Differences in laser-Doppler indices between skin-surface measurement sites in subjects with diabetes.

This study performed laser-Doppler flowmetry (LDF) measurements with the aim of identifying differences in diabetes-induced microcirculatory-blood-flow (MBF) responses between the following skin surface measurement sites: an acupoint around the wrist, an acupoint around the ankle, and a nearby nonacupoint around the ankle. The 67 study subjects were assigned to diabetic, prediabetic, and healthy groups according to the results of oral glucose tolerance tests. Beat-to-beat and spectral analyses were applied to the LDF waveform to obtain the foot delay time (FDT), the flow rise time (FRT), and the relative energy contributions (RECs) in five frequency bands. FRT and FDT were significantly shorter and the RECs of the endothelial-, neural-, and myogenic-related frequency bands were significantly smaller in the diabetic group than in the control group at the acupoint around the ankle, but there were no such prominent differences at the other sites. The acupoint around the ankle was better than the nearby nonacupoint and the acupoint around the wrist for distinguishing the age-matched diabetic, prediabetic, and healthy subjects. These findings imply that when monitoring diabetes-induced MBF responses, the measurement locations should be chosen carefully in order to minimize interference effects and to improve the ability to distinguish subjects with different conditions.

Combining laser-Doppler flowmetry measurements with spectral analysis to study different microcirculatory effects in human prediabetic and diabetic subjects.

We aimed to identify the microcirculatory regulatory mechanisms in diabetic and prediabetic humans using a noninvasive method combining spectral analysis with laser-Doppler flowmetry (LDF) measurements on the skin surface. LDF signals were measured by a moorVMS-LDF device to measure the microcirculatory blood flow flux with a time constant of 0.001 s, a cutoff frequency of 14.9 kHz, and a sampling frequency of 40 Hz. The laser operating wavelength and output power were 400-700 nm and 6 mW, respectively. LDF signals were obtained noninvasively in 115 subjects, who were assigned to three groups (diabetic, prediabetic, and normal) according to the results of the oral glucose tolerance tests. A Morlet mother wavelet transform was applied to the measured 20-min LDF signals, and periodic oscillations with five characteristic frequency peaks were obtained within the following frequency bands: 0.0095-0.02, 0.02-0.06, 0.06-0.15, 0.15-0.4, and 0.4-1.6 Hz (defined as FR1-FR5), respectively. The relative energy contribution (REC) of FR1 was significantly smaller (by using the Kruskal-Wallis test followed by Dunn's multiple-comparison tests) in diabetic subjects than in normal subjects. The REC of FR2-FR3 was significantly smaller in diabetic and prediabetic subjects than in normal subjects. The REC of FR1-FR3 from normal to prediabetic and diabetic subjects showed a progressive decrease. The present findings may aid in the development of a noninvasive method for the early detection of prediabetes and the monitoring of disease progression. This may be useful in preventing disease progression and reducing the risk of concomitant end-organ damage.

Complexity analysis of beat-to-beat skin-surface laser-Doppler signals in diabetic subjects.

MOTIVATIONS: This study performed skin-surface laser-Doppler flowmetry (LDF) measurements with the aim of verifying if complexity analysis applied to the beat-to-beat LDF waveform index can be used to discriminate diabetic, prediabetic, and normoglycemic subjects. METHODS: Sixty-six subjects were assigned to three age-matched groups according to the results of oral glucose tolerance tests. Beat-to-beat analysis was performed on the pulsatile LDF waveform to obtain the pulse-to-mean ratio (AD) and pulse width (PW), and then approximate-entropy (ApEn) values for their 20-minute index sequences were calculated to evaluate the signal complexity. RESULTS: AD and PW did not differ significantly among the three study groups. ApEn values of AD and PW were significantly larger and marginally larger, respectively, in the diabetic group than in the prediabetic and normoglycemic groups. CONCLUSION: These results indicate the presence of significant differences in ApEn indexes among diabetic, prediabetic, and normoglycemic subjects. The presence of increased complexity in the LDF index sequence may be partly attributed to the adaptability of the microcirculatory regulatory activities or the impairment of the homeostasis mechanism of microcirculatory-blood-flow perfusion. The present findings may be pertinent to the early detection of the diabetes-induced impairment of this perfusion.

