Compliance Of Segment Research Articles

Research of the influence of element deformation and manufacturing errors of planetary gears on the load distribution among satellites

A technologically advanced multi-satellite design of a toothed planetary gear is studied, in which the carrier is made in the form of two cheeks, which are connected to each other by the axes of the satellites, which act as jumpers. The problem of the stress-strain state of mating elements is solved using differential equations of the curved axis of the satellite, represented by a beam on an elastic foundation. The distribution of the load across the satellites is determined taking into account the deformation of the gear segments and the non-adherence of the gear teeth caused by errors in its manufacture. Keywords:planetary gear, non-rigid carrier, compliance of segments, load distribution Alexandrsun4009@gmail.com

24-Month Clinical Follow-Up and Mechanistic Insights From Intravascular Imaging Following Coronary Implantation of the Novel DynamX Bioadaptor Platform

Background/purposeConventional stents “cage” the coronary arteries, impairing vascular function and physiology. The DynamX Bioadaptor is a cobalt‑chromium platform with uncaging elements, designed to improve arterial pulsatility, vasomotion, compliance, and positive adaptive remodelling which may attenuate late clinical events associated with the caging of arteries through conventional stents. We present the first 24-month outcomes of this device. Methods/materialsThis European multicenter study enrolled 50 patients with 50 de novo lesions treated with the DynamX Bioadaptor. Clinical follow-up is scheduled until 36 months and imaging follow-up was performed at 9–12 months. Results24-month endpoints were target lesion failure (2 cardiac deaths), myocardial infarction (1 non-target vessel myocardial infarction), target vessel revascularisation (n = 0), and definite or probable device thrombosis (n = 0). No endpoint events occurred beyond 9 months. Paired intravascular ultrasound analysis of 18 patients from a single center revealed a 0.22 mm2 increase in device cross-sectional area at 9–12 months. Pulsatility analysis showed an increase of in-device lumen area change by 46 % compared to the caged post-procedural configuration, reducing the compliance mismatch between the treated and not-treated vessel segments (segmental compliance). Likewise, vasomotion in response to nitroglycerin improved from 0.03mm2 post-procedure to 0.17mm2 at follow-up. Conclusions24-month clinical data demonstrate promising safety and efficacy of the DynamX Bioadaptor. Imaging data confirmed its unique capacity to improve arterial pulsatility, vasomotion, compliance and positive adaptive remodelling after “uncaging” which might have led to the promising clinical outcomes that need to be confirmed in larger studies.

Information Value of the Segment Reporting in the Polish Energy Sector

Abstract Conventional energy sources dominate in the Polish energy sector, which is a huge risk to meeting environmental protection requirements. Polish energy companies are facing challenges related to meeting the requirements of the European Union and the National Energy Policy. The paper attempts to answer the question whether the ongoing discussion on the future of the energy sector, dealing with such issues as development of renewable energy sources is reflected in the annual financial reports of companies listed on the Warsaw Stock Exchange and covered by the WIG_ENERGY index. This study contributes to the extant literature on financial disclosures in several ways. First, the examination of compliance of segment reporting of selected companies listed on the Polish stock exchange with International Reporting Standards (IFRS) was carried out (particularly IFRS 8 – Operating Segments). Second, the information value of disclosures for investors in the energy industry was assessed. The empirical part was preceded by a description of segment reporting principles in accordance with IFRS 8 and the summary of challenges facing the energy sector in Poland.

Airway distension during lung inflation in healthy and allergic-sensitised mice in vivo

We evaluated the airway distention during lung inflation of varying size in healthy and allergic-sensitised mice in vivo. Computed tomography (CT) images of healthy and ovalbumin-treated mice were acquired using a synchrotron in vivo CT system when lung pressures was 0 and 20cmH2O, and the morphometric distension (diameter, length, and volume) and the compliance of airway segments (to as small as ∼150μm internal diameter) were calculated. With respect to airway size, in healthy mice, the changes in airway diameter and compliance were larger in the small-airway group. In contrast, in allergic-sensitised mice, there were no significant differences in the changes in airway distension or compliance. Airway wall thickness in allergic-sensitised mice increased significantly in all airway groups, but the change was much larger in the small than in the large-airway group. Compared with healthy airways, the changes in diameter and airway compliance of the allergic-sensitised mice were significantly smaller in the small-airway group.

