The Anatomy and Physiology of the Venous Foot Pump

Magnetic Resonance Imaging Features of Plantar Vein Thrombosis

Plantar vein thrombosis (PVT) is an underdiagnosed condition affecting the deep plantar veins, with challenging clinical diagnosis, often presenting with non-specific symptoms that mimic other foot pathologies. This study assessed the magnetic resonance imaging (MRI) features of patients diagnosed with PVT to contribute to the understanding of this condition. We performed the comprehensive analysis of a substantial dataset, including 112 patients, with a total of 130 positive MRI scans (86 of the forefoot and 44 of the ankle) presenting with PVT. Upon evaluating all the veins of the feet, we observed a higher frequency of involvement of the lateral plantar veins (53.1%) when compared to the medial veins (3.8%). The most affected vascular segments in the forefeet were the plantar metatarsal veins (45.4%), the plantar venous arch (38.5%), and the plantar communicating veins (25.4%). The characteristic findings on MRI were perivascular edema (100%), muscular edema (86.2%), venous ectasia (100%), perivascular enhancement (100%), and intravenous filling defects (97.7%). Our study provides valuable insights into the imaging evaluation of PVT and shows that MRI is a reliable resource for such diagnosis.

Vicious Circle With Venous Hypertension, Irregular Flow, Pathological Venous Wall Remodeling, and Valve Destruction in Chronic Venous Disease: A Review

Substantial advances occurred in phlebological practice in the last two decades. With the use of modern diagnostic equipment, the patients' venous hemodynamics can be examined in detail in everyday practice. Application of venous segments for arterial bypasses motivated studies on the effect of hemodynamic load on the venous wall. New animal models have been developed to study hemodynamic effects on the venous system. In vivo and in vitro studies revealed cellular phase transitions of venous endothelial, smooth muscle, and fibroblastic cells and changes in connective tissue composition, under hemodynamic load and at different locations of the chronically diseased venous system. This review is an attempt to integrate our knowledge from epidemiology, paleoanthropology and anthropology, clinical and experimental hemodynamic studies, histology, cell physiology, cell pathology, and molecular biology on the complex pathomechanism of this frequent disease. Our conclusion is that the disease is initiated by limited genetic adaptation of mankind not to bipedalism but to bipedalism in the unmoving standing or sitting position. In the course of the disease several pathologic vicious circles emerge, sustained venous hypertension inducing cellular phase transitions, chronic wall inflammation, apoptosis of cells, pathologic dilation, and valvular damage which, in turn, further aggravate the venous hypertension.

Thermoregulation of feet in cold environments: A study on alpinism

Thermal comfort plays a crucial role in the performance and well-being of mountaineers, especially in extreme environments. The aim of this study was to develop a reliable protocol to assess the thermal comfort of mountaineering boots, with a specific focus on temperature variations in different regions of the foot and their correlation with physiological factors. Two different models of mountaineering boots were tested at two different environmental temperature (-15°C and -30°C). The mean skin temperature, measured according to International Standards BS EN ISO 9886:2004, was used as an indicator of overall thermal comfort. Physiological factors such as heart rate (HR), body mass index (BMI) and body surface area (BSA) were also measured to understand their relationship to thermoregulation. Kruskal-Wallis and Pearson's ProductMoment correlation tests were performed to investigate whether there was a statistically significant relationship. The results showed significant differences in foot temperature among the Testers, indicating variations in the perception of thermal comfort. The correlation analysis showed a strong positive relationship between mean skin temperature and HR, highlighting the influence of physiological factors on thermal comfort. In addition, the analysis showed that the dorsum and hallux areas had the largest temperature variations, suggesting the occurrence of vasoconstriction and potential discomfort. This study represents a preliminary approach to establishing a reliable protocol for assessing the thermal performance of cold protective footwear.

Endovenous laser ablation vs phlebectomy of foot varicose veins

OBJECTIVE

The aim of this study was to compare the outcomes and complications of selected patients treated with endovenous laser ablation (EVLA) or ambulatory phlebectomy for foot varicose veins.

