A Novel Smart Assistance System for Blood Vessel Approaching: A Technical Report Based on Oximetry.

In clinical practice, the catheter has to be placed at an accurate position during anesthesia administration. However, effectively guiding the catheter to the accurate position in deeper tissues can be difficult for an inexperienced practitioner. We aimed to address the current issues associated with catheter placement using a novel smart assistance system for blood vessel catheter placement. We used a hollow introducer needle embedded with dual wavelength (690 and 850 nm) optical fibers to advance the tip into the subclavian vessels in anesthetized piglets. The results showed average optical density changes, and the difference between the absorption spectra and hemoglobin concentrations of different tissue components effectively identified different tissues (p < 0.05). The radial basis function neural network (RBFNN) technique was applied to distinguish tissue components (the F-measure value and accuracy were 93.02% and 94%, respectively). Finally, animal experiments were designed to validate the performance of the proposed system. Using this system based on oximetry, we easily navigated the needle tip to the target vessel. Based on the experimental results, the proposed system could effectively distinguish different tissue layers of the animals.

[Hemodynamic features assessment in submental and facial arteries in patients with early atherosclerotic disease of brachycephalic arteries].

By ultrasonicduplex scanning nature estimated haemodynamics in the arteriessubmentalis and facial of patients with early signs of atherosclerotic changes in the brakhiotsefalarteries and periodontal pathology of different stages - for perfection of prophylaxis of periodontal diseases by the means of investigation of prophylaxis vascular diseases. It was established, that influence of risk factors is more important than the age of patients.

Altered maternal left ventricular contractility and function during normal pregnancy.

OBJECTIVES: To evaluate maternal left ventricular (LV) systolic and diastolic function during normal pregnancy by non-invasive measures of LV contractility incorporating loading conditions. METHODS: Sixty-five women were examined using echocardiography, including tissue Doppler and two-dimensional speckle tracking, and subclavian artery pulse trace recordings at gestational weeks 14-16, 22-24 and 36, and at 6 months postpartum. RESULTS: The mean ± SD age of the women was 32.0 ± 4.6 years. Cardiac output and LV end-diastolic volume were on average 20% and 23% higher, respectively, during pregnancy, compared to that at 6 months postpartum (both, P < 0.01). LV ejection fraction, global peak systolic strain and rate-corrected LV velocity of circumferential fiber shortening (Vcfc) were 11%, 6% and 6% lower, respectively, at 36 weeks' gestation compared to at 6 months postpartum (all, P < 0.01). Afterload, measured as LV end-systolic wall stress (ESWS) increased by 10% between 14-16 and 36 weeks' gestation (P < 0.01). Analysis of the relationship between Vcfc and ESWS revealed that LV contractility was lower during pregnancy than at 6 months postpartum. Changes in diastolic function were demonstrated by 11% lower mitral early diastolic (E) wave velocity, 8% lower tissue Doppler early diastolic velocity (e') and 13% higher left atrial area (all P < 0.01) during pregnancy. Tissue Doppler E/e' remained unaltered (P = 0.78). CONCLUSIONS: During normal pregnancy, LV contractility is lower than it is at 6 months postpartum. This is associated with increased LV and left atrial area, whereas filling pressures are unchanged. These findings suggest that pregnancy exerts a larger load on the cardiovascular system than previously assumed.

Subclavian flap aortoplasty and preservation of left upper extremity circulation using an interposition graft.

OBJECTIVES: To introduce a surgical technique to maintain left upper limb blood flow after subclavian flap aortoplasty (SFA). METHODS: Five patients (9 to 23 months of age) with a diagnosis of long-segment aortic coarctation underwent conventional SFA. A Gore-tex graft was interposed between the stump and the proximal descending aorta to maintain perfusion of subclavian artery. RESULTS: All patients had a patent Gore-tex graft and normal blood flow of the subclavian artery and left upper limb. One patient expired and four others were discharged with a mean follow-up of 48 months. On follow-up all patients had normal development of the left upper limb and no signs of limb ischemia. Echo findings revealed normal arch flow with normal flow in the Gore-tex graft and left upper extremity. CONCLUSIONS: Interposing a Gore-tex graft between the subclavian artery stump and proximal descending aorta concomitant with SFA can be safely performed in infants with long-segment aortic coarctation, with preservation of left upper extremity circulation.

