Mohammed Aslam

Impaired Hyperaemic and Rhythmic Vasomotor Response in Type 1 Diabetes Mellitus Patients: A Predictor of Early Peripheral Vascular Disease

OBJECTIVES The smooth muscle of distal vascular networks exhibits periodical contraction and relaxation known as rhythmical vasomotion. The nature of microvascular vasomotion has been shown to correlate with severity of peripheral vascular disease. We present basal and post-ischaemic hyperaemic laser doppler flowmetry vasomotion in control and type 1 adult diabetic patients. DESIGN Prospective case control study. METHODS Laser Doppler flowmetry was used to measure vasomotion and hyperaemic responses in age and body mass index matched male subjects (25 type 1 Diabetes Mellitus and 13 controls), all with ankle/brachial pressure index (ABPI) >1.0 but <1.2. RESULTS The frequency of resting vasomotion was raised in diabetics compared to controls 8 (5-9)min(-1) vs. 5 (4-6)min(-1) (median (range); p<0.0001). The post ischaemic hyperaemia response was significantly higher in the diabetic group compared to the controls 11 (7-12)min(-1) vs. 6 (5-7)min(-1) (median (range); p<0.05). Post ischaemic hyperaemic flux (expressed as percent increase from resting) was significantly lower in the diabetic group compared to controls (234+/-62 vs. 453+/-155%, p<0.01). The time to achieve peak post ischaemic response was also significantly increased in the diabetic group compared to control: 21.4+/-0.4 vs. 12.8+/-5.4sec (mean+/-SD, p<0.05). CONCLUSIONS Vasomotion frequency and its change during hyperaemic insult is significantly different in Type 1 Diabetes Mellitus subjects compared to controls. The results are similar to patients with macrovascular atherosclerosis. Long term studies of these groups of patients will be required to determine the significance of these findings and whether these changes could be used as a non invasive screening test to predict peripheral early vascular disease in type 1 diabetic patients.

Changes in vascular flow after transdermal oestradiol therapy for prostate cancer: a mechanism for cardiovascular toxicity and benefit?

To report the influence of transdermal oestradiol therapy on the vascular dynamics of men with advanced prostate cancer.

Variation in duplex peak systolic velocity measurement in a multi-site vascular service

Objective: Duplex US (DUS) is increasingly utilised as a first-line investigation for the assessment of carotid disease. For clinical decision-making, DUS assessment must be accurate and reproducible to ensure reliability. We aimed to investigate the variability in peak systolic velocity (PSV) measurement in a multi-site vascular network. Methods: DUS measurements of PSV were taken from continuous and pulsatile flow, generated by a high fidelity phantom, by 12 experienced vascular scientists across four hospitals. Participants were blinded to the actual PSV value (50 cm/s). Results: We observed an average error of 13.2% (± 8.3) and 11.6% (± 7.5) in PSV measurements taken from pulsatile and continuous waveforms, respectively. Measurements of PSV using the pulsatile waveform demonstrated statistically significant variation across all hospitals; ((hospital/mean) A 43.9 cm/s, B 61.7 cm/s, C 57.4 cm/s, D 47.7 cm/s, p=0.001). Further analysis demonstrated statistically significant variation in 4 instrumentation-related factors when measuring from a pulsatile waveform (Doppler angle, angle of insonation, velocity range, scale range). Conclusion: We observed a significant level of error and variation in PSV measurements across four sites within our vascular network. Variation in instrumentation-related factors may be accountable for this. In light of the centralisation of vascular services, it is increasingly important to unify and implement scanning protocols in order to reduce error and inter-site variability.

The Effect of a Simulation Training Package on Skill Acquisition for Duplex Arterial Stenosis Detection