Urethral compliance in hypospadias operated by tubularized incised urethral plate (TIP) with and without a dorsal inlay graft: an experimental controlled study

Abnormal uroflowmetries are common after tubularized incised plate urethroplasties (TIP), perhaps due to low compliance. We hypothesized that (1) abnormal uroflowmetries after TIP might be caused by segmental lower compliance; (2) by adding a graft to the raw area in the incised plate (TIPG), compliance might be improved by preventing secondary intention healing of the dorsal incision. A standardized penectomy was performed in 27 adult male rabbits: 9 normal non-operated controls (G1), 6 weeks after TIP (G2: n = 9) or TIPG (G3: n = 9). A standardized isolated segment (including the whole urethroplasty in G1 and G2) was progressively distended with air (1, 2 and 3 ml) in the 3 groups. The respective intraluminal pressures were measured with a tensiometer. Pressure measurements were feasible and reproducible for this model. Mean pressures tended to be higher in the experimental groups (G1: 59.7 mmHg vs. G2: 79.6 mmHg vs. G3: 100.1 mmHg for 1 ml injections; G1: 233.1 mmHg vs. G2: 241 mmHg vs. G3: 308.4 mmHg for 2 ml injections and G1: 457.3 mmHg vs. G2: 429 mmHg vs. G3: 520 mmHg for 3 ml injections) without reaching the statistical significance. In this model, the elasticity of the TIP or TIPG neourethras tended to be reduced when compared to controls. The placement of an inlay graft on the dorsal incised area did not increase the compliance. This model allows the measurement of segmental intraluminal urethral pressures generated by controlled air distension and may be a useful tool to evaluate the experimental urethroplasty models.

Compliance and distensibility of different segments of aorta and relationships between aorta distensibility and systolic and diastolic functions of the left ventricular

Compliance and distensibility of different segments of aorta and relationships between aorta distensibility and systolic and diastolic functions of the left ventricular

Exploring policy compliance of the South African informal milk-producing segment

Our study assessed whether municipal health services were informed about and exerted adequate control over the informal milk-producing sector in South Africa. The results indicated that municipal health services had limited control. Only one municipality was authorised to allow the sale of raw milk in its area. In most metropolitan and district municipalities, the distribution of raw milk continues, even where no statutory investigations assessed the ability to control the practice. The national and provincial government should recognise and support capacity building to enable municipalities to exercise power and perform their functions regarding informal milk distribution, part of the informal sector that has provided opportunities for employment and additional income. This constitutes a challenge particularly in monitoring and control of high-risk foods.

Simulation of a Chain of Collapsible Contracting Lymphangions With Progressive Valve Closure

The aim of this investigation was to achieve the first step toward a comprehensive model of the lymphatic system. A numerical model has been constructed of a lymphatic vessel, consisting of a short series chain of contractile segments (lymphangions) and of intersegmental valves. The changing diameter of a segment governs the difference between the flows through inlet and outlet valves and is itself governed by a balance between transmural pressure and passive and active wall properties. The compliance of segments is maximal at intermediate diameters and decreases when the segments are subject to greatly positive or negative transmural pressure. Fluid flow is the result of time-varying active contraction causing diameter to reduce and is limited by segmental viscous and valvular resistance. The valves effect a smooth transition from low forward-flow resistance to high backflow resistance. Contraction occurs sequentially in successive lymphangions in the forward-flow direction. The behavior of chains of one to five lymphangions was investigated by means of pump function curves, with variation of valve opening parameters, maximum contractility, lymphangion size gradation, number of lymphangions, and phase delay between adjacent lymphangion contractions. The model was reasonably robust numerically, with mean flow-rate generally reducing as adverse pressure was increased. Sequential contraction was found to be much more efficient than synchronized contraction. At the highest adverse pressures, pumping failed by one of two mechanisms, depending on parameter settings: either mean leakback flow exceeded forward pumping or contraction failed to open the lymphangion outlet valve. Maximum pressure and maximum flow-rate were both sensitive to the contractile state; maximum pressure was also determined by the number of lymphangions in series. Maximum flow-rate was highly sensitive to the transmural pressure experienced by the most upstream lymphangions, suggesting that many feeding lymphatics would be needed to supply one downstream lymphangion chain pumping at optimal transmural pressure.

