In patients presenting with signs and symptoms of right heart failure an accurate diagnosis of underlying aetiology is vital in order to aid referral for appropriate treatment. Severe tricuspid regurgitation, constrictive pericarditis and restrictive cardiomyopathy may have similar clinical features and findings at cardiac catheterisation, including elevation and near equalisation of left and right ventricular diastolic pressures. A recent study has described criteria for distinguishing constrictive pericarditis from restrictive cardiomyopathy,1 and in this issue of Heart, Jaber et al propose novel haemodynamic criteria for differentiating tricuspid regurgitation from constrictive pericarditis using cardiac catheterisation (see page 1449).2

The underlying aetiology of pericardial constriction has changed over recent decades. Whereas in the past many patients presented with severe and global calcification of the pericardium secondary to tuberculosis, patients are now more likely to develop pericardial constriction after mediastinal irradiation or cardiac surgery (often in conjunction with myocardial involvement).3 In these patients the calcification is often more localised and less pronounced, and pericardial thickness may even lie within the normal range. In these cases diagnosis on the basis of imaging studies alone may be far more challenging, as patients with surgically proven pericardial constriction may have a normal pericardial appearance on imaging.4 In addition, determining the relative contribution of pericardial restraint and myocardial dysfunction poses a diagnostic challenge. Severe tricuspid regurgitation is seen more often owing to both the increasing number of patients with congenital heart disease surviving into adulthood and an increase in implantation rates of both cardiac resynchronisation therapy and implantable cardioverter-defibrillators. Lin et al have previously described a series of 41 patients with severe symptomatic tricuspid regurgitation due to permanent pacemaker or defibrillator leads.5 In these patients echocardiographic imaging is inherently difficult owing to acoustic dropout from the pacing leads, and in this …