Pulmonary Hypertension

Pulmonary hypertension

High blood pressure in the pulmonary arteries.

mPAP >20mmHg

Symptoms

shortness of breath

fatigue

chest pain

swelling in legs or abdomen

Pre-capillary PH

mPAP >20mmHg

PAWP 15mmHg or less

PVR >2WU

(elevated pulmonary artery pressures, normal wedge pressure)

post capillary PH

mPAP >20mmHg

PAWP >15mmHg

PVR 2WU or less

(elevated pulmonary artery and wedge pressures)

PAWP

pulmonary artery wedge pressure

indirect estimate of left sided pressures (preload)

helps determine between pre or post capillary PH

PVR

pulmonary vascular resistance

BP of lung vessels

<35mmHg

Normal pulmonary pressure estimate

35-49mmHg

mildly elevated pulmonary pressure estimate

50-59mmHg

Moderately elevated pulmonary pressure estimate

60mmHg or more

Severely elevated pulmonary pressure estimate

Modified Bernoulli equation

change in P = 4(v2² - v1²)

Simplified Bernoulli equation

change in P = 4v²

Right atrial pressure

central venous pressure

normal ranges 3-8mmHg

measured by collapsibility of the IVC during inspiration

3mmHg

RAP when IVC equal to or less than 2.1cm with inspiratory collapse

8mmHg

RAP when IVC is dilated but collapses OR normal size but reduced collapse

15mmHg

RAP when IVC >2.1cm with reduced respiratory collapse

Inconsistencies with IVC collapsibility

athletes or healthy patients with strong venous return

high BSA

mechanical ventilation

Other measures of RAP

tricuspid valve E/e’

hepatic venous flow

>6

tricuspid valve E/e’ indicative of raised RAP

inaccurate with TV surgery (tethering of the annulus)

Diastolic dominance

hepatic venous flow indicative of elevated RAP

RV systolic pressure

RVSP = PASP in absence of RVOT obstruction

normal range 15-30mmHg

measured from TR signal

RVSP from TR

Bernoulli equation

4v² + RAP

V = TR Max

PASP with pulmonary stenosis

RVSP - pulmonary valve gradient

Caveats for using TR to estimate RVSP

severe TR

V shaped signal

rapid equalisation between chambers

PV acceleration time

PW doppler pulmonary valve

interval of onset of flow to peak flow

<100m/s reflects abnormal mPAP

HR must be between 60-100bpm

RVSP from VSD

= LVSP - 4(max velocity through vsd)²

using systolic blood pressure based on BP cuff

mPAP from PR

4 (PR Vmax)² + RAP

RV end diastolic pressure

In the absence of tricuspid stenosis = RAP

Pulmonary artery EDP

Represents the pressure gradient between the PA and RV

Normal value ~10mmHg

Measured from PR signal at end diastole (Q wave)

= 4V² + RVEDP (RAP)

inaccurate in the setting of severe PR

Pulmonary vascular resistance

pressure required for the RV to eject blood into the lungs

accounts for stroke volume (helps account for when there is reduced CO and therefore only mild increase in pulmonary pressures)

Methods for calculating PVR

TR Vmax / RVOT VTI x 10 + 0.16 (Abbas method)

Simplified methods:

TR Vmax / RVOT VTI (>0.26 predicts PVR >6)

TR Vmax² / RVOT VTI (>0.95 products PVR >6)

Group 1

pulmonary artery hypertension (PAH)

• idiopathic

• heritable

• connective tissue

• congenital heart disease

Group 2

Left heart disease

• valvular

• systolic or diastolic function

Group 3

lung disease

• COPD

• hypoventilation disorders

Group 4

Chronic thromboembolic pulmonary hypertension (CTEPH)

Group 5

other

• blood disorders

• metabolic syndromes

• combined disease

Pulmonary arterial hypertension (PAH)

pre capillary

heritable

idiopathic

congenital heart disease (shunts, valvular etc)

drug induced or toxins

associated with other disease (CTD, HIV)

Connective tissue disease PH

systemic sclerosis (scleroderma)

HIV

Eisenmenger’s

Develops in the setting of a large left to right shunt

Increase in pulmonary vascular resistance and reversal of the shunt from right to left

PH due to left heart disease

post capillary

2/3 of PH

majority dye to diastolic dysfunction increasing filling pressures

ePLAR

pulmonary to left atrial ratio

differentiates between pre and post capillary PH

ePLAR = TRVmax / E∶e′

Normal ePLAR

0.30m/s

higher = pre-capillary

lower = post-capillary

Acute pulmonary embolism

clot in the pulmonary artery/lungs

sudden increase in pulmonary pressures

leads to RV dilatation and failure

may be apical sparing

Chronic thromboembolic pulmonary embolism

chronic blood clots or scar like tissue that causes narrowing of the arteries

Other causes of PH

haematology disorders

myeloproliferative disorders

chronic haemolytic anaemia sarcoidosis

glycogen storage disorders

chronic renal failure