Figure 2 . Pulmonary vascular remodelling in pulmonary arterial hypertension ( PAH ). The diagram shows a small pulmonary artery in cross-section . Vascular cells in all three layers of the vessel , the intima , media and adventitia , contribute to vessel remodelling in PAH . The result of the pulmonary vascular remodelling is narrowing or complete obstruction of the vessel lumen , further raising blood pressure in the generally low-pressure pulmonary circulation and increasing the load on the right ventricle . |
Normal distal pulmonary artery |
Remodelled distal pulmonary artery in PAH |
Narrowing / occlusion of vessel lumen |
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Table 1 . New York Heart Association classification |
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PAGE 20
If a GP identifies a case
of suspected PH and the TTE results are consistent with intermediate or
|
or greater ( measured on arterial blood gas analysis ) and NT-proBNP of less than 333pg / mL excluded PH with a |
ILD respectively . The diffusing capacity for carbon monoxide ( DLCO ) is a particularly useful test because it car- |
a sensitivity of only 76 % for diagnosing CTEPH . 3 If a patient presents with symptoms and signs highly sugges- |
Right heart catheterisation
RHC is the gold standard test for diagnosing
and classifying PH . The pro-
|
high probability , referral to the nearest |
negative predictive value of 96 %. 21 |
ries prognostic value for patients with |
tive of an acute pulmonary embolism , |
cedure , which requires significant |
|
PH specialist centre is indicated .
Twelve-lead ECG
The ECG is often normal in early disease
. Right axis deviation has a positive predictive value of 93 % in adults with suspected PH . 21 Other ECG findings include RV hypertrophy , RV strain
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Chest X-ray
Like ECGs , a normal chest X-ray does
not exclude PH . The chest X-ray may provide clues about the aetiology . Cardiomegaly , pulmonary oedema and / or pleural effusions may suggest Group 2 PH , while radiographic changes in
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idiopathic PAH , SSc-related PAH , heart failure with reduced ejection fraction and chronic thromboembolic pulmonary hypertension ( CTEPH ). 23 , 24 While a low DLCO may be useful in prognostication , the DLCO may also be normal or only mildly reduced in patients with PAH . 3 |
CTPA ( see figure 7 ) is still the investigation of choice , even in a patient with an established diagnosis of CTEPH . 3
Non-contrast CT chest imaging
Non-contrast high resolution CT
chest scans are the best modality for
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expertise and meticulous preparation , is usually only offered at specialist PH centres . Patients should be optimised to achieve euvolaemia and well controlled blood pressure beforehand . Local anaesthetic and minimal sedation with an anxiolytic are all that is usually required . Puncture sites |
pattern and right bundle branch block |
keeping emphysema or interstitial |
identifying ILD and other parenchy- |
include the internal jugular , femoral or |
|
( see figure 5 ). 22 |
lung disease ( ILD ) may suggest the |
VENTILATION / PERFUSION SCAN |
mal abnormalities , which , if pres- |
basilic veins . Contrast is not required |
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Blood tests
The blood tests in box 7 are recommended
in all patients . 3
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diagnosis is Group 3 PH . 3
Pulmonary function tests
Pulmonary function tests are usually
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It is recommended to perform a ventilation / perfusion ( V / Q ) scan ( see figure 6 ) in all patients with newly diagnosed PH because this is the imaging modal- |
ent , may point towards Group 3 PH . Non-contrast images still allow for the assessment of the pulmonary artery , aorta and heart chambers . An |
so renal impairment is not a contraindication for RHC .
The most feared complication of RHC is pulmonary artery perforation .
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Combining tests improves clin- |
normal in PAH ( Group 1 PH ). Patients |
ity of choice to exclude CTEPH . In |
enlarged pulmonary artery diameter |
However , at experienced PH centres , |
ical utility . For example , the pres- |
with Group 3 PH are more likely to |
the absence of parenchymal lung dis- |
( greater than 30mm ), a pulmonary |
the procedure-related mortality is less |
ence of NYHA class I or II dyspnoea , |
have abnormal pulmonary function |
ease , a negative V / Q scan has a nega- |
artery : aorta ratio of greater than 0.9 |
than 0.1 % and serious adverse events |
the absence of right axis deviation on |
tests , such as obstructive and restric- |
tive predictive value of 98 %, while a |
and enlarged right heart chambers |
are low at approximately 1 %. 3 |
ECG , arterial oxygen saturation 95.5 % |
tive ventilatory defects in COPD and |
CT pulmonary angiogram ( CTPA ) has |
are suggestive of PH . |
There are multiple variables that |