Evaluation of radial and ulnar artery blood flow after radial artery decannulation using colour Doppler ultrasound.

BACKGROUND: There is a lack of reports in the literature regarding changes in radial artery blood flow after decannulation. The objective of this study was to investigate changes in radial and ulnar artery blood flow after radial artery decannulation using Doppler ultrasound and to explore the factors that influence radial artery blood flow recovery. METHODS: In current observational study, we used colour Doppler ultrasound to measure the cross-sectional area of the radial (SR) and ulnar artery (SU) and peak systolic velocity of the radial (PSVR) and ulnar artery (PSVU) for both hands at four time points in patients with radial artery cannulation: pre-cannulation (T0), 30 min after decannulation (T1), 24 h after decannulation (T2), and 7 days after decannulation (T3). Repeated measures analysis of variance and logistic regression analysis were performed to analyse the data. RESULTS: Overall, 120 patients were included in the present study. We obtained the following results on the side ipsilateral to the cannulation: compared with T0, the ratio of PSVU/PSVR increased significantly at T1 and T2 (p < 0.01); compared with T1, the ratio of PSVU/PSVR decreased significantly at T2 and T3 (p < 0.01); compared with T2, the ratio of PSVU/PSVR decreased significantly at T3 (p < 0.01). Female sex (OR, 2.76; 95% CI, 1.01-7.57; p = 0.048) and local hematoma (OR 3.04 [1.12-8.25]; p = 0.029) were factors that were significantly associated with the recovery of radial artery blood flow 7 days after decannulation. CONCLUSIONS: There was a compensatory increase in blood flow in the ulnar artery after ipsilateral radial artery decannulation. Female sex and local hematoma formation are factors that may affect the recovery of radial artery blood flow 7 days after catheter removal.

A 50 Hz magnetic field affects hemodynamics, ECG and vascular endothelial function in healthy adults: A pilot randomized controlled trial.

Application of exposure to 50/60 Hz magnetic fields (MFs) has been conducted in the treatment of muscle pain and fatigue mainly in Japan. However, whether MFs could increase blood flow leading to muscle fatigue recovery has not been sufficiently tested. We investigated the acute effects of a 50 Hz sinusoidal MF at Bmax 180 mT on hemodynamics, electrocardiogram, and vascular endothelial function in healthy young men. Three types of regional exposures to a 50 Hz MF, i.e., forearm, upper arm, or neck exposure to MF were performed. Participants who received three types of real MF exposures had significantly increased ulnar arterial blood flow velocity compared to the sham exposures. Furthermore, after muscle loading exercise, MF exposure recovered hemoglobin oxygenation index values faster and higher than sham exposure from the loading condition. Moreover, participants who received real MF exposure in the neck region had significantly increased parasympathetic high-frequency activity relative to the sham exposure. The MF exposure in the upper arm region significantly increased the brachial artery flow-mediated dilation compared to the sham exposure. Computer simulations of induced in situ electric fields indicated that the order-of-magnitude estimates of the peak values were 100-500 mV/m, depending on the exposure conditions. This study provides the first evidence that a 50 Hz MF can activate parasympathetic activity and thereby lead to increase vasodilation and blood flow via a nitric oxide-dependent mechanism. Trial registration: UMIN Clinical Trial Registry (CTR) UMIN000038834. The authors confirm that all ongoing and related trials for this drug/intervention are registered.

Comparison of Ellipsys Percutaneous and Proximal Forearm Gracz-Type Surgical Arteriovenous Fistulas.