METHODS

From October 2016 to February 2022, selected patients undergoing EVLA (using 1470-nm with radial-slim or bare-tip fibers) or phlebectomy of foot varicose veins for cosmetic indications were analyzed, and the outcomes were compared. Patients were classified according to the Clinical, Etiologic, Anatomical, and Pathophysiological (CEAP) classification. Anatomic criteria provided the basis for the decision to perform EVLA or phlebectomy. Clinical and ultrasound assessments were performed on postoperative days 7, 30, and 90 for visualization of the sapheno-femoral and sapheno-popliteal junctions and the deep venous system. Disease severity was graded with the Venous Clinical Severity Score (VCSS), and quality of life was measured with the Aberdeen Varicose Vein Questionnaire (AVVQ) before and after treatment. Treatment outcomes were evaluated based on changes in VCSS and AVVQ scores. The groups were also compared for procedure-related complications. Data were statistically analyzed in SPSS v. 20.0 using the χ2, Student t test, Mann-Whitney test, Wilcoxon test, and analysis of variance. The results were presented as mean (standard deviation or median (interquartile range).

RESULTS

The study included 270 feet of 171 patients. Mean patient age was 52.3 (standard deviation, 13.1) years, ranging from 21 to 84 years; 133 (77.8%) were women. Of 270 feet, 113 (41.9%) were treated with EVLA and 157 (58.1%) with phlebectomy. The median preoperative CEAP class was 2 (interquartile range, 2-3) in the phlebectomy and EVLA groups, with no statistically significant difference between the groups (P = .507). Dysesthesia was the most common complication in both groups. Only transient induration was significantly different between EVLA (7.1%) and phlebectomy (0.0%) (P = .001). The two approaches had an equal impact on quality of life and disease severity.

CONCLUSIONS

Treatment complications were similar in phlebectomy and EVLA and to those previously described in the literature.

Species- and sex-specific chemical composition from an internal gland-like tissue of an African frog family

Intraspecific chemical communication in frogs is understudied and the few published cases are limited to externally visible and male-specific breeding glands. Frogs of the family Odontobatrachidae, a West African endemic complex of five morphologically cryptic species, have large, fatty gland-like strands along their lower mandible. We investigated the general anatomy of this gland-like strand and analysed its chemical composition. We found the strand to be present in males and females of all species. The strand varies in markedness, with well-developed strands usually found in reproductively active individuals. The strands are situated under particularly thin skin sections, the vocal sac in male frogs and a respective area in females. Gas-chromatography/mass spectrometry and multivariate analysis revealed that the strands contain sex- and species-specific chemical profiles, which are consistent across geographically distant populations. The profiles varied between reproductive and non-reproductive individuals. These results indicate that the mandibular strands in the Odontobatrachidae comprise a so far overlooked structure (potentially a gland) that most likely plays a role in the mating and/or breeding behaviour of the five Odontobatrachus species. Our results highlight the relevance of multimodal signalling in anurans, and indicate that chemical communication in frogs may not be restricted to sexually dimorphic, apparent skin glands.

Imaging Features of Plantar Vein Thrombosis: An Easily Overlooked Condition in the Differential Diagnosis of Foot Pain

Plantar vein thrombosis is a venous disorder affecting deep plantar veins that can manifest with non-specific localized pain, plantar foot pain, swelling, and sensation of fullness. Plantar veins are not routinely assessed during sonographic scans for deep venous thrombosis, which makes plantar venous thrombosis a commonly missed diagnosis. This paper provides a comprehensive review of the venous anatomy of the foot and imaging findings of plantar venous thrombosis as well as discusses the current literature on the topic and its differential diagnoses.

Effect of foot stato-dynamic disorders on hemodynamics of the lower limb using strain-gauge plethysmography

BACKGROUND

The plantar venous pump (PVP), composed of deep plantar veins, is the most distal contributor to venous return from the lower limbs. A pressing need still exists to assess how plantar muscle contraction and gait affect PVP function, how foot stato-dynamic disorders (FSDs) can contribute to venous insufficiency, and how venous return can be optimally stimulated. Our first objective is to compare the venous blood hemodynamics in lower limbs between healthy subjects with a FSD and healthy subjects without a FSD to understand the influence of foot morphology in the performance of the PVP. Our second objective is to evaluate whether PVP function varies with different plantar pressures.

