Pulmonary hypertension Flashcards
At the most basic level, what does pulmonary hypertension mean?
pressure in the pulmonary arteries
What is the most common cause of pulmonary hypertension and what group does this belong to?
Group 2 - pulmonary hypertension due to LEFT heart disease
> mechanism: elevated left atrial pressure goes to post capillary venues > alveolar bed > pulmonary vasculature = elevated pressure
What is the second most common cause of pulmonary HTN and what group does this belong to?
Group 3
- underlying lung disease & hypoxia
> COPD
> Intertistial lung diseases (related to cor pulmonale that is alteration in R heart structure + function due to a respiratory system disorder)
> obesity hypoventilation syndrome
What is group 1 pulmonary hypertension?
isolated pre-capillary PH (treated with vasodilators)
What is group 4 pulmonary hypertension?
pulmonary artery obstruction (most commonly due to thromboembolic disease)
In one sentence, summarise the 5 types of pulmonary HTN
What is the least common cause of pulmonary HTN?
- haematological conditions
- systemic conditions
(e.g. sarcoidosis)
List 3 causes of Type 1 pulmonary arterial hypertension
What pulmonary hypertension classification does sleep apnoea belong?
Thought to be group 5 - related to a metabolic type picture
Briefly describe Eisenmenger syndrome
Eisenmenger syndrome (ES) is a constellation of symptoms that arise from a congenital heart defect and result in large anatomic shunts. Due to anatomic variations present at birth, hemodynamic forces initially result in a left-right shunt, which develops into severe pulmonary arterial hypertension (PAH) and elevated vascular resistance. Ultimately, due to increased pulmonary vascular resistance, the left-to-right shunt will become a right-to-left shunt, resulting in significant hypoxemia and cyanosis
What is a common cause of idopathic pulmonary hypertension (group 1)
- genetic causes (e.g. BMPR2 mutation)
- note may be heriditary*
What are the key symptoms of pulmonary arterial hypertension?
- insidious onset of dyspnoea - months - years
- chest pain/fatigue
- syncope/pre-syncope in later disease stages
- evidence of right heart failure in advanced disease (peripheral oedema, liver congestion)
List the 3 main conditions associated with Group 2 pulmonary hypertension
- Heart failure
- HfpEF, HFref - Valvular heart disease
- congenitial/acquired cardiovascular conditions leading to post capillary HTN
Outline the pre-capillary vs. post-capillary conditions when classifying pulmonary HTN
Pre-capillary
- Group 1 - isolated pre-capillary PAH
- Group 4 - thromboelmbolic diseases
Post-capillary
- Group 1*
- Group 2 - secondary to LEFT heart disease most commonly
Group 3 sort of sits in the middle…
List 3 conditions associated with group 3 PH
List 4 types of conditions associated with ISOLATED pulmonary HTN
List 3 systemic conditions group 1 pulmonary HTN is associated with
- connective tissue disease (esp scleroderma)
- HIV infection
- porti-pulmonary HTN
- congenitial heart disease > resulting in Einsenmonger syndrome
- Schistomiasis
What group in the pulmonary HTN classification does Eisenmenger syndrome fall under?
- Group 1
- Eisenmenger syndrome is a condition that results from high blood pressure in the lungs (pulmonary hypertension) due to congenital heart disease (due to a shunt in most cases)
- Eventually, due to increased resistance and decreased compliance of the pulmonary vessels, elevated pulmonary pressures cause the myocardium of the right heart to hypertrophy (RVH). - The onset of Eisenmenger syndrome begins when right ventricular hypertrophy causes right heart pressures to exceed that of the left heart, leading to reversal of blood flow through the shunt (i.e., blood moves from the right side of the heart to the left side).
> As a consequence, deoxygenated blood returning from the body bypasses the lungs through the reversed shunt and proceeds directly to systemic circulation, leading to cyanosis and resultant organ damage
What key features of a clinical history would point to a diagnosis of pulmonary aterial hypertension (group 1)?
