Assessment of central venous physiology of Fontan circulation using peripheral venous pressure

Objective

Elevated central venous pressure is a major cause of morbidity and mortality after the Fontan operation. The difference between mean circulatory filling pressure and central venous pressure, a driving force of venous return, is important in determining dynamic changes in central venous pressure in response to changes in ventricular properties or loading conditions. Thus, noninvasive central venous pressure and mean circulatory filling pressure estimation may contribute to optimal management in patients undergoing the Fontan operation. We tested the hypothesis that central venous pressure and mean circulatory filling pressure in those undergoing the Fontan operation can be simply estimated using peripheral venous pressure and arm equilibrium pressure, respectively.

Brachial cuff measurements of blood pressure during passive leg raising for fluid responsiveness prediction

Objective

The passive leg raising maneuver (PLR) for fluid responsiveness testing relies on cardiac output (CO) measurements or invasive measurements of arterial pressure (AP) whereas the initial hemodynamic management during shock is often based solely on brachial cuff measurements. We assessed PLR-induced changes in noninvasive oscillometric readings to predict fluid responsiveness.

Study design

Multicentre interventional study.

Patients and methods

In ICU sedated patients with circulatory failure, AP (invasive and noninvasive readings) and CO measurements were performed before, during PLR (trunk supine, not modified) and after 500-mL volume expansion. Areas under the ROC curves (AUC) were determined for fluid responsiveness (> 10% volume expansion-induced increase in CO) prediction.

Results

In 112 patients (19% with arrhythmia), changes in noninvasive systolic AP during PLR (noninvasiveΔ_PLRSAP) only predicted fluid responsiveness (cutoff 17%, n = 21, positive likelihood ratio [LR] of 26 [18–38]), not unresponsiveness. If PLR-induced change in central venous pressure (CVP) was at least of 2 mmHg (n = 60), suggesting that PLR succeeded in altering cardiac preload, noninvasiveΔ_PLRSAP performance was good: AUC of 0.94 [0.85–0.98], positive and negative LRs of 5.7 [4.6–6.8] and 0.07 [0.009–0.5], respectively, for a cutoff of 9%. Of note, invasive AP-derived indices did not outperform noninvasiveΔ_PLRSAP.

Conclusion

Regardless of CVP (i.e., during “blind PLR”), noninvasiveΔ_PLRSAP more than 17% reliably identified fluid responders. During “CVP-guided PLR”, in case of sufficient change in CVP, noninvasiveΔ_PLRSAP performed better (cutoff of 9%). These findings, in sedated patients who had already undergone volume expansion and/or catecholamines, have to be verified during the early phase of circulatory failure (before an arterial line and/or a CO measuring device is placed).     

Simple formulas to determine optimal subclavian central venous catheter tip placement in infants and children

Background/Purpose

Optimal central venous catheter (CVC) tip location is necessary to decrease the incidence of complications related to their use. We sought to create a practical method to reliably predict the length of catheter to insert into the subclavian vein during CVC placement in children.

Methods

We performed a retrospective review of 727 chest radiographs of children who underwent either left or right subclavian CVC placement. We measured the distance from the subclavian entry site to the to the right atrium/superior vena cava (RA/SVC) junction, following the catheter's course. We analyzed the relationship between that length and patient characteristics, including: age, gender, height, weight and body surface area (BSA).

Results

Two derived formulas using the BSA best correlated with the optimal subclavian CVC length. For the left subclavian vein approach, the optimal catheter length was 6.5*BSA + 7 cm, and for the right subclavian vein approach it was 5*BSA + 6. The use of these formulas correlated in CVC tip placement in a clinically proper location in 92.9% of smaller children and in 95.7% of larger children.

Conclusion

The optimal length of central venous catheter to insert into the subclavian vein may be determined through the use of a simple formula using the BSA.     