RATIONALE & OBJECTIVE: Percutaneous arteriovenous fistulas (AVF) are created by establishing a proximal forearm anastomosis and offer a safe and reliable vascular access. This study compares the Ellipsys percutaneous AVF with a proximal forearm Gracz-type surgical AVF, chosen for comparison as it is constructed at the same anatomical site. STUDY DESIGN: Retrospective study of prospectively collected clinical data. SETTING & PARTICIPANTS: All vascular access procedures conducted during a 34-month period were reviewed. The study groups comprised 89 percutaneous AVFs and 69 surgical AVFs. EXPOSURE: Percutaneous or surgical AVF placement. OUTCOME: AVF patency, function, and complications. ANALYTICAL APPROACH: Patency rates for each AVF group were evaluated by competing risk survival analysis using a cumulative incidence function. Association of primary, primary assisted, and secondary patency with the AVF groups was examined by Cox proportional hazard models. RESULTS: Technical success was 100% for both groups. Average procedure times were 14 minutes for percutaneous AVFs and 74 minutes for surgical AVFs (P < 0.001). Proximal radial artery (PRA) was used in all percutaneous AVF cases. Inflow for surgical AVFs included radial (30%), ulnar (12%), and brachial (58%) arteries. Outflow veins for both groups were the cephalic and/or basilic veins. Access flow volumes, times to maturation, and overall numbers of interventions per patient-year were not significantly different. Cumulative incidence of primary patency failure at 12 months was lower for surgical AVF (47% vs 64%, P = 0.1), but secondary patency failure was not different between groups (20% vs 12%, P = 0.3). PRA surgical AVFs had similar primary patency (65% vs 64%, P = 0.8) but higher secondary patency failure rates than percutaneous AVFs at 12 months (34% vs 12%, P = 0.04). LIMITATIONS: Retrospective study with a relatively short follow-up period, and not all patients required hemodialysis at the end of study. CONCLUSIONS: Both percutaneous and surgical AVFs demonstrated high rates of technical success and secondary patency. Percutaneous AVFs required shorter procedure times. The rate of intervention was similar. When a distal radial artery AVF is not feasible, percutaneous AVF might offer an appropriate procedure for creating a safe and functional access, maintaining further proximal forearm surgical AVF creation options.

Remodeling of ipsilateral ulnar artery after radial artery harvesting for coronary artery bypass graft.

There are controversies in the literature on the blood supply to the forearm after surgical removal of the radial artery in coronary artery bypass grafting (CABG). The objective was to investigate the arterial remodeling of the ulnar artery after the removal of the radial artery in myocardial revascularization by means of ultrasound examination with color Doppler in the pre- and post-operative periods. This paper describes an observational prospective study of the remodeling of the left brachial and ulnar arteries (donor arm) in 103 right-handed non-consecutive adult patients undergoing CABG with removal of the ipsilateral radial artery using the color Doppler ultrasound examination. In the ulnar artery, a significant increase (P < 0.05) was seen in the following measurements: lumen diameter by 13%, lumen area by 26%, peak systolic flow by 40%, and average flow by 46%. Intima-media thickness measured in the ulnar artery did not show a statistically significant difference (P = 0.22), except in diabetic patients (P = 0.007). We conclude that the ulnar artery undergoes positive physiological remodeling, adapting to the new requirements of chronic increase in flow after the ipsilateral removal of the radial artery to serve as a graft in CABG. There was no evidence of increased intima-media thickness, except in diabetic patients.

A Randomized Trial Comparing Short versus Prolonged Hemostasis with Rescue Recanalization by Ipsilateral Ulnar Artery Compression: Impact on Radial Artery Occlusion-The RESCUE-RAO Trial.

BACKGROUND: Despite the enormous benefits of radial access, this route is associated with a risk of radial artery occlusion (RAO). OBJECTIVE: We compared the incidence of RAO in patients undergoing transradial coronary angiography and intervention after short versus prolonged hemostasis protocol. Also we assessed the efficacy of rescue 1-hour ipsilateral ulnar artery compression if RAO was observed after hemostasis. Material and Methods. Patients referred for elective transradial coronary procedures were eligible. After 6 F radial sheath removal, patients were randomized to short (3 hours) (n = 495) or prolonged (8 hours) (n = 503) hemostasis and a simple bandage was placed over the puncture site. After hemostasis was completed, oximetry plethysmography was used to assess the patency of the radial artery. RESULTS: One thousand patients were randomized. Baseline characteristics were similar between both groups with average age 61.4 ± 9.4 years (71% male) and PCI performed on half of the patients. The RAO rate immediately after hemostasis was 3.2% in the short hemostasis group and 10.1% in the prolonged group (p < 0.001). Rescue recanalization was successful only in the short group in 56.2% (11/19); at hospital discharge, RAO rates were 1.4% in the short group and 10.1% in the prolonged group (p < 0.001). CONCLUSION: Shorter hemostasis was associated with significantly less RAO compared to prolonged hemostasis. Rescue radial artery recanalization was effective in > 50%, but only in the short hemostasis group.

