Strain-gauge Plethysmography Research Articles

O TRÍCEPS SURAL COMO UMA BOMBA CARDIOVASCULAR

Objective: This study aims to carry out an integrative review on the anatomy of the calf, highlighting its function as a “second heart” and the muscular pump mechanisms, as well as the implications for venous circulation. Methodology: An integrative review was carried out with a selection of information published between 2020 and 2024. The research was carried out in virtual libraries, using the descriptors “anatomy”, “calf”, “second heart”, “venous circulation”, “function”. Only texts in Portuguese and English were included. Results: Data analysis revealed that the calf functions as a muscular pump, as it is essential for venous return from the lower extremity and influences preload and cardiac output. A survey was carried out in which 2,728 adult patients who underwent venous strain gauge plethysmography were analyzed, excluding those with conditions that could interfere with the results. The results showed that patients with impaired calf muscle pump (CMP) were older, predominantly female and had greater comorbidity. Conclusion: The muscular structure and function of the calf muscle pump are crucial for physical performance and the prevention of complications, especially in elderly populations and in patients with chronic conditions such as venous insufficiency and arterial claudication.

Lymphatic morphology and function in chronic right heart failure due to secondary tricuspid valve regurgitation

BackgroundIn heart failure, the capacity of the lymphatic system dictates symptoms of circulatory congestion. This study aimed at describing structural and functional changes of the lymphatic system in patients with chronic right-sided heart failure. MethodsIndividuals with long-standing severe tricuspid valve regurgitation and symptoms of heart failure were compared with age- gender- and weight-matched controls. Lymphatic structure and function were examined using non-contrast MR lymphangiography and near-infrared fluorescence imaging. Microvascular fluid dynamics and distribution were evaluated using strain gauge plethysmography and bio-impedance. ResultsIn total nine patients and nine controls were included. Lymphatic morphology was unchanged in cases compared to controls with similar thoracic duct diameters 3.1(2.1–3.5) mm vs. 2.0(1.8–2.4) mm (p-value = 0.11), similar lymphatic classifications (p-value 0.34), and an identical number of lymphatic vessels in the legs 6 ± 1 vs. 6 ± 3 vessels/field (p-value = 0.72). Lymphatic function was comparable with contraction frequencies of 0.5 ± 0.2 and 0.5 ± 0.3 /min (p-value = 0.52) and a maximal lymphatic pumping pressure of 60 ± 13 and 57 ± 12 mmHg (p-value = 0.59) for cases and controls respectively. Finally, microvascular capillary filtration, isovolumetric threshold, and fluid distribution were similar between groups (p-value≥0.16 for all comparisons). ConclusionIn this small exploratory study, individuals with severe secondary tricuspid valve regurgitation and right-sided heart failure displayed a largely similar lymphatic anatomy and function. Thoracic duct diameter displayed a trend towards increased size in the patient group. We speculate that cases were indeed stable and optimally treated at the time of examination, and with a lymphatic system largely unaffected by any of the current or prior hemodynamic changes.

Increased Microvascular Filtration and Vascular Endothelial Growth Factor-D associated with Changed Lymphatic Vessel Morphology in Breast Cancer Treated Patients.

Vascular endothelial growth factors (VEGF) and inflammatory cytokines are indicated to be implicated in lymphedema development. We aimed to describe changes in microvascular filtration and VEGFs in a patient cohort vulnerable to breast cancer-related lymphedema development correlated with data on lymphatic morphology and function. Consecutive node-positive breast cancer patients operated in the axilla and evaluated approximately 12 months after adjuvant locoregional radiotherapy were studied. Capillary filtration rate (CFR) and isovolumetric pressure of the arms were measured by strain gauge plethysmography, and 13 blood proteins were quantified by Luminex and Elisa technology in 28 patients and 18 healthy controls. The CFR was reduced in both arms from baseline to 1-year follow-up (ipsilateral: P = 0.016 and contralateral: P = 0.001). When stratifying lymphatic complications (morphologic abnormalities and/or breast cancer-related lymphedema), CFR reached a lower steady-state in the arms with normal morphology (I:P = 0.013 and C:P = 0.013) whereas the ipsilateral arm with lymphatic complications remained unchanged (P = 0.457). In patients with lymphatic abnormal vessels, the levels of VEGF-D were 86% higher than in patients with normal lymphatic vessels (P = 0.042), whereas levels of VEGFR-3 were 64% higher (P = 0.016). Through one year of follow-up, CFR did not decrease in the lymphatic complicated treated arms as observed in noncomplicated treated arms. The patients had increased levels of VEGF-D and VEGFR-3. This correlation suggests that VEGF plays a role in the appearance of subcutaneous abnormal lymphatic vessels in the treated arms, which also maintain a fluid filtration/drainage mismatch up to one year after breast cancer treatment.