Estimation of central venous pressure by measurement of proximal axillary venous pressure using a "half-way" catheter

The pressure in the proximal axillary vein (AVP) was compared with central venous pressure (CVP) in eight patients during and after elective abdominal surgery. Both pressures were recorded from soft, elastic, polyurethane catheters inserted in the basilic or cephalic veins ("half-way" catheters), punctured at the fossa cubiti (AVP), and via the right jugular vein (CVP). The AVP and CVP were recorded simultaneously using hydrostatic, conventional disposable venous pressure measurement sets. The measurements were performed during intermittent positive pressure ventilation with positive end-expiratory pressure from 0 to 7.5 cmH2O (0-0.74 kPa), as well as during spontaneous breathing. During both controlled and spontaneous respiration, small mean differences (0.2-1.0 cmH2O) (0.02-0.1 kPa), and a highly significant (P less than 0.001) positive correlation between CVP- and AVP-values were found. An increase of 1 cmH2O (0.10 kPa) in the CVP was associated with an increment of practically identical order (0.99-1.04 cmH2O) (0.10-0.11 kPa) in the AVP. The results suggest that monitoring of the AVP by a basilic "half-way" catheter produces diagnostic information similar to that from the measurement of the CVP from subclavian, external or internal jugular, as well as "long-way" brachial catheter, with no risk of the major mechanical complications which accompany the use of the latter catheters.     

Laterality of central venous sampling: lack of effect on the accuracy of intraoperative parathyroid hormone monitoring

Background

The purpose of this study was to determine if laterality of internal jugular vein (IJV) sampling affects the accuracy of intraoperative parathyroid hormone (PTH) monitoring during parathyroidectomy for primary hyperparathyroidism.

Methods

In this study, 109 patients underwent parathyroidectomy (82 with unilateral disease, 27 with multigland disease). PTH samples were taken from both the left and the right IJV at these time points: preincision (baseline) and then at 5, 10, and, in selected patients, 20 minutes after excision. The Miami criterion was used to determine operative success.

Results

In all 109 patients combined, the mean decreases in intraoperative PTH levels were 73.8 ± 22.2% for the left IJV and 71.9 ± 23.0% for the right IJV (P = .22). The Miami criterion was met in 105 patients: in 100 (95%) left IJV samples and 99 (94%) right IJV samples (P = 1.00).

Conclusions

No difference was found in the accuracy of intraoperative PTH monitoring between patients' left and right IJV samples. Central venous laterality did not affect fulfillment of the Miami criterion.     

Percutaneous central access in patients younger than 5 years: size does matter

Purpose

The purpose of this study was to determine, in a pediatric population less than 5 years of age, which size catheter is ideal for central venous access via the subclavian and internal jugular vein based on the children’s age, weight, and height.

Methods

This was a retrospective chart review of children less than 5 years of age at The Children’s Hospital in Denver, Colorado who underwent subclavian or internal jugular central venous catheter placement from January 1, 1998 through December 31, 2001. Age, height, weight, primary disease, access site, type of central venous catheter, size of central venous catheter, and complications were recorded. Age, weight, and height were stratified and compared with catheter size to determine any correlation between age, weight, height, and complications.

Results

There were 430 central venous catheters placed via the subclavian or internal jugular vein in 331 patients less than 5 years old. One hundred ninety-five catheters (45.4%) were less than 6F in size, and 235 (54.6%) catheters were ≥6F in size. Children, who were between 0.5 and 0.99 years old, 5 to 7.49 kg in weight, 7.5 to 9.99 kg in weight, and 60 to 74.9 cm in height had higher complication rates (P < .05) when catheters ≥6F were inserted. Children who were greater than 1 year of age, greater than 10 kg in weight, and longer than 75 cm in height did not experience a significant difference (P > .05) in complications versus catheter size.

Conclusions

The choice of central venous catheter size should be predicated, not only on the primary disease, but also on the child’s age, weight, and height. Insertion of central venous catheters larger than 6F in children less than 1 year of age, less than 10 kg in weight, or less than 75 cm in height, was associated with higher complications compared with other settings.     