Correlation between morphometry of the suprascapular notch and anthropometric measurements of the scapula.

The concept of the study was to find the correlation between the morphometry of the suprascapular notch and basic anthropometric measurements of the human scapula. The measurements of the human scapulae included: morphological length and width, maximal width and length projection of scapular spine, length of acromion, and maximal length of the coracoid process. The glenoid cavity was measured in two perpendicular directions to evaluate its width and length. The width-length scapular and glenoid cavity indexes were calculated for every bone. In addition to standard anthropometric measurements two other measurements were defined and evaluated for every suprascapular notch: maximal depth (MD) and superior transverse diameter (STD). The superior transverse suprascapular ligament was completely ossified in 7% of cases. Ten (11.6%) scapulae had a discrete notch. In the studied material, in 21 (24.4%) scapulae the MD was longer than the STD. Two (2.3%) scapulae had equal maximal depth and superior transverse diameter. In 47 (57.7%) scapulae the superior transverse diameter was longer than the maximal depth. There was no statistically significant difference between anthropometric measurements in the group with higher MD and the group with higher STD. The maximal depth of the suprascapular notch negatively correlated with the scapular width-length index. The maximal depth of the scapular notch correlated with the morphological length of the scapulae.

A bicarotid trunk in association with an aberrant right subclavian artery. Report of two cases, clinical impact, and review of the literature.

A combination of an aberrant right subclavian artery (ARSA) and a bicarotid trunk (BCT) appears in up to 2.5% of the population. The aim of this study is to report the higher total and male incidence of this variation in the literature and to summarise its clinical impact, providing useful knowledge to anatomists, radiologists, cardiologists, and vascular and thoracic surgeons in order to avoid diagnostic pitfalls and therapeutic complications. A total of 72 (43 female and 29 male) Greek Caucasian formalin-embalmed cadavers were studied. The international literature was reviewed along with the dissection archives of the Department of Anatomy from 1986 to 2009. Two male cadavers were found to have an ARSA combined with a BCT (incidence: total 2.78%, males 6.9%, females 0%). Both aortic arches consisted of three branches: (1) the BCT, (2) the left subclavian artery, and (3) the ARSA. The common carotids followed a normal route to the neck; the ARSA passed between the trachea and the oesophagus in the first case and behind the oesophagus in the second case, and was accompanied by a non-recurrent laryngeal nerve. In the second cadaver the ARSA formed a sharp angle (kinking/buckling) on its route to the right arm. The ARSA is associated with several congenital cardiovascular anomalies and some chromosomal and other syndromes. It is occasionaly responsible for causing dysphagia, dyspnoea, or acute ischaemia to the right upper limb, and it may present as a superior mediastinal mass in cases of aneurysm formation.

A mouse model of ischemic spinal cord injury with delayed paralysis caused by aortic cross-clamping.

BACKGROUND: Spinal cord ischemia and paralysis are devastating perioperative complications that can accompany open or endovascular repair surgery for aortic aneurysms. Here, we report on the development of a new mouse model of spinal cord ischemia with delayed paralysis induced by cross-clamping the descending aorta. METHODS: Transient aortic occlusion was produced in mice by cross-clamping the descending aorta through a lateral thoracotomy. To establish an optimal surgical procedure with limited mortality, variable cross-clamp times and core temperatures were tested between experiments. RESULTS: The onset of paresis or paralysis and postsurgical mortality varied as a function of cross-clamp time and core temperature that was maintained during the period of cross-clamp. Using optimal surgical parameters (7.5-min cross-clamp duration at 33°C core temperature), the onset of paralysis is delayed 24-36 h after reperfusion, and more than 95% of mice survive through 9 weeks after surgery. These mice are further stratified into two groups, 70% (n = 19/27) of mice developing severe hind limb paralysis and the remaining mice showing mild, though still permanent, behavioral deficits. CONCLUSION: This new model should prove useful as a preclinical tool for screening neuroprotective therapeutics and for defining the basic biologic mechanisms that cause delayed paralysis and neurodegeneration after transient spinal cord ischemia.

Flow analysis of ventricular assist device inflow and outflow cannula positioning using a naturally shaped ventricle and aortic branch.