Effects of Empagliflozin in Type 2 Diabetes With and Without Chronic Kidney Disease and Nondiabetic Chronic Kidney Disease: Protocol for 3 Crossover Randomized Controlled Trials (SiRENA Project).

Sodium-glucose-cotransporter 2 inhibitors (SGLT2is) have revolutionized the treatment of type 2 diabetes mellitus (DM2) and chronic kidney disease (CKD), reducing the risk of cardiovascular and renal end points by up to 40%. The underlying mechanisms are not fully understood. The study aims to examine the effects of empagliflozin versus placebo on renal hemodynamics, sodium balance, vascular function, and markers of the innate immune system in patients with DM2, DM2 and CKD, and nondiabetic CKD. We conducted 3 double-blind, crossover, randomized controlled trials, each with identical study protocols but different study populations. We included patients with DM2 and preserved kidney function (estimated glomerular filtration rate >60 mL/min/1.73 m2), DM2 and CKD, and nondiabetic CKD (both with estimated glomerular filtration rate 20-60 mL/min/1.73 m2). Each participant was randomly assigned to 4 weeks of treatment with either 10 mg of empagliflozin once daily or a matching placebo. After a wash-out period of at least 2 weeks, participants were crossed over to the opposite treatment. End points were measured at the end of each treatment period. The primary end point was renal blood flow measured with 82Rubidium positron emission tomography-computed tomography (82Rb-PET/CT). Secondary end points include glomerular filtration rate measured with 99mTechnetium-diethylene-triamine-pentaacetate (99mTc-DTPA) clearance, vascular function assessed by forearm venous occlusion strain gauge plethysmography, measurements of the nitric oxide (NO) system, water and sodium excretion, body composition measurements, and markers of the complement immune system. Recruitment began in April 2021 and was completed in September 2022. Examinations were completed by December 2022. In total, 49 participants completed the project: 16 participants in the DM2 and preserved kidney function study, 17 participants in the DM2 and CKD study, and 16 participants in the nondiabetic CKD study. Data analysis is ongoing. Results are yet to be published. This paper describes the rationale, design, and methods used in a project consisting of 3 double-blind, crossover, randomized controlled trials examining the effects of empagliflozin versus placebo in patients with DM2 with and without CKD and patients with nondiabetic CKD, respectively. EU Clinical Trials Register 2019-004303-12; https://www.clinicaltrialsregister.eu/ctr-search/search?query=2019-004303-12, EU Clinical Trials Register 2019-004447-80; https://www.clinicaltrialsregister.eu/ctr-search/search?query=2019-004447-80, EU Clinical Trials Register 2019-004467-50; https://www.clinicaltrialsregister.eu/ctr-search/search?query=and+2019-004467-50. DERR1-10.2196/56067.

Endothelial dysfunction is associated with reduced myocardial mechano-energetic efficiency in drug-naïve hypertensive individuals.

Impaired myocardial mechano-energetics efficiency (MEE) was shown to predict incident heart failure, but pathophysiological mechanisms linking impaired MEE with heart failure have not been elucidated. Endothelial dysfunction is a plausible candidate because it has been associated with heart failure. This study aims to investigate the association between MEE and endothelium-dependent vasodilation, among drug-naïve hypertensive individuals. 198 Drug-naïve hypertensive individuals participating in the CATAnzaro MEtabolic RIsk factors (CATAMERI) study were included. All participants underwent to an oral glucose tolerance test and to an echocardiogram for myocardial LVM-normalized mechano-energetic efficiency (MEEi) measurement. Endothelial-dependent and endothelial-independent vasodilatation were measured by strain-gauge plethysmography during intra-arterial infusion of acetylcholine and sodium nitroprusside, respectively. A multivariate linear regression analysis was conducted to investigate the independent association between maximal endothelial-dependent vasodilation and MEEi. Maximal ACh-stimulated forearm blood flow (FBF) was associated to decreased myocardial MEEi (β = 0.205, p = 0.002) independently of well-established cardiovascular risk factors including age, sex, BMI, waist circumference, smoking status, total and HDL cholesterol, triglycerides, hsCRP, glucose tolerance status, and HOMA-IR index of insulin resistance. Conversely, no association was observed between SNP-stimulated vasodilation and MEEi. Endothelium-mediated vasodilation may contribute to reduce myocardial MEEi independently of several potential confounders. Because diminished myocardial MEE has been previously associated with incident heart failure, a non-invasive assessment of myocardial MEEi may improve the identification of individuals at higher cardiovascular risk who may benefit from the initiation of pharmacological treatments ameliorating the endothelial dysfunction.

