Relationship between pulse transit time and blood pressure is impaired in patients with chronic heart failure

Abstract

Aims: Pulse transit time (PTT), the interval between ventricular electrical activity and arrival of the peripheral pulse wave, has been used to detect changes in autonomic tone during sleep and anesthesia. The purpose of this study was to evaluate PTT in patients with chronic heart failure (HF).

Methods and results: Pulse transit time was measured with R-wave gated photoplethysmography in 24 healthy volunteers and in 112 patients with chronic HF and ejection fraction (EF) <40%. PTT was mildly elevated in patients with HF (468 ± 12 vs. 430 ± 23 ms, p = 0.001). In healthy volunteers, PTT was directly proportional to blood pressure (BP): when BP increased, PTT shortened, and vice versa. This relationship between PTT and BP (PTTi) was altered in patients with HF and particularly in the 26 patients with decompensated HF (3.6 ± 0.4 vs. 4.2 ± 0.9, p = 0.04). PTTi did not correlate with functional NYHA class and levels of pro-BNP, epinephrine or norepinephrine. There was a modest correlation between PTTi and EF (p = 0.01, r = -0.48) and PTTi tended to correlate with microvascular flow measured with Laser Doppler (p = 0.08). However, there was an excellent correlation between PTTi and systolic time intervals, left ventricular ejection time (LVET) (p = 0.0014, r = -0.75) and pre-ejection time/LVET (p = 0.006, r = 0.80). The latter ratio reflects ventricular-arterial coupling.

Conclusion: The relationship between PTT and BP is altered in severe HF and may indicate impaired ventricular-arterial coupling. It merits further investigation as both parameters can be easily determined and used for serial monitoring in HF.