BLOOD SUPPLY TO THE HEART 



'525 



AORTIC VALVE 



TRUNCUS ARTERIOSUS 

 NORMAL 



LEFT CORONARY 

 ARTERY 



ANOMALOUS 



PULMONARY VALVE 



fig. 4. Diagrammatic representation of the normal and the anomalous origin of the left coronary 

 artery following torsion and division of the truncus into aorta and pulmonary artery. [From George 

 & Knowlan (127).] 



The anatomic abnormality was first described for 

 an aberrant right coronary artery in 1886 (101). At 

 that time, the suggestion of reversal of flow in the 

 aberrant vessel was postulated because of the tortuous, 

 dilated nature of the arteries involved and a simple 

 reflection on the pressure differential between the two 

 circuits. The anatomic aberration of the left coronary 

 was described in ign and the clinical syndrome of 

 infarcts in 1933 (101). Electrocardiograph findings 

 suggest a recent anterior or anterolateral myocardial 

 infarction (58, 69, 10 1, 127, 210), while angiocardiog- 

 raphy or cine-angiocardiography reveals a normal 

 right ventricle and pulmonary artery and a dilated, 

 thinned left ventricle without evidence of filling of the 

 left coronary artery from the pulmonary artery; retro- 

 grade aortography reveals a dilated right coronary and 

 late filling of the left coronary (from right coronary 

 collaterals). The aberrant artery in both adults and 

 infants is a thin-walled veinlike vessel with an atro- 

 phied media. Grossly visible right-to-left coronary 

 anastomoses were present in 27 per cent of the adult 

 specimens. 



Using pathologic specimens and surgical observa- 

 tions, but without definitive physiologic data for 

 support, Edwards earlier proposed a hypothesis 

 sustaining the concept of retrograde flow and refuting 

 that of antegrade flow from the pulmonary artery 

 (101). Physiologic proof of the retrograde nature of 



flow in the aberrant left coronary has been presented 

 at thoracotomy in a preoperatively diagnosed 2}/%- 

 month-old child (325). Prior to ligation of the vessel 

 at its origin from the pulmonary artery, the pressure 

 in the left coronary artery was 30/15 mm Hg, rising 

 to 75 mm Hg systolic distally after occlusion, while a 

 simultaneous pulmonary artery mean pressure was 25 

 mm Hg. Arterial saturations in the corresponding 

 vessels were 100 and 76 percent, respectively. A post- 

 ligation rise of 30 mm Hg systolic pressure, and a 

 decreased paradoxical bulge of the left ventricular 

 infarct area, as blood now traversed rather than 

 shunted away from the myocardial bed, lends final 

 support to the retrograde flow thesis. In contrast to 

 the invariably fatal outcome within the first year of 

 life, this patient is alive and asymptomatic. 



The Cardiac Nerves 



The nerve supply to the heart is mediated through 

 the cardiac plexuses located above the base and be- 

 tween the aortic arch and tracheal bifurcation (397). 

 Vagal, sympathetic, and dorsal root fibers intermingle 

 and tend to lose their identity as they decussate into 

 right and left halves before entering the pericardium. 

 Functionally, however, they are best divided into 

 sensory and autonomic functions. 



The sensory afferent fibers originate in thoracic 



