Page 208 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

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

because the duration of anaesthesia required for tube
placement is similar to that for division of the ligamentum.
VetBooks.ir means to improve swallowing function.
It is preferable to address the underlying cause as a

Surgical management of PRAA
Division of the ligamentum arteriosum in a dog with PRAA
can be achieved via a left fourth intercostal thoracotomy
incision (Figure 15.7a) or using thoracoscopic dissection
during anaesthesia with one-lung ventilation. With PRAA,
the trachea is often the most immediately identified struc-
ture dorsal to the heart base and to the left of the (right-
sided) aorta. This surgical finding confirms the diagnosis
of PRAA. Identification of the oesophagus can be facili-
tated by having an oesophageal tube in place. Typically,
the ligamentum arteriosum, which completes the constric-
tive ring around the oesophagus and trachea, can be
palpated either between the pulmonary artery and the
aorta or, occasionally, between the pulmonary artery and
an aberrant left subclavian artery (Figure 15.7b). The liga-
mentum is dissected free by blunt dissection using right-
angled Mixter or Lahey forceps. Once encircled, the
ligamentum is divided between ligatures and any residual
fibrous tissue constricting the oesophagus is also divided.
If an aberrant left subclavian is identified wrapping around,
and constricting, the oesophagus in the cranial thorax, it
can also be divided between secure (double) ligatures, to
release the oesophagus further. A large-bore stomach
tube is then gently guided along the oesophagus beyond
the vascular ring to confirm that there is no further con-
striction (Figure 15.7c). The chest is closed in a routine
In a dog with persistent right aortic arch, the aortic root (Ao)
15.5 can be seen to the right of the trachea, causing an abrupt manner over a thoracostomy tube. In severely emaciated
deviation in the airway that can be seen on good-quality dorsoventral animals, a surgical gastrostomy tube is placed upon com-
thoracic radiographs exposed (or digitally post-processed) to visualize pletion of the thoracotomy, to aid enteral nutrition in the
the mediastinum. The deviated right tracheal wall and the oesophagus postoperative recovery period.
are delineated by arrows.
Postoperative care
Routine post-thoracotomy care is recommended (see
Chapters 1 and 11). The thoracostomy tube is maintained
until the thorax is completely evacuated, then it is removed.
Because oesophageal dysfunction persists in the short
term, and may persist in the longer term, feeding liquidized
food from an elevated position and ensuring the animal
remains upright for a period of several minutes (up to 20
minutes has been recommended) must be continued after
surgery. Once it is clear that the animal can tolerate this
food consistency and feeding method, the food consis-
tency and feeding pattern may be changed. The process
of trialling foods of different consistencies and different
periods of time in an elevated position is continued over a
period of weeks to months to work out the optimal regime
Barium oesophagogram with liquid barium mixed with food in for each animal.
15.6 a dog with persistent right aortic arch. The oesophagus
cranial to the heart base is dilatated and there is a narrowing of the
oesophagus at the base of the heart. Barium and food are also in the Outcome of PRAA division
caudal oesophagus and the stomach. Fluoroscopy can help evaluate
motility in the caudal oesophagus. As previously mentioned, the majority of dogs that undergo
division of PRAA will be substantially improved by surgery
and many will become ‘trouble-free’ in terms of oesopha-
geal function. Occasionally, animals will continue to require
animal tolerates liquid feeding better than solid feeding, a feeding of soft food from an elevated position followed by a
return to a calorie-dense liquid diet fed from an elevated period of ‘front end’ elevation after feeding to allow gravity
position may help the animal recover by increasing to assist the persistently compromised oesophageal motil-
energy intake and decreasing the frequency of regurgita- ity (Figure 15.8). If the owners are prepared to facilitate
tion episodes. The author has stopped short of surgical this lifestyle modification, these dogs can have an excellent
placement of a gastrostomy tube to provide enteral nutri- quality of life too, although ‘dietary indiscretion’ will fre-
tion prior to surgical management of the vascular ring, quently be followed by a bout of regurgitation.

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