Compliance of Abdominal Aortic Aneurysms before and after Stenting with Tissue Doppler Imaging: Evolution during Follow-Up and Correlation with Aneurysm Diameter

Usual imaging after endovascular aneurysm repair (EVAR) of abdominal aortic aneurysm (AAA) consists of AAA diameter monitoring and endoleak detection. Among additional predictor parameters previously proposed to help clinicians in better identifying subgroups of AAA still at risk of rupture, AAA wall motion after EVAR has been studied, but its value was not clearly established. Tissue Doppler imaging (TDI) is an ultrasonographic modality which allows wall motion measurements along an arterial segment. The aim of the current study was to analyze AAA wall motion with TDI before and after EVAR and to describe its evolution in patients with more than 1 month of follow-up. Twenty-five consecutive patients undergoing EVAR between February 2005 and June 2007 gave informed consent to be prospectively investigated with the TDI system before EVAR and at each visit during follow-up. The mean (SD) follow-up was 13.7 (9.7) months. Maximum mean segmental dilation (MMSD), segmental compliance, dilation at maximum diameter, pressure strain elastic modulus (Ep), and stiffness were compared between three periods (before stenting, before discharge, and at last follow-up), and their relation with AAA diameter was analyzed. A significant decrease in AAA compliance was immediately observed after successful EVAR and remained stable during later follow-up. On the other hand, AAA diameter progressively decreased along time and was statistically lower at the last control compared to the initial value. MMSD, segmental compliance, and dilation at maximum diameter were positively related to AAA diameter. This means that the larger the AAA diameter after stenting, the higher the value for these parameters can be expected. On the contrary, percentage of AAA diameter decrease and percentage of MMSD decrease were not related after successful EVAR. There was no parallelism between loss in compliance and diameter decrease along time, and there is not a unique pattern of AAA diameter and compliance evolution after EVAR. Even if comparison between patients without and with endoleak was weak due to the small sample of the latter group (five patients with endoleak), compliance tended to be greater in case of endoleak. AAA wall motion after successful EVAR reflects complex interactions between all the components of the stented aneurysm which evolve over time, including true compliance of the aneurysm wall itself; intra-aneurysm sac pressure with possible different effects for peak, mean, and pulse pressures; remodeling of the thrombus; stiffness characteristics of the graft; and systemic pressure. Combining simultaneous MMSD records with actual intrasaccular pressure measurements in patients with and without endoleak would improve our understanding of the clinical pulsatility mechanism within AAA after EVAR.

Bronchoscopic Measurement of Collateral Ventilation in a Sheep Model of Emphysema

Background: The development of bronchoscopic therapies for emphysema has renewed interest in collateral ventilation. The success or failure of bronchoscopically placed valves or biologic glues may be determined by collateral ventilation, which is exaggerated in emphysema. Furthermore, the validity of various animal models of emphysema for testing such techniques must be understood in the context of their species-specific collateral ventilation. Objectives: To quantify collateral ventilation in a sheep model of emphysema using a simple in vivo bronchoscopic method. Methods: Collateral ventilation was measured in 8 anesthetized sheep using a simple method which measured pressure and flow through the working channel of a bronchoscope wedged in a segmental lung orifice. Animals then underwent nebulized papain treatments to generate emphysema, followed by repeat bronchoscopic measurements. Results: There was a 33% decrease in resistance to collateral ventilation following papain treatment. Changes in collateral resistance were closely correlated with disease severity as measured by changes in segmental compliance, which increased 267%. Conclusions: Collateral ventilation is significantly increased in sheep following nebulized papain. Bronchoscopic measurement of collateral ventilation may be useful for evaluating other animal models of emphysema and for predicting the response to bronchoscopic therapies in human emphysema patients.

Compliance of abdominal aortic aneurysms evaluated by tissue Doppler imaging: Correlation with aneurysm size

