Rev. Chil. Anat., 20(2):117-123, 2002.

STUDY OF THE ARTERIAL CORONARY CIRCULATION IN THE DOG
(Canis familiaris)

ESTUDIO DE LA CIRCULACIÓN CORONARIA ARTERIAL DEL PERRO (Canis familiaris)

Marilena Longo Büll & Márcia Regina Fernandes Boaro Martins

BÜLL, M. L. & MARTINS, M. R. F. B. Study of the arterial coronary circulation in the dog (Canis familiaris). Rev. Chil. Anat., 20(2):117-123, 2002

SUMMARY : Study on arterial coronary circulation was performed in 30 dog hearts, by using the dissection and clearing techniques. We observed that the heart is supplied by the right coronary artery (a. coronaria dextra) and three branches of the left coronary artery ( a. coronaria sinistra): paraconal interventricular ( ramus interventricularis paraconalis), septal ( ramus septales ) and circumflex arteries (ramus circumflexus). The left coronary artery arose from a trunk in the ventral aortic sinus and, when there was no trunk formation, it was found two different origins in the aorta, corresponding to the circumflex and paraconal interventricular arteries. The latter, after originating right anterior ventricular, left anterior ventricular and septal ventricular arteries, ended next to the heart apex. The circumflex artery presented its course to the left up to the atrial face, where it ended as subsinuous interventricular artery. Arising from the circumflex artery, it was found the auricular ( rami auricularis), ventricular ( rami ventricularis) and septal (rami septales) branches and branches to the atrio-ventricular node ( nodus atrio-ventricularis). The septal artery (ramus septales) was observed to be originated from the paraconal interventricular artery, with lower frequence of the left coronary artery and in two cases of the circumflex artery. The right coronary artery presented no arterial trunk. In that place, there were two separate origins in the aorta or 2-3 origins in a common sinus. This artery emitted auricular, ventricular branches and to the atrio-ventricular node.

KEY WORDS: 1. Anatomy; 2. Heart; 3. Coronary artery; 4. Dog.

INTRODUCTION

Beside classical descriptions on coronary circulation in human (Testut, 1911; Chiarugi, 1943; Gardner et al., 1971; Gray, 1977) and pets (Miller et al., 1979; Sisson & Grossman, 1972; Schwarze & Schröder, 1970; Nickel et al., 1975 and Getty, 1981), there are detailed quotations on bull and goat (Hegasi, 1958), pig (Lumb et al., 1962 and Fehn et al., 1968), cock (Lindsay & Smith, 1965), ox (Bhargava & Beaver, 1970), cat and sheep (Hadziselimovic et al., 1980).

Presently, much emphasis has been given in experimental works in which the dog is the model animal (Donald & Essex, 1954; Christensen & Campeti, 1959; Bloor & Lowman, 1962; Rozman et al., 1962; Filho & Borelli, 1966; Lescure & Poirson, 1968; Andretto et al., 1973 and Pina & Pereira, 1973).

There is much information in textbooks on these arteries number and distribution territory. Generically, the coronary circulation is done by two main coronary arteries: the right and the left ones, beside their primary and secondary branches, however, intraspecific and interspecific differences are described (Gardner et al. and Sisson & Grossman). According to Miller et al., such circulation in dogs is established by four arteries: right coronary artery and three branches of the left coronary artery: septal, circumflex and anterior descending; such data were confirmed in 66% of cases examined by Donald & Essex.

Kazzaz & Shanklin, 1950 (apud Pina & Pereira) described that the right coronary artery seldom extends up to the right ventricle border and send branches to the right atrium. On the other hand, Pianetto (1939) states that the atrial branches are variable in development and confirms the presence of 4 to 9 ventricular branches from the right coronary artery.

According to Meek et al. (1929), Moore (1930), Pianetto and Kazzaz & Shanklin (apud Pina & Pereira), the atrial branch is longer than the others and is related to vascularization of the atrial sinus node. This ends by anastomosing with atrial branches which come from the circumflex branch.

The left coronary artery, according to Miller et al., originates the circumflex, ventral and septal interventricular arteries, being that from these branches, ventricular and atrial secondary branches are originated. In his studies performed with dogs, Moore confirms that the left coronary artery arises from a trunk which, after short distance, is divided into circumflex, anterior descending and septal branches. On the other hand, Pianetto and Pina & Pereira found with certain frequency two left coronary arteries without emerging from a trunk, originating circumflex and anterior descending branches, while the septal branch in one third of the cases had independent origin. Paraconal and left circumflex interventricular branches arisen from a left coronary artery trunk is described by Andretto.