Quantifiable remaining reflux 1 year after treatment of superficial venous incompetence is associated with impaired clinical outcome

ObjectiveRemaining symptoms after treatment of superficial venous incompetence is a common problem. Duplex ultrasound is often used during follow-up, but does not permit an overall quantification of venous function. We have developed a plethysmographic method using occlusion cuffs for separation of superficial and deep venous reflux. By assessing the superficial component it is possible to quantify a potential suboptimal hemodynamic treatment in patients with superficial venous incompetence. The aim was to examine whether patients with hemodynamically quantifiable remaining reflux after treatment experience impaired clinical outcomes. MethodsThis single-center prospective cohort study evaluated 156 limbs with great saphenous vein incompetence treated with radiofrequency ablation or high ligation and stripping. Duplex ultrasound and strain-gauge plethysmography (SGP) with and without selective superficial occlusion were performed before and one-year after treatment. Time taken (seconds) to reach 50% of the venous volume (T50) was evaluated. A difference in the T50of >5 seconds between postoperative strain-gauge plethysmography with and without superficial occlusion was defined as remaining reflux. The Venous Clinical Severity Score (VCSS) and Aberdeen Varicose Vein Questionnaire (AVVQ) were evaluated and compared between patients with and without remaining reflux. Multivariable logistic regression was used to evaluate risk factors for remaining plethysmographic reflux. ResultsIn all patients, median (25th, 75th percentile) T50 increased preoperatively from 7 seconds (3, 12 seconds) to 17 seconds (11, 28 seconds) (P < .001) 1 year after treatment. The VCSS and AVVQ were reduced (VCSS, 8.0 [6.0, 10.0] vs 3.0 [1.0, 5.0] [P < .001]; AVVQ, 21.8 [15.8, 32.1] vs 6.4 [2.2, 11.0] [P < .001]). Of the 156 limbs, 87 (56%) demonstrated remaining reflux 1 year after treatment. Patients with remaining plethysmographic reflux displayed higher median (25th, 75th percentile) VCSS (3.0 [2.0, 5.0] vs 2.0 [1.0, 4.0]; P = .012) and AVVQ (7.5 [2.7, 14.9] vs 4.7 [1.6, 9.2]; P = .025). Multivariate logistic regression showed that higher preoperative C in the Clinical Etiology Anatomy Pathophysiology classification (CEAP) (odds ratio [OR], 2.9 [95% confidence interval [CI], 1.34-6.46), age (OR, 1.03; 95% CI, 1.001-1.065), small saphenous vein incompetence (OR, 4.2; 95% CI, 1.30-13.73) and postoperative great saphenous vein reflux below the treated area (OR, 2.16; 95% CI, 1.02-4.56) were significant risk factors for remaining plethysmographic reflux. ConclusionsA majority of treated limbs showed quantifiable reflux 1 year after intervention and these patients displayed worse patient related outcomes assessed with the VCSS and AVVQ. Remaining plethysmographic reflux was associated with preoperative small saphenous vein incompetence and reflux below the treated area as well as advanced age and higher C in CEAP.

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

BackgroundThe 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. MethodsA 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). ResultsToe 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. ConclusionsTo 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.

The Effect of Additional Treatment with Empagliflozin or Semaglutide on Endothelial Function and Arterial Stiffness in Subjects with Type 1 Diabetes Mellitus-ENDIS Study.

We investigated the effect of additional treatment with newer antidiabetic drugs on endothelium function and arterial stiffness in subjects with type 1 diabetes mellitus (T1DM) without cardiovascular diseases. A total of 89 participants, all users of CGMS (continuous monitoring glucose system), were randomized into three comparable groups, receiving empagliflozin (E; n = 30), receiving semaglutide (S; n = 30), and a control group (C; n = 29). At baseline and 12 weeks post treatment, we measured FMD (brachial artery flow-mediated dilation) and FBF (forearm blood flow as reactive hyperemia assessed with strain gauge plethysmography) as parameters of endothelial function, as well as pulse wave velocity (PWV) and peripheral resistance as parameters of arterial stiffness. Improvement in FMD was significant in both intervention groups compared to controls (E group 2.0-fold, p = 0.000 and S group 1.9-fold, p = 0.000), with no changes between those two groups (p = 0.745). During the evaluation of FBF, there were statistically insignificant improvements in both therapeutic groups compared to controls (E group 1.39-fold, p = 0.074 and S group 1.22-fold, p = 0.701). In arterial stiffness parameters, improvements were seen only in the semaglutide group, with a decline in peripheral resistance by 5.1% (p = 0.046). We can conclude that, for arterial stiffness, semaglutide seems better, but both drugs positively impact endothelial function and, thus, could also have a protective role in T1DM.

