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KARABULUT (B.) AND COLLABORATORS
Case report: Persistent truncus arteriosus with
intact ventricular septum and other cardiovascular
malformations in a calf
H. EROKSUZ1, S. YILMAZ2, Y. EROKSUZ1, A.CEVIK1, S. SOYLU1, B. KARABULUT1*
Department of Pathology, Faculty of Veterinary Medicine, University of Firat, 23200 Elazig, TURKEY
Department of Anatomy, Faculty of Veterinary Medicine, University of Firat, 23200 Elazig, TURKEY
1
2
*Corresponding author: [email protected]
SUMMARY
RÉSUMÉ
A 3-day old, male Holstein calf presented for necropsy with a history
of respiratory distress, recumbency and failure to suckle since birth.
Postmortem examination revealed the absence of an aorta and a single
artery arising from the right ventricle that became the pulmonary trunk,
which branched into the main pulmonary artery and rise to two pulmonary
arteries (type-1 persistent truncus arteriosus). Other related findings
included intact ventricular septum, left ventricular hypoplasia, left coronary
artery originating from brachiocephalic trunk, absence of right coronary
artery and patent foramen ovale. Microscopically, there was moderate,
diffuse subendocardial fibrosis, myocardial degeneration, necrosis and
multifocal mononuclear cell infiltrations, which were most prominent in
the left ventricle wall. Additionally there was marked medial thickening of
arterial and arteriolar walls in the lungs. Pulmonary parenchymal changes
included moderate edema, vascular and interstitial congestion, hemosiderin
laden macrophages and diffuse suppurative pneumonia. Consequently,
the concurrence of type-1 persistent truncus arteriosus, left ventricular
hypoplasia, single right coronary artery and anomalous origin of the right
coronary artery was unusual in many respects and contributed to this calf ’s
failure to thrive and early death.
Tronc artériel persistant avec septum ventriculaire intact et autres
malformations cardiovasculaires chez un veau
Keywords: bovine, left ventricular hypoplasia, persistent
truncus arteriosus
Introduction
Congenital defects are the abnormalities present at birth
resulting from development. They can affect all or parts of
several system or isolated organ [22]. Persistent truncus
arteriosus (PTA), otherwise known as truncus arteriosus
communis or common aortico-pulmonary trunk, is an
uncommon congenital cardiac malformation describing the
absence or complete failure of the normally divided embryonic
truncus arteriosus (TA) into aortic and pulmonary trunk.
A single truncus originates from the left, right ventricle or
interventricular septum and supplies systemic, coronary
and pulmonary blood flow [7, 22]. The incidence of cardiac
malformations in bovine fetus is reported as 0.8% [19].
In humans, the incidence of cardiovascular malformations
is 0.62% of live births and PTA consisting of approximately
1.33% of total cardiovascular malformations [24]. As PTA
has been reported sporadically in veterinary literature, its
true incidence is unknown in animals [10, 13, 21]. Up till
Un veau Holstein mâle de 3 jours est présenté pour autopsie avec
commémoratifs de détresse respiratoire, décubitus et incapacité à téter
dès la naissance. L’autopsie a révélé l’absence d’aorte et une seul artère au
niveau du ventricule droit qui a donné le tronc pulmonaire, ramifiés en
artère pulmonaire principale et deux artères pulmonaires (tronc artériel
commun de type 1). Les autres constatations étaient la présence d’un septum
intact, une hypoplasie ventriculaire gauche, une artère coronaire gauche
provenant du tronc brachiocéphalique, l’absence d’artère coronaire droite et
un foramen ovale perméable. Au microscope, il a été constaté une fibrose
diffuse modérée subendocardique, une dégénérescence du myocarde, de la
nécrose et une infiltrations de cellules mononucléaires multifocales, plus
importantes dans la paroi du ventricule gauche. En outre, il a été observé
un épaississement médial marqué des parois artérielles et artériolaires dans
les poumons. Les changements du parenchyme pulmonaire incluaient un
œdème modéré, une congestion vasculaire et interstitielle, une accumulation
d’hémosidérine dans les macrophages et une pneumonie purulente diffuse.
Ces malformations diversées ont été reconnues comme responsables de la
mort d el’animal.
Mots-clés: bovin, cœur, malformation, hypoplasie
ventriculaire gauche, tronc artériel persistant
date, PTA has been documented in 9 calves [5, 14, 19, 2426], lambs [13, 20], foals [9, 10, 17], dogs and cats [3, 6, 7, 21,
27], a pig [16], a monkey [2] and a baboon [12].
To date, PTA has always been reported concurrently with
ventricular septal defect in animal species. Other associated
reported malformations and lesions are patent foramen ovale
[23, 26], atrial septal defect [16], main pulmonary artery
hypoplasia [17], diprosopus [5], dissecting aneurysm and
cardiac tamponade [13] and ventricular aneurysm [23].