[Evaluation via ecocolordoppler before creating a vascular access for hemodyalisis: a monocentric experience].

The use of a preoperative echocolordoppler improves the clinical evaluation because provides anatomical and hemodynamic information that make it an important tool in planning vascular access strategy. The preoperative ultrasound study of the vessels can significantly reduce the failure rate and the incidence of complications of vascular access. We describe the experience of our center, lasting 10-year, where the ultrasound assessment was performed in all patients before the creation of vascular access. Indeed, ultrasound reduces the rate of fistula failure and increases the utilization of fistula, allowing proper selection of vessels. In addition, the presence of the vascular access team has allowed us to achieve quite satisfactory results.

Description and analysis of the dynamic and morphological flow pattern of the main arteries of the wrist and hand in a healthy spanish population. / Descripción y análisis del patrón de normalidad de flujo dinámico y morfológico de las arterias principales de la muñeca y mano en población sana española.

BACKGROUND AND AIM: The vascular anatomy of the hand has already been widely described macroscopically. However, there are very few papers that study the pattern of normality of in vivo vascularisation that describe and analyse the main arteries of the hand. The aim of this paper was to carry out a study to serve as a reference for the normal values of size and flow of the radial and ulnar artery at the level of the wrist, and the digital radial and ulnar arteries at the level of the fingers. MATERIAL AND METHOD: A descriptive observational cross-sectional study on 200 hands in 100 healthy volunteers aged between 20-30years. Doppler-colour ultrasound was performed on the ulnar and radial arteries in the wrist, as well as on the radial and ulnar digital arteries in each finger. Once the measurements had been taken, a general comparative analysis was performed also taking laterality, dominance and gender into account. RESULTS: It was observed that the radial artery is larger in size than the ulnar at wrist level, however, it was the ulnar artery that showed flow dominance at this level. At finger level, the arteries are greater in size and flow in the areas of the fingers more protected from injury (digital ulnar artery in the first three and radial artery in the fourth and fifth digits).

Photoplethysmography using a smartphone application for assessment of ulnar artery patency: a randomized clinical trial.

BACKGROUND: Radial artery access is commonly performed for coronary angiography and invasive hemodynamic monitoring. Despite limitations in diagnostic accuracy, the modified Allen test (manual occlusion of radial and ulnar arteries followed by release of the latter and assessment of palmar blush) is used routinely to evaluate the collateral circulation to the hand and, therefore, to determine patient eligibility for radial artery access. We sought to evaluate whether a smartphone application may provide a superior alternative to the modified Allen test. METHODS: We compared the modified Allen test with a smartphone heart rate-monitoring application (photoplethysmography readings detected using a smartphone camera lens placed on the patient's index finger) in patients undergoing a planned cardiac catheterization. Test order was randomly assigned in a 1:1 fashion. All patients then underwent conventional plethysmography of the index finger, followed by Doppler ultrasonography of the radial and ulnar arteries (the diagnostic standard). The primary outcome was diagnostic accuracy of the heart rate-monitoring application. RESULTS: Among 438 patients who were included in the study, we found that the heart rate-monitoring application had a superior diagnostic accuracy compared with the modified Allen test (91.8% v. 81.7%, p = 0.002), attributable to its greater specificity (93.0% v. 82.8%, p = 0.001). We also found that this application had greater diagnostic accuracy for assessment of radial or ulnar artery patency in the ipsilateral and contralateral wrist (94.0% v. 84.0%, p < 0.001). INTERPRETATION: A smartphone application used at the bedside was diagnostically superior to traditional physical examination for confirming ulnar patency before radial artery access. This study highlights the potential for smartphone-based diagnostics to aid in clinical decision-making at the patient's bedside. Trial registration: Clinicaltrials.gov, no. NCT02519491.

