Pulmonary Hypertension Flashcards
In people PH is defined as a PAP of or above XXXX
> 25 mm Hg
Postcapillary PH is defined as increased PAP + a PWP of above XXXX.
15 mm Hg
How does LHD lead to PH?
LHD causes volume overload of the LA –> will increase pulmonary venous pressure
initially should be without increase in pulmonary vascular resistance, but increased pressure can cause remodelling and constriction –> postcapillary can cause secondary precapillary PH
What are the 3 cardiovascular changes that can lead to PH?
- increased pulmonary blood flow (e.g., congenital shunt)
- increased pulmonary vascular resistance (e.g., PTE, pulmonary fibrosis, heart worm, etc.)
- increased pulmonary venous pressure (LHD)
Explain how you can extrapolate an approximate systolic PAP from an echocardiogram
with the modified Bernoullie equation
measure tricuspid valve regurgitation velocity (TRV)
Pressur gradient = 4 x TRV ^2
TRV in m/s
ideally for systolic PAP estimate need RA pressure, but no validated method to measure this on echo in SA, so this is ignored
What are factors besides PH that can influences and alter TRV?
pulmonary or tricuspid stenosis
RV function, pericardial restain
poor patient cooperation
labored brathing
What echocardiographic measurement can be used to estimate mean or diastolic PAP?
Pulmonary regurgitation jet velocity –> Mean PAP
add RA pressure –> diastolic PAP
List 4 changes to the ventricles that are indicative of PH
RV hypertrophy (dilation/eccentric or wall hypertrophy/concentratic)
ventricular septal flattening
LV underfilling/decreased size (not in LHD-induced PH)
RV systolic dysfunction
Name 4 changes to the PA on echo, indicative of PH
- PA enlargement PA:Ao > 1
- Peak early diastolic PR velocity > 2.5 m/s
- Right pulmonary artery distensibility < 30%
- lower RV outflow time, systolic notching of the doppler RV outflow
Name 2 changes to the RA and CVC on echo indicative of PH
RA enlargement
CVC enlargement
In addition to PH echo changes, what must be present on echo to identify LHD-PH?
- unequivocal LA enlargement
- signs of LHD (LV dysfunction or MV or AV disease)
List the 6 categories of PH classifications
Pulmonary hypertension
Vascular Occlusive disease
Left-heart disease
Respiratory disease
PTE
Parasites
Mxed
Fill in the blanks
What triscuspid regurgitation pressure gradient cutoff indicates at least moderate PH
> 46 mm Hg
What 2 breeds are predisposed to PH from interstitial lung disease?
West Highland White Terrier
Pekingese
What cardiac auscultation abnormalities may be heard with PH?
- right systolic murmur (TR)
- diastolic murmur if severe PH
- split second heart sound - takes longer to eject
Fill in the gaps
List 5 changes to thoracic radiographs indicative of PH
- tortuous/blunted/dilated pulmonary arteries
- Pulmonary trunk bulging
- assymmetric radiolycent lung fields on VD/DV
- patchy diffuse alveolar infiltrates
- R-sided cardiac enlargement
List 7 clinical changes indicative of HW disease
- hyperbilirubinemia
- Resp distress
- Coughing
- Exercise intolerance
- Ascites
- anemia
- collapse
Name 3 clinical changes indicative of Angiostrongylus disease
CNS signs
respiratory signs
bleeding diathesis
Name 8 risk factors (i.e. diseases) for PTE development
- IMHA
- PLN
- PLE
- heartworm disease
- hyperadrenocorticism
- sepsis
- neoplasia
- DIC
What are the 3 pathways leading to pulmonary arterial vasoconstriction?
- nitric oxide
- endothelin
- prostacycline
Name an alternative PDE5-i to sildenafil that has a longer half-life. Which medication is superior in clinical efficacy and outcome?
tadalafil
no difference in superiority of outcome
Explain the recommendations for PDE5-i administration in PH class 1d1
1d1 - congenital shunt
if left-to-right shunt –> occlusion is recommended and PDE5-i is not expected to make as much of a difference
if right-to-left –> initial PDE5-i therapy is thought to stabilize patient, may even reverse some shunt and may reduce risk of shunt occlusion
Explain how PDE5-i inhibitors may cause pulmonary edema in classes 1d1, 1’ and 2
pulmonary vasodilation can increased pulmonary blood flow –> will increase volume in LA and increase risk of pulmonary edema
What are situations when PDE5-i should be administered to PH class 2 patients
when there is concurrent precapillary PH, i.e., PVR is increased as well
What is the MOA of pimobendan and how does it presumably help with PH?
Increases efficacy of Ca+ binding to troponin C
PDE3-i
can help with RV systolic dysfunction
lowering LA pressure
What is the MOA of milrinone and how can it help with PH?
PDE3-i
pulmonary vasodilation
positive inotrope
What is the MOA of toceranib and imatinib?
tyrosine kinase inhibitor
How can arginine supplementation help with PH?
precursor for NO –> vasodilation
What is likely the most common cause of PH in dogs?
LHD
What is the Eisenmenger sign?
right-to-left shunt –> venous blood reaches circulation
causes polycytemia and cyanosis
What are the cutoffs for mild, moderate and severe PH by the PAP?
< 50
51-75
>75
How is NO produced and how does it induce vasodilation?
endothelial cells
L-arginine –> nitric oxide synthase –> NO
activates guanylyl cyclase –> GTP becomes cGMP
cGMP activates Protein kinase G –> reduces Ca++ in cytosol via SERCA upregulation –> vasodilation
How do phosphodiesterase inhibitors cause vasodilation?
phosphodiesterases inactivate cGMP –> inhibiting phosphodiesterases increases cGMP levels
What are 2 other functions of NO besides vasodilation?
inhibits platelet activation
reduces smooth muscle hypertrophy
Where is prostaglandin I2 produced and how does it cause vasodilation
produced in the vascular endothelial cells
actis with the cAMP pathway
What receptor does endothelin-1 bind to. What are its effects?
ETA - endothelin-1 A receptor
vasoconstriction
+ stimulates growth factors
Where is thromboxane produced, stored, and what are its effects?
produced in the platelets and stored there
vasoconstriction and platelet activation
How is serotonin produced, stored and what are its effects?
produced from tryptophan in GI tract –> stored in platelets
released after vascular endothelial damage –> vasoconstriction, vascular remodeling
What echo views can be used to measure TRV?
R parasternal basilar short axis
L parasternal long axis
What are clinical signs strongly suggestive or possible suggestive of PH?
strongly:
* syncope
* resp distress
* activity/exercise leads to resp distres
* R-sided HF (ascites)
possibly:
* tachypnea at rest
* increaed resp effort at rest
* prolonged post-exercise tachypnea
* cyanosis, pale gums
