Calculation of the aortic valve gradient from the left ventricular-femoral and aortic-femoral pairs of pressure waveforms.

Accurate measurement of the transaortic gradient is important in the invasive assessment of the significance of aortic stenosis. The mean gradient obtained from simultaneous left ventricular and aortic pressure recordings is the gold standard, but requires two central catheters. We hypothesized that a gradient calculated by subtracting the aortofemoral from the ventriculofemoral gradient would reproduce the ventriculoaortic gradient. In 24 patients sequential recordings of the aortofemoral, ventriculofemoral, and ventriculoaortic pressures pairs were obtained. The calculated ventriculoaortic gradient was obtained by subtracting the aortofemoral gradient from the ventriculofemoral gradient. Both of these gradients were measured by computer, using a systolic ejection period between the crossovers of the upslope and downslope of the left ventricular waveform with the femoral waveform. The ventriculoaortic gradient calculated using this technique correlated closely with the gradient measured by two central catheters (R = 0.99). This technique is accurate and does not require two central catheters.