A HYPERADRENERGIC STATE IN HYPERTENSION IS ASSOCIATED WITH MOOD DISTURBANCE AND IMPAIRED STRESS-MODULATED VASOMOTOR RESPONSES

Objective: Increasing evidence suggests a high prevalence of affective disorders in hypertension, however, the physiological associations remain unclear. Noradrenergic activation in the central and peripheral nervous systems is a putative mechanism that may explain the link between both conditions. Here, we investigate whether these stress-sensitive co-morbidities may be dependent on basal noradrenergic activity and whether vascular responses to centrally acting stimuli vary according to noradrenergic activity. Design and method: We examined the relation of affective disorders and stress-mediated vascular responses to plasma concentrations of normetanephrine (NMN), a measure of noradrenergic activity, in subjects with primary hypertension. Subjects on antidepressant medication, alpha- and beta-blockers were excluded. The Patient Health Questionnaire (PHQ-9), the 16-item Quick Inventory of Depressive Symptomatology-Self Report (QIDSSR-16), and Generalised Anxiety Disorder-7 (GAD-7) questionnaires were used for the evaluation of symptoms of depression and anxiety. Forearm blood flow (strain gauge plethysmography) was used to assess vascular responses to mental stress (Stroop colour-word test) and slow breathing (by biofeedback), interventions that respectively increase or decrease noradrenergic activity in the pre-frontal cortex and locus coeruleus. Results: 100 subjects (53% male) with (mean ± SD) age 43.4 ± 10.9 years were recruited. 88% of subjects were treated with anti-hypertensive medications and 4% had type 2 diabetes. 31% and 34% of the study population scored moderate to severe depression for PHQ-9 and QIDSSR-16 respectively indicating significant mood disturbance. Scores representing low mood and high anxiety were 2-3-fold higher for hypertensive subjects in the highest compared to lowest NMN tertiles (PHQ-9: 9.2 ± 5.8 vs 3.8 ± 2.7, P &lt; 0.001; QIDSSR-16: 12.3 ± 4.9 vs 4.5 ± 3.5, P = 0.003; GAD-7: 9.0 ± 5.5 vs 4.6 ± 3.8, P = 0.003). Forearm vasodilator responses to mental stress and vasoconstrictor responses to slow breathing were attenuated in those with high compared to low NMN (28.3 ± 21% vs. 47.1 ± 30% increases for mental stress and 3.7 ± 21% vs. 18.6 ± 15% decreases for slow breathing for highest vs. lowest tertiles of NMN, both P &lt; 0.01). Conclusions: A hyperadrenergic state in hypertension is associated with mood disturbance and impaired stress-modulated vasomotor responses. This association may be mediated by chronic stress impinging on pathways regulating central arousal and peripheral sympathetic nerve activity.

Variable dysregulation of circulating lipocalin-2 in different obese phenotypes: Association with vasodilator dysfunction.

Obesity is linked with heightened cardiovascular risk, especially when accompanied by metabolic abnormalities. Lipocalin (LCN) 2 and retinol-binding protein (RBP) 4, two members of the lipocalin family, may be upregulated in insulin resistance and atherosclerosis. We analyzed whether changes in circulating LCN2 and RBP4 in obese individuals relate with impaired vasodilator reactivity, an early stage in atherosclerosis. Obese individuals (n = 165), without (n = 48) or with (n = 117) metabolic abnormalities, and lean subjects (n = 42) participated in this study. LCN2 and RBP4 were measured by Luminex assay. Endothelium-dependent and -independent vasodilation to acetylcholine and sodium nitroprusside, respectively, was assessed by strain-gauge plethysmography. Circulating LCN2 was higher in obese than in lean subjects (p < 0.001), whereas RBP4 was not different between the two groups (p = 0.12). The vasodilator responses to both acetylcholine and nitroprusside were impaired in obese individuals (p < 0.001 vs lean subjects), with no difference between those with metabolically healthy or unhealthy obesity (p > 0.05). In the whole population, vasodilator responses to acetylcholine (R = 0.23, p = 0.01) and nitroprusside (R = 0.38, p < 0.001) had an inverse, linear relationship with circulating LCN2; no correlation, by contrast, was observed between circulating RBP4 and vasodilator reactivity (both p > 0.05). In a subgroup of obese patients with diabetes (n = 20), treatment with metformin (n = 10) or pioglitazone (n = 10) did not modify circulating LCN2 and RBP4 or vascular reactivity (all p > 0.05). Circulating LCN2, but not RBP4, is higher in obese than in lean individuals. Interestingly, changes in LCN2 inversely relate to those in vasodilator function, thereby making this protein a potential biomarker for risk stratification in obesity.