Tip geometry and placement of rotary blood pump inflow and outflow cannulae influence the dynamics of flow within the ventricle and aortic branch. Cannulation, therefore, directly influences the potential for thrombus formation and end-organ perfusion during ventricular assist device (VAD) support or cardiopulmonary bypass (CPB). The purpose of this study was to investigate the effect of various inflow/outflow cannula tip geometries and positions on ventricular and greater vessel flow patterns to evaluate ventricular washout and impact on cerebral perfusion. Transparent models of a dilated cardiomyopathic ventricle and an aortic branch were reconstructed from magnetic resonance imaging data to allow flow measurements using particle image velocimetry (PIV). The contractile function of the failing ventricle was reproduced pneumatically, and supported with a rotary pump. Flow patterns were visualized around VAD inflow cannulae, with various tip geometries placed in three positions in the ventricle. The outflow cannula was placed in the subclavian artery and at several positions in the aorta. Flow patterns were measured using PIV and used to validate an aortic flow computational fluid dynamic study. The PIV technique indicated that locating the inflow tip in the left ventricular outflow tract improved complete ventricular washout while the tip geometry had a smaller influence. However, side holes in the inflow cannula improved washout in all cases. The PIV results confirmed that the positioning and orientation of the outflow cannula in the aortic branch had a high impact on the flow pattern in the vessels, with a negative blood flow in the right carotid artery observed in some cases. Cannula placement within the ventricle had a high influence on chamber washout. The positioning of the outflow cannula directly influences the flow through the greater vessels, and may be responsible for the occasional reduction in cerebral perfusion seen in clinical CPB.

Hemodynamic consequences of TEVAR with in situ double fenestrations of left carotid artery and left subclavian artery.

The aortic major branches after thoracic endovascular aortic repair (TEVAR) could be preserved by in situ fenestration (ISF). This study aims to explore the hemodynamic consequences of ISF-TEVAR with double fenestrations. Two patients with aortic dissection and aneurysm, respectively, were treated by ISF-TEVAR and both the left carotid artery (LCA) and left subclavian artery (LSA) were reconstructed by fenestration technique. The blood was considered a non-Newtonian fluid and the Windkessel model was adopted at the aortic outlets. Simulations were performed in two postoperative models to analyze the effects of the double fenestration stents on the hemodynamics. The postoperative wall pressure of the LCA and LSA is relatively low and the pressure difference between the inner and outer walls of the protruding segment of the LSA stent is found. Acceleration occurs when blood flows around the fenestration stents and the shear-thinning rheological behavior is observed at the aortic arch. Moreover, regions susceptible to thrombosis are identified and the surface exposed to high relative residence time is located at the aortic arch after the LSA stent. The presence of the double fenestration stents has a profound impact on the postoperative hemodynamics, and the aortic arch and rebuilt branches should be closely watched during follow-up.

The impact of aortic/subclavian outflow cannulation for cardiopulmonary bypass and cardiac support: a computational fluid dynamics study.

Approximately 100 000 cases of oxygen deficiency in the brain occur during cardiopulmonary bypass (CPB) procedures each year. In particular, perfusion of the carotid and vertebral arteries is affected. The position of the outflow cannula influences the blood flow to the cardiovascular system and thus end organ perfusion. Traditionally, the cannula returns blood into the ascending aorta. But some surgeons prefer cannulation to the right subclavian artery. A computational fluid dynamics study was initially undertaken for both approaches. The vessel model was created from real computed tomography/magnetic resonance imaging data of young healthy patients. The simulations were run with usual CPB conditions. The flow distribution for different cannula positions in the aorta was studied, as well as the impact of the cannula tip distance to vertebral artery for the subclavian position. The study presents a fast method of analyzing the flow distribution in the cardiovascular system, and can be adapted for other applications such as ventricular assist device support. It revealed that two effects cause the loss of perfusion seen clinically: a vortex under the brachiocephalic trunk and low pressure regions near the cannula jet. The results suggest that cannulation to the subclavian artery is preferred if the cannula tip is sufficiently far away from the branch of the vertebral artery. For the aortic positions, however, the cannula should be injected from the left body side.

Wall shear rate in supra-aortic vessels: a factor for different atherosclerotic pattern?

