Direction Of Blood Flow Research Articles

The Underlying Cardiovascular Mechanisms of Resuscitation and Injury of REBOA and Partial REBOA.

Introduction: Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) is used for aortic control in hemorrhagic shock despite little quantification of its mechanism of resuscitation or cardiac injury. The goal of this study was to use pressure-volume (PV) loop analysis and direct coronary blood flow measurements to describe the physiologic changes associated with the clinical use of REBOA. Methods: Swine underwent surgical and vascular access to measure left ventricular PV loops and left coronary flow in hemorrhagic shock and subsequent placement of occlusive REBOA, partial REBOA, and no REBOA. PV loop characteristics and coronary flow are compared graphically with PV loops and coronary waveforms, and quantitatively with measures of the end systolic and end pressure volume relationship, and coronary flow parameters, with accounting for multiple comparisons. Results: Hemorrhagic shock was induced in five male swine (mean 53.6 ± 3.6 kg) as demonstrated by reduction of stroke work (baseline: 3.1 vs. shock: 1.2 L*mmHg, p < 0.01) and end systolic pressure (ESP; 109.8 vs. 59.6 mmHg, p < 0.01). ESP increased with full REBOA (178.4 mmHg; p < 0.01), but only moderately with partial REBOA (103.0 mmHg, p < 0.01 compared to shock). End systolic elastance was augmented from baseline to shock (1.01 vs. 0.39 ml/mmHg, p < 0.01) as well as shock compared to REBOA (4.50 ml/mmHg, p < 0.01) and partial REBOA (3.22 ml/mmHg, p = 0.01). Percent time in antegrade coronary flow decreased in shock (94%–71.8%, p < 0.01) but was rescued with REBOA. Peak flow increased with REBOA (271 vs. shock: 93 ml/min, p < 0.01) as did total flow (peak: 2136, baseline: 424 ml/min, p < 0.01). REBOA did not augment the end diastolic pressure volume relationship. Conclusion: REBOA increases afterload to facilitate resuscitation, but the penalty is supraphysiologic coronary flows and imposed increase in LV contractility to maintain cardiac output. Partial REBOA balances the increased afterload with improved aortic system compliance to prevent injury.

Minigames for Teaching the Cardiovascular System to Students of Human Anatomy

We are building a series of cell‐phone based minigames as a new approach to teaching cardiovascular concepts. The minigames belong to the first iteration of our intelligent textbook, Cardiovascular and Respiratory Anatomy Map (CRAM). They are part of a larger suite of games under a common umbrella that teach students the key concepts in human anatomy. Playing games engages student interest and enables students to learn at a lower stress level. Our goal is to enable students to master this material without getting distracted by different but related concepts in the cardiovascular system.The purpose of this game is to demonstrate that oxygenated and deoxygenated blood flow patterns in the pulmonary circuit are different than in the systemic circuit. We ask students to learn the names of the arteries and veins that supply and drain the heart and lungs. In the first stage of the game, students just need to identify correctly which vessels contain oxygenated and deoxygenated blood and the direction of blood flow.Students run this game on a cell phone or laptop. The screen shows the main organs involved in this process, namely the heart, the two lungs (one on each side of the screen), and a stick‐figure representation of the body. The organs are connected by the great vessels that transport blood to and from the heart and lungs. Students click on the arrows representing the vessels and color them red or blue. When they color a vessel incorrectly, the system responds with information to correct their misconception. For example, if the student colors the pulmonary arteries red, they are informed that the pulmonary arteries carry deoxygenated blood to the heart.This game is the first of a series of games teaching students the fundamentals of cardiac anatomy and function. Different from other materials that teach cardiovascular function, the first game does not make students memorize the chambers of the heart and their relationship to the great vessels. We believe that separating this issue from understanding the higher level relationship between the organs reduces the initial cognitive load on students and streamlines their ability to attain mastery of the entire system. A typical human anatomy book requires 30–40 pages of text to cover the material we present in a series of minigames. This approach appeals to contemporary students who prefer to use their cell phones for learning and are reluctant to read the assigned text.The system has two take‐home messages. In mammals, the pulmonary arteries are the exception to the rule that an artery always carries oxygenated blood because they receive deoxygenated blood from the heart. In addition, the lungs only provide oxygen to body tissues via the heart, which is a double‐circuit pump. In this game, students assimilate this information via active participation rather than by rote memorization.

