Pulmonary hypertension Flashcards
(36 cards)
What is the definition of pulmonary hypertension in people?
mean pulmonary arterial pressure (PAP) ≥ 25 mm Hg at rest measured invasively by right heart catheterization.
What is pulmonary hypertension?
abnormally increased pressure within the pulmonary vasculature
What are the 3 hemodynamic classifications of PH?
1) increased pulmonary blood flow (CO)
2) increased pulmonary vascular resistance (PVR)
3) increased pulmonary venous pressure
What is precapillary PH? What are it’s two main causes?
PH due to increased PVR in absence of increased PVP
- vasoconstriction
- structural pulmonary arterial changes due to pulmonary vascular disease
What is postcapillary PH?
PH due to increased PVP (= pulmonary venous hypertension)
- left sided heart disease
- increased LA pressure
–> ultimately increases the load the RV has to pump through the pulmonary circulation
What are some sequelae of chronic postcapillary PH?
- pulmonary arterial vasoconstriction
- pulmonary vascular disease
–> both increase PVR
What is “reactive” PH?
A combination of pre- and postcapillary PH secondary to chronic post-capillary PH due to severe left sided heart disease causing an increase in PVR.
What are the effects of increased PVR and PAP on the RV?
- increased RV afterload –> mixed hypertrophy (thickening + dilation)
- Sustained high PAP –> RV dysfunction or failure
Clinical manifestation: R-CHF (elevated systemic venous pressures, pleural and/or abdominal effusion)
What are causes of stustained increases of pulmonary arterial pressure (PAP)?
- Pulmonary artery (arteriolar) vasoconstriction
- Pulmonary arterial remodeling/vascular disease
- Increased pulmonary blood flow (e.g., left-to-right cardiac shunt, or chronically increased PVP from left-sided heart disease)
What causes increased PVP in left-sided heart disease?
- reactive vasoconstriction
- pulmonary vascular disease
–> wall stiffening
–> endothelial dysfunction
–> vascular inflammation
–> thrombosis
–> fibrosis
What ist the gold standard for assessment of PH?
Right heart catheterization with direct assessment of PAP and pulmonary artery wedge pressure (surrogate of LA pressure) –> CO can be measured + PVR calculated
Name 4 clinical findings strongly suggestive of PH
- Syncope (esp. exertion/excitement related)
- Respiratory distress at rest
- Activity/exercise terminating in respiratory distress
- R-CHF (aszites)
Name 3 clinical findings possibly suggestive of PH
- Tachypnea at rest
- increased respiratory effort at rest
- Prolonged postexcercise/activity tachypnea
Name 3 reasons for increased pulmonary blood flow
- left-to-right-shunt due to intra- or extracardiac defects (e.g. ASD, VSD, PDA)
Name 9 reasons for increased pulmonary vascular resistance
- Pulmonary arterial (arteriolar) vasoconstriction
- Pulmonary arterial thrombosis
- Pulmonary endothelial dysfunction
- Pulmonary vascular remodeling
- Perivascular inflammation
P6. ulmonary vascular luminal obstruction - Increased blood viscosity
- Pulmonary arterial wall stiffening
- Pulmonary parenchymal destruction
Name 2 reasons for increased pulmonary venous pressures
- Left heart disease (e.g., MMVD)
- Compression or stenosis of a large pulmonary
vein(s)
What 2 key components does echocardiography rely on for diagnosing PH?
- characteristic cardiac changes that occur secondary to PH (=echocardiographic signs of PH)
- estimates of systolic PAP using Doppler echocardiography
Name 6 echocardiographic findings that are indicative of PH
- RV hypertrophy
- RV systolic dysfunction
- LV underfilling
- flattening of the interventricular septum
- pulmonary artery dilation + altered blood flow profile
- RA/caudal vena cava enlargement
How can systolic PAP be estimated using echocardiography?
- quantifying peak tricuspid regurgitation velocity (TRV)
- conversion of TRV to a pressure gradient (between the RA and RV in systole) using the simplified Bernoulli equation
What equation can be used to quantify systolic PAP on echo?
Simplified Bernoulli equation
What is the simplified Bernoulle equation?
pressure gradient = 4x Velocity (m/s)^2
How can the degree of PH be quantified using a pressure gradient betweent the RA and the RV?
mild: 30-50mmHg
moderate: 50-75mmHg
severe: >75mmHg
What are is the clinical classifications scheme proposed by the ACVIM consensus guidelines for PH?
1) pulmonary arterial hypertension (PAH)
2) left-sided heart disease
3) respiratory disease/hypoxia
4) pulmonary thrombotic or thromboembolic disease (PT/PTE)
5) parasitic disease (heartworm or Angiostrongylus)
6) multifactorial (≥2 categories) or unclear mechanisms
What 2 criteria must be met for PH to be classified as secondary to left-sided herat disease?
1) documentation of LHD
2) documentation of unequivocal LA enlargement (curde surrogate marker for elevated LA pressures)
