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Surgery of Abdomen and Thorax Cavitities > Persistent Right Aortic Arch (PRAA) and Patent Ductus Arteriosus (PDA) > Flashcards

Persistent Right Aortic Arch (PRAA) and Patent Ductus Arteriosus (PDA) Flashcards

1
Q

What is a PRAA?

A

Persistent right aortic arch with left ligamentum arteriosum (PRAA) is a vascular anomaly of the thoracic great vessels, resulting in the oesophagus being encircled and constricted.

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2
Q

What is the most common (95%) vascular ring anomaly in dogs?

A

PRAA

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3
Q

Where does a PRAA extend between?

A

Left pulmonary artery and right aortic arch

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4
Q

What is encircled in a PRAA?

A

Oesophagus

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5
Q

What % of patients with a PRAA has a patent ligamentum arteriosum?

A

10%

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6
Q

When are PRAA clinical signs first identified?

A

At weaning as signs consistent with esophageal constriction

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7
Q

What is the treatment of choice for a PRAA? What is the approach made?

A

Ligation and surgical division of the compressive left ligamentum arteriosum via a left fourth intercostal thoracotomy or via a thoracoscopic approach.

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8
Q

How many primordial embryonic arches are there?

A

6

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9
Q

In an adult which primordial embryonic arches remain in original form?

A

3, 4, 6

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10
Q

What is the embryological cause of a PRAA?

A

The RIGHT 4th arch remains as the aorta (not the left)

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11
Q

What would prevent correction of a PRAA via a left lateral thoracotomy?

A

Concurrent presence of a L Cr vena cava

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12
Q

Clinical signs of a PRAA (5)

A
  • Postprandial regurgitation
  • Poor growth
  • Malnourishment despite a good appetite
  • Signs of aspiration pneumonia (e.g. coughing, pyrexia, dyspnoea)
  • German Shepherd dogs and Irish Setters are overrepresented.
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13
Q

What diagnostic tests aid PRAA diagnosis?

A
  • Serum haem and biocehm
  • Plain thorax x rays
  • Barium contrast study
  • Angiogrpahy (MRI/CT)
  • Oesophagoscopy
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14
Q

What is seen on haem/biochem with a PRAA?

A

Usually within normal limits, unless aspiration pneumonia or another comorbidity present.

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15
Q

What is seen on plain thorax x rays with a PRAA? (3)

A

Cranial oesophageal dilation
Identification of right descending aorta (which may also cause left tracheal deviation)
Aspiration pneumonia.

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16
Q

What is seen on barium contrast studies with a PRAA? (2)

A

Cranial oesophageal dilation
Oesophageal constriction at the level of the heart base.

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17
Q

What is seen on angiography (CT/MRI) with a PRAA?

A

Useful in identifying vascular ring anomaly.

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18
Q

What is seen on oesophagostomy with a PRAA? (2)

A

Aortic pulse on the right side of oesophagus
Extraluminal compression of oesophagus at level of heart base.

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19
Q

How successful is medical management of a PRAA?

A

Unrewarding because of progressive oesophageal dilation and regurgitation.

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20
Q

Prior to surgery of PRAA, what should be done? (2)

A
  • Malnourished animals should be fed liquid food from a height (or via a gastrotomy tube)
  • Aspiration pneumonia should be treated.
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21
Q

What needs to be monitored in surgery and in post op period? (think - age of patients)

A

Glucose

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22
Q

What is the surgical treatment including approach of a PRAA?

A

The treatment of choice is ligation and surgical division of the compressive left ligamentum arteriosum via a left fourth intercostal thoracotomy or via a thoracoscopic approach.

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23
Q

What else need to be divided in PRAA surgery which form under the ligamentum arteriosim?

A

Perioesophageal fibrous bands

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24
Q

What needs to be performed following PRAA surgery, but before routine closure of thoracotomy site?

A

Intraoperative oesophagoscopy and oesophageal balloon dilation should be performed to confirm that all the extraluminal oesophageal compression has been removed