BACKGROUND: Atherosclerotic lesions of the upper extremity arise three to five times more often at the origin of the left subclavian artery than on the right side. The aim of this study was to investigate, whether the hemodynamic forces (peak wall shear rate) in the large supra-aortic branches measured by MRI differ in healthy subjects. PATIENTS AND METHODS: Peak wall shear rate (WSR) and blood flow was assessed in the left carotid, left subclavian and innominate artery in ten healthy volunteers (5 females, mean age of 35.2 +/- 9 years) using high resolution (pixel size 0.6 mm 2) magnetic resonance imaging (MRI) flow velocity measurements. RESULTS: There is no difference between the maximum WSR of the three large supra-aortic vessels. Only within the proximal (327 +/- 132s-1) and distal wall (458 +/- 154s-1) of the innominate artery a significant difference (p = 0.011) of the WSR was found. CONCLUSION: The results from this study indicate that WSR is not different in the supra-aortic vessels. Therefore the atherosclerotic pattern in the subclavian and innominate arteries may not be explained by differences in these hemodynamic forces.

The role of vascular injury and hemodynamics in rat pulmonary artery remodeling.

Vascular remodeling in adult human elastic pulmonary arteries is characterized by diffuse neointimal lesions containing smooth muscle cells expressing extracellular matrix genes. Recent studies suggest vascular injury is needed to initiate remodeling and that growth factor mediators participate in the repair response. However, because neointimal formation is only observed in patients with pulmonary artery blood pressures approaching systemic levels, it has been hypothesized that systemic-like hemodynamic conditions are also necessary. To test that hypothesis, subclavian-pulmonary artery anastomoses were created in Sprague-Dawley rats under three different experimental conditions: no accompanying injury, or after monocrotaline or balloon endarterectomy injury. Pulmonary vascular remodeling was not induced by the subclavian-pulmonary artery anastomosis alone. A non-neointimal pattern of remodeling after mild monocrotaline-induced injury was converted into a neointimal pattern in the presence of the anastomosis. Neointima was also observed after severe, balloon endarterectomy-induced injury even in the absence of anastomosis. Tropoelastin, type I procollagen and TGF-beta gene expression, and angiotensin converting enzyme immunoreactivity, was confined to the neointima resembling the pattern of gene expression and immunoreactivity in human hypertensive elastic pulmonary artery neointimal lesions. These observations introduce the concepts that the type of injury and the associated hemodynamic conditions can modify the elastic pulmonary artery response to injury.

Left subclavian artery occlusion by thoracic aortic stent graft: long-term clinical and duplex follow-up.

BACKGROUND: In recent years there has been an increase in endovascular repair of thoracic aortic aneurysms. In cases of insufficient neck length, occlusion of left subclavian artery achieves proper sealing and is usually well tolerated. Selected cases require revascularization of the left subclavian artery, including patients after coronary bypass surgery (left internal mammary to left anterior descending) and those with arm claudication or subclavian steal syndrome. OBJECTIVES: To evaluate the tolerability of left subclavian artery occlusion by stent graft without revascularization. METHODS: Thirty patients with thoracic aortic aneurysms underwent endovascular repair between July 2000 and November 2004. Eleven of them had occlusion of the left subclavian artery that required revascularization in two. Follow-up (average 3 years) included: a) blood pressure measurements of both arms at rest, after effort and pulse palpation, and b) vertebral blood flow by duplex scan. RESULTS: Of nine patients with no revascularization, 8 (89%) tolerated left subclavian artery occlusion with no claudication or steal syndrome; one (11%) suffered mild claudication only after effort and required no intervention. No left radial pulses were palpated in the nine patients. Blood pressure measurements in the left arm showed an average decrease of 40%, which remained constant after induced effort in all patients and was clinically insignificant. Duplex scan demonstrated reverse flow in the left vertebral artery in 8 of 9 patients (89%) and occlusion in 1 (originating in the arch and covered by the stent graft) with no clinical symptoms. CONCLUSIONS: Left subclavian artery occlusion by stent graft is a tolerable procedure in the long term. In most cases, the constant decrease in blood pressure remained unchanged during follow-up and had no significant adverse affects. Most patients do not require revascularization prior to the endovascular procedure.

Computational fluid dynamics simulation of the right subclavian artery cannulation.