[Reliability and validity of the modified Allen test: a systematic review and metanalysis]. / Validez y fiabilidad del test modificado de Allen: una revisión sistemática y metanálisis.

OBJECTIVES: The objective was to evaluate the reliability and validity of the modified Allen test in screening for collateral circulation deficits in the palm and for predicting distal hand ischemia. We performed a systematic review of the literature indexed in 6 databases. We developed a search strategy to locate studies comparing the Allen test to Doppler ultrasound to detect circulation deficits in the hand, studies assessing the incidence of ischemic events on arterial puncture after an abnormal Allen test result, and studies of Allen test interobserver agreement. Fourteen articles met the inclusion criteria. Nine assessed the validity of the test as a screening tool for detecting collateral circulation deficits. From data published in 3 studies that had followed comparable designs we calculated a sensitivity of 77% and specificity of 93% for the Allen test. Four studies that assessed the ability of the test to predict ischemia did not predict any ischemic hand events following arterial puncture in patients with abnormal Allen test results. A single study assessing the test's reliability reported an interobserver agreement rate of 71.5%. This systematic review and metanalysis allows to conclude that the Allen test does not have sufficient diagnostic validity to serve as a screening tool for collateral circulation deficits in the hand. Nor is it a good predictor of hand ischemia after arterial puncture. Moreover, its reliability is limited. There is insufficient evidence to support its systematic use before arterial puncture.

OBJETIVO: El objetivo de esta revisión se centra en evaluar la validez y fiabilidad del test modificado de Allen como prueba de cribado para déficits en la circulación colateral palmar y como predictor de isquemia distal de la mano. Para ello, se realizó una revisión sistemática de la literatura a través de 6 bases de datos. Se elaboraron protocolos de búsqueda para localizar estudios que comparasen el test de Allen con la ecografía Doppler para detectar déficits de la circulación colateral de la mano; que evaluasen la incidencia de eventos isquémicos cuando la arterioclisis se realizaba ante un test de Allen anormal y que estudiasen la concordancia interobservador del test. En total, 14 artículos cumplieron los criterios de búsqueda. Nueve estudios evaluaron la validez del test como prueba de cribado para déficits de circulación colateral. En base a 3 estudios de metodología análoga, se calculó una sensibilidad y especificidad del test del 77% y 93%, respectivamente. Cuatro estudios que valoraban la capacidad del test para predecir isquemia no objetivaron ningún evento isquémico de la mano tras arterioclisis cuando el test de Allen era anormal. Un único estudio evaluó la fiabilidad del test, determinando una concordancia interobservador del 71,5%. Esta revisión sistemática y metanálisis permite concluir que el test de Allen no presenta una adecuada validez diagnóstica como prueba de cribado de déficits de la circulación colateral de la mano, ni resulta un buen predictor de isquemia de la mano tras una punción arterial. Además, presenta una limitada fiabilidad, por lo que no existen evidencias que sustenten su realización sistemática previa a una punción arterial.

Delayed Repair of Ulnar Artery at the Distal Forearm.

Background:The purpose of this study was to evaluate the rate of patency after delayed repair of the ulnar artery following primary ligation. Methods: Adult patients with primary ligation of the injured ulnar artery at the forearm who had a delayed repair of the artery were included. Postoperative arterial patency was determined by either physical examination or color Doppler ultrasonographic imaging. Postoperative complications and Disabilities of the Arm, Shoulder and Hand score were recorded. Results: Eight consecutive patients during a 3-year period were included. The mean age was 35 years. Four cases were women. The surgery was performed at a mean of 5 days after the injury and ligation. At a mean follow-up of 22 months, 7 patients had a patent artery. One patient suffered a hematoma. Conclusions: A high rate of patency can be obtained after delayed repair of the ulnar artery at the forearm.

Investigation of Ultrasound-Measured Flow Velocity, Flow Rate and Wall Shear Rate in Radial and Ulnar Arteries Using Simulation.

