Coronary Artery Anomalies in Animals

Abstract

Coronary artery anomalies represent a disease spectrum from incidental to life-threatening. Anomalies of coronary artery origin and course are well-recognized in human medicine, but have received limited attention in veterinary medicine. Coronary artery anomalies are best described in the dog, hamster, and cow though reports also exist in the horse and pig. The most well-known anomaly in veterinary medicine is anomalous coronary artery origin with a prepulmonary course in dogs, which limits treatment of pulmonary valve stenosis. A categorization scheme for coronary artery anomalies in animals is suggested, dividing these anomalies into those of major or minor clinical significance. A review of coronary artery development, anatomy, and reported anomalies in domesticated species is provided and four novel canine examples of anomalous coronary artery origin are described: an English bulldog with single left coronary ostium and a retroaortic right coronary artery; an English bulldog with single right coronary ostium and transseptal left coronary artery; an English bulldog with single right coronary ostium and absent left coronary artery with a prepulmonary paraconal interventricular branch and an interarterial circumflex branch; and a mixed-breed dog with tetralogy of Fallot and anomalous origin of all coronary branches from the brachiocephalic trunk. Coronary arterial fistulae are also described including a coronary cameral fistula in a llama cria and an English bulldog with coronary artery aneurysm and anomalous shunting vessels from the right coronary artery to the pulmonary trunk. These examples are provided with the intent to raise awareness and improve understanding of such defects.

Keywords: cat; congenital; dog; heart; single coronary; veterinary.

Figure 1

Canine specimen of the heart base, viewed from the dorsal perspective. The left coronary artery (*) can be seen arising from the left-adjacent cusp (LC) of the aortic valve and dividing into the paraconal interventricular branch (large arrow) and circumflex branch (multiple small arrows), which wraps around the mitral valve (MV) annulus to descend as the subsinuosal interventricular branch (+). The right coronary artery (arrowheads) can be seen arising from the right-adjacent cusp (RC) of the aortic valve and passing to the right and caudal of the tricuspid valve (TV) annulus. PV = pulmonary valve; NC = non-adjacent cusp of aortic valve.

Figure 2

Variations of normal coronary ostia in the dog. (a) Left coronary trifurcation in a dog with a very short (nearly absent) left main coronary artery in whom the left coronary ostium gives rise to a septal branch (s), paraconal interventricular branch (p), and a circumflex branch (c). Ao = aorta; LAA = left auricular appendage; PA = pulmonary artery. (b) View of the left aortic valvar sinus from the dog in panel (a) showing the trifurcation of the left coronary system. (c) Photograph of the right aortic valvar sinus from a different dog showing a right coronary ostium (arrowhead) with an additional small ostium (arrow) consistent with the right accessory or conus branch.

Figure 3

Photograph from a 2-month-old calf with double outlet right ventricle and a coronary artery anomaly. A single right coronary ostium (arrowhead) gives rise to the right coronary artery (arrows) as well as the left main coronary artery (L), which crosses cranial (prepulmonary) to the pulmonary trunk (PT) before dividing into the paraconal interventricular branch (P) and the circumflex branch (Cx). Note that the autopsy cut along the interventricular groove has transected the left coronary artery. AAo = ascending aorta, BCT = brachiocephalic trunk, LAA = left auricular appendage.

Figure 4

Schematic representation of anomalies of coronary arterial origin and course. The normal anatomy is shown superimposed on a ventrodorsal radiograph and this same orientation is maintained for each drawing. The drawings demonstrate variations in anomalous course (dashed lines) for the major coronary arterial branches in the setting of either a single right or single left coronary ostium. AoV = aortic valve; Cx = circumflex branch; LCA = left coronary artery; Pc = paraconal interventricular branch; PV = pulmonary valve; RCA = right coronary artery; and S = subsinuosal interventricular branch.

