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PubMed1988

An in vitro experimental comparison of Edwards-Duromedics and St Jude bileaflet heart valve prostheses.

An in vitro comparison of the hydrodynamic characteristics of the Edwards-Duromedics (DM) and St Jude (SJ) bi-leaflet aortic valve prostheses is presented. Aortic valves 27 mm in diameter were mounted in a pulse duplicator simulating physiological pulsatile flow using a glycerol solution as the blood analogue fluid. Mean trans-valvular pressure difference (TPD) in systole, the per cent regurgitation (PCR) and the projected valve orifice area (VOA) were compared at a range of flow rates and heart rates to reflect the functioning of the valve under resting as well as exercise conditions. Our results showed that the TDP for DM (0.99 +/- 0.28 kPa) valve was slightly larger than the SJ (0.81 +/- 0.19 kPa) valve (mean difference of 0.18 +/- 0.26 kPa, P less than 0.05). However, the PCR for the DM (13.6 +/- 7.8) valve was smaller than the SJ (17.9 +/- 9.0) valve (mean difference of 4.3 +/- 4.2%, P less than 0.01). Moreover, VOA for the DM (2.51 +/- 0.10 cm2) valve was smaller than the SJ (3.13 +/- 0.04 cm2) valve (mean difference of 0.63 +/- 0.10 cm3, P less than 0.001).

Aortic Valve↗
PubMed1988

Hydrodynamic function of ten prosthetic heart valves in the aortic position.

The hydrodynamic function of five mechanical, four pericardial and one porcine size 23 mm aortic prosthetic valves has been analysed by measuring pressure differences, regurgitation and energy losses in our pulsatile flow test rig. St Jude Medical, Hancock pericardial and Mitral Medical pericardial valves had the lowest pressure drop. Calculations of total energy loss showed that the Bjork-Shiley monostrut had similar overall function to the above valves, while the Ionescu-Shiley Standard, Ionescu-Shiley Low Profile, Omniscience and Duromedics valves had slightly greater total energy losses. The Bjork-Shiley spherical disc and Wessex Medical porcine valve had the greatest energy losses. The function of the newer designs of pericardial valves compared well with the mechanical valves currently available.

Bioprosthesis↗
PubMed2005

Pulse oximetry in the oesophagus.

Pulse oximetry has been one of the most significant technological advances in clinical monitoring in the last two decades. Pulse oximetry is a non-invasive photometric technique that provides information about the arterial blood oxygen saturation (SpO(2)) and heart rate, and has widespread clinical applications. When peripheral perfusion is poor, as in states of hypovolaemia, hypothermia and vasoconstriction, oxygenation readings become unreliable or cease. The problem arises because conventional pulse oximetry sensors must be attached to the most peripheral parts of the body, such as finger, ear or toe, where pulsatile flow is most easily compromised. Since central blood flow may be preferentially preserved, this review explores a new alternative site, the oesophagus, for monitoring blood oxygen saturation by pulse oximetry. This review article presents the basic physics, technology and applications of pulse oximetry including photoplethysmography. The limitations of this technique are also discussed leading to the proposed development of the oesophageal pulse oximeter. In the majority, the report will be focused on the description of a new oesophageal photoplethysmographic/SpO(2) probe, which was developed to investigate the suitability of the oesophagus as an alternative monitoring site for the continuous measurement of SpO(2) in cases of poor peripheral circulation. The article concludes with a review of reported clinical investigations of the oesophageal pulse oximeter.

Adult↗
PubMed2000

Fabrication of a trileaflet heart valve scaffold from a polyhydroxyalkanoate biopolyester for use in tissue engineering.