Parameters of blood flow measured by ultrasound in radial and ulnar arteries, such as flow velocity, flow rate and wall shear rate, are widely used in clinical practice and clinical research. Investigation of these measurements is useful for evaluating accuracy and providing knowledge of error sources. A method for simulating the spectral Doppler ultrasound measurement process was developed with computational fluid dynamics providing flow-field data. Specific scanning factors were adjusted to investigate their influence on estimation of the maximum velocity waveform, and flow rate and wall shear rate were derived using the Womersley equation. The overestimation in maximum velocity increases greatly (peak systolic from about 10% to 30%, time-averaged from about 30% to 50%) when the beam-vessel angle is changed from 30° to 70°. The Womersley equation was able to estimate flow rate in both arteries with less than 3% error, but performed better in the radial artery (2.3% overestimation) than the ulnar artery (15.4% underestimation) in estimating wall shear rate. It is concluded that measurements of flow parameters in the radial and ulnar arteries with clinical ultrasound scanners are prone to clinically significant errors.

Investigation of Ultrasound-Measured Flow Rate and Wall Shear Rate in Wrist Arteries Using Flow Phantoms.

The aim of this study was to evaluate the errors in measurement of volumetric flow rate and wall shear rate measured in radial and ulnar arteries using a commercial ultrasound scanning system. The Womersley equations were used to estimate the flow rate and wall shear rate waveforms, based on the measured vessel diameter and centerline velocity waveform. In the experiments, each variable (vessel depth, diameter, flow rate, beam-vessel angle and different waveform) in the phantom was investigated in turn, and its value was varied within a normal range while others were fixed at their typical values. The outcomes revealed that flow rate and wall shear rate were overestimated in all cases, from around 13% to nearly 50%. It is concluded that measurements of flow rate and wall shear rate in radial and ulnar arteries with a clinical ultrasound scanner are vulnerable to overestimation.

Flexible Non-Constrained RF Wrist Pulse Detection Sensor Based on Array Resonators.

This paper presents the development of a non-contact, nonintrusive wrist pulse sensor based on the near-field variation of an array resonator. A compact resonator and its array were designed and fabricated on flexible substrate. The reflection coefficient of the resonator can vary as a function of the distance between the resonator and the walls of the major arteries, and the corresponding variation is utilized to obtain heart rate information at the wrist. To detect very weak pulse signals from the main arteries, a sensitivity enhancement technique was devised using a radio frequency (RF) array resonator. The sensor system was implemented with an RF switch to combine or select appropriate signals from the resonator element and was tested using the 2.4 GHz ISM band. The results demonstrated the sensor system's excellent performance in both sequential and simultaneous detection schemes. The measurement results showed that a heartbeat pulse can be detected from both radial and ulnar arteries via the array resonators. Considering the high sensitivity and characteristics, the proposed detection system can be utilized as a wearable, long-term health monitoring device.

[Anatomical rationale for elevating revascularized ulnar forearm fasciocutaneous flap for head and neck reconstruction].

In this paper we studied in detail features of the blood supply to the tissues of the forearm of the pools ulnar and radial arteries, the technique of line access and the formation of skin-fascial ulnar flap by using a layered dissection with contrast vessels on non fixed human cadavers. Blood supply of the forearm carried out by branches radial and ulnar arteries, which allows to create in this area radial flap and ulnar flap loo. The size of the skin-fascial ulnar flap can reach 3-10 cm in length, 2-6 cm in width, the length of vessel pedicle of the transplant can reach 12 cm. The research studied the characteristics of blood supply of the forearm and the comparative evaluation of tissue perfusion of the radial and ulnar arteries; proved localization forming ulnar flap. Studies have shown that revascularised skin-fascial ulnar flap may be can be an alternative donor material for elimination of soft tissue defects with less traumatization donor area and reduce upper limb function compared with radial flap.

Forearm arterial anatomy and flow characteristics: a prospective observational study.

