Chapter 26 - Pulmonary thromboembolism

Question 1

Obstruction of the pulmonary vascular bed can occur due thromboembolism (PTE). List 4 other causes of pulmonary vascular obstruction.

Answer 1

fat emboli
septic emboli
metastatic neoplasia
parasites (Dirofilaria or Angiostrongylus)

Question 2

Embolus formation in PTE most commonly occurs at which 2 locations?

Answer 2

Right side of heart
Distant site of venous system
(in situ is less common, associated with PH, HW dx, other disorders of pulmonary vasculature)

Question 3

List 9 risk factors for PTE

Answer 3

IMHA
Neoplasia
Sepsis
PLE/PLN
Amyloidosis
Cardiac disease (DCM in dogs, HCM, RCM in cats)
Hyperadrenocorticism
Central catheter use (hemodialysis, TPN)
Hip replacement surgery (cemented)
Trauma

Question 4

Why is necropsy confirmation of PTE difficult?

Answer 4

50% dissolution of clot w/in 3 hrs (smaller clot volume if on heparin)

Question 5

PTE often leads to hyperventilation. Which mechanisms may contribute to hyperventilation in dogs with PTE?

Answer 5

1. hypoxemia
2. bronchoconstriction
3. concurrent CNS embolisation
4. reduced lung compliance
5. platelet aggregation

Question 6

In a retrospective study of 29 dogs with PTE, how many had abnormal neurological status?

Answer 6

> 1/3

Question 7

What two laboratory findings were suggestive of PTE in dogs with IMHA in one case series?

Answer 7

Hyperbilirubinemia

Negative Coomb’s test

Question 8

What percentage decrease of antithrombin III may increase risk of embolic complications?

Answer 8

50-75%

Question 9

PTE can be excluded as a DDx if D-dimer concentration is normal. True/False.

Answer 9

False. Human study found negative D-dimer ruled out 93% of large pulmonary emboli, 50% of sub segmental emboli. Doesn’t conclusively rule it out.

Question 10

List 3 echocardiographic findings of acute ventricular overload.

Answer 10

right ventricular hypokinesis/dilation
paradoximal septal motion
tricuspid regurgitation

Question 11

How is PTE definitively diagnosed in human med?

Answer 11

Selective pulmonary angiography (more recently contrast angiography during CT)

Question 12

In current human guidelines, what are the criteria for thrombolysis in PTE?

Answer 12

Massive PTE (= PTE + hypotension or cardiogenic shock) or PTE associated with R ventricular enlargement/hypokinesis.