The objective of this study was to contribute to the systematization of arterial coronary circulation and, as much as possible, try to solve the problem of ischemic infarction of some myocardio areas.

MATERIAL AND METHOD

It was studied the arteries of 30 adult dogs (Canis familiaris) of unknown family and age, both male and female, from Biotério Central at UNESP Botucatu Campus. The animals were sacrificed by using intravenous anesthesia of sodium pentabarbital (Nembutal). The sternal plastron was opened and the heart was along with the basal vessels. After suture, the coronary arteries were cannulated and washed with normal saline solution. Both arteries were injected with contrast through two different procedures:

A group of 20 hearts had their arteries injected with aqueous solution of neoprene latex colored with specific pigment. After 12 hours at 16°C, they were submerged in formalin 10%. After fixation, they were dissected under magnifying glass.

In other group of 10 animals, the coronary arteries were injected with gelatin (Anglo) solution colored with cinnabar.

The organs were cleared after Spalteholz method and the coronary arteries behavior was analyzed, described and photographed.

RESULTS

In our results, it was observed that the dog heart is supplied by four coronary arteries, being three of them branches of the left coronary (a. coronaria sinistra), paraconal interventricular (ramus interventricularis paraconalis), septal (ramus septales) and circumflex (ramus circunflexus) arteries, and right coronary artery (a. coronaria dextra).

The left coronary artery arose from a trunk in the ventral or left aortic sinus (Fig. 1a). However, in four animals there was no observation of a trunk formation, but two separate origins in the aorta corresponding to its two branches; circumflex and paraconal interventricular arteries (Fig. 1b).

Fig. 1 a. Observe the left coronary artery (LCA) and its branches: paraconal interventricular artery (PIA); circumflex artery (CA) and septal artery (SA).

Normally, the left coronary artery, soon after its origin, provides as terminal branches the paraconal interventricular and circumflex arteries; however, in 4 out of 20 cases, this artery also provided as terminal branch the septal artery (Fig. 1a).

Fig. 1b. Paraconal interventricular artery (PIA) with its right anterior ventricularbranches (RA) and left anterior (LA). Circumflex artery (CA), auricular (AB) and ventricular (VB) branches.

Fig. 1c. Circumflex artery (CA) and paraconal interventricular artery (PIA), originating separately from the aorta.

Thus, in most cases, the paraconal interventricular artery had its origin in the left coronary artery bifurcation (Fig. 1a), while in 4 cases it originated isolatedly from the aorta (Fig. 1b); went through the paraconal interventricular groove (sulcus intraventricularis paraconalis) and ended next to the heart apex. In 80% of cases, we could observe this artery anastomosis with branches of the subsinuous interventricular artery (ramus interventricularis subsinuosus). During its way, this artery emitted right anterior ventricular branches with variable length and thickness located in the paraconal interventricular groove adjacences, irrigating the right ventricle wall; left anterior ventricular branches also with variable length, but usually longer than the former, assuring the left ventricle irrigation (Fig. 1b), and septal branches (rami septales) as well (Fig. 2a). These septal branches arose from the paraconal interventricular artery in most cases, however, we observed that in 12 cases they arose from the left anterior ventricular branches. In another case, it was observed that one septal branch arose from the bifurcation of the paraconal interventricular artery trunk which also originated the left anterior ventricular branch (Fig. 2b). In 2 cases, the septal branch arose from the bifurcation of a circumflex artery trunk, which originated the angular branch as well (Fig. 2c).

Fig. 2 a. Observe septal branch (SB) originating from the paraconal interventricularartery (PIA).

Fig. 2b. Septal branch (SR) and left anterior ventricular branch (LAVB) originating from a common trunk(*) of the paraconal interventricular artery (PIA).

Fig. 2 c. Septal branch (SB) and angular branch (AB) originating from a common trunk of the circumflex artery (CA). Angular artery (AA) originating from the paraconal interventricular artery (PIA).

It was verified, thus, that the paraconal interventricular artery is responsible for vascularization of 2/3 of heart auricular face.

The septal artery ( ramus septales) presented arising, in most cases, from the paraconal interventricular artery (Fig. 3a), with less frequency from the coronary artery (Fig. 1a), and only in two cases from the circumflex artery (Fig. 3b).

