Aortic valve impedance

The points B and X correspond to the first and second heart sounds. They are synchronous with the maximal deflection at the apex and the closure of the aortic valve, respectively. In some cases the identification of the B point location is difficult because the characteristic upstroke that provides a marker of this point is not always pronounced [3]. The E point is defined by the peak of dZidt curve which reflects the maximal derivative in the impedance. Ultrasound method measurements confirm that the E point may be associated with the maximal velocity of the heart ejection [4]. For ICG the first maximum (i.e. E-wave) is related to the systolic phase of the cardiac cycle and the second maximum with a smaller amplitude (O-wave) is related to the diastolic phase. The amplitude of the E-wave is proportional to the SV, and the am-... 

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