Super-Resolution Ultrasound Imaging Can Quantify Alterations in Microbubble Velocities in the Renal Vasculature of Rats.

Super-resolution ultrasound imaging, based on the localization and tracking of single intravascular microbubbles, makes it possible to map vessels below 100 µm. Microbubble velocities can be estimated as a surrogate for blood velocity, but their clinical potential is unclear. We investigated if a decrease in microbubble velocity in the arterial and venous beds of the renal cortex, outer medulla, and inner medulla was detectable after intravenous administration of the α1-adrenoceptor antagonist prazosin. The left kidneys of seven rats were scanned with super-resolution ultrasound for 10 min before, during, and after prazosin administration using a bk5000 ultrasound scanner and hockey-stick probe. The super-resolution images were manually segmented, separating cortex, outer medulla, and inner medulla. Microbubble tracks from arteries/arterioles were separated from vein/venule tracks using the arterial blood flow direction. The mean microbubble velocities from each scan were compared. This showed a significant prazosin-induced velocity decrease only in the cortical arteries/arterioles (from 1.59 ± 0.38 to 1.14 ± 0.31 to 1.18 ± 0.33 mm/s, p = 0.013) and outer medulla descending vasa recta (from 0.70 ± 0.05 to 0.66 ± 0.04 to 0.69 ± 0.06 mm/s, p = 0.026). Conclusively, super-resolution ultrasound imaging makes it possible to detect and differentiate microbubble velocity responses to prazosin simultaneously in the renal cortical and medullary vascular beds.

Kinking of Frozen Elephant Trunk Hybrid Prostheses: Incidence, Mechanism, and Management.

IntroductionKinking of the Frozen Elephant Trunk (FET) stent graft is one of the most devastating complications of the FET procedure. It can present post-operatively with reduced arterial pressures in the lower limbs and intermittent claudication. However, it can also be visualized intra-operatively by the surgeons. Unresolved kinking of the stent graft can result in intraluminal thrombus formation and subsequent multi-organ septic emboli.AimsThe main scope of this review is to collate, summarize and present all the evidence in the literature on kinking of FET stent grafts.MethodsWe carried out a comprehensive literature search on multiple electronic databases including PubMed, EMBASE, Ovid, and Scopus to collate all research evidence on the incidence, mechanism, and management of FET graft kinking.ResultsIncidence of kinking is variable, ranging from 0% to 8% in the literature, with varying rates associated with each stent graft type. The Thoraflex HybridTM prosthesis seemed to be the most commonly used and superior graft, and out of all the 15 cases of kinking reported in the literature, 5 (33.3%) were associated with just the Frozenix graft which had the highest incidence. There are multiple theories regarding the mechanism of kinking, including the direction of blood flow, the length of the stent grafts used, and the position of the prosthesis in relation to the flexure of the aorta. Multiple reparative management techniques have been suggested in the literature and include total endovascular repair, open repair, balloon dilatation, and deploying a second stent graft.ConclusionGraft kinking is one of the most critical complications of the FET technique. Its life-threatening sequelae warrant appropriate follow-up of these patients post-operatively, in addition to time management if kinking is suspected. Given the limited evidence in the literature, future studies should incorporate graft kinking into their outcomes reporting.

Tuning the signal: ATP-sensitive K+ channels direct blood flow to cerebral capillaries.

Cerebral blood flow must be exquisitely regulated to match the metabolic demands of neurons. In this issue of Science Signaling, Sancho et al. characterize functional ATP-sensitive K+ (KATP) channels in cerebral capillary endothelial cells and pericytes that can be activated by adenosine signaling, thereby leading to increases in capillary blood flow.