Calf blood flow is augmented in habitually aerobically trained versus untrained postmenopausal women in association with favorable modulation of vasculo-metabolic interactions.

Menopause is associated with vascular dysfunction and increased risk of developing metabolic syndrome. Associations between vascular and metabolic health, and interactions with aerobic exercise training, are unknown in postmenopausal women (PMW). In habitually aerobically trained PMW (PMWtr; n= 10; 57 ± 1 years; 40 ± 1mL/kg/min), strain-gauge plethysmography was used to compare resting and peak calf blood flow (CBFr and CBFpk, respectively) and vascular resistance (CVRr; CVRpk) versus untrained PMW (PMWun; n= 13; 56 ± 1 years; 29 ± 1mL/kg/min) and premenopausal women (PreM; n= 14; 26 ± 1 years; 40 ± 1mL/kg/min). Vascular measures were taken before and 1 hour after 45 minutes of aerobic exercise (60% V̇ O2peak ), a known nitric oxide stimulus. Blood analyses included low- (LDLc) and high-density lipoprotein cholesterol (HDLc), insulin, and glucose. Pre-exercise, CBFr and CVRr did not differ (p> 0.05) between PMW groups, nor between PreM and PMWtr. CBFpk was highest (p< 0.05) and CVRpk was lowest (p< 0.05) in PMWtr. Blood markers were similar (p> 0.05) in PMW groups. However, in PMWtr, CBFpk was associated inversely (p< 0.05) with insulin (r= -0.725). Conversely, in PMWun, CBFpk correlated (p< 0.05) inversely with glucose (r= -0.717), positively with HDLc (r= 0.633), and CVRpk positively (p< 0.05) with LDLc (r= 0.568). Post-exercise, CBF increased and CVR decreased (p< 0.05) in all groups, yet CBFpk remained higher and CVRpk lower (p< 0.05) in PMWtr. In untrained PMW, peak CBF is associated inversely with circulating pro-atherogenic lipids and glucose. In contrast, peak CBF is associated inversely with insulin levels only in trained PMW. Habitual aerobic exercise may favorably modulate vasculo-metabolic interactions in PMW.

PS-C29-7: ASSOCIATION OF SERUM LEPTIN TO ADIPONECTIN RATIO AND CARDIOVASCULAR STRUCTURAL INDICES IN ESSENTIAL HYPERTENSIVE PATIENTS WITHOUT CHRONIC KIDNEY DISEASE

Objective: Dysregulated leptin and adiponectin profile is known to be associated with atherosclerotic disease. The evaluation of the leptin to adiponectin (L/A) ratio has been suggested as a powerful useful atherosclerotic index compared with adiponectin and leptin alone in patients with type 2 diabetes and obesity. In this study, we investigated the usefulness of L/A ratio for vascular structural abnormalities in essential hypertensive patients. Design and method: In 151 untreated essential hypertensive patients (86 males, average age 56 ± 12 years) without chronic kidney disease (urinary albumin excretion (UAE) less than 300 mg/g of creatinine and estimated glomerular filtration rate 60 mL/min/1.73m2 or more), blood sampling, 24-hour urine collection, and 24-hour blood pressure monitoring were performed. Intima-media thickness of carotid artery (IMT) and minimal forearm vascular resistance (MVR) (wall to lumen ratio in resistance vessel) were also measured by using ultrasonography and strain-gauge plethysmography, respectively. Results: L/A ratio was higher in men than in women (1.23 ± 1.56 vs 0.73 ± 0.87, p &lt; 0.05). There was no correlation between L/A ratio and systolic and diastolic blood pressure, and pulse rate. L/A ratio correlated positively with body mass index, triglyceride, hemoglobin A1c, HOMA-R and urinary C-peptide excretion (r = 0.57, 0.20, 0.20, 0.31, 0.27, p &lt; 0.05, respectively) and negatively with HDL-cholesterol (r = -0.24, p &lt; 0.05). In addition, UAE, IMT and MVR were increased accompanying incremental L/A ratio (r = 0.20, 0.17, 0.19, p &lt; 0.05, respectively)In addition, UAE, IMT and MVR were increased accompanying incremental L/A ratio (r = 0.20, 0.17, 0.19, p &lt; 0.05, respectively), whereas these indices did not associated with leptin and adiponectin individually. In multiple regression analysis, L/A ratio was an independent determinant for UAE, IMT and MVR. Conclusions: In patients with essential hypertension, L/A ratio was associated with obesity, abnormal glucose and lipid metabolism, increase in microalbuminuria, and arterial and arteriolar sclerosis. L/A ratio was considered as a useful indicator of vascular structural abnormalities in patients with essential hypertension.

