Generalised wavelet analysis of cutaneous flowmotion during post-occlusive reactive hyperaemia in patients with peripheral arterial obstructive disease.

The purpose of the present study was to assess whether the generalised wavelet analysis (GWA) of the leg cutaneous laser Doppler (LD) flowmotion waves recorded during baseline (Bsl) and after skin post-occlusive hyperaemia (POH) can provide information on the leg cutaneous microcirculatory adaptation to stage II peripheral arterial obstructive disease (PAOD). With this aim the flowmotion was characterised in 20 healthy subjects (HS) and 20 stage II PAOD patients by GWA of LDF tracings during Bsl and POH test. The vascular endothelial and smooth muscle function was also evaluated exploring the arm skin vasodilatory response to iontophoretically delivered acetylcholine (Ach) and sodium nitroprusside (SNP) using LD. During Bsl there was no significant difference in leg skin perfusion between HS and PAOD patients (7.3+/-5.6 vs. 5.8+/-2.9 AU, respectively). PAOD patients revealed higher peak powers in the frequency interval of 0.007-0.02 Hz (120+/-82 vs. 85+/-62 AU(2)/Hz; P < 0.05), 0.02-0.06 Hz (116+/-128 vs. 63+/-48 AU(2)/Hz, respectively; P < 0.05) and 0.06-0.2 Hz (39+/-49 vs. 14+/-10 AU(2)/Hz; P < 0.05). These flowmotion frequencies are related to vascular endothelium activity, sympathetic activity and vessel wall myogenic activity, respectively. During POH the mean peak power of the flowmotion waves increased significantly (P < 0.05) in HS respect to Bsl with the only exception of the 0.02-0.06 Hz band. In the PAOD patients, compared to Bsl the amplitude of the flowmotion waves did not significantly change during POH. In addition, the PAOD patients presented an increased time from release to peak-flux (18.25+/-15.5 vs. 2.16+/-1.28 s, respectively; P < 0.05), an increased time from release to recovery of the basal perfusion (90.26+/-39.14 vs. 26.55+/-14.05 s, respectively; P < 0.05) and a lower slope of the POH curve (10+/-15 vs. 54+/-17 degrees , respectively; P < 0.05), compared with HS. The cutaneous arm vasodilatory response to Ach and to SNP was reduced in PAOD patients in comparison with HS (P < 0.001). In conclusion, our findings showed an increased amplitude of the frequency interval 0.007-0.02, 0.02-0.06 and 0.06-0.2 Hz during Bsl in PAOD patients which did not change during the POH test. All data suggest that in stage II PAOD patients the leg skin perfusion is not impaired during Bsl because of a compensatory mechanism related to increased endothelial, myogenic and sympathetic activities. However during reactive hyperaemia these mechanisms appear to be exhausted in accordance with the reduced vasoreactivity to Ach and SNP.