Fig. 3 a. Septal artery (SA) originating from the paraconal inter-ventricular artery (PIA); circumflex artery (CA).

Fig. 3b.Septal artery (SA) originating from the circumflex artery (CA); paraconal interventricular artery (PIA).

The third and last branch of the left coronary artery, the circumflex artery (Fig. 1a), in four cases only, presented independent origin in the aorta, although its absence has never been observed. It has a way to the left over the left atrial-ventricular groove (sulcus coronaries) up to the heart atrial face (facies atrialis) and, before ending as subsinuous interventricular artery (ramus interventricularis subsinuosus) (Fig. 3c), originated auricular collateral branches destined for irrigating the left atrium wall; ventricular branches which provided proximal branches (left ventricle auricular face), marginal (left ventricle margin) and distal (left ventricle atrial face) and, as last collateral branches, branches to atrio-ventricular node and septal branches

Fig. 3c.Circumflex artery (CA) ending as subsinuous interven-tricular artery (SIA).

In most cases, the subsinuous interventricular artery was observed as circumflex artery terminal branch, however, in 15 cases, after its origin, it was verified a very short branch that continued along the atrial-ventricular groove (Fig. 3d).

Fig. 3d. Circumflex artery (CA), subsinuous interventricular artery (SIA) and subsinuous artery branch (SB).

In most cases, the subsinuous interventricular artery anastomosed with the right coronary artery and ventricular branches of the paraconal interventricular artery. It emitted right posterior ventricular branches (right ventricle posterior wall), left posterior (left ventricle posterior wall) and septal branches (interventricular septum).

With regard to the right coronary artery, it was observed the absence of an arterial trunk in 26% of cases. In that place, there were two separate origins in the aorta; or even, two or three origins inside a common sinus. One of these branches irrigated the regions of the arterial cone and the other constituted the right coronary artery itself. In case of a third branch, it behaved as a proximal branch of the right coronary artery, spreading in the right ventricle auricular face (facies auricularis). This artery reached the atrio-ventricular groove and ended next to the subsinuous interventricular groove; emitted auricular and ventricular collateral branches, and to the atrio-ventricular node (Fig. 3e).

Fig. 3e. Aortic sinus with orifice of origin from the branch to the arterial cone (VC), orifice of origin from the artery to the auricular face (AF) and orifice of origin from the right coronary artery (RCA).

DISCUSSION

Similarly to our results, Moore, Lescure & Poirson and Andretto et al. described the origin of the right coronary artery from a trunk in the left ventral aortic sinus. On the other hand, Pianetto and Pina & Pereira, in studies performed in dogs, and Ahmed & Harrison (1971), in human, found out two independent origins in the aorta, corresponding to the origin of the circumflex and paraconal interventricular arteries without an arterial trunk, in a similar way to that we have observed in 4 cases. Our descriptions about terminal branches originated from this artery, that is, the paraconal interventricular and circumflex arteries, were confirmed by Lescure & Poirson, Andretto et al. and Pina & Pereira. The presence of the septal artery as third terminal branch is confirmed by Moore and Pina Pereira. The paraconal interventricular artery way through the paraconal interventricular groove was in accordance with previous studies by Moore, Pianetto, Christensen & Campeti, Bloor & Lowman, Lescure & Poirson and Pina & Pereira. The latter observed in 18.05% of cases the anastomosis of collateral branches of this artery with subsinuous interventricular artery branches; such behavior was observed by us in 80% of cases.

Previous studies by Moore described the presence of 4 to 6 right anterior ventricular branches; Pianetto, 3 to 5; Lescure & Poirson, 4 to 11 and Pina Pereira, 3 to 10 branches, being that we detected a range from 4 to 19 branches. The presence of left anterior ventricular branches as collateral branches of the paraconal interventricular artery is in accordance with previous descriptions by Lescure Poirson and Pina & Pereira. According to Moore, Pianetto and Pina & Pereira, these branches vary in numbers of 3 to 5, 3 to 7 and 4 to 17, respectively, and in our study we observed 5 to 23 branches. Among them, we found in 6 cases the angular artery; data corroborating with results by Pina & Pereira. In our observations, in most cases, the septal branches detached from the paraconal interventricular artery; in 12 cases, they detached from the left anterior ventricular branches; in 2 cases, from a trunk of the circumflex artery and, in 1 case, from a trunk of the paraconal interventricular artery. Similarly, Pianetto (1939) states that in 70% of the cases analyzed, the first septal branch arose from the paraconal interventricular artery and, in 30% directly from the coronary cavity. Pianetto (1939) suggests to this branch the name of septum ventricularum artery because it supplies the biggest part of the septum, however, Fehn et al. (1968) state that paraconal interventricular and circumflex arteries branches supply just a little portion of the interventricular septum.