OBJECTIVE: The purpose of this study was to evaluate the efficacy of right subclavian artery cannulation using computational fluid dynamics. METHODS: Patient-specific models of the aortic arch were made with 4 patterns (1: normal aorta, 2: ascending aorta aneurysm, 3: distal arch aneurysm, 4: bovine arch) based on the computed tomography images. Right subclavian artery and ascending aorta cannulation models were created to simulate the physiologic pulsatile flow. Perfusion flow through the arterial cannula was set to 2.50 L/min (50% flow), 3.75 L/min (75% flow), and 5.0 L/min (100%), respectively, and a 3-dimensional movie was made of 1 cardiac cycle to evaluate the blood flow. RESULTS: In both 50% and 75% flow simulation with right subclavian artery cannulation, the blood streamline from the right subclavian artery produced retrograde flow of the brachiocephalic artery and antegrade flow of the right common carotid artery throughout the cardiac cycle in all cases. Right subclavian artery flow deflected ascending aorta flow to the descending aorta. Left-side supra-aortic branches were perfused by blood flow from both the right subclavian artery cannula and the aortic valve. The ascending aortic cannulation model showed that blood flow from the aortic valve reached all 3 supra-aortic vessels in systole. CONCLUSIONS: Right subclavian artery cannulation was cerebroprotective, especially on the right side.

In vitro set-up of modified Blalock Taussig shunt: vascular resistance-flow relationship.

BACKGROUND: A modified Blalock-Taussig (mBT) shunt is an anastomosis created between the systemic and pulmonary arterial tree in order to improve pulmonary blood flow in neonates and children with congenital heart disease. The aim of this study was to assess vascular resistance-flow relationship in an in vitro set-up of a modified Blalock Taussig shunt. METHODS: A shunt set-up was constructed with the vessels of a sheep. A modified BT shunt was anastomosed between an innominate (brachiocephalic) and a right pulmonary artery. A Medos pump (ventricular assist device) was used to create pulsatile flow. Three different mean pulmonary artery flow rates (Q PA ) were applied. Once mean pulmonary and mean aortic flows (Q AO ) were fixed, shunt flow rates for twelve different pulmonary vascular resistances (R p ) were investigated. RESULTS: For all three pulmonary flow rates, the shunt flow decreased with increasing pulmonary resistance. In addition, systemic flow decreased compared to pulmonary flow. When pulmonary flow rate was set at 800 ml/min and aorta flow rate at 900 ml/min, the distribution of flow between pulmonary and systemic organs flow rates ranged between 69% - 70% and 30% - 31% respectively. Similarly, when both pulmonary and aorta flow rates were set at 900 ml/min, pulmonary and systemic organ flows ranged between 73% - 77% and 23% - 27% respectively. For pulmonary and aorta flow rates of 1000 ml/min and 900 ml/min, respectively, the distribution of flow between pulmonary and systemic organ flow rates varied between 79% - 83% and 17% - 21% respectively. CONCLUSION: Knowledge of the relationship between vascular resistances and flow in this surgically created in vitro mBT shunt set-up may be helpful in the clinical management of the patients whose survival is crucially dependent on the blood flow distribution between the pulmonary and systemic circulation.

Hemodynamic analysis of outflow grafting positions of a ventricular assist device using closed-loop multiscale CFD simulations: Preliminary results.

Subclavian arteries are a possible alternate location for left ventricular assist device (LVAD) outflow grafts due to easier surgical access and application in high risk patients. As vascular blood flow mechanics strongly influence the clinical outcome, insights into the hemodynamics during LVAD support can be used to evaluate different grafting locations. In this study, the feasibility of left and right subclavian artery (SA) grafting was investigated for the HeartWare HVAD with a numerical multiscale model. A 3-D CFD model of the aortic arch was coupled to a lumped parameter model of the cardiovascular system under LVAD support. Grafts in the left and right SA were placed at three different anastomoses angles (90°, 60° and 30°). Additionally, standard grafting of the ascending and descending aorta was modelled. Full support LVAD (5l/min) and partial support LVAD (3l/min) in co-pulsation and counter-pulsation mode were analysed. The grafting positions were investigated regarding coronary and cerebral perfusion. Furthermore, the influence of the anastomosis angle on wall shear stress (WSS) was evaluated. Grafting of left or right subclavian arteries has similar hemodynamic performance in comparison to standard cannula positions. Angularity change of the graft anastomosis from 90° to 30° slightly increases the coronary and cerebral blood flow by 6-9% while significantly reduces the WSS by 35%. Cannulation of the SA is a feasible anastomosis location for the HVAD in the investigated vessel geometry.