Image-guided placement of long-term central venous catheters reduces complications and cost

Background

The goals of this study were to evaluate the complication rate for intraoperative placement of a long-term central venous catheter (CVC) using intraoperative ultrasound (US) and fluoroscopy and to examine the feasibility for eliminating routine postprocedure chest X-ray.

Methods

Retrospective data pertaining to operative insertion of long-term CVC were collected and the rate of procedural complications was determined.

Results

From January 2008 to August 2013, 351 CVCs were placed via the internal jugular vein using US. Of these, 93% had a single, successful internal jugular vein insertion. The complications included 4 arterial sticks (1.14%). Starting in October 2012, postprocedure chest radiography (CXR) was eliminated in 170 cases, with no complications. A total of $29,750 in charges were deferred by CXR elimination.

Conclusions

This review supports the use of US for CVC placement with fluoroscopy in reducing the rate of procedural complications. Additionally, with fluoroscopic imaging, postprocedural CXR can be eliminated with associated healthcare savings.     

Risk factors for venous thromboembolism in critically ill nontrauma surgical patients who cannot receive chemical prophylaxis

Background

We sought to identify independent predictors of venous thromboembolism in critically ill general surgery patients who cannot receive chemical prophylaxis in order to identify those who may benefit from aggressive screening and/or prophylactic inferior vena cava filter placement.

Methods

Nontrauma patients in the surgical intensive care unit were prospectively followed for 2 years. Patients who had contraindications to prophylactic anticoagulation and received routine screening duplex examinations were included. Data regarding lower-extremity deep venous thrombosis or pulmonary embolism (PE) rates, past medical history (PMH), surgeries, and transfusions were collected. Logistic regression was used to identify independent predictors of lower-extremity deep venous thrombosis or PE (venous thromboembolism) with a P < .05.

Results

Data were complete for 204 patients. Twenty (9.8%) patients developed venous thromboembolism. Independent predictors of venous thromboembolism included postoperative blood product requirements (odds ratio = 1.04 per unit), a PMH of PE (OR = 10.1), and a PMH of renal insufficiency (odds ratio = 5.1).

Conclusions

Aggressive screening and/or prophylactic inferior vena cava filter may be considered when prophylactic anticoagulation is prohibited in patients with increased postoperative transfusion requirements or a PMH of either PE or renal insufficiency.     

Instructional design affects the efficacy of simulation-based training in central venous catheterization

Background

Simulation-based learning is a common educational tool in health care training and frequently involves instructional designs based on Experiential Learning Theory (ELT). However, little research explores the effectiveness and efficiency of different instructional design methodologies appropriate for simulations. The aim of this study was to compare 2 instructional design models, ELT and Guided Experiential Learning (GEL), to determine which is more effective for training the central venous catheterization procedure.

Methods

Using a quasi-experimental randomized block design, nurse anesthetists completed training under 1 of the 2 instructional design models. Performance was assessed using a checklist of central venous catheterization performance, pass rates, and critical action errors.

Results

Participants in the GEL condition performed significantly better than those in the ELT condition on the overall checklist score after controlling for individual practice time (F[1, 29] = 4.021, P = .027, Cohen's d = .71), had higher pass rates (P = .006, Cohen's d = 1.15), and had lower rates of failure due to critical action errors (P = .038, Cohen's d = .81).

Conclusions

The GEL model of instructional design is significantly more effective than ELT for simulation-based learning of the central venous catheterization procedure, yielding large differences in effect size.     

Validation of the Pliance X System in measuring interface pressure generated by pressure garment

Introduction

Pressure monitoring is crucial for effective pressure therapy. Precise and reliable interface pressure measurement system, however, remains unavailable in current practice.

Methodology

This is a validation study on the application of a recently developed device, the Pliance X System, for static interface pressure measurement. Sensor properties were evaluated through series of laboratory tests in the first phase of the study. Phase II was a clinical study using the Pliance X system to differentiate the loading generated on the patients’ scars through additional inserts and pressure garment.

