SACCM 22: Pulmonary Hypertension Flashcards
What is the human mean pulmonary arterial pressure defining as pulmonary hypertension?
meanPAP > 25 mm Hg
cutoff fairly arbitrary, newer definition > 20 mm Hg
What are the 3 categoris of pulmonary hypertension etiologies?
- increased pulmonary blood flow (increased CO)
- increased pulmonary vascular resistance
- increased pulmonary venous pressure
What is Precapillary pulmonary hypertension
increased pulmonary vascular resistance without increased pulmonary venous pressure
typically from pulmonary vascular disease, vasoconstriction
What is postcapillary pulmonary hypertension?
increased pulmonary venous pressure from left-sided heart disease
What is reactive pulmonary hypertension?
postcapillary PH with secondary precapillary PH (from pulmonary arterial vasoconstriction and pulmonary vascular disease)
What are the characteristic changes to ventricles from pulmonary hypertension seen on echo?
- RV hypertrophy
- LV underfilling
- flattened interventricular septum
Besides characteristic changes to ventricles, what other findings on echo support pulmonary hypertension?
- pulmonary artery dilation and altered blood flow
- caudal vena cava and RA enlargement
How do you estimate systolic pulmonary arterial pressure?
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
For the RA to RV pressure gradient to assess degree of pulmonary hypertension, how do you classify mild, moderate, and severe?
- mild 30-50 mm Hg
- moderate 50-75 mm Hg
- severe > 75 mm Hg
What degree of tricuspid regurgitation velocity and echo changes gives you a high probability of pulmonary hypertension?
- 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
What are the 6 clinical groups of pulmonary hypertension according to the ACVIM consensus guidelines?
- Pulmonary arterial hypertension (PAH)
- Left-sided heart disease
- Respiratory diseae/ hypoxia
- Pulmonary thrombotic or thromboembolic disease
- Parasitic disease (HW or angiostrongyliasis)
- Multifactorial/unclear mechanism
What is the mechanism of action of sildenafil?
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
In what type of pulmonary hypertension is sildenafil contraindicated and why?
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