Pulmonary Hypertension Flashcards
Normal systolic pulmonary arterial pressure
25mmHg
Normal diastolic pulmonary arterial pressure
10
What is pulmonary hypertension?
When there is increased pressure in the pulmonary circuit
(from heart to lungs to heart)
Describe normal pulmonary circulation
From RV to PA to lungs to PV to LA
Usually a low pressure, low resistance, high capacitance system
How are increases in pulmonary blood flow usually compensated?
Minimal increase in pulmonary artery pressure is due to:
* Highly distensible thin walls
* recruitment of under-perfused vessels
* Large pulmonary capillary surface area
Causes of pulmonary hypertension
Alveolar hypoxia with pulmonary vasoconstriction
Pulmonary vascular obstructive disease
Pulmonary over circulation
High pulmonary venous pressure
Idiopathic
Examples of alveolar hypoxia with pulmonary vasoconstriction/remodelling
interstitial pulmonary fibrosis
Neoplasia
Examples of pulmonary vascular obstructive disease
Pulmonary thromboembolism
Heart worm
Examples of pulmonary over-circulation
Large congenital shunts
Examples of high pulmonary venous pressure
Left sided heart failure
* Various causes
What is cor pulmonale
Abnormal enlargement of the RIGHT side of the heart as a result of disease of the lungs or the pulmonary blood vessels
How does cor pulmonale occur?
Pulmonary artery vasoconstricts in response to alveolar hypoxia (due to lung disease)
Increased pulmonary vascular resistance increases pulmonary arterial pressure = pulmonary hypertension
If this is severe PH induces angioproliferative changes which permanently reduce vascular compliance and lumen size
When enough vessels are damaged, ability to dilate is lost and PVR increases further
If pulmonary artery pressure increases then he RV has to contract more to overcome this pressure - leads to forward failure
Backs up into right atrium
How do shunts cause pulmonary hypertension
Large volumes of blood get shunted through lungs due to congenital heart disease
E.g. VSA where blood shunts from left to right - goes back to pulmonary circulation
Causes pulmonary arterial remodelling
How does LCHF cause secondary pulmonary hypertension?
Blood backs up from LA into PV
Pressure in PV increases
leading to pulmonary oedema
This contributes to increased pulmonary vascular resistance by causing reduced lung compliance and increased resistance to airflow
Induces structural changes in pulmonary capillaries and increases muscularity of arterioles
Pathophysiology of pulmonary hypertension
Pulmonary hypertension causes right ventricular hypertrophy and dilation
* RV needs to work harder to overcome PA pressure
* Results in reduced forward flow
RV diastolic pressure increases
CO reduces as RV function declines
