Arterial Input Impedance

  • Nicolaas Westerhof
  • Nikolaos Stergiopulos
  • Mark I. M. Noble
  • Berend E. Westerhof


Input impedance completely and comprehensively describes an arterial (sub) system. The ratio of the mean arterio-venous pressure drop and mean flow is total vascular resistance or peripheral resistance, Rp. To obtain information about the oscillatory aspects of the arterial system wave shapes of pressure and flow are used; and Fourier analysis applied. The amplitude ratio and the phase difference of the sine waves of pressure and flow give the modulus and phase angle of the impedance (application of Ohm’s law). At zero frequency Rp is found. For intermediate frequencies (1–3 times heart rate) the modulus decreases precipitously and the phase angle is negative. This shows the major contribution of (total) arterial compliance, C. For high frequencies the modulus approaches a constant value and the phase angle is close to zero. This is the contribution of the aortic characteristic impedance. These three elements together give a good description of the input impedance, suggesting the three-element Windkessel as acceptable arterial model.


Fourier analysis Impedance modulus Impedance phase Peripheral resistance Total arterial compliance Aortic characteristic impedance Impulse response 


  1. 1.
    Murgo JP, Westerhof N, Giolma JP, Altobelli SA. Aortic input impedance in normal man: relationship to pressure wave forms. Circulation. 1980;62:105–1116.CrossRefPubMedGoogle Scholar
  2. 2.
    Stergiopulos N, Meister J-J, Westerhof N. Scatter in the input impedance spectrum may result from the elastic nonlinearity of the arterial wall. Am J Phys. 1995;269:H1490–5.Google Scholar
  3. 3.
    Westerhof N, Elzinga G, Sipkema P. An artificial system for pumping hearts. J Appl Physiol. 1971;31:776–81.CrossRefPubMedGoogle Scholar
  4. 4.
    Stergiopulos N, Westerhof BE, Westerhof N. Total arterial inertance as the fourth element of the windkessel model. Am J Phys. 1999;276:H81–8.Google Scholar
  5. 5.
    Sipkema P, Westerhof N. Effective length of the arterial system. Ann Biomed Eng. 1975;3:296–307.CrossRefPubMedGoogle Scholar
  6. 6.
    Westerhof BE, van den Wijngaard JP, Murgo JP, Westerhof N. Location of a reflection site is elusive: consequences for the calculation of aortic pulse wave velocity. Hypertension. 2008;52:478–83.CrossRefPubMedGoogle Scholar
  7. 7.
    Sipkema P, Westerhof N, Randall OS. The arterial system characterized in the time domain. Cardiovasc Res. 1980;14:270–9.CrossRefPubMedGoogle Scholar
  8. 8.
    Van Huis GA, Sipkema P, Westerhof N. Coronary input impedance during the cardiac cycle as obtained by impulse response method. Am J Phys. 1987;253:H317–24.Google Scholar
  9. 9.
    Westerhof N, Elzinga G. Normalized input impedance and arterial decay time over heart period are independent of animal size. Am J Phys. 1991;261:R126–33.Google Scholar
  10. 10.
    Murgo JP, Westerhof N, Giolma JP, Altobelli SA. Manipulation of ascending aortic pressure and flow reflections with the Valsalva maneuver: relationship to input impedance. Circulation. 1981;63:122–32.CrossRefPubMedGoogle Scholar
  11. 11.
    Latham RD, Westerhof N, Sipkema P, Rubal BJ, Reuderink P, Murgo JP. Regional wave travel and reflections along the human aorta: a study with six simultaneous micromanometric pressures. Circulation. 1985;72:1257–69.CrossRefPubMedGoogle Scholar
  12. 12.
    Ting CT, Chen JW, Chang MS, Yin FC. Arterial hemodynamics in human hypertension. Effects of the calcium channel antagonist nifedipine. Hypertension. 1995;25:1326–32.CrossRefPubMedGoogle Scholar
  13. 13.
    O’Rourke MF. Pulsatile arterial haemodynamics in hypertension. Aust N Z J Med. 1976;6(Suppl 2):40–8.CrossRefPubMedGoogle Scholar

Copyright information

© Springer International Publishing AG, part of Springer Nature 2019

Authors and Affiliations

  • Nicolaas Westerhof
    • 1
  • Nikolaos Stergiopulos
    • 2
  • Mark I. M. Noble
    • 3
  • Berend E. Westerhof
    • 1
  1. 1.Department of Pulmonary Diseases, Amsterdam Cardiovascular SciencesVU University Medical CenterAmsterdamThe Netherlands
  2. 2.Laboratory of Hemodynamics and Cardiovascular TechnologyEcole Polytechnique Fédérale de Lausanne (EPFL), Institute of BioengineeringLausanneSwitzerland
  3. 3.Cardiovascular Medicine, Department of Medicine and TherapeuticsUniversity of AberdeenAberdeenUnited Kingdom

Personalised recommendations