The fifth chamber of the heart: huge left atrial aneurysm.

Cardiomegaly is a common but nonspecific finding in the emergency department. The etiology may be explained by left ventricular dilation, biventricular dilation, right ventricular dilation, or pericardial abnormalities, or it may be found to be spurious on the echocardiogram. Rarely, isolated abnormalities of the atrium, particularly the left atrium, may cause abnormalities on the chest radiograph but will not cause true cardiomegaly. We reported a 37-year-old woman who presented with persistent palpitation of a 6-hour duration. An electrocardiogram revealed atrial fibrillation with rapid ventricular response. A chest radiograph showed cardiomegaly with unusual prominence of the left heart border. A subsequent transthoracic echocardiography demonstrated an echo-free chamber adjacent to the left lateral wall of the left ventricle. The diagnosis of a rare huge left atrial aneurysm was finally established by multidetector-row computed tomography, which had been seldom used as a diagnostic tool in the past. Patients with this cardiac anomaly usually are asymptomatic until the second or third decade of life, when the aneurysms can reach remarkable sizes and are often complicated with atrial tachyarrhythmia or thromboembolic events. Early surgical intervention is advised even in asymptomatic patients to prevent the occurrence of myocardial dysfunction, atrial fibrillation, and systemic embolism.

Characteristics in the beat-to-beat laser-Doppler waveform indices in subjects with diabetes.

MOTIVATIONS: The present study performed laser-Doppler flowmetry (LDF) measurements on the skin surface around the ankle with the aim of verifying if beat-to-beat analysis of the LDF waveform can help to discriminate the microcirculatory-blood-flow (MBF) characteristics between diabetic, prediabetic, and healthy subjects. METHODS: 84 subjects were assigned to three groups (diabetic, prediabetic, and normal) according to the results of oral glucose tolerance tests. Beat-to-beat analysis was performed on the pulsatile LDF waveform to obtain foot delay time (FDT), flow rise time (FRT), and the corresponding MBF-variability parameters (FDTCV and FRTCV). RESULTS: Relative to the control group, FDT and FRT were significantly shorter in prediabetic subjects, FDT was significantly shorter in diabetic subjects, and FRTCV and FDTCV were significantly larger in prediabetic and diabetic subjects. There were no significant associations for FRT after adjustment for age and gender. CONCLUSION: The present results indicate that FRT may help to discriminate differences in the elastic properties of local vascular beds during diabetes or even during prediabetic stages. The proposed blood-filling-volume model can help to explain the underlying mechanism. The present findings may aid the noninvasive early detection of diabetes-associated vascular damage, and could be used in the development of home-care and telemedicine applications.

Acute microcirculatory responses induced by skin-surface vibration stimulation at a frequency near the heart rate.

OBJECTIVE: We aimed to elucidate the frequency-specific microcirculatory blood-flow (MBF) effect induced by weak vibration stimulation (VS) in healthy human subjects. METHODS: VS was implemented by a rod (connected to a DC motor) hitting a water-filled bag. VS was applied to the left palm at frequencies near to the heart rate (HR) (n=35; Group A) and 50% higher than the HR (n=20; Group B), and laser-Doppler-flowmetry measurements were made on the back of the left hand (Site 1). A control group without applying VS was also used (n=21). RESULTS: The mean MBF (MMBF), pulsatile MBF, and pulse width at Site 1 only increased significantly in Group A, and the coefficient of variance of the MMBF sequence increased significantly at Site 1 in Groups A and B. CONCLUSION: These results illustrate the VS-induced changes in the regulatory activities of arteriolar openings, and improvement of the MBF near the VS application site in Group A. The improvement in MBF depended on whether the VS frequency was near to, or higher than the HR. The present findings may be pertinent to amelioration of disease induced by an abnormal MBF.