This paper describes concurrent occurrence of PTA with
intact interventricular septum, left ventricular hypoplasia,
patent foramen ovale, atrioventricular fistula and coronary
artery malformations in a male Holstein calf.
Case report
A 3-day-old, male Holstein calf was reported to be
showing respiratory distress and recumbency with no
Revue Méd. Vét., 2015, 166, 5-6, 122-126
CARDIOVASCULAR MALFORMATIONS IN A CALF
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sucking reflex since the birth and colostrum was given with
the aid of feeding bottle. Referring veterinarian injected
intramuscular antibiotic (Baytril® 100, 100 mg enrofloxacin
in 1 mL, Bayer) injection for 2 previous days with diagnosis
of pneumonia. After death on third day, he was presented
for the necropsy to the Pathology Department of Veterinary
Medical School, Firat University. He weighed 23.80 kg,
having a poor body condition, and was the third offspring of
a naturally inseminated dam. The previous calves of the dam
had no clinical problem.
Results
Postmortem examination showed that the calf was
underdeveloped and the muzzle was markedly cyanotic.
The heart was remarkably enlarged with globoid appearance
weighing 285 gr. Its apex was constituted completely by
the right ventricle. There was no aorta arising from the
left ventricle. The left ventricle was extremely hypoplastic
measuring 2.51x1.43 cm and weighing 40 gr. The left
ventricular wall was considerably thickened and showed
concentric hypertrophy. The weight of interventricular
septum was 85 gr. The vertical and lateral thickness of the left
ventricular wall was 3.6 cm and 2.5 cm, respectively. There
was a fistular connection measuring 5 mm in diameter in
the lateral margin of left ventricle communicating with the
left atrium at the level of pulmonary vein. The right ventricle
was dilated by 6.0x5.8 cm, weighing 155 gr and completely
formed the apex. The foramen ovale between the atria was
patent having a flap (1.92x1.0 cm) and fenestrated hole
(6.0x5.0mm) in size (Figure 1). TA exhibited tricuspid valves.
Single large arterial vessel having 2.8 cm diameter originating
from the right ventricle became pulmonary trunk at 7.30
distance cm and branched into main pulmonary artery
and then giving rise to two pulmonary arteries. After that,
the arterial truncus at 12.30 cm distance from the origin
gave the branch resembling ascending aorta whose first
division was brachiocephalic (arterial) trunk (Figure 2).
There was apparently no right coronary artery. The area was
vascularized by the ramifications of ramus flexus of the left
coronary artery. The first thick division of brachiocephalic
trunk directing to the right ventricle gave rise the left
coronary arterial ramus, in 34 mm in length, and ended at
the level of interventricular sulcus (Figure 3). According to
criteria used in humans [8], the malformation was classified
as Type-1 PT. Both of the atria and the right ventricle were
moderately dilated. The endocardium of left ventricle was
moderately thickened and opaque. The lungs were heavy
and showed severe, diffuse hyperemia, edema and hard
consistency. The liver was also hyperemic in appearance. The
abomasum and intestines were completely full of colostral
ingesta. For microscopic examination, tissue samples from
the TA, ascendent aorta, liver, lungs, pancreas, brain, smalllarge intestines and kidneys were fixed in 10% formalin
and processed routinely. The sections were stained with
hematoxylin and eosin (H&E), and selected heart sections
were also stained with Masson’s trichrome.
Revue Méd. Vét., 2015, 166, 5-6, 122-126
Figure 1: Ventral view of opened left ventricle. Markedly hypopastic left
ventricle (LV-dotted line), dilated right ventricle (RV) and left atrium
(LA), patent foramen ovale (FO), and fistular connection between left
atrium and ventricular (canulated), truncusarteriosus (TA) originating
from right ventricle(RV) giving rise to pulmonary artery (PA), ascendant aorta like branch (AA), and brachyo-cephalic truncus (BT) and
left coronary artery (LCA), Bar: 2 cm.
Figure 2: Truncus arteriosus (TA) giving rise to pulmonary arteries (PA),
aorta (AO), and brachyo-cephalic truncus (BT) and left coronary
artery (LCA).
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Figure 3: Dorsal view of right ventricle. Truncus arteriosus originating
from RV, pulmonary artery, trachea (TR), ascendant aorta (AA), and
brachyo-cephalic truncus (BT) and left coronary artery (LCA).
Microscopic examination in the heart consisted of
myofibrillary degeneration, focal necrosis and focal postnecrotic mononuclear cell infiltrations in both ventricles.