Figure 5

Angiograms of unique coronary artery anomalies in 4 dogs. (a) Levophase from a digitally-subtracted right ventriculogram in an English bulldog with pulmonary valve stenosis showing a single left coronary ostium (*) that gives a short left main coronary artery before branching into the paraconal interventricular (arrowheads), circumflex (Cx), and subsinuosal interventricular (S) branches. There is no right coronary ostium and the right coronary artery (arrows) can be seen arising from either the left main or circumflex branch. (b) Aortic root angiogram from an English bulldog with a single right coronary ostium that gives the right coronary artery (RCA) as well as a short left main coronary artery (arrow) that passes between the aortic root and right ventricular outflow tract before giving off the circumflex branch (Cx) and small septal or paraconal branches. (c) 3-dimensional, volume-rendered reformat of a computed tomography angiogram from an English bulldog with a single right coronary ostium from which arises the right coronary artery (RCA), absence of the left coronary artery, a prepulmonary course for the paraconal interventricular branch (P), and an interarterial course for the circumflex branch (Cx). A portion of the right ventricular outflow tract has been digitally removed to show the left coronary branches encircling the pulmonary trunk (*). LV = left ventricle, Ao = aorta. (d) Selective arteriogram from a mixed breed dog with tetralogy of Fallot whose entire coronary circulation arises off the brachiocephalic trunk (arrow), traverses lateral to the ascending aorta, and then trifurcates caudal to the aortic root into the right coronary artery (RCA) and the paraconal interventricular (P), circumflex (Cx), and subsinuosal interventricular branches.

Figure 6

Echocardiographic examples of anomalous coronary artery origin or course. (a) Transthoracic short-axis image of the aortic root (Ao) showing a large single right coronary ostium with an anomalous coronary artery (CAA) traversing over the pulmonary valve (PV) annulus. RV = right ventricle. (b) Transthoracic short-axis image of the aortic root (Ao) from a dog with normal coronary anatomy demonstrating a normal paraconal interventricular branch (P) that appears to cross cranial to the PV annulus. (c) Transesophageal long-axis image of the RV outflow tract of a dog with a CAA seen crossing the PV at the base of the pulmonary trunk (PT). (d) Three-dimensional transesophageal image of the Ao from a dog with single right coronary ostium and a prepulmonary left coronary artery (LCA) showing the position of the LCA encircling the three PV leaflets (labeled 1 through 3) and the stenotic PV orifice (*).

Figure 7

Angiographic examples of anomalous coronary artery origin and course. (a) Lateral angiogram from a French bulldog showing simultaneous aortic root (AoV) and right ventricular (RV) injections that demonstrate RV hypertrophy, post-stenotic dilation of the pulmonary trunk (PT), and a single right coronary ostium from which arises the left coronary artery (LCA) that encircles the RV outflow tract before branching into the paraconal interventricular (P), circumflex (Cx), and subsinuosal (S) branches. (b) Digitally-subtracted angiogram in a ventrodorsal oblique projection from the same dog as in panel (a) showing similar anatomy and highlighting the prepulmonary course of the LCA around the RV outflow tract which occupies the position highlighted by the *.

Figure 8

Computed tomography angiography examples of the coronary circulation from two different English bulldogs. (a) 3-dimensional volume-rendered reformat showing normal coronary artery anatomy. Ao = aorta, Cx = circumflex branch, LCA = left coronary artery, LV = left ventricle, P = paraconal interventricular branch, RCA = right coronary artery, and Sp = septal branch. (b) 3-dimensional volume-rendered reformat showing a single right coronary ostium with prepulmonary left coronary artery encircling the pulmonary valve annulus in a dog with concurrent pulmonary valve stenosis. PT = pulmonary trunk.

Figure 9

Photograph of the heart from a 6-day-old llama cria showing a severely dilated and tortuous right coronary artery fistula, which drained to the proximal right ventricle.

Figure 10

Angiographic images from an English bulldog with single right coronary ostium, aneurysmal dilation of the prepulmonary left coronary artery and circumflex branch (Cx), and coronary to pulmonary arterial fistulae/malformation. (a) The aortic root (Ao) injection shows the single right coronary ostium (arrow), aneurysmal dilation of the Cx, and a more normal diameter right coronary artery (RCA). (b) Selective right coronary angiogram from the same dog as in (a) showing one of several fistulous connections (arrowheads) from the RCA to the pulmonary trunk (PT).

Figure 11

A photograph of a myocardial bridge (arrow) covering a portion of the left paraconal interventricular branch of the left coronary artery in a dog. Ao = aorta, LAA = left auricular appendage, LV = left ventricle, RV = right ventricle.