Differentials
Pulmonary arterial hypertension (PAH) associated with left-sided heart disease (pulmonary venous hypertension)
SIGNS / SYMPTOMS
Older patients, male preponderance, usual cardiovascular risk factors (diabetes, hypertension, smoking). Left ventricular gallops and mitral valve murmurs.
INVESTIGATIONS
Transthoracic echo: left atrial enlargement, left ventricular systolic and/or diastolic dysfunction, mitral valve disease.[3]
Right heart catheterisation: elevated pulmonary arterial wedge pressure, transpulmonary gradient <12 mmHg.
Left heart catheterisation: coronary disease, elevated left ventricular end-diastolic pressure.
PAH associated with respiratory diseases and/or hypoxia
SIGNS / SYMPTOMS
COPD: older than 40-50 years, history of smoking, chronic cough and sputum production, decreased breath sounds, wheezing.
Interstitial lung disease: history of occupational exposures, drug use, smoking, or connective tissue disease; chronic non-productive cough, bi-basilar inspiratory crackles, digital clubbing.
Sleep-disordered breathing (e.g., obstructive sleep apnoea): loud snoring, excessive daytime sleepiness, morning headaches, obesity, mild elevations in pulmonary artery pressure.[48]
Alveolar hypoventilation disorders: obesity-hypoventilation syndrome, neuromuscular disease.
INVESTIGATIONS
Pulmonary function tests: obstructive or restrictive defects (obstructive: FEV₁ <60%; restrictive: forced vital capacity (FVC) <70%).
ABG: hypoxaemia, hypercapnia.
Overnight oximetry: de-saturation, screening for sleep apnoea.
Polysomnography: obstructive sleep apnoea.
High-resolution chest CT scan: emphysema, interstitial lung disease.
PAH due to chronic thrombotic and/or embolic disease
SIGNS / SYMPTOMS
History of pulmonary embolism; bruits over the lung fields (pulmonary flow murmurs) are present in 30% of cases but are not present in IPAH.[49]
PAH associated with connective tissue disease
SIGNS / SYMPTOMS
Multi-system organ involvement: skin lesions, arthralgias/arthritis, GORD, Raynaud's phenomenon, oral ulcers, serositis, renal disease, haematological abnormalities, etc.
Scleroderma: especially the limited form (CREST syndrome: calcinosis, Raynaud's phenomenon, oesophageal dysmotility, sclerodactyly, and telangiectasis) in the absence of interstitial lung disease.
Less common in systemic lupus erythematosus, mixed connective tissue disease, and rheumatoid arthritis.
PAH associated with congenital systemic-to-pulmonary shunts
SIGNS / SYMPTOMS
Simple shunts (more common than complex): ventricular septal defect (highest risk, especially if >1 cm), atrial septal defect (especially if >2 cm and sinus venosus type), patent ductus arteriosus, anomalous pulmonary venous return.
Complex shunts: truncus arteriosus (almost all patients develop PAH), atrioventricular septal defects.
For all defects, risk of PAH is highest if unrepaired.
Eisenmenger's physiology: secondary erythrocytosis, iron deficiency, haemoptysis, 'paradoxical' embolisation, brain abscesses.[50]
PAH associated with portal hypertension (portopulmonary hypertension)
SIGNS / SYMPTOMS
Mean age of presentation is the fifth decade of life; male-to-female ratio of 1.1:1.[52]
Signs of underlying liver disease: jaundice, spider telangiectasia lower extremity oedema, ascites.
INVESTIGATIONS
LFTs: abnormal.
Abdominal ultrasound with colour Doppler: liver cirrhosis, increase in the transhepatic venous gradient.
Right heart catheterisation: increased gradient between free and occluded (wedged) hepatic vein pressure.
PAH associated with HIV infection
SIGNS / SYMPTOMS
HIV risk factors.
INVESTIGATIONS
Positive HIV serology.
PAH associated with drugs and toxins
PAH associated with other medical disorders
Pulmonary veno-occlusive disease/pulmonary capillary haemangiomatosis
SIGNS / SYMPTOMS
Digital clubbing and/or basilar rales on examination.[3]
INVESTIGATIONS
More severe hypoxaemia and decreased in diffusing capacity of the lung for carbon monoxide.
CT chest: ground-glass opacities with a centrilobular distribution, septal lines, and adenopathy.
Elevated numbers of haemosiderin-laden macrophages in bronchoalveolar lavage fluid.
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