Explain the diagnostic approach in PH
Screen and monitor patients with conditions at high risk of PH for suggestive clinical features
If clinical suspicion is high for PH, perform transthoracic echocardiography (TTE) to noninvasively identify markers of elevated pulmonary artery pressure.
If TTE suggests PH and the etiology is not yet known, begin evaluation for the most common underlying causes.
Identify clinical evidence of left heart disease and/or chronic lung disease and consider supportive investigations (e.g., ECG, CXR, BNP, PFTs) as directed by clinical suspicion.
If these are inconclusive, perform a V/Q scan to evaluate for thromboembolic disease.
If the etiology remains unclear, TTE is equivocal, and/or severe PH is identified:
Consult a PH specialist.
Refer for confirmatory right heart catheterization.
Consider more advanced investigations, e.g., genetic screening.
What are findings in TTE?
↑ Tricuspid regurgitation velocity (TRV)
Right ventricular pressure overload
Flattening of the interventricular septum
Hypertrophy of the right ventricle
Dilation of the coronary sinus
Right ventricular failure
Dilation and hypokinesis of the right ventricle
Right atrial dilation
Underfilled left heart chambers
Evidence of underlying cardiovascular disease
Left ventricular dysfunction
Thrombus in the right heart, pulmonary artery, or IVC
Name indications for right heart catheterization
Confirmatory test for pulmonary hypertension
Detailed assessment of other cardiac diseases (e.g., valvular heart disease, coronary artery disease)
Name findings in right heart catheterization
mPAP > 20 mm Hg at rest is considered diagnostic for PH
Precapillary pulmonary hypertension, e.g., PAH
Pulmonary vascular resistance ≥ 3 Wood units (normal: 0.25–1.6 Wood units)
PCWP ≤ 15 mm Hg
Postcapillary pulmonary hypertension and mixed pre- and postcapillary pulmonary hypertension, e.g., secondary to left heart disease
Pulmonary vascular resistance is variable.
PCWP > 15 mm Hg
What ECG findings can be seen?
Typically shows nonspecific changes secondary to increased right ventricular workload
Right ventricular hypertrophy
Incomplete or complete right bundle branch block
May also show signs of underlying etiology, e.g., ischemic heart disease
What chest x-ray findings can be seen in PH?
Chest x-ray findings may help to support the diagnosis of PH
Right heart hypertrophy
Prominent right heart border
Lateral view: loss of retrosternal space due to right ventricular enlargement
Enlarged central pulmonary arteries
Reduction in number and size of vessels of the peripheral pulmonary vasculature (referred to as pulmonary vascular pruning)
Signs of the underlying cause (e.g., nodular opacities in interstitial lung disease, hyperinflation in COPD, pulmonary venous congestion in left heart disease)
What investigations should be done to find out the underlying cause?
Left heart disease: NT-proBNP
Chronic lung disease
Arterial blood gas
Pulmonary function tests
Diffusion capacity for carbon monoxide
Consider CT chest and sleep studies.
Chronic pulmonary thromboembolism: V/Q scan
What to consider if etiology remains still unclear?
Drug-induced: e.g., urine drug screen
Portopulmonary hypertension: Send liver chemistries, consider ultrasound liver.
Infection (based on risk factors): e.g., screen for HIV and schistosomiasis.
Connective tissue disease (most commonly systemic sclerosis): e.g., antinuclear antibodies, anticentromere antibodies, anti-Scl-70 and anti-RNA polymerase III
Sarcoidosis: e.g., inflammatory markers, serum calcium, ACE levels
Hereditary: e.g., genetic testing