pulsatile

Pulsatile describes a pattern of flow, pressure, or release that occurs in repeated bursts or pulses rather than continuously. It conveys the sense of rhythmic, beat-like variation over time and is often linked to biological or mechanical systems that generate periodic activity.

In physiology, pulsatile processes are common. In the cardiovascular system, arterial blood flow is inherently pulsatile, produced by the beating heart. Each systolic contraction ejects blood, creating pressure and velocity waves that travel through the arteries. The resulting waveform has a systolic peak and a diastolic trough, with characteristics influenced by pulse pressure and arterial stiffness. Pulsatility is also observed in hormonal and neural signaling, where secretions can occur in bursts rather than at a constant rate.

In medicine and technology, pulsatile patterns are used in therapy and devices. Pulsatile drug delivery aims to mimic natural rhythms to improve efficacy or reduce side effects, particularly for hormones such as GnRH. Some cardiac support devices were historically pulsatile pumps; contemporary left ventricular assist devices more often use continuous flow but may still study pulsatile dynamics.

Pulsatility can be quantified with metrics such as the pulsatility index, commonly derived from Doppler ultrasound measurements. The index helps assess vascular resistance and compliance in arteries and placental blood flow, and aids in diagnosing circulatory or fetal conditions.

Etymology: the term derives from Latin pulsus, a beating or strike.