Identifying Coronary Artery Lesions by Feature Analysis of Radial Pulse Wave: A Case-Control Study

Background. Cardiovascular diseases have been always the most common cause of morbidity and mortality worldwide. Health monitoring of high-risk and suspected patients is essential. Currently, invasive coronary angiography is still the most direct and accurate method of determining the severity of coronary artery lesions, but it may not be the optimal clinical choice for suspected patients who had clinical symptoms of coronary heart disease (CHD) such as chest pain but no coronary artery lesion. Modern medical research indicates that radial pulse waves contain substantial pathophysiologic information about the cardiovascular and circulation systems; therefore, analysis of these waves could be a noninvasive technique for assessing cardiovascular disease. Objective. The objective of this study was to analyze the radial pulse wave to construct models for assessing the extent of coronary artery lesions based on pulse features and investigate the latent value of noninvasive detection technology based on pulse wave in the evaluation of cardiovascular disease, so as to promote the development of wearable devices and mobile medicine. Method. This study included 529 patients suspected of CHD who had undergone coronary angiography. Patients were sorted into a control group with no lesions, a 1 or 2 lesion group, and a multiple (3 or more) lesion group as determined by coronary angiography. The linear time-domain features and the nonlinear multiscale entropy features of their radial pulse wave signals were compared, and these features were used to construct models for identifying the range of coronary artery lesions using the k -nearest neighbor (KNN), decision tree (DT), and random forest (RF) machine learning algorithms. The average precision of these algorithms was then compared. Results. (1) Compared with the control group, the group with 1 or 2 lesions had increases in their radial pulse wave time-domain features H2/H1, H3/H1, and W2 ( P < 0.05 ), whereas the group with multiple lesions had decreases in MSE1, MSE2, MSE3, MSE4, and MSE5 ( P < 0.05 ). (2) Compared with the 1 or 2 lesion group, the multiple lesion group had increases in T1/T ( P < 0.05 ) and decreases in T and W1 ( P < 0.05 ). (3) The RF model for identifying numbers of coronary artery lesions had a higher average precision than the models built with KNN or DT. Furthermore, average precision of the model was highest (80.98%) if both time-domain features and multiscale entropy features of radial pulse signals were used to construct the model. Conclusion. Pulse wave signal can identify the range of coronary artery lesions with acceptable accuracy; this result is promising valuable for assessing the severity of coronary artery lesions. The technique could be used to development of mobile medical treatments or remote home monitoring systems for patients suspected or those at high risk of coronary atherosclerotic heart disease.

Metformin Improves Skeletal Muscle Microvascular Insulin Resistance in Metabolic Syndrome

Aims: Microvascular insulin resistance is present in metabolic syndrome and may contribute to increased cardiovascular disease risk and the impaired metabolic response to insulin observed. Metformin improves metabolic insulin resistance in humans. Its effects on macro and microvascular insulin resistance has not been defined. Methods: Eleven non-diabetic, metabolic syndrome subjects were studied four times (before and after 12 weeks treatment with placebo or metformin) using a crossover design, with an eight week washout interval between treatments. On each occasion, we measured three indices of large artery function (pulse wave velocity-PWV, radial pulse wave separation analysis (PWSA), brachial artery endothelial function (flow-mediated dilation-FMD) as well as muscle microvascular perfusion (contrast-enhanced ultrasound-CEU) before and 120 min into a 150 min, 1 mU/min/kg euglycemic insulin clamp. RESULTS: Metformin decreased body mass index (BMI), fat weight, and % body fat (P<0.05, each), placebo had no effect. Metformin (not placebo) improved metabolic insulin sensitivity, (clamp glucose infusion rate, P<0.01). PWV, and FMD after insulin were unaffected by metformin treatment. PWSA improved with insulin only after metformin P<0.01). Insulin decreased muscle microvascular blood volume measured by contrast ultrasound both before and after placebo and before metformin (P<0.02 for each) but not after metformin. CONCLUSIONS: Short-term metformin treatment improves both metabolic and muscle microvascular response to insulin. Metformin's effect on microvascular insulin responsiveness may contribute to its beneficial metabolic effects. Metformin did not improve aortic stiffness or brachial artery endothelial function, but enhaced radial pulse wave properties consistent with relaxation of smaller arterioles.

