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Investigations


oxygen saturation – a significant step-up in oxygen saturation from site to site may indicate the presence of an intracardiac left to right shunt. Decreased venous oxygen saturation is a poor prognostic indicator.


PH is defined as a mean PA pressure (MPAP) ≥25mmHg (note MPAP = diastolic PAP + 1/3 (systolic – diastolic)).1


Cases of pre-capillary PH are


defined as PAWP ≤15mmHg whereas post-capillary PH PAWP >15mmHg. Pre-capillary causes include Groups 1, 3, 4 and 5, whereas post-capillary PH is group 2 (left heart disease).17 The role of left heart catheterisation in diagnosis of PH is controversial and is not recommended routinely by current guidelines.17


Some authors have


demonstrated that PAWP may underestimate high left ventricular filling pressures, leading to overdiagnosis of pre-capillary PH, notably in patients with scleroderma.18,19


Coronary angiography


may also be performed, which is useful in cases of left heart disease, patients with suspected CTEPH (Group 4 PH) who possibly require pulmonary endarterectomy, and even in PAH patients who frequently complain of anginal chest pain and have increased incidence of coronary disease.20 Disadvantages of left-sided cardiac catheterisation include increased costs and procedure time, use of intravenous contrast, and vascular complications. In addition to diagnosis, RHC parameters such as RA pressure and cardiac index have significant prognostic impact on the patient. RAP >10mmHg and/or cardiac index (CI) ≤2.4l/kg/m2


are regarded as poor prognostic indicators.1


Additional procedures during RHC During initial RHC in patients with suspected idiopathic PAH, it is recommended that ‘vasoreactivity’ testing is performed.1,17


During


vasoreactivity testing, the patient receives a pulmonary vasodilator (for example, inhaled nitric oxide, intravenous adenosine, intravenous epoprostenol, inhaled iloprost) and the PAP and cardiac output are re-measured. A significant response is a reduction in mean PA pressure of ≥10mmHg to a final MPAP ≤40mmHg, with unchanged or increased cardiac output. Patients who are ‘responders’ may have significant therapeutic benefit from calcium channel blockers and have a relatively good prognosis.21


As discussed previously, relying on PAWP alone may result in underdiagnosis of left heart disease. Recently there has been interest in giving fluid challenge during RHC, based on the understanding that PAWP will not increase after a modest 500ml fluid bolus in normal patients or those with pre-capillary PH. A series revealed cases of occult left heart disease in scleroderma patients.19


Currently, clear guidelines and


normal values for response to fluid challenge are lacking, and this remains a research technique.


There is also much interest in exercise testing during RHC.22


Some patients


with normal resting haemodynamics may develop PH during exercise. Limitations to the technique include lack of standardised exercise protocols, and lack of normal ranges for exercise haemodynamics and difficulty in obtaining reliable pressure measurements due to the swings in intrathoracic pressure from exercise- induced tachypnoea. Previous guidelines have suggested that mean PAP>30mmHg on exercise is pathological, although this definition has been withdrawn.17


References 1. Galiè N et al. The Joint Task Force for the Diagnosis and Treatment of Pulmonary Hypertension. 2015 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension. Eur Respir J 2015;46(4):903–75.


2. Poms A et al. Comorbid conditions and outcomes in patients with pulmonary arterial hypertension: a REVEAL registry analysis. Chest 2013;144(1):169–76.


3. Martinuzzo M et al. Lupus anticoagulant, high levels of anticardiolipin, and anti-beta2- glycoprotein i antibodies are associated with chronic thromboembolic pulmonary hypertension. J Rheumatol 1998;25(7): 1313–19.


4. Soon E et al. Log-transformation improves the prognostic value of serial NT-probnp levels in apparently stable pulmonary arterial hypertension. Pulm Circ 2011;1(2):244–9.


5. Bendayan D et al. Hyperuricemia as a prognostic factor in pulmonary arterial hypertension. Respir Med 2003;97(2):130–33.


6. Forfia P et al. Hyponatremia predicts right heart failure and poor survival in pulmonary arterial hypertension. Am J Respir Crit Care Med 2008;177(12):1364–9.


7. Adir Y et al.Severe pulmonary hypertension associated with emphysema: a new phenotype? Chest 2012;142(6):1654–8.


8. Iyer A et al. CT scan-measured pulmonary


artery to aorta ratio and echocardiography for detecting pulmonary hypertension in severe COPD. Chest 2014;145(4):824–32.


9. Mineo G et al. Pulmonary veno-occlusive disease: the role of CT. Radiol Med 2014;119(9):667–73.


10. Remy-Jardin M et al. Management of suspected acute pulmonary embolism in the era of CT angiography: a statement from the Fleischner society. Radiology 2007;245(2):315–29.


11. Sugiura T et al. Role of 320-slice ct imaging in the diagnostic workup of patients with chronic thromboembolic pulmonary hypertension. Chest 2013;143(4):1070–7.


12. Kim N et al. Chronic thromboembolic pulmonary hypertension. J Am Coll Cardiol 2013;62(25 Suppl):D92–D99.


13. Kurzyna M, Torbicki A. Imaging: Echocardiography. Hodder Arnold, London, UK;2011:100–14.


14. Rudski L et al. Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography endorsed by the European Association of Echocardiography, a registered branch of the European Society of Cardiology, and the Canadian Society of Echocardiography. J Am Soc Echocardiogr 2010;23(7):685–713.


15. Khanna D et al. Recommendations for screening and detection of connective tissue disease-associated pulmonary arterial hypertension. Arthritis Rheum 2013;65(12):3194–201.


16. Shimony A et al. Incidence and significance of pericardial effusion in patients with pulmonary arterial hypertension. Can J Cardiol 2012;29:678–82.


17. Hoeper M et al. Definitions and diagnosis of pulmonary hypertension. J Am Coll Cardiol 2013;62(25 Suppl):D42–D50.


18. Halpern S, Taichman D. Misclassification of pulmonary hypertension due to reliance on pulmonary capillary wedge pressure rather than left ventricular end-diastolic pressure. Chest 2009;136(1):37–43.


19. Fox BD et al. High prevalence of occult left heart disease in scleroderma-pulmonary hypertension. Eur Respir J 2012;42(4):1083–9.


20. Shimony A et al. Prevalence and impact of coronary artery disease in patients with pulmonary arterial hypertension. Am J Cardiol 2011;108:460–4.


21. Sitbon O et al. Long-term response to calcium channel blockers in idiopathic pulmonary arterial hypertension. Circulation 2005;111(23):3105–11.


22. Provencher S et al. Changes in exercise haemodynamics during treatment in pulmonary arterial hypertension. Eur Respir J 2008;32(2):393–8.


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