In summary, major surgery can be performed safely in the Jehovah's Witness who refuses blood transfusion by utilizing preoperative and intraoperative techniques that decrease surgical blood loss, decrease oxygen consumption, and increase oxygen delivery. Even if significant intraoperative blood loss occurs, successful postoperative management is possible by utilizing techniques that minimize oxygen consumption and maximize oxygen delivery.

Two echo‐Doppler cardiographic investigations were performed 7 years apart in 17 insulin‐dependent diabetic children without hypertension or nephropathy in order to detect early signs of cardiac abnormalities in this group without ischaemic heart disease. Relative to two matched control groups, the patients had reduced increase in left ventricular size (p < 0.01) and stroke volume (p < 0.05). An initially reduced end systolic wall stress and increased fractional shortening (p < 0.003) was normalized during the 7 years. Concomitant with early signs of autonomic neuropathy and aortic stiffening, left ventricular filling changed with increased velocity during atrial contraction (p < 0.01) correlating to the decreased stroke volumes (r = −0.57, p = 0.016). These early changes could suggest left ventricular restriction but could also reflect a changed sympathetic/parasympathetic balance in diabetic children. A reduced left ventricular cavity size and increased atrial ejection has thus been described in these insulin‐dependent children without hypertension, nephropathy or evidence for ischaemic heart disease, suggesting the existence of a metabolically‐induced cardiomyopathy.

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Mechanical heart valve replacement is the preferred alternative in younger patients with severe symptomatic aortic valve disease. However, thrombus and pannus formations are common complications associated with bileaflet mechanical heart valves.This leads to risks of valve leaflet dysfunction, a life-threatening event. In this experimental study, we investigate, using time-resolved planar particle image velocimetry, the flow characteristics in the ascending aorta in the presence of a dysfunctional bileaflet mechanical heart valve. Several configurations of leaflet dysfunction are investigated and the induced flow disturbances in terms of velocity fields, viscous energy dissipation, wall shear stress, and accumulation of viscous shear stresses are evaluated. We also explore the ability of a new set of parameters, solely based on the analysis of the normalized axial velocity profiles in the ascending aorta, to detect bileaflet mechanical heart valve dysfunction and differentiate between the different configurations tested in this study. Our results show that a bileaflet mechanical heart valve dysfunction leads to a complex spectrum of flow disturbances with each flow characteristic evaluated having its own worst case scenario in terms of dysfunction configuration. We also show that the suggested approach based on the analysis of the normalized axial velocity profiles in the ascending aorta has the potential to clearly discriminate not only between normal and dysfunctional bilealfet heart valves but also between the different leaflet dysfunction configurations. This approach could be easily implemented using phase-contrast MRI to follow up patients with bileaflet mechanical heart valves. K E Y W O R D Sbileaflet mechanical heart valve, flow dynamics, shear stress accumulation, valve dysfunction, viscous energy dissipation E250 | DARWISH et Al.

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