Center-To-Periphery Arterial Stiffness Gradient Is Attenuated and/or Reversed in Pregnancy-Associated Hypertension

Background: Non-pregnant (NP) women have a progressive increase in arterial stiffness from central-to-peripheral arteries [“stiffness gradient” (SG)], which is of physiologic importance since excessive pulsatility is filtered by the creation of wave reflections. If the aorta gets stiff with minimal or no change in the periphery, the SG is dissipated transmitting pressure disturbances to the microcirculation. It remains unknown the status of the SG in both women with healthy pregnancies (HP) and complicated by pregnancy-associated hypertension (PAH).Objective: To determine whether HP and PAH are associated with changes in SG. Secondarily, we aim at identifying potential differences between the subgroups of PAH (pre-eclampsia and gestational hypertension).Methods: HP (n = 10), PAH (n = 16), and healthy NP women (n = 401, to be matched for age, and cardiovascular risk with the pregnant women) were included. Carotid-to-femoral (cfPWV) and carotid-to-radial pulse wave velocity (crPWV), common carotid artery (CCA) and brachial artery (BA) diameters and elastic modulus (EM), and regional (cfPWV/crPWV or “PWV ratio”) and local (CCA EM/BA EM or “EM ratio”) SG were quantified.Results: HP showed no changes in PWV ratio compared with NP, in the presence of significantly lower cfPWV and crPWV. HP exhibited higher arterial diameters and lower CCA EM/BA EM compared to NP, without differences with PAH. PAH was associated with a significant increase in the PWV ratio that exceeded the levels of both NP and HP, explained by a lower (although significant) reduction of cfPWV with respect to that observed in HP with respect to NP, and a higher reduction in crPWV with respect to that observed between HP and NP. The blunted reduction in cfPWV observed in PAH coincided with an increase in the CCA EM.Conclusions: Compared with NP, HP was associated with unchanged PWV ratio but with a reduction in CCA EM/BA EM, in the setting of a generalized drop in arterial stiffness. Compared with NP and HP, PAH was associated with an “exaggerated rise” in the PWV ratio without changes in CCA EM/BA EM, in the setting of a blunt reduction in cfPWV but exaggerated crPWV drop. The SG attenuation/reversal in PAH was mainly driven by pre-eclampsia.

Supracondylar fractures of the humerus in children: is departmental documentation hitting national standards?

Background/aims The British Orthopaedic Association's Standards for Trauma for the management of supracondylar humerus fractures in children specify that: ‘A documented assessment of the limb, performed on presentation, must include the status of radial pulse, digital capillary refill time and the individual function of the radial, median (including anterior interosseous) and ulnar nerves.’ Methods The documentation of cases of supracondylar humerus fractures over 1 year was retrospectively analysed. An electronic pro forma for supracondylar humerus fractures was introduced, with prompts for the pieces of documentation required to meet national standards. The use of this pro forma was audited after 6 months and 12 months use. Results Documentation ranged from 10% for anterior interosseous nerve to 53% for radial pulse. In the second reaudit, documentation ranged from 86% for anterior interosseous nerve to 95% for median nerve function. There were 17 patients for whom all documentation was present, and for these patients the pro forma had been used. Use of an electronic clerking pro forma improves adherence. Conclusions Full documentation of neurovascular status in paediatric supracondylar fractures is vital to allow for effective preoperative and postoperative further assessment. With the move into paperless documentation, online pro formas can help clinicians with effective assessment and documentation.

A Transfer Function Model Development for Reconstructing Radial Pulse Pressure Waveforms Using Non-Invsasively Measured Pulses by a Robotic Tonometry System

The primary goal of this study is to develop a mathematical model that can establish a transfer function relationship between the “external” pulse pressures measured by a tonometer and the “internal” pulse pressure in the artery. The purpose of the model is to accurately estimate and rebuild the internal pulse pressure waveforms using arterial tonometry measurements. To develop and validate a model without human subjects and operators for consistency, this study employs a radial pulse generation system, a robotic tonometry system, and a write model with an artificial skin and vessel. A transfer function model is developed using the results of the pulse testing and the mechanical characterization testing of the skin and vessel. To evaluate the model, the pulse waveforms are first reconstructed for various reference pulses using the model with tonometry data. They are then compared with pulse waveforms acquired by internal measurement (by the built-in pressure sensor in the vessel) the external measurement (the on-skin measurement by the robotic tonometry system). The results show that the model-produced pulse waveforms coinciding well with the internal pulse waveforms with small relative errors, indicating the effectiveness of the model in reproducing the actual pulse pressures inside the vessel.