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25
Following PRAA surgery, what is critical in the post-op care?
Fed liquid diets from a height
26
What does post op prognosis of PRAA depend on (4)
- Presence of aspiration pneumonia - Presence of oesophageal dysmotility, - Degree of oesophageal dilation - Concurrent systemic debilitation.
27
What are complications of PRAA surgery? High light most common
- Persistent regurgitation **** - Haemorrhage - Oesophageal perforation - Fibrotic bands remaining and constricting the oesophagus - Pain - Perforation/penetration of the vascular structures or lungs.
28
What is the effect of age at time of PRAA surgery on outcome?
No effect
29
What % of PRAA patients have a poor outcome? (still having daily regurg)
13%
30
With a PDA what happens if the pressure in the L heart is higher than the R?
Blood will flow from systemic to pulmonary circulations (‘left to right’)
31
What has developed with a PDA if the blood flow will reverse and travel from the pulmonary to the systemic circulations (‘right to left')?
Pulmonary hypertension
32
How can a PDA be closed? (3)
-O pen approach and surgical ligation, or preferably - Percutaneous placement of embolisation coils - Amplatzer ductal occluders.
33
Which sex is more likely to develop a PDA?
Female
34
Which dog breeds are predisposed to a PDA? (11)
Keeshonds Poodles Maltese Bichon Frises Yorkshire terriers Cocker Spaniels Pekingese Collies Shelties Pomeranians Welsh Corgis.
35
Which breed has shown heritability for a PDA? (3)
Poodle Welsh Corgi Dutch Stabyhoun
36
What is the role of ductus arteriosus in the uterus?
Carries blood from the pulmonary artery to the aorta, bypassing the not yet functioning lungs
37
When does the ductus arteriosus close?
Within the first week of life
38
What are the major causes of a PDA? (2)
-Smooth muscle hypoplasia -Asymmetry of the ductus tissue
39
If left untreated, most patients with PDA will...
Die within a year from progressive heart failure
40
What clinical signs do patients with a L-R PDA show?
Asymptomatic at first and then develop clinical signs associated with left-sided heart failure.
41
What is the main clinical sign of a R-L PDA?
Cyanosis
42
What is the main way to diagnose a R-L PDA?
Echocardiography with Doppler or bubble study.
43
Clinical signs of L-R PDA (5)
- Exercise intolerance - Cough - Exertional tachypnoea - Dyspnoea - Stunted growth
44
Clinical signs of R-L PDA (3)
- Exercise intolerance - Differential cyanosis - Pelvic limb collapse
45
What is seen on clinical exam with L-R PDA: A. Pulses B. Murmur
A. Hyperkinetic B. Continuous murmur at L heart based
46
What is seen on clinical exam with L-R PDA: A. Pulses B. Murmur C. MM
A. Normal B. None or a soft systolic at L heart base C. Brick red (Polycythaemia)
47
What is seen on thorax xrays with L-R PDA: A. Pulmonary vasculature? B. What is seen in DV? C. Which chambers are enlarged?
A. Enlarged B. Dilation of descending aorta C. L atria and ventricle
48
What is seen on thorax xrays with R-L PDA: A. Which chamber enlarged? B. Pulmonary artery? C. Pulmonary arteries?
A. R atria B. Marked dilation C. Enlarged/tortuous
49
What is seen on ECG with L-R PDA? (3)
- Tall R waves (>2.5mV) on lead II in some cases - Atrial fibrillation - Supraventricular and ventricular ectopic beats
50
What is seen on ECG with R-L PDA?
Right axis deviation and increased S wave amplitude due to right ventricular hypertrophy
51
Echocardiography of L-R PDA: A. .... ventricular hypertrophy B. Can you visualise PDA? C. Aortic ejection velocity? D. Doppler of pulmonary artery shows?
A. Eccentric left B. Yes C. Increased D. Reverse turbulent flow in pulmonary a.
52
Echocardiography of R-L PDA: A. Chamber changes? B. Can you visualize PDA? C. What interventricular change? D. Pulmonary artery
A. R atrial dilation and R ventricle hypertrophy B. Yes C. Septal flattening D. Dilated
53
Prior to L-R PDA shunt, what should be treated?
Clinical signs of CHF
54
What is the treatment for R-L PDA shunt?
Pulmonary hypertension (e.g. sildenafil) and polycythaemia (e.g. phlebotomy, hydroxyurea). DUCTAL OCCLUSION CONTRAINDICATED
55
What is treatment of choice in L-R PDA shunt?
Once stable - surgery.
56
What age can surgical ligation of PDA be performed?
8 weeks
57
Where is open surgery of PDA approached from?
4-5th intercostal thoracotomy
58
What is the anatomical landmark for a PDA? Where does this run in relation to PDA?
The vagus nerve travels along the ventral border of the aorta and is a landmark for identification of the PDA- the vagus nerve courses directly over and perpendicular to the PDA.
59
How is the vagal nerve handled in a PDA Sx?
Blunt dissect Retract dorsally (with a stay suture)
60
What should not be opened when isolated PDA with blunt dissection?
Pericardium
61
What ligatures are placed around PDA?
Non-absorbable ligatures (e.g. silk or polypropylene) are passed around the PDA and slowly tightened.
62
Why is it not advised to use haemostatic clips in PDA surgery? (2)
- Residual ductal flow - Recanalisation
63
Tie 2 sutures for PDA, which is tied first?
Closest to aorta
64
What effect should resolved straight away when tying off PDA?
No palpable thrill associated with PDA
65
When tying ligature for PDA, at least this is done slowly - why?
HR and BP
66
What is surgical mortality of PDA?
0-7%
67
Possible complication of surgical ligation of a PDA? (5)
- Intraoperative haemorrhage - Recanalisation of the ductus - Recurrent laryngeal nerve injury - Left atrial herniation - Ductus aneurysmal rupture.
68
How can complications of PDA repair be reduced?
Serious complications (e.g. death) are reduced with percutaneous occlusion (<1%) compared with an open approach.
69
Possible Amplatzer complication
- Device embolisation = detah/cardiac perforation
70
How many dogs with coil embolisation has residual ductal flow?
<5%
71
Possible complications of coil embolisation (6)
- Accidental pulmonary artery embolisation (not typically associated with adverse effects in dogs); - Significant residual ductal flow requiring a second coil embolisation procedure; - Severe femoral artery haemorrhage; - Late pulmonary artery embolisation requiring second procedure (surgical ligation); - Partial aortic deployment; - Haemolysis.
72
How many patients have complete PDA occlusion with amplatzer?
100%

Surgery of Abdomen and Thorax Cavitities (10 decks)

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