In relation to the septal artery, our studies were in accordance with Pina & Pereira, Lescure & Poirson and Rozman et al. who state that this artery arises mainly from the paraconal interventricular artery. The origin of this artery from the left coronary artery is supported by Pina & Pereira. Pianetto and Pina &Pereira observed this artery originating directly from the aorta, which was not observed by us, or still from the aorta bifurcation point in paraconal interventricular and circumflex arteries (Christensen & Campeti and Rozman et al.)

In the analyzed hearts, the circumflex artery arose from the left coronary artery, agreeing with descriptions by Pina & Pereira. Although, Pianetto reports this artery originating beside the paraconal interventricular artery, without a common trunk as in human.

Unlikely our findings, Ahmed & Harrison observed in 43% of human hearts the absence of this artery and state its replacement by the right coronary artery and its branches. In textbooks, studies agree with the circumflex artery division into auricular, ventricular, to auricular-ventricular node, septal and terminal branches, being the divergences as for their number (Bloor & Lowman; Pianetto; Moore; Pina & Pereira and Lescure & Poirson).

We observed, similarly to Pina & Pereira that the subsinuous interventricular artery was a terminal branch of the circumflex artery, however, in many cases, after its origin, many other branches arose and continued in the atrioventricular groove. In accordance with our results, Moore states that the subsinuous interventricular artery is an invariable continuation of the circumflex artery and never of the right coronary artery, according to Gross (apud Moore). We agree with Andretto et al. when they stated that the subsinuous interventricular branch is responsible for arterial irrigation of the right and left ventricles atrial face, as well of part of the interventricular septum.

In our studies, it was observed in 26% of cases the absence of an arterial trunk to the right coronary artery. In that place, we verified two separate origins in the aorta, or two or three origins in a common sinus. Pianetto describes in 40% of cases the presence of a main artery and an additional one, which is confirmed by Moore and Kazzaz & Shanklin. On the other hand, Bloor & Lowman could not visualize exactly the origin of the right coronary artery.

RESUMEN: El estudio de la circulación coronaria arterial fue realizado en 30 corazones de canes, aplicando técnicas de disección y diafanización. Verificamos que el corazón estaba irrigado por la arterias coronaria izquierda, arterias interventricular paraconal, septal y circunfleja. La arteria coronaria izquierda se originaba de un tronco en el seno aórtico ventral y, en los casos donde no hubo formación del tronco, encontramos dos orígenes separados en la aorta, correspondientes a las arterias circunfleja e interventricular paraconal. Esta última, después de originar ramas ventriculares ántero-derecha, ántero izquierda y septales, terminaba próxima al ápice del corazón. La arteria circunfleja presentaba un trayecto para la izquierda hasta la cara atrial, donde terminaba como arteria interventricular subsinuosa. Originándose de la arteria circunfleja encontramos las ramas atriales, ventriculares, septales y para el nódulo atrioventricular. La arteria septal, fue observada originándose de la arteria interventricular paraconal y con menor frecuencia de la arteria coronaria izquierda y, en dos casos, de la arteria circunfleja. La arteria coronaria derecha no presentaba tronco arterial. En lugar de éste, había dos orígenes separados en la aorta ó 2-3 orígenes dentro de un seno común. Esta arteria emitía ramas atriales, ventriculares y para el nódulo atrio-ventricular.

PALABRAS CLAVE: 1. Anatomía; 2. Corazón; 3. Arterias coronarias; 4. Perro.

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Correspondence to:
Profa. Dra. Marilena Longo Büll
Departamento de Anatomia
Instituto de Biociências
Universidade Estadual Paulista
Botucatu, SP, CEP 18618-000
BRASIL

Email: anatomia@ibb.unesp.br

Recibido : 06-12-2001
Aceptado: 02-03-2002 

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Departamento de Anatomia, IB, Universidade Estadual Paulista ­ Botucatu / SP (UNESP), Brasil