What is the normal PA pressure?
25 mmHg (systole)
What is considered PHT?
>30 mmHg (systole)
What is mild PHT?
What is moderate PHT?
What is severe PHT?
The lungs are _____ pressure, _____ resistance, _____ capacitance.
low, low, high
Which side of the heart is at a lower pressure than the other?
R side is much lower pressure than the L
What are the 4 causes of PHT?
- L-sided heart disease (MVDz, DCM)
- Chronic pulmonary disease (bronchitis, pulm fibrosis)
- Pulmonary thromboembolic disease
What causes idiopathic/primary PHT?
Retention of fetal PVR
What does L-sided heart disease lead to in terms of PHT?
pulm venous hypertension
What does chronic pulmonary disease lead to in terms of PHT?
Hypoxemia and vasoconstriction
What are some pulmonary thromboembolic diseases?
HWD, PLN, PLE, Cushings
What side of the heart has precapillary PHT?
What side of the heart has post-capillary PHT?
What is pre-capillary PHT?
Disease before the blood reaches the capillaries
What is post-capillary PHT?
High pressure after the capillaries that backed up across the capillary bed
All PHT causes are ____-capillary EXCEPT _____.
pre, L-sided heart disease
What happens to the pulmonary arteries/arterioles in PHT?
Medial hypertrophy of tunica media, intimal proliferation and fibrosis, plexiform lesions
What happens to the heart in PHT?
High RV afterload --> RV hypertrophy/dilation --> MPA enlargement --> tricuspid regurg --> pulmonic regurg --> IVS flattening/small LV
PHT occurs due to too much _____.
What are the CS associated with PHT?
Syncope, dyspnea, exercise intolerance cough (from underlying lung disease)
PHT is often misdiagnosed as _____ secondary to _____.
How can PHT be differentiated from L-CHF secondary to MVDz?
PHT primarily presents with syncope and exercise intolerance (MVDz is dyspnea and cough)
There is none or a SOFT murmur, R > L (LOUD murmur in MVDz)
Sinus arrhythmia or bradycardia (tachycardia in MVDz)
RV enlargement (vs. LA), pulm artery distention (vs. pulm veins)
What are some lateral radiographic findings that can point to PHT?
Lack of LA enlargement, apex of heart not touching sternum (due to RV enlargement pushing it up), enlargement of cranial lobar pulm artery
What are some VD radiographic findings that can point to PHT?
Bulge on MPA, generalized interstitial pattern (can be due to heartworm pneumonitis)
Doppler echo measures _____ of blood flow.
Velocity of blood flow is determined by _____ _____.
What is the modifed bernoulli equation?
PG = 4v2
We can estimate PA pressure using velocity of what two things?
Tricuspid regurg (systolic) or pulmonic regurg (diastolic)
How is PHT estimated echocardiographically?
High velocity of tricuspid regurg --> high RV systolic P --> high PA systolic P