis of its peripheral patent end to a 

 systemic artery has not yet been attempted in man. 



In dogs, a nonsuture anastomosis by intima-to-intima 

 contact between the left coronary artery and the left 

 internal mammary artery has been highly successful 

 (171). In almost all the dogs (24 of 33), the anasto- 

 moses have been demonstrated to be patent and 

 without myocardial infarction as evidenced by gross 

 observation, angiography, and measurement of 

 coronary blood flow through the anastomosis up to 

 the time of dog sacrifice (12-24 months after opera- 

 tion). Other technical achievements in this area 

 include chronic anastomoses of two branches of the 

 left subclavian artery to the peripheral and central 

 ends, respectively, of the left circumflex coronary, the 

 central end of the main left coronary being tied 

 (unpublished observations), and end-to-end anasto- 

 mosis of the central end of the main left coronary 

 artery to the peripheral end of the left subclavian 

 artery (251). Since anastomosis of a coronary artery 

 branch to a systemic artery is almost always successful 

 in the dog in which the anastomosed vessels are only 

 2 to 3 mm diameter, there should be no difficulty at 

 all in the human heart in which the coronary artery 

 branches have a much greater diameter. This proce- 

 dure might, therefore, have an application in the 

 creation of a permanent new blood supply in the 

 presence of coronary artery disease in man. One 

 should not, however, overlook a probably late com- 

 plication to successful coronary endarterectomy or 

 coronary bypass in man. In the presence of such a 

 large new blood supply, the existing collateral flow 

 will disappear. If another coronary occlusion subse- 

 quently occurs, the patient will be in difficulty, 

 having lost his collaterals. 



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'95°- 



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