Several studies have shown that an increase in abdominal aortic aneurysm (AAA) growth rate occurs when the diameter reaches 40 to 50 mm. AAA expansion is related to remodeling of the parietal extracellular matrix. The parietal mechanisms involved in this critical phase of sudden increase remain unexplained. Analysis of AAA wall movements and determination of AAA compliance may provide information about the constitution of the arterial wall. If a change in parietal wall motion somewhere between 40 and 50 mm could be shown, this would contribute to the understanding of the growth of AAA. Furthermore, it would provide a valuable additional parameter for AAA monitoring. This study had two aims: first, to evaluate the relationship between AAA compliance and maximum diameter using the tissue Doppler imaging system; and second, to test the hypothesis of a change in AAA behavior at around 45 mm in diameter. Fifty-six patients with AAA (mean diameter, 39 mm) were prospectively investigated using the tissue Doppler imaging system, which provides information concerning arterial wall motion. Maximum mean segmental dilation (MMSD), segmental compliance, pressure strain elastic modulus (Ep), and stiffness were determined and related to the maximum diameter of AAA. Results After natural log transformation of all variables, there was a significant positive linear relationship between maximum diameter and both MMSD (P < .001) and segmental compliance (P < .001) but not with Ep or stiffness (P = .37 and .22, respectively). MMSD and segmental compliance were significantly higher in AAA > or = 45 mm than in AAA < 45 mm (P < .0002 and <. 004, respectively). Ep and stiffness tended to decrease in larger AAAs, but this was not statistically significant (P < .43 and .24, respectively). Dispersion of Ep and stiffness values seemed to be wider among AAA < 45 mm compared with those > or = 45 mm. Compliance parameters can easily be measured during routine AAA ultrasound monitoring using the tissue Doppler imaging system. The study showed an increase in MMSD and segmental compliance as well as a nonsignificant trend toward increased distensibility (decreased Ep and stiffness) with increased AAA diameter. A change in dispersion of AAA distensibility may appear around 45 mm in diameter, but a larger study will be needed to clarify this.

Compliance of abdominal aortic aneurysms: Evaluation of tissue Doppler imaging

Expansion of abdominal aortic aneurysms (AAA) is due to remodeling of the parietal extra-cellular matrix and may lead to rupture. This remodeling is reflected by compliance which may be an indicator of AAA behavior and thus useful for clinicians. Tissue Doppler Imaging (TDI) is an ultrasonographic modality which allows wall motion measurements along an arterial segment. It has previously been evaluated in normal aortas and was then evaluated in thirty-five patients with AAA. Mean values (±standard deviation) characterizing maximum diameter AAA compliance were dilation 809 μm (±465), strain 2.2% (±1), pressure strain elastic modulus 3.94 10 5 Pa [3.25; 4.8] and stiffness 28.8 [24; 34.5], last values being expressed as geometric mean [interquartile range]. They were in accordance with those previously obtained with other systems. Segmental parameter values were maximum mean segmental dilation 534 μm (±305) and segmental compliance 14.6 (±8.3) 10 −2 μm/Pa. Reproducibility was appropriate for clinical studies. The TDI system is simple and reliable for measurement of AAA compliance, and compliance can easily be recorded during routine ultrasound control. (E-mail: along@chu-reims.fr)

Stent implantation alters coronary artery hemodynamics and wall shear stress during maximal vasodilation.

Coronary stents improve resting blood flow and flow reserve in the presence of stenoses, but the impact of these devices on fluid dynamics during profound vasodilation is largely unknown. We tested the hypothesis that stent implantation affects adenosine-induced alterations in coronary hemodynamics and wall shear stress in anesthetized dogs (n = 6) instrumented for measurement of left anterior descending coronary artery (LAD) blood flow, velocity, diameter, and radius of curvature. Indexes of fluid dynamics and shear stress were determined before and after placement of a slotted-tube stent in the absence and presence of an adenosine infusion (1.0 mg/min). Adenosine increased blood flow, Reynolds (Re) and Dean numbers (De), and regional and oscillatory shear stress concomitant with reductions in LAD vascular resistance and segmental compliance before stent implantation. Increases in LAD blood flow, Re, De, and indexes of shear stress were observed after stent deployment (P < 0.05). Stent implantation reduced LAD segmental compliance to zero and potentiated increases in segmental and coronary vascular resistance during adenosine. Adenosine-induced increases in coronary blood flow and reserve, Re, De, and regional and oscillatory shear stress were attenuated after the stent was implanted. The results indicate that stent implantation blunts alterations in fluid dynamics during coronary vasodilation in vivo.

Effects of cool, dry air stimulation on peripheral lung mechanics in asthma.

We have previously demonstrated that peripheral airway resistance (Rp) rises more in asthmatics than in nonasthmatic control subjects after segmental challenge with cool, dry air. To better understand this rise in Rp, we used a stop-flow method to measure the decay of segment pressure with time that yielded information on airway resistance (Raw), final plateau pressure (Pp), and peripheral lung compliance (Cp). After stop-flow maneuvers in all seven asthmatics and all seven normal subjects, pressure decayed smoothly without an initial sudden drop. This finding suggests that Raw was negligible and that the predominant site of flow resistance was the collateral pathways of the obstructed segment. Asthmatics had a significantly higher Pp and lower Cp at baseline than did normal subjects, but neither Pp nor Cp changed after challenge. Pp and Rp were significantly correlated. When interpreted in terms of a single-compartment nonlinear model, we concluded that Rp is predominantly determined by the resistance of the collateral airways rather than the more proximal airways. We also concluded that, compared with normal subjects, asthmatics have (1) more collateral airway narrowing and closure and lower segmental compliance, and (2) after challenge, increased collateral airway narrowing or closure without a change in compliance of the distal lung parenchyma. These results reflect the fundamental differences in peripheral lung mechanics between asthmatic and nonasthmatic subjects and in their response to directly instilled cool, dry air.