Previously, we reported the implantation of a single tissue engineered leaflet in the posterior position of the pulmonary valve in a lamb model. The major problems with this leaflet replacement were the scaffold's inherent stiffness, thickness, and nonpliability. We have now created a scaffold for a trileaflet heart valve using a thermoplastic polyester. In this experiment, we show the suitability of this material in the production of a biodegradable, biocompatible scaffold for tissue engineered heart valves. A heart valve scaffold was constructed from a thermoplastic elastomer. The elastomer belongs to a class of biodegradable, biocompatible polyesters known as polyhydroxyalkanoates (PHAs) and is produced by fermentation (Metabolix Inc., Cambridge, MA). It was modified by a salt leaching technique to create a porous, three-dimensional structure, suitable for tissue engineering. The trileaflet heart valve scaffold consisted of a cylindrical stent (1 mm X 15 mm X 20 mm I.D.) containing three valve leaflets. The leaflets were formed from a single piece of PHA (0.3 mm thick), and were attached to the outside of the stent by thermal processing techniques, which required no suturing. After fabrication, the heart valve construct was allowed to crystallize (4 degrees C for 24 h), and salt particles were leached into doubly distilled water over a period of 5 days to yield pore sizes ranging from 80 to 200 microns. Ten heart valve scaffolds were fabricated and seeded with vascular cells from an ovine carotid artery. After 4 days of incubation, the constructs were examined by scanning electron microscopy. The heart valve scaffold was tested in a pulsatile flow bioreactor and it was noted that the leaflets opened and closed. Cells attached to the polymer and formed a confluent layer after incubation. One advantage of this material is the ability to mold a complete trileaflet heart valve scaffold without the need for suturing leaflets to the conduit. Second advantage is the use of only one polymer material (PHA) as opposed to hybridized polymer scaffolds. Furthermore, the mechanical properties of PHA, such as elasticity and mechanical strength, exceed those of the previously utilized material. This experiment shows that PHAs can be used to fabricate a three-dimensional, biodegradable heart valve scaffold.

Animals↗
PubMed2002

Tissue-engineering bioreactors: a new combined cell-seeding and perfusion system for vascular tissue engineering.

One approach to the tissue engineering of vascular structures is to develop in vitro conditions in order ultimately to fabricate functional vascular tissues before final implantation. In our experiment, we aimed to develop a new combined cell seeding and perfusion system that provides sterile conditions during cell seeding and biomechanical stimuli in order to fabricate autologous human vascular tissue in vitro. The cell seeding and perfusion system is made of Plexiglas and is completely transparent (Berlin Heart, Berlin, Germany; University Hospital Benjamin Franklin, Berlin, Germany). The whole system consists of a cell seeding chamber that can be incorporated into the perfusion system and an air-driven respirator pump connected to the bioreactor. The cell culture medium continuously circulates through a closed-loop system. We thus developed a cell seeding device for static and dynamic seeding of vascular cells onto a polymeric vascular scaffold and a closed-loop perfused bioreactor for long-term vascular conditioning. The cell seeding chamber can be easily connected to the bioreactor, which combines continuous, pulsatile perfusion and mechanical stimulation to the tissue-engineered conduit. Adjusting the stroke volume, the stroke rate, and the inspiration/expiration time of the ventilator allows various pulsatile flows and different levels of pressure. The whole system is a highly isolated cell culture setting, which provides a high level of sterility and a gas supply and fits into a standard humidified incubator. The device can be sterilized by ethylene oxide and assembled with a standard screwdriver. Our newly developed combination of a cell seeding and conditioning device provides sterile conditions and biodynamic stimuli for controlled tissue development and in vitro conditioning of an autologous tissue-engineered vessel.

Bioreactors↗
PubMed1999

Fabrication of branched hybrid vascular prostheses.