- consider this in patients with
> undifferentiated dyspnoea
> exercise limitation - onsent of dypnoea insidiously over months > years
- consider non-specific symptoms of fatigue/chest pain/pre-syncope/syncope
What clinical signs would point to advanced right heart failure?
- hepatic congestion
- raised JVP
- peripheral oedema
What is the key investigation that will aid/favour in a diagnosis of hypertension?
Echocardiogram!
When looking at an Echocardiogram to aid in the diagnosis of pulmonary HTN, what is the first parameter that would assist?
- peak tricuspid regurg velocity (probability of severe PH), not this is not diagnostic as it does not provide other data such as PAWP (which helps diagnose pulmonary venous hypertension)
- if this number is >2.8, which corresponds to a pulmonary artery systolic pressure of >35 this is suggestive of pulmonary HTN
*note estimate can be inacurate in patients with obesity or obstructive lung disease
List the haemodynamic parametres that assist with diagnosing the CLASS of pulmonary hypertension
- mPAP (mean pulmonary artery pressure) i.e. blood pressure in the pulmonary artery
- PAWP - surrogate for left ventricular end diastolic pressure (preload of LV) on a RIGHT heart catheter
- PVR - measurement of resistance of the pulmonary vascular bed to blood flow (wedge units)
What is the mean aterial pressure suggestive of pulmonary hypertension?
> 20 (new guidelines) and this is meausured by a RIGHT heart catheter
What is a pulmonary wedge pressure and what would >15 suggest (a PAWP>15)
- surrogate marker for LVEDP
- suggestive of component of LEFT heart disease
> should avoid vasodilator therapy in these patients (?reduce preload)*
When is a situation a patient with group 2 pulmonary HTN may not have an elevated wedge pressure?
- if they are adequately diuresied
- if risk factors > fluid challenge should be attempted
In terms of the pre-capillary PH causes, list the haemodynamic characteristics and which would be elevated
- mPAP >20
- PAWP <15 = note basically a NORMAL or LOW left atrial pressure (minimal blood flow into LA)
- PVR >2
*note other Ix should serve as an adjunct as patients with thromboembolic disease, ILD > may all look similar based on these numbers
What is IpCPH & what are the haemodynamic characteristics?
- this refers to ISOLATED post-capillary PH (as opposed to pre-capillary PH)
- PAP>20
- PVR<2
List 3 risk factors for left heart disease PH
- age >70 years
- systemic hypertension
- obesity
- glucose intolerance
- prior coronary intervention
A patient has a tricuspid jet velocity >2.8. What other echo parameters with increase the likelihood of a diagnosis of PH?
- right atrial dilation
- right ventricular (RV)/left ventricular basal diameter >1.0
- flattening of the interventricular septum
- decreased RV systolic function
What is the purpose of a right heart catheter?
- diagnoses PH
- clarifies the PH subtype
- stages disease severity
What is the cause of combined pre and post-capillary PH and what haemodynamic parametres would suggest this?
mPAP > 20
PAWAP > 20
PVR >2
Outline the non-pharmacological approach to group 1 pulmonary HTN
- avoid pregnancy
- O2 supplementation
- exercise program for patients that are deconditioned
Outline the pharmacological therapy associated with vasodilator therapies
3 pathways
> endothelian pathway using endothelian receptor antagonists
> Nitric oxide pathway using PDE5 inhibitors
> prostocyclin pathway
Acute phase/rapid progression (likely triple therapy)
- IV epoprostonol (prostocyclin pathway), short half life - GOLD STANDARD
- addition of PDE5 and NO inhibitor
Milder symptoms (low risk status)
functional class III without Right heart failure
- dual therapy > continue to assess
Explain why vasodilator therapy is not suitable for patients with Group 2 pulmonary hypertension
- In type 2 pulmonary HTN note there is fixed elevated post-capillary pressure arising from the LEFT atrium
- if vasodilators are prescribed this worsens the pressure gradient over the post capillary bed and can precipitate pulmonary oedema
Why are vasodilators contraindicated in patients with Group 3 pulmonary HTN?
Where does a right heart catheter start and what is the pressure in this region?
