Page 198 - Clinical Manual of Small Animal Endosurgery

186 Clinical Manual of Small Animal Endosurgery

As for other thoracoscopic procedures, patient positioning and port-
site selection are dependent on the anticipated pathology and its location,
guided by the results of preoperative imaging. In cases of diffuse pathol-
ogy, or uncertainty as to which hemithorax is affected, a dorsal recum-
bency approach is recommended to allow examination of both sides of
the chest.

Pericardiectomy

Thoracoscopic pericardiectomy is arguably the best-established and
-evaluated of veterinary thoracoscopic procedures (Jackson et al., 1999;
Walsh et al., 1999; Dupre et al., 2001; Radlinsky, 2008; Mayhew et al.,
2009). The decrease in postoperative pain and stress is well established
(Walsh et al., 1999), and the procedure is regarded as the standard of
care for pericardiectomy (Radlinsky, 2008). A partial or pericardial
window procedure may be performed in either lateral or dorsal recum-
bency, while a subtotal (sub-phrenic) pericardiectomy requires dorsal
recumbency. Dorsal recumbency has the further advantage of not neces-
sitating single-lung ventilation (see below).
While a lateral approach from either side is possible if performing a
pericardial window, the left lateral approach gives access to the right
atrial appendage and base of the aorta for evaluation of possible neo-
plasia. Several different lateral recumbency port placements have been
described, including the third, fourth and fifth intercostal spaces; second,
fifth and ninth intercostal spaces; fourth, sixth and eighth intercostal
spaces; or the fourth, sixth and tenth intercostal spaces (Radlinsky,
2008).
Dorsal recumbency is the position of preference in the majority of
cases. This allows an examination of both sides of the chest, and allows
a subtotal pericardiectomy to be performed. While many veterinary texts
advise a technique using a paraxiphoid transdiaphragmatic approach to
placement of the primary optical trocar, the author favours an alternative
technique. A soft cannula with a blunt trocar is inserted in the left mid
chest (typically sixth or seventh intercostal space) dorsal to the costo-
chondral junction. After a brief initial examination of the chest, the next
two ports are inserted under visual guidance, as far caudally and ventrally
as feasible on either side of the chest. There is marked anatomical varia-
tion between different large dog breeds, and this visually directed variable
placement is more helpful than identical placement in differing patients.
The endoscope is then transferred to the left caudal port, but instruments
and endoscope can be alternated between the different ports if needed.
In performing a subtotal pericardiectomy, a fourth port placed in the
ventral mid right chest is useful and, in conjunction with a second pair
of grasping forceps and alternating the endoscope between ports, can aid
more rapid completion of the procedure. In dorsal recumbency the heart
flops dorsally, which inexperienced surgeons may find disorientating.