We devised a branched, or bifurcated, hybrid vascular prosthesis that was mainly composed of bovine smooth muscle cells (SMCs) and type I collagen with minimal reinforcement by a knitted fabric mesh made of segmented polyester. The tubular hybrid medial tissue with small (3 mm) or large (6 mm) inner diameter was prepared by pouring a cold mixed solution of SMCs and collagen into a corresponding tubular mold and by subsequent thermal gelation, followed by 7-day culturing. A branched hybrid medial tissue was prepared by an end-to-side anastomosis between these tubes of different sizes. Two-week culture of the branched tissue resulted in continuous tissue formation at the anastomotic site. Upon seeding and culture of bovine endothelial cells (ECs), a fully endothelialized branched hybrid vessel was prepared. Under a continuous pulsatile flow condition, morphological alterations of ECs, responding to local flow dynamics generated by the branched configuration, were seen. Reinforcement with an elastomeric mesh improved mechanical strength of the hybrid tissue and created compliance matching with native arteries. A branched hybrid graft with mesh reinforcement is expected to be applicable to arterial replacement in a branching region.

Animals↗
PubMed1999

Oxygenator exhaust capnography as an index of arterial carbon dioxide tension during cardiopulmonary bypass using a membrane oxygenator.

We have studied the relationship between the partial pressure of carbon dioxide in oxygenator exhaust gas (PECO2) and arterial carbon dioxide tension (PaCO2) during hypothermic cardiopulmonary bypass with non-pulsatile flow and a membrane oxygenator. A total of 172 paired measurements were made in 32 patients, 5 min after starting cardiopulmonary bypass and then at 15-min intervals. Additional measurements were made at 34 degrees C during rewarming. The degree of agreement between paired measurements (PaCO2 and PECO2) at each time was calculated. Mean difference (d) was 0.9 kPa (SD 0.99 kPa). Results were analysed further during stable hypothermia (n = 30, d = 1.88, SD = 0.69), rewarming at 34 degrees C (n = 22, d = 0, SD = 0.84), rewarming at normothermia (n = 48, d = 0.15, SD = 0.69) and with (n = 78, d = 0.62, SD = 0.99) or without (n = 91, d = 1.07, SD = 0.9) carbon dioxide being added to the oxygenator gas. The difference between the two measurements varied in relation to nasopharyngeal temperature if PaCO2 was not corrected for temperature (r2 = 0.343, P = < 0.001). However, if PaCO2 was corrected for temperature, the difference between PaCO2 and PECO2 was not related to temperature, and there was no relationship with either pump blood flow or oxygenator gas flow. We found that measurement of carbon dioxide partial pressure in exhaust gases from a membrane oxygenator during cardiopulmonary bypass was not a useful method for estimating PaCO2.

Adult↗
PubMed1987

Validation of beat by beat pulsed Doppler measurements of ascending aortic blood velocity in man.

The volume, velocity, and acceleration of ascending aortic blood were measured in man using a pulsed Doppler ultrasound instrument, with online spectral analysis and offline computer processing of velocity data. This system was firstly validated in a test rig capable of generating pulsatile flow of talc particles in water at physiological velocities and accelerations in a model aorta. Doppler measurements correlated well (r greater than or equal to 0.90) with simultaneous electromagnetic measurements of stroke volume, peak ejection velocity, and maximum acceleration in this rig. In vivo validation was performed firstly by comparing simultaneous Doppler and thermodilution cardiac output (Q) measurements; this yielded the following regression equation: Doppler Q = 0.90 X thermodilution Q + 0.03 litre.min-1, r = 0.92; n = 38. Beat by beat measurements were then validated against simultaneous invasive aortic blood velocity measurements made using a Mills electromagnetic cathetertip probe. When paced single beats of different size were compared within subjects the correlation coefficients between Doppler and electromagnetic measurements averaged 0.89 for stroke volume, 0.91 for peak ejection velocity, and 0.79 for maximum acceleration in five subjects. The absolute values for velocity and acceleration from the Doppler system differed significantly from the absolute values given by the electromagnetic system and this difference was not consistent between subjects. It is concluded that the Doppler system can non-invasively record relative changes in left ventricular ejection in man.

Aorta↗
PubMed2006

Vitreous cryopreservation maintains the viscoelastic property of human vascular grafts.