Evaluation of the Pressure and Wall Shear Stress on the Aneurysm Wall According to the Growth Position of a Femoral Artery Pseudoaneurysm by Numerical Analysis

In this study, the effect of the angle change between the neck region and the aneurysm region of a femoral artery pseudoaneurysm (β) on the pressure and shear stresses on the aneurysm wall was investigated with the computational fluid dynamics (CFD) method. The CFD method is an important tool in observing the direction and velocity of blood flow. With the numerical analysis results, it was aimed to evaluate the growth rate and rupture risk of the aneurysm. Findings obtained as a result of the change of β angle between 0˚ and 15˚ for a certain value of the angle between the femoral artery and the aneurysm neck region (α=45˚) were presented in graphs containing velocity vectors inside the aneurysm, pressure, and wall shear stresses on the aneurysm wall. When all the analysis results were evaluated, it was understood that for a pseudoaneurysm formed in the femoral artery, the highest growth rate and risk of rupture could occur at the β =0˚ angle. It was predicted that the obtained findings will be beneficial in determining the treatment method and time in the treatment of femoral artery pseudoaneurysm.

The crescendo pulse frequency of shear stress stimulates the endothelialization of bone marrow mesenchymal stem cells on the luminal surface of decellularized scaffold in the bioreactor

ABSTRACT A completely confluent endothelial cell (EC) monolayer is required to maintain proper vascular function in small diameter tissue-engineered vascular graft (TEVG). However, the most effective method for EC attachment to the luminal surface and formation of an entire endothelium layer that works in vitro remains a complicated challenge that requires urgent resolution. Although pulsatile flow has been shown to be better suited for the generation of functional endothelium, the optimal frequency setting is unknown. Several pulsatile flow frequencies were used to implant rat bone mesenchymal stem cells (MSC) into the lumen of decellularized porcine carotid arteries. The endothelium's integrity and cell activity were investigated in order to determine the best pulse frequency settings. The results showed that MSC were maximally preserved and exhibited maximal morphological changes with improved endothelialization performance in response to increased pulse stimulation frequency. Increased pulse frequency stimulation stimulates the expression of mechanoreceptor markers, cytoskeleton reorganization in the direction of blood flow, denser skeletal proteins fibronectin, and stronger intercellular connections when compared to constant pulse frequency stimulation. MSC eventually develops an intact endothelial layer with anti-thrombotic properties on the inner wall of the decellularized tubular lumen. Conclusion: The decellularized vessels retain the three-dimensional structure of the vasculature, have a surface topography suitable for MSC growth, and have good mechanical properties. By increasing the frequency of pulsed stimulation, MSC endothelialize the lumen of the decellularized vasculature. It is expected to have anti-thrombotic and anti-neointimal hyperplasia properties after implantation, ultimately improving the patency of TEVG.

Physiological basis for longitudinal motion of the arterial wall.

As opposed to arterial distension in the radial plane, longitudinal wall motion (LWM) is a multiphasic and bidirectional displacement of the arterial wall in the anterograde (i.e., in the direction of blood flow) and retrograde (i.e., opposing direction of blood flow) directions. Although initially disregarded as imaging artifact, LWM has been consistently reported in ultrasound investigations in the past decade and is reproducible beat-to-beat, albeit with large interindividual variability across healthy and diseased populations. Emerging literature has sought to examine the mechanistic control of LWM to explain the shape and variability of the motion pattern but lacks considerations for key foundational vascular principles at the level of the arterial wall ultrastructure. The purpose of this review is to summarize the potential factors that underpin the causes and control of arterial LWM, spanning considerations from the arterial extracellular matrix to systems-level integrative theories. First, an overview of LWM and relevant aspects wall composition will be discussed, including major features of the multiphasic pattern, arterial wall extracellular components, tunica fiber orientations, and arterial longitudinal prestretch. Second, current theories on the systems-level physiological mechanisms driving LWM will be discussed in the context of available evidence including experimental human research, porcine studies, and mathematical models. Throughout, we discuss implications of these observations with suggestions for future priority research areas.