OBJECTIVES In vascular surgery, duplex ultrasonography is a valuable diagnostic tool in patients with peripheral vascular disease, and there is increasing demand for vascular surgeons to be able to perform duplex scanning. This study evaluates the role of a novel simulation training package on vascular ultrasound (US) skill acquisition. MATERIALS AND METHODS A total of 19 novices measured predefined stenosis in a simulated pulsatile vessel using both peak systolic velocity ratio (PSVR) and diameter reduction (DR) methods before and after a short period of training using a simulated training package. The training package consisted of a simulated pulsatile vessel phantom, a set of instructional videos, duplex ultrasound objective structured assessment of technical skills (DUOSATS) tool, and a portable US scanner. Quantitative metrics (procedure time, percentage error using PSVR and DR methods, DUOSAT scores, and global rating scores) before and after training were compared. RESULTS Subjects spent a median time of 144 mins (IQR: 60-195) training using the simulation package. Subjects exhibited statistically significant improvements when comparing pretraining and posttraining DUOSAT scores (pretraining = 17 [16-19.3] vs posttraining = 30 [27.8-31.8]; p < 0.01), global rating score (pretraining = 1 [1-2] vs posttraining = 4 [3.8-4]; p < 0.01), percentage error using both the DR (pretraining = 12.6% [9-29.6] vs posttraining = 10.3% [8.9-11.1]; p = 0.03) and PSVR (pretraining = 60% [40-60] vs posttraining = 20% [6.7-20]; p < 0.01) methods. CONCLUSION In this study, subjects with no previous practical US experience developed the ability to both acquire and interpret arterial duplex images in a pulsatile simulated phantom following a short period of goal direct training using a simulation training package. A simulation training package may be a valuable tool for integration into a vascular training program. However, further work is needed to explore whether these newly attained skills are translated into clinical assessment.

Randomized study of teaching ultrasound-guided vascular cannulation using a phantom and the freehand versus needle guide-assisted puncture techniques.

The task of ultrasound‐guided vessel cannulation can be technically difficult. Needle guides have been designed to facilitate vessel puncture. We aimed to identify and compare the learning curves of participants performing vessel puncture with conventional freehand (FH) and needle guide–assisted (NG) techniques.

Intensive Simulation Training in Lower Limb Arterial Duplex Scanning Leads to Skills Transfer in Real-World Scenario

OBJECTIVES To train novices to perform an abbreviated duplex lower limb ultrasound scan using simulation training and assess real-world skills transference. METHODS Novices undertook 3 days of simulation training. Their progress was assessed using the Duplex Ultrasound Objective Structured Assessment of Technical Skills (DUOSATS) for simulation and Cumulative Imaging Score (CIS). A final assessment day was held to assess DUOSATS for simulation and real patient scanning, CIS, cumulative diagnostic accuracy, and sections A and B of the Society of Vascular Technology examination. MSc students in vascular ultrasound were also assessed for comparison. RESULTS A total of 17 novices and 7 MSc students with 3-month training participated. Novices improved DUOSATS for simulation scores between days 1, 3, and 4: 18 (17-19) vs 27 (25-28) vs 30 (28-32), (median [interquartile range], p < 0.001). Novices improved in CIS between days 1 and 3: 10 (10-13) vs 21 (19-21), p < 0.001, with a decline on day 4: 15.3 (11.3-18.3), p < 0.001. On the final assessment day, there were no significant differences between novices and MSc students in: DUOSATS for simulation scores (30 [28-32] vs 31 [6-31.5], p = 0.85); DUOSATS for patient assessment (31 [28.7-33.7] vs 26.7 [24.5-35.7], p = 0.41); CIS (15.3 [11.3-18.7] vs 20.7 [12.3-22.2], p = 0.2), respectively. However, novices performed better in section B of the Society of Vascular Technology examination compared with MSc students (72.9% vs 54.3%, p < 0.001). Novices also demonstrated a higher diagnostic accuracy when compared with MSc students (65.7% of arterial segments correctly assessed vs 47.6%, respectively [p = 0.044]). CONCLUSIONS Intensive simulation of 3-day training achieved real patient-based assessments that were comparable to MSc students who were 3 months into their traditional training program.

Venous Reflux Duplex Ultrasound Objective Structured Assessment of Technical Skills (V-DUOSATS)

