Adaptation of the pulmonary circulation and of the right heart in intracardiac inveterate shunts: under pressure or let it flow?

Abstract Congenital heart disease can be associated with pulmonary hypertension (PH) development and heart right remodelling. Nevertheless, the adaptation of the pulmonary circulation and of the right heart can be extremely heterogeneous, so that an accurate diagnostic work up may be advisable when an intracardiac shunt is suspected. Case Presentation A 53 years old woman, with no relevant clinical history and asymptomatic, was incidentally found to have clinical, ECG and echocardiographic signs of PH, and was referred to our Center. Diagnostic and Therapeutic Work Up Echocardiography showed: normal left ventricle (LV 3D volumes 88/35 ml), mild left atrial dilatation (39 ml/m2); severe right chambers dilatation (RV 3D 347/124 ml, EF 3D 62%, AD 116 ml/m2), moderate tricuspid regurgitation with a regurgitant jet velocity of 2.9 m/s. Right heart catheterization showed normal pulmonary pressures at rest (mPAP 20, PAWP 5 mmHg), extremely high pulmonary blood flow (Qp 29 L/min, calculated with the direct Fick method), with normal pulmonary vascular resistance (PVR 0.5 WU). During the oxymetric run, a step up in hemoglobin saturation between superior vena cava and right atrium (from 74 to 97%) was found, with a Qp/Qs ratio of 5.5. During exercise, Qp reserve was normal, suggesting a normal contractile reserve function of RV despite the extreme dilatation. Additionally, the patient did not develop exercise PH and exercise capacity was normal, based on a measured oxygen consumption (VO2) at peak of 24 ml/kg/min (104% of predicted). Angio–CT of the chest was performed, confirming the presence of a sinus venosus atrial septal defect. The patient was then referred for surgical correction. Conclusion Echocardiography signs are useful to direct correctly diagnostic work up. A severe RV dilatation with normal systolic function in an asymptomatic middle age woman should raise the possibility of an intracardiac shunt. Despite a large intracardiac shunt with a high Qp/Qs ratio for decades, PVR was normal, confirming that individual predisposition may play a role in the development of PH in pre–tricuspid shunts. Exercise test showed an optimal RV reserve, suggesting a low cardiac surgery risk.