Effects of trigeminal nerve stimulation on parameters derived from pulse wave analysis in young healthy subjects

Studies on trigeminal nerve stimulation (TNS) by facial cooling (FC) could give an insight to physiological mechanisms of cardiovascular response to activation of both parasympathetic and sympathetic nervous systems. We hypothesised that trigeminal nerve stimulation would positively influence on the factors which increase left ventricle work. The aim of the present study was to investigate hemodynamic changes assessed by pulse wave analysis (PWA) in the very early phase of this reflex. In 15 young (aged 20.3±1.3 y/o; mean ±SD) healthy individuals (10 males) PWA was performed before and after 30 seconds of FC. TNS caused decrease in heart rate (76.8±9.4 bpm vs 66.6±9.8 bpm; p=0.0038; mean ±SD) and increase in peripheral diastolic blood pressure (68±5.9 mmHg vs. 70.9±8.6 mmHg; p=0.028; mean ±SD) and no changes in other blood pressure values (peripheral and central), nor augmentation index were observed. PWA showed decrease in time of the peak pressure of left ventricle contraction (107.6±15.9 ms vs. 100.2±12.06 ms; p=0.027; mean ±SD), increase in time of the peak pressure of the reflected wave return (cT2, 187±28.03 ms vs 198.6±27.9 ms; p=0.028; mean ±SD) and increase in the difference between cT2 and time of the beginning of the reflected wave return (43.3±18.7 ms vs. 59.7 vs. 59.7±20.99 ms; p=0.0076; mean ±SD). We conclude that in the early phase of response to TNS, there is an increase in contractility of left ventricle and aortic compliance, as well as increase in peripheral vascular resistance and pressure load of returning pulse wave occurs.