Background: Treatment of a symptomatic incompetent saphenous vein is routinely accomplished using radiofrequency ablation (RFA). Treatment efficacy is dependent upon, among other factors, effective exsanguination of the target vein. Trendelenburg positioning is often used to facilitate emptying the vein. However, the angle of torso inversion is limited to approximately 15 due to patient stability in a head down position. In November 2007, our clinic implemented a technique whereby the patient’s leg was elevated to a consistent 30 angle while maintaining the torso horizontal, thus achieving enhanced vein emptying. Methods: Patient records for treatments prior to (May-October 2007; Group 1) and subsequent to (November 2007-December 2012; Group 2) implementing the enhanced vein drainage technique were retrospectively analyzed for outcomes. The VNUS Medical Technologies (Covidien, San Jose, Calif) ClosureFast catheters were used for all treatments. Results: Table I summarizes the patient demographics. Incomplete vein obliteration at first postoperative ultrasound was observed in one of 105 (1.0%) treatments in Group 1 (G1), compared with two of 895 (0.2%) in Group 2 (G2; P 1⁄4 NS). Documentation of an early first postoperative ultrasound was lacking for one G2 patient. For outcome analysis, treatments for which an ultrasound follow-up examination was not performed beyond 1 month were excluded. Results are shown in Table II. As would be expected since the G2 patients were treated more recently than the G1 patients, the months of follow-up were skewed toward a shorter interval in G2. In November 2009, we altered our technique from performing two heating passes in the proximal vein segment to a single pass. In comparing G2 treatments that received proximal vein double heating (n 1⁄4 161) to the G1 technique having a similar proximal heating protocol, it was found that one of the six G2 recanalizations occurred in this sub-group (P 1⁄4 .0404). The difference in outcomes between the G2 sub-groups, 1/161 (0.6%) vs 5/ 356 (1.4%), was not significant. Conclusions: An analysis of our clinical experience, although retrospective in nature, suggests that using enhanced leg elevation during saphenous vein RFA, by facilitating exsanguination, may be an effective technique to achieve durable vein obliteration.

Chronic venous insufficiency: a new concept to understand pathophysiology at the microvascular level - a pilot study

Objectives: The real mechanism for the development of the later stages of chronic venous insufficiency still remains unclear. Venous hypervolemia and microvascular ischemia have been reported to be the consequences of venous insufficiency. The aim of this study was to investigate the effects of induced venous hypovolemia by dorsiflexion exercise in patients with venous leg ulcers. Methods: Thirty-six participants, all of whom had an ankle brachial pressure index between 0.8 and 1.2 mmHg, were chosen for this study. The participants were divided into two groups: Group A, a non-exercise group and Group B which performed regular exercise in the form of dorsiflexion. The basic assessment, including the history and examination, ankle-brachial pressure index (ABPI), Duplex scan and tcPO2 measurements, was performed on two occasions at the beginning of the trial and after three months. Results: The tcPO2 level was low in the beginning in all the subjects, but the picture was different at the end of the trial. There was a significant increase in the tcPO2 level (p<0.001) in the patients who performed exercise while there was no difference in the measurements (p>0.05) in the non-exercise group. Conclusions: Induced venous hypovolemia through regular evacuation of the peripheral venous system improved tissue oxygenation at skin level. Venous hypervolemia may be the main contributing factor for the development of venous hypoxia and microvascular ischemia.

Upper Extremity Medial Arterial Calcification and Peripheral Artery Disease in Asymptomatic Patients With Chronic Kidney Disease in Predialysis Stage

Two types of peripheral artery disease (PAD) in asymptomatic patients with chronic kidney disease (CKD) can be detected by the use of duplex Doppler: medial arterial calcification (MAC) and occlusive PAD. The aim of this pilot study is to evaluate different types of subclinical PAD in upper extremities of patients with CKD. The prevalence of upper extremity MAC and occlusive PAD was investigated in 41 asymptomatic patients with CKD and 18 controls with normal kidney function, using duplex Doppler ultrasound, according to the vascular laboratory protocol. A mild-to-severe MAC was significantly more prevalent in patients with CKD compared to the control group (P = .015), mostly in radial arteries (RAs; P = .002 and P = .016, respectively). The prevalence of occlusive PAD was not significantly different between the 2 groups (P = .381). Patients in the CKD group were younger, nonsmokers, and more often had hypertension (P = .038, P = .038, and P = .034, respectively). A duplex ultrasound screening for upper extremity subclinical PAD in patients with CKD in a predialysis stage may identify patients with mild-to-severe MAC which is important in surgery of hemodialysis access.

Evolution of Robot-assisted ultrasound-guided breast biopsy systems

Abstract Robot-assisted ultrasound-guided breast biopsy combines ultrasound (US) imaging with a robotic system for medical interventions. This study was designed to provide a literature review of a robotic US-guided breast biopsy system to delineate its efficacious impact on current medical practice. In addition, the strengths and limitations of this approach were also addressed. Articles published in the English language between 2000 and 2016 were appraised in this review. A wide range of systems that bind robotics with US imaging and guided breast biopsy were examined in this article. The fundamental safety and real-time imaging capabilities of US, together with the accuracy and maneuverability of robotic devices, is clearly an effective association with unmatched capabilities. Numerous experimental systems have obvious benefits over old-fashioned techniques, and the future of robot-assisted US-guided breast biopsy will be characterized by increasing levels of automation, and they hold tremendous possibility to impact doctor achievement, patient recovery, and clinical management.