Contribution of strain gauge plethysmography and photoplethysmography to the quantification of the hemodynamic disturbance in varicose vein disease

The significance of strain gauge plethysmography and photoplethysmography in the diagnostics of hemodynamic disturbance in primary varicose veins is discussed. Both methods have the ability to measure volume changes induced by calf pump activity and to quantify the pre-treatment hemodynamic disorders, the immediate post-treatment hemodynamic improvement, as well as the post-treatment deterioration occurring during the follow up. The most frequently used parameters are refill times t-90 and t-50; they yield precise and reliable results. For this reason, plethysmography is a rational supplement to duplex ultrasonography in the diagnostic investigation of varicose vein disease.

The Effect of Submaximal Exercise on Jugular Venous Pulse Assessed by a Wearable Cervical Plethysmography System.

The jugular venous pulse (JVP) is a one of the crucial parameters of efficient cardiovascular function. Nowadays, limited data are available regarding the response of JVP to exercise because of its complex and/or invasive assessment procedure. The aim of the present work is to test the feasibility of a non-invasive JVP plethysmography system to monitor different submaximal exercise condition. Twenty (20) healthy subjects (13M/7F mean age 25 ± 3, BMI 21 ± 2) underwent cervical strain-gauge plethysmography, acquired synchronously with the electrocardiogram, while they were carrying out different activities: stand supine, upright, and during the execution of aerobic exercise (2 km walking test) and leg-press machine exercise (submaximal 6 RM test). Peaks a and x of the JVP waveform were investigated since they reflect the volume of cardiac filling. To this aim, the Δax parameter was introduced, representing the amplitude differences between a and x peaks. Significant differences in the values of a, x, and ax were found between static and exercise conditions (p < 0.0001, p < 0.0001, p < 0.0001), respectively. Particularly, the ax value for the leg press was approximately three times higher than the supine, and during walking was even nine times higher. The exercise monitoring by means of the novel JVP plethysmography system is feasible during submaximal exercise, and it provides additional parameters on cardiac filling and cerebral venous drainage to the widely used heartbeat rate value.

Toward a Better Understanding of Muscle Microvascular Perfusion During Exercise in Patients With Peripheral Artery Disease: The Effect of Lower-Limb Revascularization

Purpose: Leg muscle microvascular blood flow (perfusion) is impaired in response to maximal exercise in patients with peripheral artery disease (PAD); however, during submaximal exercise, microvascular perfusion is maintained due to a greater increase in microvascular blood volume compared with that seen in healthy adults. It is unclear whether this submaximal exercise response reflects a microvascular impairment, or whether it is a compensatory response for the limited conduit artery flow in PAD. Therefore, to clarify the role of conduit artery blood flow, we compared whole-limb blood flow and skeletal muscle microvascular perfusion responses with exercise in patients with PAD (n=9; 60±7 years) prior to, and following, lower-limb endovascular revascularization. Materials and Methods: Microvascular perfusion (microvascular volume × flow velocity) of the medial gastrocnemius muscle was measured before and immediately after a 5 minute bout of submaximal intermittent isometric plantar-flexion exercise using contrast-enhanced ultrasound imaging. Exercise contraction-by-contraction whole-leg blood flow and vascular conductance were measured using strain-gauge plethysmography. Results: With revascularization there was a significant increase in whole-leg blood flow and conductance during exercise (p<0.05). Exercise-induced muscle microvascular perfusion response did not change with revascularization (pre-revascularization: 3.19±2.32; post-revascularization: 3.89±1.67 aU.s−1; p=0.38). However, the parameters that determine microvascular perfusion changed, with a reduction in the microvascular volume response to exercise (pre-revascularization: 6.76±3.56; post-revascularization: 2.42±0.69 aU; p<0.01) and an increase in microvascular flow velocity (pre-revascularization: 0.25±0.13; post-revascularization: 0.59±0.25 s−1; p=0.02). Conclusion: These findings suggest that patients with PAD compensate for the conduit artery blood flow impairment with an increase in microvascular blood volume to maintain muscle perfusion during submaximal exercise. Clinical Impact The findings from this study support the notion that the impairment in conduit artery blood flow in patients with PAD leads to compensatory changes in microvascular blood volume and flow velocity to maintain muscle microvascular perfusion during submaximal leg exercise. Moreover, this study demonstrates that these microvascular changes are reversed and become normalized with successful lower-limb endovascular revascularization.