METHODS

A total of 52 healthy volunteers (26 feet with a normal arch as the control group and 26 feet with dysmorphism [13 flat feet and 13 hollow feet]) were included. Strain-gauge plethysmography was performed 8 cm above the medial malleolus at different conditions of PVP stimulation: (1) toe flexion, (2) intermittent pneumatic compression (IPC) with and without an insole, and (3) 3-km/h speed walking on a treadmill barefoot, with shoes, and with shoes and insoles. From the strain-gauge plethysmography, we measured the venous blood ejection fraction (EF). From the pressure sensor placed at the midfoot on the plantar arch during IPC, we obtained the maximal pressure (N/cm2).

RESULTS

Toe flexion allowed for ejection of an average of 20% of the total venous volume in both groups. IPC and gait generated a mean EF superior to 100% of the available venous volume. The maximal pressure applied at the midfoot during IPC was lower than the pressure set. No significant differences in the EF or maximal pressure were observed between the two groups. The mean EF was not significantly affected for the pronator and supinator walkers compared with those with normal walking dynamics. Wearing shoes did not significantly affect the mean EF. However, wearing insoles during gait significantly increased the venous return in feet with plantar dysmorphism.

CONCLUSIONS

To the best of our knowledge, this clinical study is the first to assess the PVP function in 52 healthy volunteers with and without FSDs. We found that wearing shoes did not significantly affect PVP efficiency but that wearing morphologically adapted insoles significantly improved the venous return in the dysmorphic feet. In our sample of healthy volunteers, the differences observed between the control group and feet with FSDs were not statistically significant.

Vascular impulse technology versus elevation for reducing the swelling of upper and lower extremity joint fractures

Soft-tissue conditioning due to posttraumatic oedema after complicated joint fractures is a central therapeutic aspect both pre- and postoperatively. On average, 6-10 days pass until the patient is suitable for surgery. This study compares the decongestant effect of vascular impulse technology (VIT) with that of conventional elevation. In this monocentric RCT, 68 patients with joint fractures of the upper (n = 36) and lower (n = 32) extremity were included and randomized after consent in a 1:1 ratio. Variables were evaluated for all fractures together and additionally subdivided into upper or lower extremity for better clinical comparability. Primary endpoint was the time in days from hospital admission to operability. Secondary endpoints were total length of stay, oedema reduction, pain intensity, complications, and revisions. The time from admission until operability was reduced by 1.4 (95% CI - 0.4; 3.1) days in the mITT analysis (p = 0.120) and was statistically significant with 1.7 (95% CI 0.1; 3.3) days in the as-treated sensitivity analysis (p_AT = 0.038). Significantly less pain and a faster oedema reduction were found in the intervention group. Due to rare occurrences, nothing can be concluded regarding complications and revisions. Administration of VIT therapy did not lead to a significant reduction in time until operability in the whole population but was superior to elevation for soft-tissue conditioning and pain reduction. However, there was a significant reduction by 2.5 days (95% CI 0.7; 4.3) in the subgroup of lower extremity fractures. VIT therapy therefore seems to be a helpful tool in the treatment of posttraumatic oedema after complex joint fractures of the lower and upper extremity, especially in tibial head and lower leg fractures.

The effects of shoe type on lower limb venous status during gait or exercise: A systematic review

This systematic review evaluated the literature pertaining to the effect of shoes on lower limb venous status in asymptomatic populations during gait or exercise. The review was conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The PubMed-NCBI, EBSCO Host, Cochrane Library and Science Direct databases were searched (March 2019) for words around two concepts: shoes and venous parameters. The inclusion criteria were as follows: (1) the manuscript had to be published in an English-language peer-reviewed journal and the study had to be observational or experimental and (2) the study had to suggest the analysis of many types of shoes or orthotics on venous parameters before, during and/or after exercise. Out of 366 articles, 60 duplications were identified, 306 articles were analyzed, and 13 articles met the eligibility criteria after screening and were included. This review including approximately 211 participants. The methodological rigor of these studies was evaluated with the modified Downs and Black quality index. Nine studies investigated the effect of shoes on blood flow parameters, two on venous pressure and two on lower limb circumferences with exercise. Evidence was found that unstable shoes or shoes with similar technology, sandals, athletic or soft shoes, and customized foot orthotics elicited more improvement in venous variables than high-heeled shoes, firm shoes, ankle joint immobilization and barefoot condition. These venous changes are probably related to the efficiency of muscle pumps in the lower limbs, which in turn seem to be dependent on shoe features associated with changes in the kinetics, kinematics and muscle activity variables in lower limbs during gait and exercise.