Effect of augmentation on the mechanics of vertebral wedge fractures.

The effect of cement augmentation of wedge-fractured vertebral bodies on spine segment compliance was studied in 16 cadaver specimens. 1) To assess the mechanical effects of cement augmentation of vertebral wedge fractures. 2) To determine whether a new reduction/injection procedure has the same mechanical effects as the established direct injection procedure. Although wedge fractures cause pain and disability in hundreds of thousands of people, few effective treatments are available. Clinical studies have shown that cement augmentation, a new procedure, effectively relieves pain and restores mobility in patients suffering from weak or fractured vertebrae. However, only a few studies have examined the mechanics of vertebral augmentation. A wedge fracture was created in the middle vertebra of 16 three-vertebra cadaver spine segments. Neutral and full-load compliance of each fractured spine segment in flexion/extension and lateral bending were assessed by measuring the relative rotation of the vertebral bodies in response to applied moments. Eight of the fractured vertebral bodies were then augmented using direct injection, while the remaining eight fractured vertebral bodies were augmented using a combined reduction/injection procedure. Compliance of the augmented segments was then assessed. Augmentation significantly reduced the neutral compliance (reduction of 25% +/- 23%) (mean +/- standard deviation) and the full-load compliance (reduction of 23% +/- 20%) in flexion/extension (P < 0.005). Augmentation also significantly reduced the neutral compliance (reduction of 34% +/- 20%) and the full-load compliance (reduction of 26% +/- 17%) in lateral bending (P < 0.0001). No significant difference was found between the two procedures for compliance reduction. Augmentation of wedge fractures using both direct injection and reduction/injection reduces spine segment compliance significantly.

In vitro and finite-element model investigation of the conductance technique for measurement of aortic segmental volume.

This investigation examined the feasibility of applying the conductance catheter technique for measurement of absolute aortic segmental volume. Aortic segment volume was estimated simultaneously in vitro by using the conductance catheter technique and sonomicrometer crystals. Experiments were performed in five isolated canine aortas. Vessel diameter and pressure were altered, as were the conductive properties of the surrounding medium. In addition, a three-dimensional finite-element model of the vessel and apparatus was developed to examine the electric field and parallel conductance volume under different experimental conditions. The results indicated that in the absence of parallel conductance volume, the conductance catheter technique predicted absolute changes in segmental volumes and segmental pressure-volume relationships that agreed closely with those determined by sonomicrometry. The introduction of parallel conductance volume added a significant offset error to measurements of volume made with the conductance catheter that were nonlinearly related to the conductive properties of the surrounding medium. The finite-element model was able to predict measured resistance and parallel conductance volume, which correlated strongly with those measured in vitro. The results imply that absolute segmental volume and distensibility may be determined only if the parallel conductance volume is known. If the offset volume is not known precisely, the conductance catheter technique may still be applied to measure absolute changes in aortic segmental volume and compliance.

Aortic wall structural strengthening by intraluminal net prosthesis to arrest aneurysm progression and to prevent dissection and rupture.

The major limitation implicit in the endovascular procedures for aortic prosthetic substitution is that they cannot be used in those tracts of the aorta where important collateral branches originate (aortic arch, thoraco-abdominal tract, upper abdominal), that would be occluded by the prosthesis. In order to overcome this limitation we hypothesized the endovascular positioning of a prosthesis in the form of a wide mesh network that would be gradually and spontaneously covered by new intima and included in the aortic wall. The fabric framework linked to the aortic wall would then condition its significant, regular and uniform mechanical strengthening that fractionates and partially absorbs the centrifuge pulsatile stress of the bloodstream. The purpose of this paper is to report the results of the insertion of a braided Prolene net prosthesis in the first 7 cm of the descending aorta of ten swine. The animals were killed after 6 weeks, the substituted segment removed and aortic wall compliance measured under standardized conditions. The prosthesis was found entirely covered by new intima, well embodied in the aortic wall. The intercostal collateral included in the substituted segment was patent, as proved by bubble formation during underwater insufflation. Compliance of the prosthesis segment was significantly lower than that of the adjacent descending aorta. Histology showed a regular net prosthesis inclusion deep in the neo-intima layer. Present results indicate the technical feasibility of the procedure, achieving significant aortic wall strengthening without affecting the collateral (intercostal) circulation.