Results

Results showed high test–retest and inter-rater reliability (ICC ≥ 0.995) with good linearity (adjusted R-square = 0.997) by measuring standard weights. The maximum deviation between the measurement generated by the sensor and the sphygmomanometer cuff was ±1.451 mmHg. Results in the clinical trial revealed its discriminant ability in distinguishing different levels of pressure loading on patients with scars (p < 0.01).

Conclusion

The commercially available pressure measurement system was found to be a reliable tool for measurement of low interface pressure under static condition.     

The impact of intracranial pressure monitoring on mortality after severe traumatic brain injury

Background

The effect of intracranial pressure (ICP) monitoring on mortality after severe traumatic brain injury (sTBI) remains unclear. We hypothesized that ICP monitoring would not be associated with improved survival in patients with sTBI.

Methods

A retrospective analysis was performed on sTBI patients, defined as admission Glasgow Coma Scale score of 8 or less with intracranial hemorrhage. Patients who underwent ICP monitoring were compared with patients who did not. The primary outcome measure was inhospital mortality.

Results

Of 123 sTBI patients meeting inclusion criteria, 40 (32.5%) underwent ICP monitoring. On bivariate and multivariate regression analyses, ICP monitoring was associated with decreased mortality (odds ratio = .32, 95% confidence interval = .10 to .99, P = .049). This finding persisted on propensity-adjusted analysis.

Conclusions

ICP monitoring is associated with improved survival in adult patients with sTBI. In addition, significant variability exists in the use of ICP monitoring among patients with sTBI.     

Outcome of tunnelled central venous catheters used for haemodialysis in children weighing less than 15 kg

Purpose

Central venous catheters (CVC) are frequently used for haemodialysis (HD) in children. However, there is paucity of information on the outcomes of CVCs when used for HD in very young patients. Our objective is to report the success, safety and complication rates of CVCs used for HD in children weighing less than 15 kg.

Materials and methods

This is a single-center retrospective study of all patients with end-stage renal disease (ESRD) weighing < 15kg, who underwent a tunneled CVC placement for HD, between July 2006 and June 2012 at our institution. Analysed data included clinical background, age and weight at initiation of HD, outcome of HD, CVC vein insertion site, reason for removal, and catheter survival (in days).

Results

Thirty-one CVC were placed in 11 patients weighing < 15 kg, 8 males and 3 females. The main causes of ESRD were renal dysplasia and congenital nephrotic syndrome. At the beginning of HD, mean age was 27.5 (range 5–60) months and mean weight was 10.4 kg (4.5–13 kg). The preferred insertion site was the right internal jugular vein (90%). Mean duration of HD was 312 days. Mechanical factors were the main reason for catheter removal (39%). Mean catheter survival was 110 days/catheter.

Conclusions

We believe our study provides relevant information and encouraging data to support the use of CVC for HD in this cohort of infants; however, further improvement in prevention of catheter thrombosis and management of infections needs to be achieved.     

The influence of intraoperative central venous pressure on delayed graft function in renal transplantation: a single-center experience

Introduction

Delayed graft function (DGF) is a common complication in kidney transplantation. We sought to evaluate possible correlates for DGF including intraoperative parameters, focusing on fluid replacement and central venous pressure (CVP) values among patients undergoing kidney transplantation at our center.

Methods

One hundred fifty-five cadaveric donor transplantations performed at our center between 2001 and 2005 were selected for the study. We compared intraoperative parameters together with 15 other clinical and socio-demographic recipient and donor variables among patients experiencing DGF (n = 58) versus those with immediate graft function (IGF; n = 97). All significant variables at P < .05 upon univariate analysis were entered into a multivariate logistic regression model to identify risk factors for DGF.

Results

CVP at awakening of ≤8 mm Hg (odds ratio [OR] = 3.53; 95% confidence interval [CI], 1.63-7.63), fluid input during surgery ≤2.250 mL (OR = 2.12; 95% CI, 1.00-4.51), and recipient age ≥50 years (OR = 2.72; 95% CI, 1.11-6.68) were the strongest correlates of DGF.