Assess the effects of cryopreservation (cryo) and vitrification (vitro) on the viscoelastic properties of blood vessels. Human external Iliac artery vessels were harvested from liver organ donors (n=8). In each case the vessel was segmented into 3 equal parts, which were randomly placed in one of 3 categories: Fresh (stored in 4 degrees C UW for 6 h), Cryo (Placed in 10% Dulbecco's modified Eagle medium (DMEM) and slowly frozen to -196 degrees C), or Vitro (Placed in 40% DMEM and rapidly cooled to -196 degrees C). A pulsatile flow circuit was used to perfuse arterial segments at physiological pulse pressure and flow. Intraluminal pressure was measured using a Millar Mikro-tip catheter transducer, and vessel wall motion was determined with duplex ultrasonography coupled with a novel echo-locked vessel wall tracking system. Diametrical compliance (DC), Petersons elastic modulus (Ep), and stiffness index (beta) were then calculated for each of the three groups over 3 mean pressure ranging from 40 to 80 mmHg. The change in the viscous component of arterial wall (lag phase angle, theta) was calculated from hysteresis plots. No significant changes were observed in the elastic properties of fresh and vitrified vessels (P>0.05 for each of DC, Ep, and beta). Similarly, variation in the wall viscosity between fresh and vitrified vessels appeared to be nonsignificant (theta=12.60+/-4.04 vs. 17.60+/-1.14, respectively). In contrast, statistical analysis of results obtained for cryopreserved vessels to the fresh vessels showed significant reduction in elastic parameter values. There was also a significant increase in the phase angle theta of the cryopreserved vessels (theta=24.30+/-6.32; P<0.001) compared with fresh vessel. Results suggest that vitrification maintains both elastic and viscous components of the mechanical properties of vascular grafts, which is positively correlated with their functional patency. In contrast, damage caused during cryopreservation significantly affects the overall tensile strength and elasticity of the vessel (i.e., Ep and beta), the dynamic properties (DC), and appears to significantly affect the viscous component of the vessel wall (theta), which is likely reduce the patency of the graft for transplantation purposes.

Cryopreservation↗
PubMed1979

Halothane-induced renal vasodilation.

Halothane-induced changes in renal function have generally been attributed to alterations in systemic hemodynamics, sympathetic tone, and various hormones. Studies were performed to determine whether halothane directly affects the kidney. Twenty-one canine kidneys were perfused in vitro utilizing hemodilution, pulsatile flow, and membrane oxygenation. Temperature and arterial blood-gas variables were controlled and mean and pulse pressures were maintained. Four experimental periods (I-IV)(each consisting of two 10-min sample collection periods) were conducted, with a 20-min "rest" period between succeeding experimental periods (elapsed time = 140 min). Responsiveness was assured by obtaining a normal response to furosemide, acetylcholine, or epinephrine after Period IV. In eight additional kidney preparations halothane was administered to achieve either a "low" (17 +/- 3 mg/100 ml) or "high" (35 +/- 5 mg/100 ml) concentration in Period II, the sequence reversed for Period III, and halothane eliminated by Period IV. Halothane produced marked increases in blood flow (21-26 per cent), total (203-267 per cent) and fractional (173-179 per cent) sodium excretion, osmolal clearance (62-111 per cent) and urinary volume (130-161 per cent). These changes were associated with a shift of microspheres from outer to inner cortex, and were completely reversible by eliminating the halothane. In the absence of external influences, halothane produces renal vasodilation and natriuresis. Direct tubular depression cannot be ruled out.

Acetylcholine↗
PubMed1981

Effect of external pressure on axillofemoral bypass grafts.

External compression of axillofemoral grafts has been suggested many times as a cause for graft thrombosis. Thrombosis during sleep is the most common presentation of axillofemoral graft failure. Therefore, external compression of the graft by the body weight has been implicated in graft thrombosis. Six consecutive patients with axillofemoral bypass grafts for aortoiliac disease were studied on routine clinic visits. Pulsatile flow characteristics were studied by pulse volume recordings (PVR) and segmental Doppler pressure measurements in calf and ankle, prior to and during attempted graft compression, by having the patient lay on the graft. External compression by body weight did not alter the PVR and segmental Doppler pressure (P = NS) in the distal circulation. Therefore, these data suggest that external compression by the body weight may not be the primary cause of graft failure.

