PHYSIOLOGIC CONSEqUENCES OF CONGENITAL HEART DISEASE 



419 



and the pulmonary artery. In this condition the 

 aortic and pulmonary valves are normally formed, 

 but a fistulous opening exists between the ascending 

 aorta and the main pulmonary artery. Functionally, 

 this condition resemijles patent ductus arteriosus and 

 may give clinical signs readily confused with those 

 of that condition. 



Anomalies of coronary arteries. The coronary arteries 

 may be abnormal in origin or in distribution. One or 

 both may arise from the pulmonary artery. The com- 

 monest arrangement in which the pulmonary artery 

 communicates with the coronary arterial system is 

 that wherein the left coronary artery arises from the 

 pulmonary artery, whereas the right coronary origi- 

 nates from the aorta. The incidence of this anomaly 

 is less than i per cent. Rarely a coronary artery may 

 arise from a cardiac chamber. The clinical picture of 

 anomalous origin of the left coronary artery follows 

 roughly the pattern of hypoxia due to acquired 

 coronary insufiiciency in adults. When the right 

 coronary artery arises from the pulmonary artery 

 there are as a rule no disturbances in cardiac func- 

 tion; however, when both coronary arteries arise from 

 this site, a rare condition, death occurs shortly after 

 birth. 



Pulmonary arteriovenous fistula. This anomah' is a 

 direct communication between the pulmonary arterial 

 system and the pulmonary venous system. This allows 

 venous unsaturated blood to enter the pulmonary 

 veins and thus the systemic circulation. When the 

 fistula is large and there is sufficient venous blood 

 entering the systemic circulation, cyanosis, clubbing 

 of digits, and secondary polycythemia are manifest. 



Aortic-sinus aneurysm. Aneurysm of an aortic sinus 

 is rare, most commonly involving the right and less 

 commonlv the posterior sinus. It is doubtful whether 

 congenital aneurysms of the left aortic sinus ever 

 occur. 



The aneurysm usually presents toward the right 

 atrium or the right ventricle and may communicate 

 congenitally with either of these chambers, or there 

 may be no communication on a developmental 

 basis. Acquired communication between the aorta 

 and one of the atria or ventricles may appear spon- 

 taneously or as a complication of bacterial infection 

 of the aneurysm. 



The functional disturbance from an aneurysm of 

 an aortic sinus that communicates with one of the 

 right-sided cardiac chambers is comparal^le to that 

 from patent ductus arteriosus, and peripheral signs 

 suggesting aortic insufficiency may be prominent. 



VENOUS ANOMALIES. Anomalous pulmonary venous con- 

 nections. Pulmonary veins may drain anomalouslv 

 into the right atrium or one of its tributary veins 

 instead of the left atrium. Such anomalous venous 

 connection may be partial or complete. The complete 

 form represents nearly 2 per cent of all cases of con- 

 genital cardiovascular defects. In partial anomalous 

 venous connection some of the pulmonary veins 

 communicate normally with the left atrium and others 

 communicate anomalously with the right atrium 

 or one of its tributary veins. In complete anomalous 

 connection all the pulmonary veins are connected 

 to the right atrium or one of its tributary veins; none 

 drain directly into the left atrium. In the latter anom- 

 aly an atrial septal defect is present, which is the 

 only route whereby blood can reach the left side of 

 the heart for distribution to the systemic circulation. 

 In partial anomalous venous connection there is 

 pulmonary recirculation of oxygenated blood, and 

 the condition has functional characteristics similar 

 to those of atrial septal defect. 



In complete anomalous pulmonary venous con- 

 nection there is not only an arteriovenous but also a 

 venoarterial shunt. In this condition there is relatively 

 complete mixing of pulmonary venous and systemic 

 venous blood, and arterial hypoxemia is always pres- 

 ent; however, when the pulmonary flow is high, 

 cyanosis may not be evident. Death during early 

 infancy is common, particularly if there is some ob- 

 struction to pulmonary venous drainage. However, 

 if the pulmonary venous pathway is not restricted 

 and a large atrial septal defect is present, such patients 

 may attain adult life without being aware of the 

 presence of this rather severe hemodynamic anomaly. 



Cor triatriatum is a rare congenital anomalv usually 

 associated with partial obstruction to drainage of the 

 pulmonary veins into the left atrium; it comprised 

 less than 0.3 per cent of one series of 357 cardiac 

 malformations (106). In this condition the pulmonary 

 veins empty into an accessory chamber lying superior 

 to the true left atrial chamber and communicating 

 with it by means of an opening which is usually 

 small. The narrow opening between the accessory 

 chamber and the true left atrium constitutes a point 

 of partial obstruction to pulmonar\- venous flow, 

 functionally resembling mitral stenosis. The accessory 

 chamber is believed to represent the common pul- 

 monary vein of the embryo which failed to become 

 incorporated into the left atrium as it normally should. 



Variants of cor triatriatum include a connection 

 of this accessory chamber to one of the tributary 

 veins of the right atrium and thus functionallv re- 