Conclusions

Our data suggested that reduced intraoperative perfusion as measured using CVP monitoring might increase DGF risk. This study provides the rationale to further investigate the optimal CVP target during this surgery.     

Effect of retension sutures on abdominal pressure after abdominal surgery

Purpose: To evaluate the effect of retention sutures on abdominal pressure and postoperative prognosis in abdominal surgery patients. Methods: This prospective cohort study included patients who were admitted to Daping Hospital from May 15, 2014 to October 11, 2014. A total of 57 patients were enrolled, including 18 patients in the “U” type retention suture group, 17 patients in the intermittent retention suture group, and 22 patients in non-retention suture group. The demographic data, clinical data and risk factors for abdominal wound dehiscence were recorded. The bladder pressure (IVP) was monitored preoperatively, intraoperatively, and four days postoperatively. Additionally, the incidence of abdominal wound dehiscence and infection 14 days after the operation was recorded. Results: During the operation, the IVP decreased and then increased; it was at its lowest 1 h after the start of the operation (5.3 mmHg ± 3.2 mmHg) and peaked after tension-reducing (8.8 mmHg ± 4.0 mmHg). The IVP values in the “U” type retention suture group and intermittent retention suture group were higher than in the non-retention suture group 4 days after operation (p < 0.005). The Visual Analogue Scale (VAS) pain scores were 3.9 ± 2.2, 3.8 ± 2.0, and 3.0 ± 1.0 in the retention suture group, intermittent retention suture group and non-retention suture group, respectively. The VAS pain scores in the “U” type tension-reducing group and intermittent tension-reducing group were higher than in the non-tension-reducing group (p < 0.005). Conclusion: Although retention sutures may reduce the incidence of postoperative wound dehiscence in abdominal surgery patients, they can increase the IVP and postoperative pain.     

Intrahepatic portal venous systems in children with noncirrhotic prehepatic portal hypertension: Anatomy and clinical relevance

Background

Children with extrahepatic portal hypertension typically present with cavernomatous transformation of the portal vein and a poorly defined intrahepatic portal vein system on conventional imaging. With the Meso-Rex Bypass becoming the gold-standard intervention for a cure, a precise assessment of the intrahepatic portal vein system provides helpful data for deciding whether a Meso-Rex Bypass is feasible or not.

Methods

All children with extrahepatic portal hypertension were prospectively assessed by wedged hepatic venous portography. Venous anatomy was categorized into five subtypes (A to E), depending on the presence of thrombosis in the Rex recessus, or not, and its extension within the intrahepatic portal venous system.

Results

Eighty-nine children entered the study. Previous umbilical vein catheterization is usually associated with Rex thrombosis, while the Rex recessus and the intrahepatic portal venous system are patent in idiopathic cases, thus allowing for the performance of a Meso-Rex Bypass with a good outcome.

Conclusions

Wedged hepatic venous portography is a very effective tool for detailed preoperative assessment and identification of children being considered for Meso-Rex Bypass surgery. An anatomic–radiological classification is useful in selecting patients for Meso-Rex Bypass with anticipation of a high rate of success.     

Does ultrasonographic measurement of the inferior vena cava diameter correlate with central venous pressure in the assessment of intravascular volume in patients undergoing gastrointestinal surgery?

Background

Ultrasonography has been suggested as a useful noninvasive tool for the detection of hypovolemia in critically ill patients. Hypovolemia after preoperative fasting and bowel preparation may compromise hemodynamic function during gastrointestinal surgery. However, there are few data comparing ultrasonographic examination of the inferior vena cava (IVC) diameter with central venous pressure (CVP) measurement in patients undergoing gastrointestinal surgery in the assessment of intravascular volume status.

Materials and methods

Forty American Society of Anesthesiologists I–II patients who underwent elective gastrointestinal surgery and 32 healthy volunteers were enrolled in the study. The IVC diameters, both during expiration (IVCe) and inspiration (IVCi), and right ventricle (RV) were measured with ultrasonography in patients both before and after fluid resuscitation. Volunteers were also measured during the time they participated in the study.