S.T.R.I.D.E. Professional Guide to Compression Garment Selection for the Lower Extremity

The following supplement is a rare example of a paper that combines clinical experience and theoretical knowledge on textiles used in compression therapy. The authors' intention is to propose a decision support system for choosing specific compression devices, which can be adjusted to counteract the individual signs and symptoms in an optimally adopted way. The document concentrates on compression devices which can be self-applied by the patients—compression stockings and adjustable wraps. The acronym ‘S.T.R.I.D.E.’, incorporating both textile characteristics and clinical presentation, stands for: Shape, Texture, Refill, Issues, Dosage and Etiology. The intent of the mnemotechnical value is to highlight that successful compression includes more than dosage alone. In addition to dosage, etiology and patient presentation need to be incorporated, including a patient's physical ability to use compression effectively as part of the daily routine, thereby promoting adherence.

The suggested algorithms provide a valuable guide to stride across the important, but still underestimated field of medical compression therapy and will help to put the prescription of a specific product on a more rational basis. Enjoy reading!

Hugo Partsch Emeritus Professor Medical University of Vienna, Austria

Changes in lower extremity blood flow during advancing phases of pregnancy and the effects of special footwear

Background

During pregnancy, a number of changes affecting venous blood flow occur in the circulatory system, such as reduced vein wall tension or increased exposure to collagen fibers. These factors may cause blood stagnation, swelling of the legs, or endothelial damage and consequently lead to development of venous disease.

Objectives

The aim of this study is to evaluate the effect of special footwear designed to improve blood circulation in the feet on venous blood flow changes observed during advancing phases of pregnancy.

Methods

Thirty healthy pregnant women participated in this study at 25, 30, and 35 weeks of gestation. Participants were allocated at random to an experimental group (n = 15) which was provided with the special footwear, or a control group (n = 15). At each data collection session, Doppler measurements of peak systolic blood flow velocity and cross-sectional area of the right popliteal vein were performed using a MySonoU6 ultrasound machine with a linear transducer (Samsung Medison). The differences were compared using Cohen's d test to calculate effect size.

Results

With advancing phases of pregnancy, peak systolic velocity in the popliteal vein decreased significantly in the control group, whereas it increased significantly in the experimental group. No significant change in cross-sectional area was observed in any of the groups.

Conclusions

Findings in the experimental group demonstrated that wearing the footwear tested may prevent venous blood velocity from reducing during advanced phases of pregnancy. Nevertheless, there is a need for further investigation of the beneficial effect on venous flow of the footwear tested and its application.

Effects of plantar stimulation on cardiovascular response to orthostatism

PURPOSE

Walking is a complex locomotor process that involves both spinal cord reflexes and cortical integration of peripheral nerve input. Maintaining an upright body position requires not only neuromuscular activity but also cardiovascular regulation. We postulated that plantar mechanical stimulation might modulate autonomic nervous system activity and, thereby, impact blood pressure adaptation during standing.

METHODS

Twelve healthy subjects underwent three randomly ordered 45-min 70°-saddle tilt tests while the plantar surfaces of the feet were stimulated using specially engineered Korvit boots in the following modes: (1) no stimulation, (2) disrupted stimulation, and (3) walking mode. Orthostatic tolerance time was measured for each trial. During testing, we obtained an electrocardiogram and measured blood pressure, skin blood flow, and popliteal vein cross-sectional area. We estimated central hemodynamics, baroreflex sensitivity and heart rate variability.

