Pulse transit time as an indirect marker for variations in cardiovascular related reactivity.

Study of cardiac functions has shown to be important in understanding the prognosis and pathogenesis of vascular diseases. A physiologic parameter termed pulse transit time (PTT) has been studied intensively to be used as an indirect marker of such pathologic conditions. It is defined as the time it takes a pressure pulsation to travel between two arterial sites. For convenience of measurement, the interval between the peak of the R-wave on the electrocardiogram and the onset of the corresponding pulse in the finger pad measured by photoplethysmography is usually used. In this review, its definition, current applications in cardiovascular related studies and issues are presented in turn. Investigational studies suggest that PTT did not meet the level of accuracy required for medical practice as a marker for beat-to-beat blood pressure (BP). However, documented evidences indicate that PTT has high correlations when it is utilised as a surrogate semi-quantitative monitor of abrupt BP changes. Present literature suggests that description of disease-specific cardiovascular reactivity pattern is possible with techniques based on PTT. The attraction of PTT due to its non-invasive nature and revealing properties can only increase. Hence, the use of this simple technique in a clinical setting is still to realise its full potential.