Pulmonary hypertension: diagnosis, imaging techniques, and novel therapies

Abstract

Pulmonary hypertension (PH), defined as the elevation of mean pulmonary arterial pressure (mPAP) above 25 mmHg, has numerous causes, which the World Health Organization (WHO) has divided into five distinct categories based upon the underlying mechanism of action. This review will explore the pathophysiology, diagnostic testing, and treatment of PH. Identification of PH depends on a strong clinical suspicion, a detailed history, and a thorough physical exam. We review the evidence supporting experimental and clinical laboratory parameters for diagnosis and monitoring of PH. Transthoracic echocardiogram (TTE) is the initial screening test of choice. This review will detail specific echocardiographic techniques for the assessment and classification of PH. Furthermore, the importance of advanced imaging, including computed tomography (CT) and magnetic resonance imagining (MRI) is explored. New developments in pharmacology, percutaneous intervention, and surgical approaches are summarized. Finally, we will address the tools available to predict morbidity and mortality.

Keywords: Pulmonary hypertension (PH); World Health Organization (WHO); computed tomography (CT); transthoracic echocardiogram (TTE).

Figure 1

The current 2013 WHO classification of pulmonary hypertension patients. WHO, World Health Organization.

Figure 2

ECG of a 56-year-old man with group 1 PH. Note the evidence of right atrial enlargement and right ventricular hypertrophy with RV strain and p-pulmonale. PH, pulmonary hypertension; RV, right ventricular.

Figure 3

Apical 4-chamber view on TTE showing RV and RA enlargement in response to PH. There is also right ventricular hypertrophy with mildly depressed RV systolic function. TTE, transthoracic echocardiogram; RV, right ventricular; RA, right atrial; PH, pulmonary hypertension.

Figure 4

High resolution computed tomography images showing intra and interlobular septal thickening and early honeycombing predominantly involving the lung bases with associated traction bronchiectasis consistent with interstitial lung disease associated with dermatomyositis with HRCT pattern suggesting fibrotic non-specific interstitial pneumonia versus possibly usual interstitial pneumonia. The main pulmonary artery (not pictured) is enlarged measuring up to 5.1 cm, consistent with PH. HRCT, high-resolution computed tomography; PH, pulmonary hypertension.

Figure 5

Cardiac MRI from a 28-year-old man with group 1 PAH. The RVEDVi is 151 mL/m² (severely enlarged) with moderately depressed RV systolic function. The RVSP is 75 mmHg and PVR is 8 wood units. There is also septal flattening consistent with pressure overload. MRI, magnetic resonance imagining; PAH, pulmonary arterial hypertension; RVEDVi, right ventricular end-diastolic index; RVSP, right ventricular systolic pressure; PVR, pulmonary vascular resistance.