- RAP
- pressure range 0-8 mmHg
A right heart catheter has passed through the right atrium. It moves to where next and what is the pressure in this area?
- right ventricle
- systolic pressure 20-30 / diastolic pressure 0-8 (e.g. a reading could be 25/8)
A right heart catheter goes RA > RV > Pulmonary artery
What are the approximate pressures in the pulmonary artery?
Systolic - 20-30
diastolic - 8-15
A right catheter is eventually wedged into the pulmonary artery tree. What is this an estimation of ?
left atrial pressure (~8-10mmHg)
What two measurements obtained by a right heart catheter enable differentiation about the type of pulmonary hypertension?
- pulmonary artery pressure
- LVEDP (as estimated by the wedge pressure)
Explain the mechanism of pre-capillary pulmonary hypertension
- Blood without oxygen flows from the right side of the heart to the lungs. In the lungs, it receives oxygen in small vessels called capillaries. The oxygenated blood then flows from the lungs to the left side of the heart. The circulation of blood from the right side of the heart to the lungs to the left side of the heart is known as the pulmonary circuit.
- “Precapillary” means “before the capillaries” within the pulmonary circuit. Precapillary PH originates from problems in the pulmonary arteries.
What is the TPG (total pressure gradient) and how is this relevant in pre-capillary pulmonary HTN?
TPG = PAP - PAWP
In a precapillary scenario this is HIGH because the PAP is elevated, and the PAWP is usually low
What is the TPG and how is this relevant in post-capillary pulmonary HTN?
- High LA pressure > back pressure causes a high PA pressure
> normal TPG (as they are both proportionally high)
*note ePLAR ?surrogate marker for TPG in a TTE
How is the RVSP calculated?
- 4(TR Vmax) + right atrial pressure
list one example of a medication that is used for blockade of the endothelian pathway in group 1 pulmonary hypertension
- Ambriesantan
- Bosentan
- Macitentan
list one example of a medication that is used for blockade of the NO pathway in group 1 pulmonary hypertension
?PDE5 inhibitors
- Sidenafil
- Tadalafil
- Riociguat
What class of medication does Epoprostenol belong to?
Prostocyclin pathway
In what PH classification might you see a PVR<2
isolated post-capillary (in pre-capillary and combined pre & post capillary the PVR>2 wedge units)
A patient has a PAWP between 13-15. What might you do to distuguish if this is pre-capillary vs. post-capillary HTN?
Give a fluid challenge - if a component of LEFT heart disease (i.e. Group 2) this will cause the wedge pressure to increase
Outline why vasodilator therapy is contraindicated among patients with Type 2 pulmonary HTN
- fixed post-capillary pressure arising from the LEFT atrium
- vasodilator therapy will dilate the pre-capillary arterioles > pressure differential can precipitate pulmonary oedema
In a simplified sense, explain why in pre-capillary HTN, the LA pressure is low/normal
Due to high PAP, there is very minimal blood moving across to the left atrium
How do prostacyclin agonists work (used in type 1 PAH)
prostacyclin binding to GPCR leads to intracellular cAMP that activates protein kinase A -> inhibition of platelet aggregation, relaxation of smooth muscle and vasodilation of the pulmonary arteries
*note prostacyclin has a short half-life which makes its clinical use challenging
Examples: Epoprostenol & iloprost
suitable for patients with NHYA Class IV
Explain the mechanism of PDE-5 inhibitors in the treatment of PAH
Work by increasing the accumulation of cGMP in smooth muscle
- PDE5 degrades cGMP
- a PDE5 inhibitor prevents the degradation of GMP
- GMP causes activation of protein kinase G, leading to relaxation of vascular smooth muscle
- in pulmonary HTN, this allows vasodilation of the pulmonary arteries + inhibitions of remodelling of the pulmonary vasculature
PDE5 inhibitors are preferred in patients with NYHA class 2 or 3 with negative acute vasodilator response
Briefly describe the classes of NYHA Heart failure
List the PH categories that fall into PAWP <15 vs >15