Axillary Artery↗
PubMedDate not supplied

Ventricular pressure slope and bileaflet mechanical heart valve closure.

The maximum left ventricular pressure slope (dP/dt) value has been used by several investigators as the criterion for studying mitral valve closure. In this article, the relationship between the ventricular pressure slope (dP/dt) and the leaflet closing behavior of bileaflet mechanical heart valves (BMV) is investigated. Two current BMVs, the St. Jude Medical 29 mm and CarboMedics 29 mm, installed in the mitral position of a mock circulatory pulsatile flow loop were used as the study model. Under simulated physiologic pressures and flow conditions, the experiment was conducted at 70, 90, and 120 beats/min with corresponding flow rates of 5.0, 6.0, and 7.5 liters/min, respectively. A laser sweeping technique was used to monitor the leaflet closing motion within the last 3 degrees excursion at valve closure. A modified dual beam laser sweeping technique system was used to register the difference of leaflet/housing impact time between the two BMV closing leaflets in asynchronous closure. Common BMV asynchronous closures were found in both BMVs at all three heart rates tested. The second closing leaflet was found to always close at higher velocity than the first. Simultaneous measurements of the ventricular pressure (Pv) and the leaflet closing time showed that Pv exhibited three stage characteristics. In the first stage, Pv gradually increased as the ventricle was filled. A sudden rise of Pv occurred immediately after closing of the first leaflet. The maximum dp/dt occurred in the third stage after closure of both BMV leaflets. The BMV closing behavior and the corresponding Pv pattern were found to depend strongly upon valve type and heart rate. The time averaged ventricular pressure slope (dp/dt) values at 70, 90, and 120 beats/min were about 40, 70, and 150 mmHg/sec for the St. Jude Medical valve and 40, 105, and 205 for the CarboMedics valve during the first closing stage. The maximum dp/dt values were 2670, 4350, and 5000 mmHg/sec for the St. Jude Medical valve and 1210, 2530, and 3210 mmHg/sec for the CarboMedics valve at the three heart rates tested, respectively. The study showed that the left ventricular pressure patterns (dP/dt) at valve closure were the result of valve operation under given driving conditions. The dp/dtmax cannot be used as the criterion for studying BMV closure.

Biomechanical Phenomena↗
PubMed2001

In vitro evaluation of the effect of aortic compliance on pediatric intra-aortic balloon pumping.

OBJECTIVES: To evaluate the effect of aortic compliance on pediatric intra-aortic balloon pumping (IABP). DESIGN: In vitro study using a mechanical model of the pediatric left heart circulation. SETTING: Cardiovascular fluid dynamics research laboratory. SUBJECT: Pulsatile flow system simulating the pediatric left heart circulation and two different aortas with compliances comparable to those of the pediatric aorta (0.12 and 0.07 mL/mm Hg). INTERVENTIONS: Measurements were made at a baseline peak aortic flow of 4 L/min, at simulated shock (1.7 L/min), and with 1:1 IABP (rates, 130 and 150 bpm; balloon volumes, 2.5 and 5.0 mL). MEASUREMENTS AND MAIN RESULTS: Peak flow rates were measured in the ascending aorta, coronary arterial system, and brachiocephalic arterial systems. Aortic pressure was measured in the ascending aorta. For both aortas (0.12 and 0.07 mL/mm Hg), IABP resulted in diastolic augmentation (38 +/- 8 and 43 +/- 16 mm Hg) and afterload reduction (4 +/- 2 and 6 +/- 3 mm Hg). For both aortas, compared to shock, IABP resulted in significant increases in coronary arterial and brachiocephalic arterial flow and aortic pressure for both aortas. Aortic flow significantly increased only in the less-compliant aorta. CONCLUSIONS: In a laboratory model of pediatric left heart circulation, IABP results in diastolic augmentation, afterload reduction, and improved hemodynamics, even in aortas of greater compliance.

