Pulmonary Hypertension & PTE Flashcards
pulmonary hypertension
abnormally increased blood pressure in the pulmonary vasculature
MANY underlying causes
how does pulmonary hypertension lead to R-CHF
increased pulmonary pressure –> pressure overload on the RV –> RV concentric hypertrophy –> R-CHF
factors that contribute to developing pulmonary hypertension
- increased pulmonary blood flow
- increased pulmonary vascular resistance
- increased pulmonary venous pressure
causes of PH
- pulmonary arterial hypertension
- left heart disease
- respiratory disease or hypoxia
- pulmonary thromboembolism
- parasitic disease
- multifactorial or unclear mechanisms
causes of pulmonary arterial hypertension
L to R cardiac shunts
- PDA, VSD, ASD
chronic overcirculation –> severe pulmonary hypertension –> remodelling of vasculature
how does left heart disease cause PH
POSTCAPILLARY CAUSE
- MMVD, DCM, congenital, endocarditis
severe L heart disease –> increased LA pressure –> increased pulmonary pressures
treating L heart disease should resolve PH
how does respiratory disease/hypoxia cause PH
chronic respiratory disease –> damage to and remodeling of the pulmonary vasculature –> pulmonary hypertension
how does pulmonary thromboembolism cause PH
acute or chronic thromboemboli that obstruct the pulmonary vessels prior to the level of the capillaries
how does parasitic disease cause PH
heartworm disease
even once resolved –> can cause chronic damage to vasculature that requires treatment
clinical signs of pulmonary hypertension
- syncope
- respiratory distress
- tachypnea + increased effort at rest
- R-CHF
- ascites, hepatomegaly, jugular venous distention, pleural effusion - cyanotic or pale MM
- +/- cough
- +/- heart murmur
how is PH diagnosed
echocardiography
gold standard is a direct PAP (pulmonary arterial pressure) measurement but is rarely done b/c invasive
how to diagnose PH on echocardiogram
measure tricuspid regurgitation velocity
ESTIMATES peak RV systolic pressure
- deltaP = 4 x tricuspid regurg velocity^2
- RVSP = deltaP + (5 to 10)
- RVSP = sPAP
only if NO pulmonary stenosis on echo
normal systolic pulmonary arterial pressure (sPAP)
25 mmHg
normal TR velocity
<3 m/s
what tricuspid regurgitation velocity is suggestive of PH
> 3.4 m/s
additional signs of pulmonary hypertension on echo
RV concentric hypertrophy
septal flattening
RV systolic dysfunction
elevated RA pressure
how are thoracic radiographs used for pulmonary hypertension
evaluate for causes of PH that are not heart disease
pulmonary hypertension treatment
Sildenafil
&
treat underlying cause
- LCHF: furosemide, pimobendan, spironolactone, enalapril
- shunts: surgical closure
- HW: hw treatment
- PTE: antithrombotics
right heart support - pimobendan, furosemide
sildenafil
phosphodiesterase 5 inhibitor - prevents the breakdown of cGMP in the lung vasculature
effects:
- vasodilation
- antiproliferation
- antithrombotic
do NOT use if evidence of L heart disease or L-CHF
how to monitor response to therapy of PH
improvement of clinical signs
can NOT use tricuspid regurge velocity - will not change significantly
can monitor echo for changes to R heart
how are pulmonary thromboembolisms formed
virchow’s triad
1. stasis of blood flow
2. endothelial damage
3. hypercoagulability
what are risk factors for developing a PTE
- glucocorticoids
- recent surgery
- IV catheters
- cytotoxic drugs
diagnosis of PTE
- coagulation tests - TEG, D-dimers
- CT angiography
not always visible on thoracic rads or echo
PTE treatment
antithrombotics - clopidogrel
thrombolysis - tissue platelet activator
- treat hemodynamic instability/shock
- O2 supplementation
- control primary disease
- IMHA, PLE/PLN, Cushings, feline heart disease, sepsis/SIRS, neoplasia, HW