Cerebral Arterial Asymmetries in the Neonate: Insight into the Pathogenesis of Stroke

Neonatal and adult strokes are more common in the left than in the right cerebral hemisphere in the middle cerebral arterial territory, and adult extracranial and intracranial vessels are systematically left-dominant. The aim of the research reported here was to determine whether the asymmetric vascular ground plan found in adults was present in healthy term neonates (n = 97). A new transcranial Doppler ultrasonography dual-view scanning protocol, with concurrent B-flow and pulsed wave imaging, acquired multivariate data on the neonatal middle cerebral arterial structure and function. This study documents for the first-time systematic asymmetries in the middle cerebral artery origin and distal trunk of healthy term neonates and identifies commensurately asymmetric hemodynamic vulnerabilities. A systematic leftward arterial dominance was found in the arterial caliber and cortically directed blood flow. The endothelial wall shear stress was also asymmetric across the midline and varied according to vessels’ geometry. We conclude that the arterial structure and blood supply in the brain are laterally asymmetric in newborns. Unfavorable shearing forces, which are a by-product of the arterial asymmetries described here, might contribute to a greater risk of cerebrovascular pathology in the left hemisphere.

Efficacy of a temporary CentriMag ventricular assist device in acute fulminant myocarditis patients revived with extracorporeal cardiopulmonary resuscitation

Although extracorporeal life support (ECLS) can provide emergency systemic perfusion for acute fulminant myocarditis (AFM), the mortality rate remains extremely high, especially in those undergoing extracorporeal cardiopulmonary resuscitation (ECPR). Temporary ventricular assist device (VAD) can provide a more physiological blood flow direction and better subsequent organ perfusion than ECLS. We investigated temporary VAD efficacy in ECPR-revived AFM patients. During January 2012-May 2019, we retrospectively recruited 22 AFM patients with hemodynamic collapse and ECPR; 11 underwent ECLS only and 11 underwent additional VAD support after ECLS. Systemic perfusion was compared via laboratory biochemistry at post-ECPR days 2 (D2) and 4 (D4). Consciousness and cardiac function were assessed through the Glasgow Coma Scale (GCS) and echocardiography, respectively. All major complications and causes of mortality were recorded; 30-day survival was analyzed and risk factors were predicted. The VAD group had significantly better hemodynamic improvement; more inotropes being tapered at D2 and D4; better data representative of systemic perfusion, including albumin, pH, bicarbonate, and lactate levels at D4; and better 30-day survival (72.7% vs. 27.2%, p=0.033). The causes of mortality included central failure, multiple organ failure, and bacteremia with sepsis. The risk factors included lethal dysrhythmia before ECLS, GCS <5at D2, and elevated cardiac enzymes at D4. For AFM patients, temporary VAD could provide better systemic perfusion and organ preservation than ECLS. VAD had better survival, including improved recovery and successful transplantation. Hence, temporary VAD should be considered if ECLS cannot revive the sustained cardiogenic shock.

Diagnóstico ecocardiográfico de defeito do septo interventricular com agravo de síndrome de Eisenmenger em cão adulto – relato de caso