Journal Article↗
PubMed2003

Effects of levosimendan on right ventricular function and ventriculovascular coupling in open chest pigs.

OBJECTIVE: Levosimendan is a promising calcium sensitizer that potentially could be useful in settings of pulmonary vasoconstriction and right ventricular dysfunction. There is a shortage of information concerning its effects on right ventricular function and ventriculovascular coupling. The aim of the present study was to characterize the effects of levosimendan on right ventricular and pulmonary vascular function by means of pressure-volume and pulsatile flow analysis. DESIGN: Prospective laboratory investigation. SETTING: University hospital laboratory. SUBJECTS: Eight landrace pigs (mean weight, 37 kg). INTERVENTIONS: Following instrumentation with biventricular conductance catheters, pulmonary and right coronary artery flow probes, a high-fidelity pulmonary pressure catheter, and a right coronary venous catheter, hemodynamic measurements were performed in baseline conditions and during levosimendan infusion at three increasing plasma concentrations (mean values, 27.5, 67.6, and 142.5 ng/mL). MEASUREMENTS AND MAIN RESULTS: Levosimendan increased heart rate and cardiac output, reduced systemic vascular resistance, and had a positive inotropic effect on the left ventricle and increased left ventricular mechanical efficiency. Moreover, levosimendan increased right ventricular contractility and hydraulic power. However, total pulmonary vascular resistance and characteristic impedance did not change throughout the protocol, and right ventricular mechanical efficiency decreased slightly at the highest concentration of levosimendan. CONCLUSIONS: At clinical concentrations in the present model, levosimendan increases right ventricular contractility and performance without significantly influencing pulmonary vascular tone. Further studies are required in a model of pulmonary vasoconstriction to disclose possible pulmonary vasodilator effects of levosimendan.

Animals↗
PubMedDate not supplied

Endothelial and smooth muscle cell seeding onto processed ex vivo arterial scaffolds using 3D vascular bioreactors.

Biomaterials derived from ex vivo tissues offer a viable alternative to synthetic materials for organ replacement therapies. In this study, we describe the use of a tissue engineering scaffold derived from ex vivo arterial tissue to assess vascular cell adhesion within a three-dimensional perfusion bioreactor. With the aim of maximizing seeding efficiency, five methods for endothelial cell (EC) and three independent methods for vascular smooth muscle cell (VSMC) adhesion were explored. Seeded constructs were maintained in vascular bioreactors under pulsatile flow conditions, culminating at 165 ml/min at 1.33 Hz to validate cell attachment and retention over time. Progressive modification of the seeding and flow regime protocols resulted in an increased of EC retention from 5.1 to 634 cells/mm2. Seeding VSMCs as sheets rather than cell suspensions bound and stabilized surface EC matrix fibers, resulting in multiple cell layers adhered to the scaffold with cells migrating to the medial/adventitial boundary. In conjunction with the bioscaffold, the vascular perfusion system serves as a useful tool to analyze cell adhesion and retention by allowing controlled manipulation of seeding and perfusion conditions.

Animals↗
PubMedDate not supplied

Use of a covered stent modification to produce a transcatheter valve: laboratory and animal testing.

