Left ventricular mechanics in humans with high aerobic fitness: adaptation independent of structural remodelling, arterial haemodynamics and heart rate.

Individuals with high aerobic fitness have lower systolic left ventricular strain, rotation and twist ('left ventricular (LV) mechanics') at rest, suggesting a beneficial reduction in LV myofibre stress and more efficient systolic function. However, the mechanisms responsible for this functional adaptation are not known and the influence of aerobic fitness on LV mechanics during dynamic exercise has never been studied. We assessed LV mechanics, LV wall thickness and dimensions, central augmentation index (AIx), aortic pulse wave velocity (aPWV), blood pressure and heart rate in 28 males (age: 21±2 years SD) with a consistent physical activity level (no change>6 months). Individuals were examined at rest and during exercise (40% peak exercise capacity) and separated post hoc into a moderate and high aerobic fitness group (˙V(O2peak): 49 ± 5 and 63 ± 7ml kg−1 min−1, respectively, P <0.0001). At rest and during exercise, there were no significant differences in gross LVstructure, AIx, blood pressure or heart rate (P >0.05).However, for the same AIx, the high ˙V(O2peak) group had significantly lower LV apical rotation (P =0.002) and LV twist (P =0.003) while basal rotation and strain indices did not differ between groups (P >0.05).We conclude that young males with high aerobic fitness have lower LVapical rotation at rest and during submaximal exercise that can occur without changes in gross LV structure, arterial haemodynamics or heart rate. The findings suggest a previously unknown type of physiological adaptation of the left ventricle that may have important implications for exercise training in older individuals and patient populations in which exercise training has previously failed to show clear benefits for LV function.

Autoimmune pancytopenia occurring late after simultaneous pancreas and kidney transplantation.

A 35-year-old woman presented with a widespread petechial rash and pancytopenia. She underwent simultaneous pancreas and kidney transplantation for type 1 diabetes 8 years previously followed by a renal transplant 1 year prior to presentation, and was taking tacrolimus as long-term immunosuppression. The full blood count showed haemoglobin 97 g/L, platelet count 2×109/L and neutrophil count 0.22×109/L. Peripheral blood film examination confirmed genuine thrombocytopenia in the absence of any haemolytic or malignant features. Serological testing identified autoantibodies against all three blood lineages, consistent with a diagnosis of autoimmune pancytopenia. Treatment with steroids, intravenous immunoglobulins, romiplostim and mycophenolate mofetil achieved only fleeting remissions. Blood counts eventually normalised following the administration of rituximab and a change from tacrolimus to ciclosporin immunosuppression. Cytopenias are a well-recognised complication of post-transplantation care but we believe this to be the first reported case of autoimmune pancytopenia following solid organ transplantation. In this case report, we discuss the approach to investigation of haematological abnormalities post-transplant and the rationale for, and outcome of, the management of this rare case.