Spinal soft tissue compliance in juvenile chronic arthritis by vacuum

A vacuum tissue compliance meter (VTCM) was used in the paraspinal region of 69 healthy children and 31 children with juvenile chronic arthritis (JCA), all aged between 6 and 17 years. The JCA children were subdivided into groups with inflamed knee(s) and ankles (n = 15) and those in remission (n = 16). Tissue compliance was assessed paraspinally at levels C6, T1, T3, T6, T10, L3 and L5 in order to determine whether the VTCM provides useful information regarding alterations in segmental compliance in the paraspinal region that is related to inflamed joints. Significantly less displacement was found in the JCA group than in the healthy group at levels T3 and T6. However, these areas could not be related to inflamed knees or ankles. No significant differences were found between the JCA groups with and without inflamed joints. We conclude that the VTCM did not show changes in paraspinal tissue compliance that could be segmentally related to inflamed joints in JCA. The hypothesis that inflamed joints may caus...

Theory and measurements of snores

Upper airway narrowing, collapsibility, and resistance are recognized predisposing factors for snoring and obstructive sleep apnea, but the mechanisms of their action and interaction are not known. We studied a simple theoretical model of the upper airways, consisting of a movable wall in a channel segment that connects to the airway opening via a conduit with a resistance. Inspiratory flow (V) through the channel segment causes local pressure changes due to viscous losses and the Bernoulli force that may overcome the elastic forces acting on the movable wall. The model predicts instability leading to upper airway closure over a wide range of parameter values. Increasing inspiratory V above a boundary, determined by values of upper airway resistance, segment compliance, length, width, and diameter, as well as gas density, leads to a dynamic airway closure. The mathematical model establishes the power relationships between parameters and provides physiologically realistic quantitative simulation of upper airway closure when values are adapted from literature and from radiographic measurements of upper airway motion induced by negative pressure. The rate of appearance of repetitive sound structures during snoring was favorably compared with the model's prediction of the time course of wall motion during collapse. V measurements during simulated snores revealed an asymmetric oscillatory pattern compatible with repetitive upper airway closure. We conclude that snoring may be modeled as a series of dynamic closure events of the upper airways. The model predicts that the width and length of the movable portion of the upper airways and the gas density are likely to affect the onset of snoring, in addition to other, previously recognized, parameters.

Spatial and temporal changes in compliance following implantation of bioresorbable vascular grafts.

Compliance matching between the host vessel and vascular grafts used for small-diameter arterial replacements is thought to be important for long-term patency. However, currently available grafts elicit fibroplastic reactions, resulting in decreasing compliance with time after implantation. Bioresorbable prostheses elicit ingrowth of myofibroblasts containing abundant contractile elements. This led us to investigate whether compliance of implanted bioresorbable prostheses decreased as a function of time and if the kinetics of change correlated with the progression of tissue ingrowth. Woven polyglactin 910 prostheses (10 mm x 4 mm i.d.) were implanted into adult NZW rabbit infrarenal aortas and replicates were harvested serially through 8 months. Control grafts were implanted, and immediately resected. Dynamic compliance was measured at 1-mm axial increments along each explant using a pulse duplicator apparatus which exposed the harvested samples to realistic pulsatile hemodynamics. Compliance was calculated for proximal, mid, and distal segments of each graft and averaged at each time point by grouping into control (zero time, n = 3), early (1-4 weeks, n = 13), and late (6-36 weeks, n = 9) explant periods. At late explant periods both proximal and distal compliance were significantly greater than mid graft compliance (p < .02 and p < .03, respectively). There was a significant increase in proximal compliance between early and late explant times (p < .01). Measured increases in mid and distal segment compliance over time did not reach statistical significance. Myofibroblast laden tissue ingrowth into the inner capsule followed macrophage phagocytosis and was nearly complete prior to the time that an increase in compliance was demonstrated. Thus since the major histologic episodes precede the change in compliance, these are not likely initiated by this biomechanical change. We hypothesize the graft resorption coupled with the ingrowth of more compliant tissue likely leads to the increased compliance of the graft material.