RESULTS

Orthostatic tolerance time was not found to differ significantly between test conditions (37.2 ± 10.4, 40.9 ± 7.6, and 41.8 ± 8.2 min, for no stimulation, disrupted stimulation, and walking mode, respectively). No significant differences between treatment groups were observed for stroke volume or cardiac baroreflex sensitivity, both of which decreased significantly from baseline during tilt testing in all groups. Cardiac sympathetic index and popliteal vein cross-sectional area increased at the end of the tilt period in all groups, without significant differences between treatments.

CONCLUSIONS

Plantar mechanical stimulation is insufficient for immediate modulation of cardiac sympathetic and parasympathetic activity under orthostatic stress.

Effects of Hypochlorous Acid Solutions on Venous Leg Ulcers (VLU): Experience With 1249 VLUs in 897 Patients

In order to assess the impact of comorbidities and identify factors that accelerate the healing rate of venous leg ulcers we performed an extensive, retrospective analysis of our experience in a diverse population. From June, 2006 to June, 2014, 897 patients with 1249 venous leg ulcers were treated at Lake Wound Clinics. Treatment protocols utilized the standard regimen of wound cleaning, debridement and compression bandaging. Wound cleaning, autolytic debridement, packing and dressing of venous leg ulcers utilized aqueous solutions of hypochlorous acid (HCA) rather than the standard normal saline. This protocol caused all ulcers to close completely. Comorbidities that delayed healing included uncontrolled or poorly controlled diabetes mellitus, advanced peripheral artery occlusive disease (PAD), active smoking, use of steroid medications and/or street drugs, large initial ulcer size and significant depth. Other factors, including advanced age, recurrent venous ulceration, stasis dermatitis, lipodermatosclerosis, morbid obesity and infection with one or more multidrug resistant organisms did not delay closure. From this experience we conclude that venous leg ulcer care protocols that clean, debride, pack and dress with hypochlorous acid solutions can reduce the effects of some comorbidities while accelerating healing times. Additional benefits are described.

Anatomy and physiology of the lower-extremity deep and superficial veins

A thorough understanding of venous anatomy and physiology is foundational to the diagnosis and management of venous disease. Compared with the arterial system, there is significantly greater developmental variation in the venous system. The veins of the lower extremity include the superficial and deep veins, which are defined by their respective relationships to the muscular fascia. Perforating veins traverse the muscular fascia to connect superficial and deep veins. Communicating veins connect veins within the same venous compartment, either deep to deep or superficial to superficial. The deep veins of the lower extremities primarily drain muscles and are encompassed by muscular fascia. The veins located between the skin and the muscular fascia are considered superficial veins. Superficial veins drain the cutaneous microcirculation. The pelvic venous system is a complex transitional outflow pathway between the lower extremities, the pelvic structures, and the inferior vena cava. The terminology used to describe lower-extremity, pelvic, and abdominal vasculature conforms to published international standards.

Venous emptying from the foot: influences of weight bearing, toe curls, electrical stimulation, passive compression, and posture

This study investigated the hemodynamic properties of the plantar venous plexus (PVP), a peripheral venous pump in the human foot, with Doppler ultrasound. We investigated how different ways of introducing mechanical changes vary in effectiveness of displacing blood volume from the PVP. The contribution of the PVP was analyzed during both natural and device-elicited compressions. Natural compressions consisted of weight bearing on the foot and toe curl exercises. Device-elicited compressions consisted of intermittent pneumatic compression (IPC) of the foot and electrically elicited foot muscle contractions. Ten healthy participants had their posterior tibial, peroneal, anterior tibial, and popliteal vein blood flow monitored while performing these natural and device-elicited compressions of the PVP supine and in an upright position. Results indicated that 1) natural compression of the PVP, weight bearing and toe curls, expelled a significantly larger volume of blood than device-elicited PVP compression, IPC and electrical stimulation; 2) there was no difference between the venous volume elicited by weight bearing and by toe curls; 3) expelled venous volume recorded at the popliteal vein under all test conditions was significantly greater than that recorded from the posterior tibial and peroneal veins; 4) there was no significant difference between the volume in the posterior tibial and peroneal veins; 5) ejected venous volume recorded in the upright position was significantly higher than that recorded in the supine position. Our study shows that weight bearing and toe curls make similar contributions to venous emptying of the foot.