Interventricular septal defect (IVSD) is a congenital heart disease characterized by communication or non-closure of the interventricular septum in the embryonic or postnatal period, causing a failure in the separation between the systemic and pulmonary circulation. The severity of the hemodynamic consequences depends on the extent of the defect and the magnitude of the flow through it. Blood flow commonly occurs from left to right, because systemic vascular resistance is greater than pulmonary resistance. This report describes the echocardiographic findings in a 4-year-old male Poodle treated at the Veterinary Hospital with a history of exercise intolerance, cyanosis and episodes of syncope. On echocardiography, perimembranous IVSD was diagnosed with atrial and right ventricular dilatation, discontinuity of the interventricular septum in the subaortic region measuring approximately 5 mm. In the Doppler evaluation, reverse turbulent flow was evidenced, characterizing shunt from right to left (Eisenmenger syndrome). Despite preserved systolic function, abnormal relaxation was observed. Doppler echocardiography was a fundamental complementary imaging test for the diagnosis of this congenital heart disease since its suspicion is not commonly raised in adult patients. Doppler echocardiography allowed us to identify the defect, define its size and extension, determine the direction of blood flow as well as its hemodynamic consequences.

Impact of physiological loads of arterial wall on nucleus deformation in endothelial cells: A computational study

IntroductionComputational modeling can enhance the understanding of cell mechanics. To achieve this, finite element models of endothelial cells were proposed with shapes mimicking their natural state inside the endothelium within the cardiovascular system. Implementing the recently proposed bendo-tensegrity concept, these models consider flexural (buckling) as well as tensional/compressional behavior of microtubules and also incorporate the waviness of intermediate filaments. Materials and methodsFour different models were created (flat and domed hexagons, both regular and elongated in the direction of blood flow) and loaded by biaxial deformation, blood pressure, and shear load from blood flow – natural physiological conditions of the arterial endothelium – aiming to investigate the “in situ” mechanical response of the cell. ResultsThe impact of individual components of loads on the nucleus deformation (more specifically on the first principal strain) potentially influencing mechanotransduction was investigated and the role of the cytoskeleton and its constituents in the mechanical response of the endothelial cell was assessed. The results show (i) the impact of pulsating blood pressure on cyclic deformations of the nucleus, which increase substantially with decreasing axial pre-stretch of the cell, (ii) the importance of relatively low shear stresses in the cell response and nucleus deformation. ConclusionNot only the pulsatile blood pressure but also the wall shear stress may induce significant deformation of the nucleus and thus trigger remodelation processes in endothelial cells.

Fractional model of MHD blood flow in a cylindrical tube containing magnetic particles

In recent years, the use of magnetic particles for biomedicine and clinical therapies has gained considerable attention. Unique features of magnetic particles have made it possible to apply them in medical techniques. These techniques not only provide minimal invasive diagnostic tools but also transport medicine within the cell. In recent years, MRI, drug supply to infected tissue, Hyperthermia are more enhanced by the use of magnetic particles. The present study aims to observe heat and mass transport through blood flow containing magnetic particles in a cylindrical tube. Furthermore, the magnetic field is applied vertically to blood flow direction. The Caputo time fractional derivative is used to model the problem. The obtained partial fractional derivatives are solved using Laplace transform and finite Hankel transform. Furthermore, the effect of various physical parameters of our interest has also been observed through various graphs. It has been noticed that the motion of blood and magnetic particles is decelerated when the particle mass parameter and the magnetic parameter are increased. These findings are important for medicine delivery and blood pressure regulation.

Use of Duplex Ultrasound Imaging Post-Endovascular Aneurysm Repair (EVAR)

Individuals who undergo endovascular aneurysm repair (EVAR) require annual surveillance to detect endoleaks and guide surgical management. Endoleaks are classified into five categories based on the direction of blood flow in the aneurysmal sac outside the graft, determining prognosis and management. Currently, evaluation with computed tomography angiography (CTA) is favored as the gold standard for evaluation of endoleak. However, there is associated patient exposure to nephrotoxic intravenous contrast as well as radiation. Each of the five subtypes of endoleak can be characterized and subsequently followed on ultrasound. This practice offers a safe and cost-effective alternative to CTA.