Endovascular repair of thoracic aortic aneurysm associated with right-sided aortic arch: report of two cases.

Right-sided aortic arch (RAA) is a rare congenital disorder. We describe herein two cases of thoracic aortic aneurysm with a right aortic arch and right-sided descending aorta treated with thoracic endovascular aortic repair (TEVAR). In one case, a 70-year-old man with Edwards type 1 RAA underwent TEVAR using a Relay stent-graft (Bolton Medical, Barcelona, Spain). In another case, a 72-year-old woman with Edwards type 3 RAA underwent TEVAR using a Kawasumi Najuta stent-graft (Kawasumi Laboratories, Inc., Tokyo, Japan) with the "buffalo horn chimney technique", our original method for left subclavian artery flow preservation. The postoperative courses were uneventful. Postoperative computed tomography showed complete exclusion of the aneurysm without endoleakage. Compared to conventional open surgical repair, TEVAR is challenging in patients with a RAA and right-sided descending aorta. However, our results showed that TEVAR might be feasible and a treatment option even in a patient with a RAA and right-sided descending aorta.

Left Subclavian Artery Perfusion During the Norwood Operation for Interrupted Aortic Arch With Aortic Atresia.

The combination of aortic atresia and interrupted aortic arch is a rare condition. We describe a case of Norwood operation for this defect, in which a collateral artery from the descending aorta supplied coronary perfusion. The devised cardiopulmonary bypass technique is discussed, in which the left subclavian artery perfusion was utilized in addition to the cannulation to the descending aorta to secure the cerebral perfusion.

An autoperfusion technique for nonsteady-state vascular pressure-flow analysis in the rat.

A technique was developed to measure pressure-flow relationships in the autoperfused intact subclavian vascular bed of areflexic rats. Changes in blood flow and perfusion pressure were produced by occlusion of the aortic arch. This perfusion technique is suitable for evaluating vascular distensibility and responsiveness in the rat.

Investigation of hemodynamics in an in vitro system simulating left ventricular support through the right subclavian artery using 4-dimensional flow magnetic resonance imaging.

OBJECTIVES: Left ventricular assist devices are an important treatment option for patients with heart failure alter the hemodynamics in the heart and great vessels. Because in vivo magnetic resonance studies of patients with ventricular assist devices are not possible, in vitro models represent an important tool to investigate flow alterations caused by these systems. By using an in vitro magnetic resonance-compatible model that mimics physiologic conditions as close as possible, this work investigated the flow characteristics using 4-dimensional flow-sensitive magnetic resonance imaging of a left ventricular assist device with outflow via the right subclavian artery as commonly used in cardiothoracic surgery in the recent past. METHODS: An in vitro model was developed consisting of an aorta with its supra-aortic branches connected to a left ventricular assist device simulating the pulsatile flow of the native failing heart. A second left ventricular assist device supplied the aorta with continuous flow via the right subclavian artery. Four-dimensional flow-sensitive magnetic resonance imaging was performed for different flow rates of the left ventricular assist device simulating the native heart and the left ventricular assist device providing the continuous flow. Flow characteristics were qualitatively and quantitatively evaluated in the entire vessel system. RESULTS: Flow characteristics inside the aorta and its upper branching vessels revealed that the right subclavian artery and the right carotid artery were solely supported by the continuous-flow left ventricular assist device for all flow rates. The flow rates in the brain-supplying arteries are only marginally affected by different operating conditions. The qualitative analysis revealed only minor effects on the flow characteristics, such as weakly pronounced vortex flow caused by the retrograde flow via the brachiocephalic artery. CONCLUSIONS: The results indicate that, despite the massive alterations in natural hemodynamics due to the retrograde flow via the right subclavian and brachiocephalic arteries, there are no drastic consequences on the flow in the brain-feeding arteries and the flow characteristics in the ascending and descending aortas. It may be beneficial to adjust the operating condition of the left ventricular assist device to the residual function of the failing heart.