The use of strain-gauge plethysmography in the functional assessment of chronic venous disease: five-year experience at a single centre.

Plethysmography can be used in the diagnosis and evaluation of chronic venous disease in the lower extremities. This study aimed to evaluate the applicability and reliability of strain-gauge plethysmography (SDP) in the functional assessment of chronic venous disease. This descriptive study was conducted between 2016 and 2021 at a single centre. Four hundred and thirty-two patients with symptomatic chronic venous disease were included in the study. All participants were diagnosed initially with Doppler ultrasonography. SGP was then performed to evaluate venous outflow capacity, venous reflux and muscle pump function. The average age was 45.16 ± 12.54 years (median age 46 years; range 20-78 years), and 239 (55.3%) women and 193 (44.7%) men were included in the study. The age groups, diagnosis, pathological distribution and risk factors were quantitatively determined according to gender. Localisation and lateralisation statistics of the pathologies are given. SGP measurements, including venous volume (V), venous emptying (VE), expelled volume ratio in four seconds (EV4/V), half refilling time (t½) and refilling volume (RV) of each lower extremity, were done individually to compare the involved extremity with the normal contralateral side. SGP measurements of each affected lower limb were also compared separately by gender, age group and disease onset. The correlation between t½ values and skin discolouration or oedema of the affected limb was examined. Finally, receiver operating characteristic curve analyses of the V, VE, EV4/V, t½ and RV values were done, and the cut-off values of each parameter were defined accordingly. High reliability and consistent results indicate that SGP is a practical and sensitive test for quantitative functional assessment of patients with chronic venous disease. It can be used as an effective method in diagnosing and following up chronic venous disorders. As there are no currently accepted cut-off values, we suggest that ours can be used as new reference values for SGP measurements.

Relationship between clinical severity and hemodynamic impact of great saphenous vein incompetence using strain gauge plethysmography and duplex ultrasound.

To evaluate the relation of quantitative Duplex ultrasound (DUS) and strain gauge plethysmography (SGP) parameters with clinical severity and quality of life in patients with superficial venous incompetence. DUS volume flow and distal SGP refilling times (T50 and T90) were evaluated in 152 patients (164 Limbs) with superficial incompetence. Clinical severity and quality of life were evaluated with C of the CEAP classification, venous clinical severity score (VCSS), Aberdeen varicose vein questionnaire (AVVQ), and EuroQol 5D-3L. Higher DUS volume flow was associated with higher C in CEAP scores. Volume flow was also related to T50 and T90. Shorter T50 and T90 were associated with higher C in CEAP and VCSS. T50 was also associated with EQ-5DVAS. Reflux extension to the foot wase associated with shorter T50 and T90 and higher DUS volume flow. DUS volume flow and SGP refilling times are related with clinical severity and provide quantitative information regarding venous function in patients with superficial incompetence.

Effects of hypoxia and hyperoxia on venous capacity and compliance in healthy men and women.

Blood oxygen is an important modulator of arterial function, but its impact on peripheral venous function is incompletely understood. Herein, we sought to determine the effect of hypoxia and hyperoxia on venous capacity and compliance in the lower limb. In 16 healthy individuals (7 women; age: 28.3 ± 7.6 yr, mean ± SD), we assessed peripheral oxygen saturation ([Formula: see text]), the cross-sectional area (CSA) of the great saphenous vein (GSV; Doppler ultrasound), and calf volume (strain-gauge plethysmography) during a standard 60 mmHg thigh cuff inflation-deflation protocol. Separate trials were undertaken during breathing of room air, hypoxia [fraction in inspired oxygen ([Formula: see text]): 0.10], and hyperoxia ([Formula: see text]: 0.50), according to a single-blinded, randomized design. Lower limb pressure-CSA and pressure-volume relationships were modeled using a quadratic regression equation and compliance derived. [Formula: see text] was decreased by hypoxia (83.6 ± 5.6%) and increased by hyperoxia (98.7 ± 0.5%) compared with room air (96.4 ± 1.0%, P < 0.001). Compared with room air (17.0 ± 7.9 mm2), hypoxia decreased GSV CSA (13.4 ± 5.7 mm2, P < 0.001), whereas no change was observed with hyperoxia (17.1 ± 8.7 mm2, P = 0.883). GSV compliance derived from the pressure-CSA relationships was elevated approximately twofold with hyperoxia (-0.0061 ± 0.0046 a.u.) when compared with room air (-0.0029 ± 0.002 a.u., P = 0.027) and hypoxia (-0.0030 ± 0.0032 a.u., P = 0.007). No differences were observed in calf pressure-volume parameters with either hypoxia or hyperoxia (P > 0.05). Our data indicate that GSV capacity is reduced by hypoxia, and that GSV compliance is increased by hyperoxia, thus highlighting the often overlooked role of oxygen in the regulation of venous circulation.

