Hemodynamic analysis could resolve the pulsatile blood flow controversy.

Reasons for fluctuations in the popularity of pulsatile cardiopulmonary bypass are discussed. The advantages of pulsatile flow have previously been stated in terms of physiologic parameters. This has produced a weak theoretic framework that has led to serious misunderstandings of the fundamental mechanical properties of pulsatile flow. Failure to consider these properties in the past may have allowed modified roller pumps to be accepted as "pulsatile," even though their pulsatile power outputs are small compared with those of the human heart. A fresh approach is required in which pulsatile blood flow is analyzed in terms of hemodynamic power and impedance parameters.