Anomalous Origin of the Left Coronary Artery from the Pulmonary Artery (ALCAPA) in Four Calves

Abstract

Abstract. Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA), or Bland-White-Garland syndrome, is a rare congenital malformation described in children and adults. In this condition, the left coronary artery, which normally originates from the left coronary sinus in the aorta, instead originates from the pulmonary trunk, which results in retrograde flow of blood away from the myocardium into the lower-pressure pulmonary artery. Myocardial hypoxic-ischemic injury results in cardiac dysfunction, failure, and eventually in patient death if not surgically repaired. This report describes gross and microscopic findings in 4 beef calves with ALCAPA. All the calves had a history of being found dead with few or no premonitory signs, 2 shortly after sudden strenuous exercise. Gross necropsy lesions suggestive of heart failure included cardiomegaly with atrial and ventricular dilation and/or ventricular hypertrophy, and hepatomegaly. Dissection of each heart revealed the origin of the left coronary artery arising in the pulmonary trunk above the anterior cusp of the pulmonic valve. No other cardiac anomalies were identified. Histopathologic changes in the heart included cardiomyocyte degeneration; mineralization; and fiber loss, with replacement by fibrous connective tissue, predominantly in the left ventricular papillary muscle and the interventricular septum. Changes observed in the liver and lungs, including hepatomegaly, sinusoidal congestion, centrilobular fibrosis, and pulmonary congestion, edema, and intra-alveolar pigment-laden macrophages were consistent with heart failure.

Cardiovascular magnetic resonance findings in repaired anomalous left coronary artery to pulmonary artery connection (ALCAPA)

“…This pattern was seen in 5 of 6 patients and would be consistent with the brightly echogenic myocardium seen during echocardiography in neonates with this condition [10]. Furthermore, the pattern of LGE we observed is in keeping with animal observation [11], but has a different localization to that observed by Browne and colleagues in 2 neonates referred for cardiac transplantation - predominantly apical LGE [12]. …”

Coronary Artery Anomalies in Animals

“…Reports of CAA in dogs include the single right coronary ostium with an anomalous prepulmonary LCA first reported in 1959 in a necropsy study of an asymptomatic mongrel dog [ 29 ] and later characterized in association with PS [ 6 , 7 , 30 , 31 , 32 ], single left coronary ostium with an anomalous prepulmonary RCA [ 33 , 34 ], single right coronary ostium with suspected interarterial LCA in an English bulldog [ 35 ], single right coronary ostium in a Keeshond with common arterial trunk [ 36 ], single right coronary ostium in a Collie with double outlet right ventricle [ 37 ], anomalous origin of the LCA from the pulmonary trunk in a miniature poodle [ 38 ], LCA aneurysm in a German shepherd dog with subaortic stenosis [ 39 ], coronary to pulmonary artery fistula in a German shepherd dog [ 40 ], and incidental myocardial bridging in many dogs found on autopsy [ 41 , 42 ]. In the cow, single right coronary ostium with an interarterial LCA [ 43 ], single right coronary ostium with a prepulmonary LCA and coronary-to-pulmonary artery fistula [ 9 ], LCA to left ventricle fistula [ 44 ], dual origin of the LCA [ 45 ], left circumflex branch to right ventricle fistula [ 46 ], and several cases of anomalous origin of the LCA from the pulmonary trunk [ 47 , 48 , 49 ] have been described. In the horse, single right coronary ostium with a prepulmonary LCA [ 50 ] as well as single right coronary ostium with an interarterial LCA have been reported [ 51 ].…”

“…Anomalous origin of a coronary artery from the pulmonary trunk results in myocardial steal and a left-to-right shunt as the low pulmonary vascular resistance drives blood flow away from the myocardium and to the pulmonary circulation. Reports in animals are rare, being described in a dog [ 38 ] and several bovine cases [ 47 , 48 , 49 ]. Re-implantation to the aorta is the preferred treatment strategy in humans, though ligation of the LCA at the pulmonary valvar sinus may be a feasible treatment strategy in the dog to resolve shunt flow if sufficient collateral flow to the myocardium is provided through the RCA.…”

Congenital heart defects in calves

“…Anomalous location of the left coronary artery is classed as a major vascular anomaly and has been reported in calves, other animals and humans. 6,7 In most animals the left coronary artery supplies the majority of oxygenated blood to the left ventricle and interventricular septum. Ischaemic cardiomyopathy will have resulted because of hypoxic blood perfusing the left coronary artery.…”