Cardiology

Question 1

Define pulmonary hypertension

Answer 1

Pulmonary arterial systolic pressure >30 mmHg

Question 2

Name 3 mediators of pulmonary vasoconstriction

Answer 2

Alveolar hypoxia, endothelin-1, and thromboxane A2

Question 3

Name two mediators of pulmonary vasodilation

Answer 3

Prostacyclin, nitric oxide (NO)

Question 4

Vasoconstrictors tend to have what effect on platelets?

Answer 4

Platelet agonists that promote coagulation (thromboxane A2)

Question 5

How does nitric oxide promote vasodilation? What limits it’s action?

Answer 5

NO activated cGMP => vasodilation. Phosphodiesterase 5 (PDE5) inactivates cGMP to limit vasodilation

Question 6

What is the mechanism of action of sildenafil?

Answer 6

Phosphodiesterase 5 (PDE5) inhbitor => vasodilation/prolonged vasodilation

Question 7

What are the six classifications of pulmonary hypertension? Give an example for each

Answer 7

1. PH due to pulmonary arteriolar vascular disease (idiopathic, congenital systemic to pulmonary shunts, genetic disease)
2. PH due to pulmonary venous hypertension (left sided heart disease)
3. PH with pulmonary disease/hypoxia (pulmonary fibrosis, neoplasia, edema)
4. PH due to thromboembolic disease (PTE)
5. Parasitic disease (heartworm, Angiostrongylus)
6. Miscellaneous or multifactorial (compression due to neoplasia)

Question 8

Peak regurgitant flow velocity of the tricuspid valve can be used estimate pulmonary arterial pressure. What is the equation?

Answer 8

pressure gradient = 4 x (peak velocity)2

Question 9

Name 3 other echocardiographic findings in pulmonary hypertension

Answer 9

RV concentric/eccentric hypertrophy, RA enlargement, septal flattening, RV systolic dysfunction, enlargement of the pulmonary artery

Question 10

Definitive diagnosis of pulmonary hypertension would require what diagnostic?

Answer 10

Right heart catheterization and direct pressure measurements

Question 11

While treatment with sildenafil has been shown to improve clinical signs and QOL, it may not improve what?

Answer 11

Pulmonary arterial pressure (as estimated by tricuspid valve regurgitation). Depends on the study. One study showed improvement (83 to 55mmHg)

Question 12

What drug may be used instead of sildenafil and has a longer half life (q24 hour dosing)?

Answer 12

Tadalafil

Question 13

In dogs with congenital shunts or left sided heart disease, sildenafil should be used with caution. Why?

Answer 13

Can lead to acute pulmonary edema

Question 14

Cardiac troponin n is a biomarker of what?

Answer 14

Cardiac cellular injury

Question 15

In one study of dogs with PH due to respiratory disease, how many dogs died within one month? 50% mortality was reached when?

Answer 15

32% died in the first month. 50% by 6 months after diagnosis

Question 16

Of dogs with bronchomalacia, what percent had an intermediate or high probability of PH?

Answer 16

40%

Question 17

What is pulmonary veno-occlusive disease?

Answer 17

Occlusive remodeling of small and medium pulmonary veins

Question 18

What is pulmonary capillary hemangiomatosis?

Answer 18

An angioproliferative disorder characterized by proliferation of alveolar capillaries, which may infiltrate into pulmonary veins and bronchioles

Question 19

What is the typical signalment of dogs with either pulmonary veno-occlusive disease or pulmonary capillary hemangiomatosis

Answer 19

Older, present with acute respiratory signs (typically respiratory distress)

Question 20

What is the typical survival time of dogs with either pulmonary veno-occlusive disease or pulmonary capillary hemangiomatosis?

Answer 20

3 days median survival