Page 204 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

Chapter 15 · Surgery of the heart, pericardium and great vessels

is complete, the sternopericardial ligament must be cut, Postoperative care
preferably using electrosurgery, and the pericardium can The thoracostomy tube is maintained until the thorax is
VetBooks.ir must be carefully evaluated, especially the mediastinal completely evacuated and until the volume of fluid produc-
be removed (Figure 15.3). The site of pericardial excision
tion has fallen to an acceptable level. Routine post-thora-
reflections, as small bleeding vessels that require attention
cotomy care is recommended (see Chapters 1 and 11).
can be hidden within mediastinal fat. The thorax should be
flushed with sterile saline and a thoracostomy tube placed.
Patent ductus arteriosus
Thoracoscopic pericardial window and subtotal
pericardectomy The ductus arteriosus, which joins the descending aorta to
The thoracoscopic creation of a pericardial window is, the left main pulmonary artery, is required in the develop-
perhaps, most appropriate for palliation in older dogs with ing fetus to allow blood ejected by the right ventricle to
slow-growing tumours of the aortic body (chemodectoma) avoid the highly resistant pulmonary vasculature and gain
that have developed tamponade. In addition, subtotal (sub- access to the systemic circulation (right to left shunt) in
phrenic) pericardectomy can be performed on dogs with order for the fetus to receive oxygen from the placenta.
presumed idiopathic pericardial effusions. The techniques Normally, the ductus should close in the first few days of
can be performed from a lateral or ventral approach, extrauterine life, in response to changes in blood oxygen
although the author has only performed this from a ventral content and reduced resistance to blood flow associated
approach with the camera in a subxiphoid position and two with lung ventilation. If this closure mechanism fails, the
ports for surgical manipulation, one on either side of the ductus remains patent (PDA) and, providing the pulmonary
thorax in the sixth or seventh intercostal position. vasculature has developed normally, blood flow through
the ductus typically reverses (i.e. becomes left to right),
creating a relative overload of the pulmonary vasculature,
Complications left atrium and left ventricle. This overload can ultimately
Potential complications associated with subtotal pericard- lead to fatal left heart failure, if left untreated.
ectomy include: haemorrhage; cardiac herniation (through James Buchanan (Buchanan, 1978, 2001) described
a restrictive pericardial window); phrenic nerve injury; and the anatomy of the ductus arteriosus in a series of animals
recurrence of either pericardial or pleural effusion. with naturally occurring PDA. His description of the overall

(a) (b)

(c) (d)
a The vie from a right fifth intercostal thoracotomy in a dog undergoing open subtotal pericardectomy. ericardial fluid is seen gushing
15.3
from a small incision in the pericardium made almost immediately on entry to the thora to relieve any tamponade. The phrenic nerve can
also be seen. b The phrenic nerve has been dissected free of the pericardium and is gently held dorsally using a silicone vessel loop. ilk stay sutures
are holding the pericardium open after a vertical incision has been made from the base to the ape of the pericardial sac. c levation of the phrenic
nerve allo s the T-shaped incision to be made close to the dorsal pericardial reflection. If the left phrenic nerve can be isolated in a similar ay the
incision in the pericardium is continued at this level all the ay around the base of the heart. d nce removed the pericardium is inspected and a
sample of tissue submitted for microbiological analysis ith the remainder submitted for histopathological analysis. It is good practice to submit pleural
biopsy specimens and sternal lymph node samples from dogs ith presumed idiopathic disease.

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