Respiratory

Question 1

What are the cut-offs for pulmonary arterial (PA) systolic and mean pressures that define pulmonary hypertension (PH)?

Answer 1

PA systolic > 30mmHg, PA mean >20mmHg

Question 2

List the 5 disease classes which can lead to pulmonary hypertension.

Answer 2

ACVIM consensus
Group 1 (pulmonary arterial hypertension) – primary diseases of the vasculature. E.g. idiopathic, familial, drugs/toxins, congenital heart disease (systemic-to-pulmonary shunts), HWD, veno-occlusive disease, persistent PH of newborns.

Group 2 (pulmonary venous hypertension) – left-sided heart disease & chronic increases in LA pressure. Valvular or myocardial dz. MOST COMMON in dogs.

Group 3 (PH associated with lung diseases or hypoxemia) – obstructive pulmonary disease, interstitial lung disease, alveolar hypoventilation, sleep apnea, chronic exposure to high altitude, developmental abnormalities.

Group 4 (PH associated with chronic thrombotic or embolic) – obstruction of proximal or distal PAs, non-thrombotic embolism (HWD or other parasites, neoplasia, foreign material – catheter or coil)

Group 5 (systemic & other disorders) – compression of pulmonary vessels, lymphadenopathy, neoplasia, fibrosing mediastinitis, granulomatous disease, others (histiocytosis, sarcoidosis, lymphangiomatosis)

Question 3

Bronchial collapse occurs most commonly in which regions?

Answer 3

L cranial & R middle bronchi

Question 4

Bronchial collapse occurs most commonly in which regions?

Answer 4

L cranial & R middle bronchi

Question 5

Thoracic radiographs most sensitive for the diagnosis of airway collapse in which regions of the lungs?

Answer 5

Sn for the detection of bronchoscopically identified collapse was highest for radiography at the trachea, left lobar bronchi & right middle bronchus. But relatively low Sp.

Question 6

What clinical sign can epiglottic entrapment of the soft palate cause?

Answer 6

Reverse sneezing

Question 7

How to calculate estimated systolic PA pressure from echo?

Answer 7

Measure TRV max
Modified Bernoulli equation:
Pressure gradient (aka estimated systolic PAP) = 4 x (TRVmax)^2 in mmHg

Question 8

ACVIM consensus panel’s definition (cut-offs) for pulmonary hypertension in dogs?

Answer 8

TR PG cut-off of >46 mmHg (TRVmax >3.4 m/s)
Defined as moderate PH historically

Question 9

Specific treatment for PH targets which 3 pathways?

Answer 9

ACVIM consensus.
NO, endothelin & prostacyclin pathways
These mediate pulmonary arterial/arteriolar vasoconstriction (secondary to endothelial injury).

Question 10

What is a rare disease to be suspected if a dog with pulmonary hypertension develops pulmonary oedema after sildanefil treatment? How does this occur?

Answer 10

ACVIM consensus
Pulmonary veno-occlusive disease or pulmonary capillary hemangiomatosis.
Also caution when administering PDE5-i in dogs with LHD & congenital shunts.

Reactive” or “responsive” pulmonary arteries (or arterioles) have an unpredictable response to tx. Increased right sided CO, acutely increases pulmonary VR to the LA&raquo_space; subsequently increase LA & thus pulmonary venous and capillary pressures&raquo_space; pulmonary oedema.

Question 11

What anti-neoplastic drug may be considered as an adjunct treatment for refractory PH in dogs & MOA? What evidence is there to support its efficacy?

Answer 11

ACVIM consensus
TKIs (e.g. toceranib, imatinib) - cause PA vasodilation by inhibiting action of PDGF (by inhibiting phosphorylation of PDGF-receptor TK). Used in people, little data in dogs, but imatinib reduced PAP in dogs with PH 2’ to LHD in 1 study.