SACCM 22: Pulmonary Hypertension

Question 1

What is the human mean pulmonary arterial pressure defining as pulmonary hypertension?

Answer 1

meanPAP > 25 mm Hg

cutoff fairly arbitrary, newer definition > 20 mm Hg

Question 2

What are the 3 categoris of pulmonary hypertension etiologies?

Answer 2

• increased pulmonary blood flow (increased CO)
• increased pulmonary vascular resistance
• increased pulmonary venous pressure

Question 3

What is Precapillary pulmonary hypertension

Answer 3

increased pulmonary vascular resistance without increased pulmonary venous pressure

typically from pulmonary vascular disease, vasoconstriction

Question 4

What is postcapillary pulmonary hypertension?

Answer 4

increased pulmonary venous pressure from left-sided heart disease

Question 5

What is reactive pulmonary hypertension?

Answer 5

postcapillary PH with secondary precapillary PH (from pulmonary arterial vasoconstriction and pulmonary vascular disease)

Question 6

What are the characteristic changes to ventricles from pulmonary hypertension seen on echo?

Answer 6

• RV hypertrophy
• LV underfilling
• flattened interventricular septum

Question 7

Besides characteristic changes to ventricles, what other findings on echo support pulmonary hypertension?

Answer 7

• pulmonary artery dilation and altered blood flow
• caudal vena cava and RA enlargement

Question 8

How do you estimate systolic pulmonary arterial pressure?

Answer 8

With the modified Bernoulli equation calculate RA to RV pressure gradient –> the higher, the more PAP
Pressure gradient = 4 x velocity [m/s]2
* velocity here: measured peak tricuspid regurgitation velocity

Question 9

For the RA to RV pressure gradient to assess degree of pulmonary hypertension, how do you classify mild, moderate, and severe?

Answer 9

• mild 30-50 mm Hg
• moderate 50-75 mm Hg
• severe > 75 mm Hg

Question 10

What degree of tricuspid regurgitation velocity and echo changes gives you a high probability of pulmonary hypertension?

Answer 10

• TRV higher than 3.4 m/s + 1 or more changes on echo
• TRV 3.0 - 3.4 + 2 or more changes on echo
• TRV < 3.0 or not measurable + 3 changes on echo

Question 11

What are the 6 clinical groups of pulmonary hypertension according to the ACVIM consensus guidelines?

Answer 11

1. Pulmonary arterial hypertension (PAH)
2. Left-sided heart disease
3. Respiratory diseae/ hypoxia
4. Pulmonary thrombotic or thromboembolic disease
5. Parasitic disease (HW or angiostrongyliasis)
6. Multifactorial/unclear mechanism

Question 12

What is the mechanism of action of sildenafil?

Answer 12

phosphodiesterase-5 inhibitor -> inhibits cGMP metabolism -> will cause accumulation of cGMP in pulmonary vascular smooth muscle cells
-> relaxation of smooth muscles and inhibition of hypertrophy

Question 13

In what type of pulmonary hypertension is sildenafil contraindicated and why?

Answer 13

PH from left-sided heart disease
sildenafil will increase right-sided CO in these patients due to decreased afterload -> increased venous return to the LA -> increased PA, pulmonary venous and pulmonary capillary pressure -> iatrogenic pulmonary edema