Stent-based transcatheter valves continue to require large sheaths inappropriate for deployment in children. Low-profile covered stent valves (CSVs) were constructed by removing triangular sections from two sides of partially expanded Palmaz P308 stents before covering the stents with 0.1 mm polytetrafluoroethylene. Valves were carefully crimped onto balloon catheters and deployed in a pulsatile flow loop. With fixed afterload and pump output, flow, degree of stenosis, effect on pulse pressure, and ease of deployment were determined for each valve. In vivo transcatheter feasibility studies were then performed by disabling the aortic valve of two 25-kg pigs, and deploying transcatheter CSVs into their descending aorta. All transcatheter valves deployed consistently via sheaths three French sizes larger than the recommended sheath for their balloon and none created significant obstruction. With the bicuspid and supravalvar CSVs, the flow was 64% and 79% (respectively) of a commercially available valve. Angiograms revealed excellent acute CSV function after deployment with only mild regurgitation and without significant obstruction to systolic flow. Although long-term testing is required, a modified CSV design may have utility in low-profile pediatric transcatheter valve replacement.

Adult↗
PubMedDate not supplied

Construction of tissue-engineered homograft bioprosthetic heart valves in vitro.

Human mesenchymal stem cells (MSCs) differentiate into multiple cell-lineages and may serve as an alternative source of seed cells for tissue engineering. We investigated whether MSCs could be induced to differentiate into endothelial cells (ECs) and function as seed cells for the in vitro construction of tissue-engineered heart valves (TEHVs). Aortic or pulmonary valve homografts were decellularized with 0.1% sodium dodecylsulphate and used as scaffolds for TEHVs. The MSCs were isolated from human bone marrow by Percoll gradient centrifugation (1.073 g/ml), differentiated into ECs with vascular endothelial growth factor (10 ng/ml), and seeded onto a decellularized scaffold (high-density seeding, >10(5) cells/cm2) and grown in static culture for 14 days. Over 90% of the differentiated cells from MSCs stained positively for von Willebrand factor and Tie-2-related antigen. Additionally, Weibel-Palade corpuscle was observed in the cytoplasm of these cells. Levels of reendothelialization in static culture on days 7, 14, and 20, were 73%, 85%, and 95%, respectively. These results show that MSCs from human bone marrow can differentiate, in vitro, into ECs that can then be used to construct TEHVs. Reendothelialization in static culture can be used to provide the basic material for pulsatile-flow cultivation.

Adult↗
PubMed2006

An experimental model for the treatment of lethal bleeding injury to the juxtahepatic vena cava with stent graft.

BACKGROUND: Juxtahepatic vein injuries present a high mortality rate. Our objectives were to develop an experimental model of endovascular lethal injury of the juxtahepatic inferior vena cava (JHIVC) and to evaluate its hemodynamic alterations; to treat the lesion with volume replacement, and a stent graft (SG); and to follow the animals after treatment. METHODS: Twenty dogs were anesthetized and monitored [heart rate (HR), mean arterial pressure (MAP), vesical and peritoneal pressures], and submitted to a JHIVC endovascular injury. After volume replacement the dogs were divided into two groups: control (GI) and experimental (GII). GI was observed until death. GII was treated with SG and followed by Doppler ultrasound (DUS) and cavography for 4 (GIIA), and 8 weeks (GIIB), and then sacrificed and IVC and SG were analyzed. RESULTS: GI presented increased abdominal pressures, arterial hypotension, and death after 80 minutes. GII had a 100% survival rate till sacrifice, without clinical repercussions. At DUS and cavography all SG were patent, with monophasic pulsatile flow. On US, SG diameters after 2, 4, and 8 weeks did not show differences. On cavography IVC diameters presented no difference between groups GIIA and GIIB throughout the experiment. These data analyzed for the GII as a whole, showed statistically significant differences. Average lumen diameter reduction of SG was 27.43+/-20,00%. Pressure values in the IVC cranially, caudally to the SG, and inside the SG, did not show differences. In the IVC with the SG we observed a thicker neointima layer, and the injury in the media layer was covered with fibroconnective tissue. CONCLUSIONS: We developed an experimental dog model of endovascular lethal injury of the JHIVC with significant increase in abdominal pressures, and a mortality rate of 100%. The treatment of this lesion with SG resulted in a thickened neointima layer, and a 27% reduction in the JHIVC lumen diameter, without clinical repercussion, and with a 100% survival rate.

Analysis of Variance↗