Results

Forty patients (mean age 51 y; 45% female) and 32 volunteers (mean age 46 y; 44% female) underwent IVC and RV sonographic measurements. The diameters of the IVCe, IVCi, and RV in patients (1.83, 1.34, and 3.23 cm) were significantly lower compared with those of healthy volunteers (1.18, 0.62, and 2.71 cm). After fluid resuscitation, IVCe, IVCi, and RV in hypovolemic patients (1.75, 1.25, and 3.27 cm) significantly increased. The pre-IVCe and the post-IVCe were closely correlated to the CVP (r = 0.585 and r = 0.609, respectively). Similarly, the pre-RV and the post-RV were correlated to the CVP (r = 0.347 and r = 0.439, respectively).

Conclusions

Our data demonstrate that the IVC and RV diameters are consistently low in patients undergoing gastrointestinal surgery when compared with healthy subjects. Ultrasonographic measurements of the IVC and RV diameters are useful supplement of CVP for the evaluation of preoperative patients with hypovolemia.     

Intracranial pressure versus cerebral perfusion pressure as a marker of outcomes in severe head injury: a prospective evaluation

Background

Intracranial pressure (ICP) monitoring is a standard of care in severe traumatic brain injury when clinical features are unreliable. It remains unclear, however, whether elevated ICP or decreased cerebral perfusion pressure (CPP) predicts outcome.

Methods

This is a prospective observational study of patients sustaining severe blunt head injury, admitted to the surgical intensive care unit at the Los Angeles County and University of Southern California Medical Center between January 2010 and December 2011. The study population was stratified according to the findings of ICP and CPP. Primary outcomes were overall in-hospital mortality and mortality because of cerebral herniation. Secondary outcomes were development of complications during the hospitalization.

Results

A total of 216 patients met Brain Trauma Foundation guidelines for ICP monitoring. Of those, 46.8% (n = 101) were subjected to the intervention. Sustained elevated ICP significantly increased all in-hospital mortality (adjusted odds ratio [95% confidence interval]: 3.15 [1.11, 8.91], P = .031) and death because of cerebral herniation (adjusted odds ratio [95% confidence interval]: 9.25 [1.19, 10.48], P = .035). Decreased CPP had no impact on mortality.

Conclusions

A single episode of sustained increased ICP is an accurate predictor of poor outcomes. Decreased CPP did not affect survival.     

Prevention or reversal of deep venous insufficiency by aggressive treatment of superficial venous disease

Background

This study of patients who received either aggressive or less-aggressive treatment for superficial venous disease was undertaken to determine its effects on deep venous insufficiency (DVI).

Methods

From 1998 to 2004, we treated 1,500 consecutive patients with superficial venous disease at our outpatient care center. A total of 100 patients were available for the study; the remaining patients were not available for the complete follow-up duplex scans 6 months after therapy, irrespective of the therapeutic results. Sixty-four patients underwent aggressive therapy, which included high ligation with partial selective perforation-invagination (PIN) axial stripping of the greater saphenous vein, ambulatory stab phlebectomy of the varicose veins, and transdermal treatment of the spider veins. Thirty-six patients underwent less-aggressive treatment, which included high ligation with selective partial PIN axial stripping of the greater saphenous vein and ambulatory phlebectomy of varicose vein clusters but no spider vein treatment.

Results

Follow-up duplex scanning after aggressive treatment of superficial venous disease showed improvement or complete reversal of DVI in the majority of patients. This improvement was defined as a marked decrease in the size of the deep veins in 80% of patients and a decrease of the reflux closure time of the deep venous valves in 83% of patients. Only 28% of patients receiving less-aggressive treatment without transdermal laser therapy of the spider veins showed improvement in their reflux valve closure time; the remaining 72% were unchanged or deteriorated.

Conclusions

Aggressive treatment of superficial venous disease can prevent or even eliminate deep vein insufficiency (DVI).     