BACKGROUND: Morphometric data on Caucasian radial and ulnar arteries are limited, with no data on flow interdependence in the forearm arterial circuit. METHODS: A total of 250 upper extremities in 125 patients were evaluated. Ultrasonography was performed and radial and ulnar artery lumen diameters were measured. Ulnar artery (UA) was compressed at the level of the wrist, and flow parameters in radial artery (RA) were recorded using duplex Doppler ultrasound. RESULTS: Radial and ulnar artery diameters were comparable at the level of the distal forearm (RA = 2.03 ± 0.28 mm, UA = 2.07 ± 0.27 mm; P=.14). There was no significant difference in radial or ulnar artery diameter between the dominant upper extremity and the non-dominant upper extremity. Upon compression of the ulnar artery, radial artery velocity-time integral (VTI) increased from 8.4 ± 3.8 cm to 12.8 ± 5.5 cm, which was statistically significant (P<.001). There was a significant inverse correlation between radial artery diameter and the magnitude of increase in radial VTI observed with UA compression (r² = 0.106; P<.001). CONCLUSION: RA diameter at the level of the distal forearm is comparable to UA. RA-VTI and likely flow significantly increase by compression of the UA. The smaller the radial artery, the larger the increase in radial artery flow with ulnar compression.

Vascular access-induced hand ischemia: risks and safe management.

Hand ischemia is rare but complex and multifactorial. Distal arteriopathy below the vascular access (VA) is responsible in the vast majority of patients and not a problem of high flow of the VA. Therefore, surgical technique should focus on improving blood flow and pressure instead of reducing blood flow. We present an overview of the standard techniques which are recommended to treat VA-induced hand ischemia. The banding techniques, most of which empirical and not codified, have been abandoned by the majority of the authors because of a high rate of failure and reintervention. Ligation may be necessary in patients with severe ischemia and diffuse arterial lesions and in case of ischemic monomelic neuropathy.

Myogenic responses occur on a beat-to-beat basis in the resting human limb.

Investigations of human myogenic responses typically use maneuvers that evoke robust changes in transmural pressure. Although this strategy has demonstrated peripheral myogenic responsiveness in the limbs, particularly in glabrous skin of the hand or foot, it has not considered the potential influence of the myogenic mechanism in beat-to-beat blood flow (BF) control during unprovoked rest. In the present study, we examined the interactions of spontaneous beat-to-beat mean arterial pressure (MAP; Finapres) with BF (Doppler ultrasound) supplying the forearm (brachial artery), lower leg (popliteal artery), and hand (ulnar artery) during 10 min of supine rest in healthy young men. Cross-correlation analyses revealed a negative association between MAP and BF, which was more prominent in the forearm than lower leg. The strongest correlation resulted when a -2-heart beat offset of MAP was applied (R=-0.53±0.04 in the forearm and -0.23±0.05 in the leg, P<0.05), suggesting an ∼2-s delay from instances of high/low MAP to low/high BF. Negatively associated episodes (high MAP/low BF and low MAP/high BF) outnumbered positively associated data (P<0.05). BF during low MAP values was greater than the steady-state average BF and vice versa. Wrist and ankle occlusion blunted the strength of correlations, homogenized the incidence of MAP and BF pairings, and reduced the magnitude of deviation from steady-state values. In contrast, these relationships were matched or accentuated for hand BF. Overall, these results suggest that myogenic responses are present and occur rapidly in human limbs during rest, overwhelm perfusion pressure gradient influences, and are primarily mediated by the distal limb circulation.

The effect of upper limb position on ultrasonographic arterial flow to the ulnar nerve.

We measured the pulsatility indices in the inferior collateral and posterior recurrent ulnar arteries, which supply the ulnar nerve at the elbow, in 38 conscious adults. Compared with a straight 30° abducted arm, elbow flexion to 120° reduced the mean (SD) pulsatility index in the inferior artery and increased the pulsatility index in the posterior artery: from 3.36 (0.86) to 3.04 (0.94), p = 0.001, and from 3.14 (0.81) to 3.64 (1.05), p < 0.0005, respectively. The mean (95% CI) pulsatility index in the inferior artery was unaffected by shoulder abduction to 120°, but it was decreased in the posterior artery in men, from 3.06 (2.76-3.36) to 2.64 (2.34-2.95), but not women, from 3.22 (2.94-3.50) to 3.25 (2.97-3.53), p = 0.01 for men vs women. Researchers should measure arterial pulsatility indices under general anaesthesia and associate them with measures of nerve function.