Lymphatic Function in the Arms of Breast Cancer Patients-A Prospective Cohort Study.

Background:Lymphedema is a highly feared complication of breast cancer treatment, but the underlying complex mechanisms are still unknown. Thus, we investigated the lymphatic morphology and contractility in the lymphatic vessels of arms of high-risk breast cancer patients treated for node-positive early breast cancer.Methods:In this prospective cohort study 32 women treated for unilateral node-positive breast cancer were enrolled and studied 36 ± 23 days after loco-regional radiotherapy. Near-infrared fluorescence imaging was used to assess morphology and function of the superficial lymphatic vessels. Strain-gauge plethysmography was performed to evaluate the capillary filtration of fluid.Both arms were investigated, with the non-treated arm acting as control. The patients were questioned about the presence of lymphedema yearly and finally 574 ± 118 days after ended radiotherapy.Results:Morphologically, 25% of the treated arms expressed lymphatic vessel abnormalities compared to the control arms (p = 0.0048). No difference in functional parameters (maximal pumping pressure, p = 0.20; contraction frequency, p = 0.63; contraction velocity, p = 0.55) was found between the treated and control arms. Patients who later developed lymphedema had a difference in velocity compared to those who did not develop lymphedema (p = 0.02). The capillary filtration rate was similar between the two arms (p = 0.18).Conclusions:Peripheral lymphatic vessels were morphologically changed in the ipsilateral arm in 25% of the patients and patients who later developed lymphedema showed an early increase in velocity. Other functional parameters and capillary filtration were unchanged in this early phase. These discrete changes might be early indicators of later development of lymphedema.

The Influence Of Limb Blood Flow On Muscle Growth With Different Resistance Training Protocols

Exercise-induced muscle growth may be dependent upon the baseline vascular network or the ability to increase this network through training. Given the cost of protein synthesis, the delivery of nutrients to the muscle could serve as a physiologic limiter to exercise-induced growth. PURPOSE: To determine if baseline resting blood flow or the change in resting blood flow moderates the change in muscle thickness throughout different resistance training protocols. METHODS: Forty individuals were included for analysis. Four distinct training conditions were compared throughout the upper and lower body before and after eight weeks of training: 1) 15% 1RM with no blood flow restriction (Low Load); 2) 15% 1RM with 40% of resting arterial occlusion pressure (Low Load+40%); 3) 15% 1RM with 80% of resting arterial occlusion pressure (Low Load+80%); and 4) traditional resistance training at 70% 1RM (High Load). Each limb of the participant was randomly assigned to a training condition. Blood flow was quantified by strain gauge plethysmography and muscle size was measured via ultrasound at 11 separate sites (3 in the biceps and 8 in the thighs). To examine if limb blood flow moderated the changes in muscle thickness between groups, while accounting for our within/between subject design, two-factor (condition x limb blood flow) analysis of variance was used. RESULTS: Muscle thickness increased in all conditions. Resting blood flow changed the greatest for the Low Load +80% and High Load conditions in both the upper and lower body (~0.5 ml·min·100 ml-1). There was no evidence for moderation for baseline resting limb blood flow. However, there was for the change in blood flow at the 70% site for the biceps. Those with smaller changes in resting blood flow had greater changes in muscle size following high load resistance training compared to the Low Load (β = 0.26, p = 0.0024), Low Load+40% (β = 0.21, p = 0.0022), and the Low Load+80% (β = 0.17, p = 0.038) conditions. CONCLUSIONS: The baseline vascular network seems sufficient for young individuals to mount an anabolic response. Participants who had the smallest change in blood flow in the high load condition had the greatest changes in muscle thickness compared to the other exercise conditions. The lack of moderation at other sites indicates that this finding should be interpreted with caution.