Abstract

Objectives: To determine potential interactions between the heart and arterial system in patients with β thalassaemia major.

Design and patients: Vascular compliance, systemic vascular resistance, and left ventricular (LV) contractility was determined in 34 asymptomatic thalassaemia patients at 2–4 hours after blood transfusion and also in 34 age and sex matched controls using a non-invasive device. The results were compared between groups and inter-relationships between LV contractility and indices of vascular load were explored.

Setting: Tertiary paediatric cardiac centre.

Results: When compared with controls, patients had greater systemic vascular resistance (1633 (259) v 1377 (276) dynes/s/cm⁵, p < 0.001) and effective arterial elastance (E_a) (1.86 (0.25) v 1.65 (0.29) mm Hg/ml, p  =  0.001), an index of combined pulsatile and static vascular load. On the other hand, their systolic blood pressure (104 (9) v 112 (13) mm Hg, p  =  0.006), pulse pressure (45 (9) v 57 (10) mm Hg, p < 0.001), adjusted systemic vascular compliance (1.21 (0.09) v 1.37 (0.14), p < 0.001), adjusted brachial artery distensibility (21 (0.29) v 7.95 (0.29)%/mm Hg, p < 0.001) and LV+dP/dt (1059 (183) v 1239 (237) mm Hg/s, p  =  0.001) were significantly lower. Significant determinants of LV contractility, as reflected by LV+dP/dt, were age (standardised β  =  −0.24, p  =  0.003), body mass index (standardised β  =  −0.34, p  =  0.004), systolic blood pressure (standardised β  =  0.90, p < 0.001), and effective E_a (standardised β  =  −0.50, p < 0.001) (model R²  =  0.69). No significant correlation existed between serum ferritin concentration and any of the cardiac or vascular indices.

Conclusion: An unfavourable ventriculo-vascular interaction, as characterised by impaired cardiac contractility and increased static and pulsatile vascular load, occurs in patients with β thalassaemia major.