P ulmonary hypertension (PH) is a hemodynamic and pathophysiological state defined as increased mean pulmonary artery pressure ≥25 mm Hg at rest (assessed by right heart catheterization [RHC]).1 PH can be precapillary (pulmonary wedge pressure ≤15 mm Hg, normal or reduced cardiac output) where the changes occur in the pulmonary arterial circulation or postcapillary (pulmonary wedge pressure >15 mm Hg) where the left ventricle (LV) or the mitral valve is likely to be involved. Clinical Perspective on p 114In precapillary PH, increased pressure in the pulmonary arteries overloads the right ventricle (RV), causing hypertrophy and failure. [2][3][4] Most measures that predict survival in PH relate directly to RV function (eg, right atrial pressure and cardiac index) or correlate with measures related to RV function (eg, exercise capacity and functional class [FC]).5-7 Until recently, little was known about the RV; however, improved imaging techniques have allowed prognostic factors beyond the traditional variables of 6-minute walk distance (6MWD) and FC to be studied to identify factors more directly linked to RV function.During the past 2 decades, several treatments targeting the pathophysiological mechanisms of pulmonary arterial hypertension (PAH) have been introduced.

Pulmonary hypertension is a disease of the pulmonary arteries resulting in a progressive increase in pulmonary vascular resistance, ultimately leading to right ventricular failure and death. The functional capacity of the right ventricle is a major prognostic determinant. Our understanding of right ventricle performance in pulmonary hypertension has been hindered by the lack of techniques that give a reliable picture of right ventricle morphology and function. Cardiac magnetic resonance (CMR) imaging enables a unique combination of morphological and functional assessment of the right ventricle and pulmonary circulation. In this review article, we introduce the technique of CMR imaging, review its use in imaging of the heart and pulmonary circulation and discuss its current and future application to the management of patients with pulmonary hypertension.There have been recent major advances in our understanding of the mechanism of disease development, in the diagnostic process, and in the treatment of pulmonary hypertension. Therapeutic advances in the management have reinforced the requirement for noninvasive, accurate and reproducible methods of assessment to act as ''end-points'' to measure the effects of treatment. We anticipate CMR imaging will increasingly be utilised as the primary modality for combined anatomic and functional assessments that enable more complete and efficient evaluation of pulmonary hypertension patients.

Pulmonary hypertension (PH) is a disease of the pulmonary arteries resulting in a progressive increase in pulmonary vascular resistance, ultimately leading to right ventricular failure and death. It is a rare disease with a poor prognosis. The functional capacity of the right ventricle (RV) is a major prognostic determinant in PH. Our understanding of RV performance in PH has been hindered by the lack of techniques that give a reliable picture of right ventricular morphology and function. There have been recent major advances in our understanding of the mechanism of disease development, in the diagnostic process and in the treatment of PH. There are now three classes of medications that are effective in the treatment of PH: prostanoids, endothelin receptor antagonists and phosphodiesterase-5 inhibitors. Therapeutic advances in the management of PH have reinforced the requirement for non-invasive, accurate and reproducible methods of assessment to act as 'end-points' to measure the effects of treatment. It is our opinion that the most useful 'end-point' would be one that evaluates right heart morphology and function. We introduce and discuss the techniques currently used to image the heart in patients with PH. Imaging modalities discussed include echocardiography, radionuclide ventriculography, cardiac computed tomography and cardiac magnetic resonance (CMR) imaging focusing on the rapidly evolving technique of CMR imaging.

Cardiac magnetic resonance imaging and IGR using photoacoustic analysis in patients with suspected PAH provided non-invasive measurements of SV that agreed closely with those obtained from TD measured during RHC.