Correlation of Intraoperative and Early Postoperative Transvalvular Gradients Following Aortic Valve Replacement
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Intraoperative transesophageal echocardiography (TEE) provides imaging that is useful in planning and guiding many cardiac surgical procedures, particularly in aortic valve replacement (AVR). In order to assess valvular function, surgeons routinely request hemodynamic data derived from TEE (in the form of gradients), following implantation of the prosthetic valve. Although aortic gradients are commonly assessed, there are multiple conflicting factors that may affect their reliability in the operating room. The present study was performed to determine the correlation of intraoperative and postoperative gradients following aortic valve replacement (AVR), in order to assess the relevance of measuring gradients intraoperatively. Intraoperative and follow-up echocardiography reports including aortic gradient measurements were obtained for 28 patients that underwent AVR at the University of Michigan Hospital. Scatter graphs with corresponding linear regression equations were constructed and analyzed using the Pearson linear coefficient to determine if a correlation existed between gradients. Separate graphs, constructed by valve type, were also similarly analyzed. Gradients varied unpredictably between intraoperative and postoperative echocardiograms. Statistical analysis indicated that gradients measured in the operating room after AVR are not predictive of those at follow-up (R 2 was 0.10 for mean gradients and 0.20 for peak gradients). These findings were not isolated to valve type. The results of this study suggest that measuring intraoperative gradients following AVR surgery may not be relevant to the immediate assessment of aortic valvular function.