There was severe to moderate subendocardial fibrosis in the
left ventricle (Figure 4) and marked thickening in the vessel
walls and narrowing of the lumen in intramural coronary
arteries and mild to moderate perivascular fibrosis (Figure
5), whereas in the right ventricle there was mild perivascular
edema and fibrosis.
The changes in the lung included marked medial
thickening of the wall of arteries and arterioles, perivascular
edema and mild fibrosis. In alveoli, there was moderate,
multifocal accumulation of neutrophils and lymphocytes,
hyperemia, hemosiderin laden macrophages, edema and
congestion. The liver also showed severe to moderate, diffuse
hyperemia.
KARABULUT (B.) AND COLLABORATORS
Figure 5: Marked thickening in walls and narrowing of the lumen in
intramural coronary arteries (arrows) and perivascular fibrosis (arrow
head).
Discussion
To our knowledge, this report represents the first
case of PTA with intact interventricular septum and left
ventricular hypoplasia in animals. However, concurrence
of these malformations was reported as a rare variant in a
few human infants [1]. In these reports; TA arising from left
ventricle or right ventricle [1] co-existed with the opposite
ventricular hypoplasia. Left ventricular hypoplasia defines
a congenital and lethal heart abnormality occurring usually
association with obstruction of left ventricular outflow [15].
Taken together; our findings support the conclusion that left
ventricular hypoplasia seems to be secondary to obstruction
of left ventricular flow. PTA is divided into 4 anatomic
subtypes according to location of pulmonary artery and
TA in humans [8]. The present case resembled Type-1 PTA
of human classification due to a single pulmonary trunk
dividing into 2 pulmonary arteries and a single ascending
aorta.
The formation of left atrioventricular fistula and patent
foramen ovale in the present report might be related with
high intracardiac pressure in left heart.
Figure 4: Endocardial and subendocardial fibrosis (arrows) in left ventricle.
Genetic factors and familial occurrence have been
reported in keeshond dogs. A genetic study suggested that
specific mutations in oligenic genes including CFA2, CFA9
and CFA15 may be responsible for conotruncal heart
malformations. These mutations might be spontaneous
or induced by teratogens [27]. The clinical signs in PTA
are directly related with the proportion of pulmonary to
systemic blood flow [7]. In the present case, due to intact
ventricular septum, there is insufficent blood flow to the both
pulmonary artery and aorta. Macroscopic lesions including
cyanosis, left to right shunting and pulmonary congestionedema were consistent with heart failure. Blood flowing
from right ventricle through TA enter either pulmonary
circulation or systemic circulation. Incase of pulmonary
Revue Méd. Vét., 2015, 166, 5-6, 122-126
CARDIOVASCULAR MALFORMATIONS IN A CALF
vascular resistance is not high, blood flows into pulmonary
circulation, and heart failure ensues and resulting in death
in a few days. When pulmonary hypertension is present,
desaturated blood from the right ventricle is ejected into
systemic circulation, resulting from hypoxemia and cyanotic
membranes [7]. In the present report, pulmonary circulatory
in adequancy and pulmonary hypertension were marked by
cyanosis and thickening of arterial wall and severe purulent
pneumonia. The occurence of pneumonia in present and
previous studies might be explained as a complication of
heart failure and pulmonary edema.
In humans; 42% of TA originates from the right ventricle,
42% of TA from left ventricle and 16% orginates from
interventricular septum [4]. Similar to presented case, TA
originated from the right ventricle is predominantly reported
form of PTA in animals [6, 7, 9, 13, 16, 17, 21, 25, 26].
The PTA is usually fetal in newborn period in animals.
In humans; 80% or more infants die within first year of life
without surgical intervention [24]. In animals, there are three
published PTA cases having long term survival including
a dog with Type-3 (8 years), in a cat with Type-1 (6 year)
and in a steer with Type-2 (2 years) [14, 21]. The common
malformation in all of these cases is a large ventricular defect.
Currently, pathogenesis of PTA is not fully understood,
but appears to involve the inhibition of the migration of
cardiac crest cells resulting in failure of septation of TA [22,
27].
The coronary artery arising from brachiocephalic artery
and absence of right coronary artery has never been reported
earlier either alone or simultaneously with PTA in animals.
However, a single coronary artery (like the present case)
arising from posterior aspects of truncus pulmonalis was
noted among the 4 of 30 human PTA cases, corresponding
13% of total cases [4]. As there is possibility of neural crest
involvement in coronary arterial systemdevelopment [18]
hence, it is also reasonable to assume that coronary artery
malformations could also arise as the same mechanism with
PTA.
In conclusion, the concurrence of type-1 PTA, left
ventricular hypoplasia, single right coronary artery and
anomalous origin of the right coronary artery was unusual in
many respects and combination of these factors along with
pneumonia might contribute to the early prenatal death in
the calf.
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