PAH 1 Flashcards
What is the pulmonary circulation and what important aspects of it are there
- Makes up half of the body’s total blood supply and is designed to push blood through thin-walled areas at a low pressure to allow proper exchange of gases
Clinical threshold for PAH?
Bp >25mmHg
Causes of PAH?
Shunting (hole in septum of heart causes blood to move from LHS to RHS)
Thrombus formation
Vascular remodelling
Sustained pulmonary vasoconstriction
Concequences of PAH?
Right Ventricular Hypertrophy
Right heart failure
High death rates and morbidity
Symptoms of PAH
Syncope, shortness of breath, breathlessness, chest pain
How might you investigate a patient for PAH? why
ECG - strains in blood supply can be identified from current patterns
Lung function tests
X ray - check for blood vessel enlargements and vessel malformations
Echocardiograms - unusual structure of heart
RIGHT HEART CATHETERISATION!
Equation for pulmonary vascular resistance?
Pulm vascular resistance = (mPAP - PAWP) / CO
mPAP - mean pulmon arterial pressure
PAWP - pulmonary arterial wedge pressure (approximate to the LV filling pressure)
Catheter clinical thresholds for PAH?
mPAP = >25mmHg PVR = More than 3 woods units PAWP/LVEDP = <15mmHg
PH classifications - treatable
1) chronic thromboembolic pulmonary hypertension - caused by build up of pulmonary embolisms and impacts blood flow. TREATABLE BY SURGERY
2) PAH - treatable by drugs
PH classifications - untreatable
Multifractional
Left heart pulm hypertension
PH lung disease / hypoxia
Epidemiology and prognosis of PAH?
Rare - 15/50 per million of population
More common in women but more men die from it
Lag time between onset of symptoms and prognosis - presents a problem as cannot treat from the start!!
Increase seen in patients with left heart disease
40% idiopathic, 10% heritable
Pathogenesis of PAH
- SUSTAINED PULMONARY VASOCONSTRICTION - the hallmark for PAH
- EC dysfunction and apoptosis
- vascular remodelling
- LV dysfunction
- right and left heart failure
- RV hypertrophy
Cell proliferation in the vessel wall - how can this lead to PAH?
Cells in the wall are stimulated to proliferate due to dysregulation of the ECs (due to sustained vasoconstriction)
This causes blockages of vessels and ultimately leads to increased resistance
This is progressive, perpetual and leads to later onset symptoms
Histopathology of PAH lung - vessels
- Increased number of cells and several areas of growth
- Areas in middle consisting of inflammatory cells
- Plexiform regions form
- ECM and elastin degrades - increased vascular stiffness, vascular leak and loss of vascular integrity
What are plexiform regions in the vessel walls?
Groups of cells in vessel walls resistant to apoptosis – increase blockages present in vessel walls and therefore increase in peripheral vascular resistance