Selective non-operative management of civilian gunshot wounds to the abdomen: A systematic review of the evidence

Background

Selective non-operative management (SNOM) of penetrating abdominal wounds has become increasingly common in the past two or three decades and is now accepted as routine management for stab wounds. Gunshot wounds are more frequently managed with mandatory laparotomy but recently SNOM has been successfully applied. This review systematically appraises the evidence behind SNOM for civilian abdominal gunshot wounds.

Methods

A Medline search from 1990 to present identified civilian studies examining success rates for SNOM of abdominal gunshot wounds. Case reports, editorials and abstracts were excluded. All other studies meeting the inclusion criteria of reporting the success rate of non-operative management of abdominal gunshot wounds were analysed.

Results

Sixteen prospective and six retrospective studies met the inclusion criteria, including 18,602 patients with abdominal gunshot wounds. 32.2% (n = 6072) of patients were initially managed non-operatively and 15.5% (n = 943) required a delayed laparotomy. The presence of haemodynamic instability, peritonitis, GI bleeding or any co-existing pathology that prevented frequent serial examination of the abdomen from being performed were indications for immediate laparotomy in all studies. Delayed laparotomy results in similar outcomes to those in patients subjected to immediate laparotomy. Implementation of SNOM reduces the rates of negative and non-therapeutic laparotomies and reduces overall length of stay.

Conclusions

SNOM can be safely applied to some civilian patients with abdominal gunshot wounds and reduces the rates of negative or non-therapeutic laparotomy. Patients who require delayed laparotomy have similar rates of morbidity and mortality and similar length of stay to those patients who undergo immediate laparotomy.     

Role and mechanism of tissue plasminogen activator in venous wall fibrosis remodeling after deep venous thrombosis via the glycogen synthase kinase-3 beta signaling pathway

Background

Deep venous thrombosis (DVT) confers vein wall injury associated with fibrosis and extracellular matrix turnover. The activation of vascular smooth muscle cells (VSMCs) and phenotypic switching are postulated to be the significant contributing factors in the evolution of the pathogenic processes. This study investigated the effect of tissue plasminogen activator (tPA) on the phenotypic switching and collagen deposition of VSMCs, as well as related signaling pathway that leads to this activation.

Materials and methods

The model of stasis-induced DVT was established by ligation of the femoral vein. VSMCs transfected with the plasmid vector carrying a rat recombinant tPA gene with an enhanced green fluorescent protein (EGFP) tag (AdtPA-EGFP). Fibrotic change, expression of collagen type I, the cell number of media, and intimal thickness score were evaluated; the comparisons were made among the AdtPA-EGFP–transfected group, an empty vector (AdNull-EGFP) transfected group, and a phosphate-buffered saline perfused group in vivo. tPA induced VSMCs phenotypic switching and collagen deposition in vitro. The related signaling pathway molecules and the cell cycle progression were also investigated by western blot and flow cytometry.

Results

In the AdtPA-EGFP stasis DVT model, early vein wall collagenolysis and deposition occurred more remarkable. Histological studies showed that the expression of vein wall collagen type I protein, cell number of media, and intimal thickness score was significantly increased (P < 0.05). In primary culture VSMCs, sustained stimulation with tPA induced collagen type I upregulation and triggered sequential signaling events involving Akt, extracellular signal–regulated kinases 1/2 (ERK1/2), glycogen synthase kinase-3 (GSK3)-β phosphorylation, and cyclin D1 induction. Blockade of phosphatidylinositol 3-kinase-Akt and ERK1/2 activation suppressed tPA-induced GSK3β phosphorylation, cyclin D1 expression, and the deposition of collagen type I.

Conclusions

tPA was a profibrotic factor that potentiated the phenotypic switching and the deposition of collagen in VSMC. The effect of tPA on VSMCs involved activation of Akt and ERK1/2 pathways and inhibition of GSK3β activity, which could promote a switch of the synthetic phenotype in VSMCs and lead to the remodeling of vascular injury.