Spectrum of Vertebral Artery Pathologies on Imaging: Case Series

Background: Vertebral artery pathologies are not as common on ultrasound examination. Careful ultrasound examination of the vertebral artery can provide useful information about the proximal brachiocephalic vessels as well as the intracranial portion of the vertebral artery. Objectives: To illustrate a variety of vertebral artery pathologies on ultrasound and their abnormal color Doppler findings with confirmation of some cases on magnetic resonance imaging. Materials and Methods: A 3-12 MHz linear ultrasound probe was used to examine the vertebral artery segments. The examination began with a B-mode examination of the first and second portions of the vertebral arteries, followed by color Doppler examination to determine the direction of blood flow. Spectral Doppler is used to identify flow anomalies. Conclusion: Evaluation of proximal great vessels by ultrasound can sometimes be difficult, so careful examination of vertebral artery by ultrasound can be an important tool to detect occlusions or stenosis of proximal great vessels. In addition, vertebral artery waveforms in the cervical segment provide useful information regarding the intracranial portion of the vertebral artery.

Analysis of mechanical bi-leaflet heart valve made of biomaterial-polypropylene

The heart has four major valves, which are responsible for directing blood flow and producing a pulse. Using reference geometry from [1] Krzysztof Jozwik, Artificial Heart Valves Designs, Medical Engineering & Physics, March 2011, we designed a mechanical bi-leaflet heart valve. The main goal of this article is to conduct an examination of a 3D printable mechanical heart valve made of polypropylene (PP) biomaterial and to compare the findings with other 3D printing materials such as Acrylonitrile Butadiene Styrene (ABS).

Diagnostic accuracy of color doppler Ultrasonography and FNAC in differentiating benign and malignant cervical lymphadenopathies at Birat Medical College Teaching Hospital, Morang, Nepal

Introduction: Among various imaging modalities useful in diagnosis of cervical lymphadenopathies, Color Doppler ultrasound (CDUS) is useful to evaluate and determine the presence of vascularity, resistance, direction, and velocity of blood flow in lymph nodes. It can determine the morphological and vascular nature of lymphadenopathies which will further help in the differentiation between benign and malignant nodes. Methods: This study was conducted on 61 patients referred to the Department of radiodiagnosis and imaging of BiratMedcical College for an ultrasound of cervical lymphadenopathy. These patients had subsequently undergone FNAC examination. Color Doppler sonographic procedures were done with an 11L linear probe with a frequency of 4.5-12MHz and CDUS evaluation of lymph nodes for Resistive Index and Peak systolic velocity were carried out and correlated with FNAC findings. Results: Among 61 lymph nodes, 52 were benign and 9 were malignant in the Color Doppler study where the final diagnosis by FNAC showed 53 benign and 8 malignant nodes. RI above the cutoff value of 0.5 had 83.3% sensitivity, 79.6% specificity, 50% PPV and 95.1% NPV. PSV above the cutoff value of 16cm/sec had 66.6% sensitivity, 95.9% specificity, 80.0% PPV and 92.2% NPV with diagnostic accuracy of 91.8%. Conclusion: Morphological features of the nodes such as shape, absence of echogenic hilum, abnormal vascular pattern, and Doppler indices cutoff values of 0.5 and 16cm/s respectively for RI and PSV were sensitive and specific for the diagnosis of malignant lymph nodes.

AAV-BR1 targets endothelial cells in the retina to reveal their morphological diversity and to deliver Cx43.

Endothelial cells (ECs) are key players in the development and maintenance of the vascular tree, the establishment of the blood-brain barrier and control of blood flow. Disruption in ECs is an early and active component of vascular pathogenesis. However, our ability to selectively target ECs in the CNS for identification and manipulation is limited. Here, in the mouse retina, a tractable model of the CNS, we utilized a recently developed AAV-BR1 system to identify distinct classes of ECs along the vascular tree using a GFP reporter. We then developed an inducible EC-specific ectopic Connexin 43 (Cx43) expression system using AAV-BR1-CAG-DIO-Cx43-P2A-DsRed2 in combination with a mouse line carrying inducible CreERT2 in ECs. We targeted Cx43 because its loss has been implicated in microvascular impairment in numerous diseases such as diabetic retinopathy and vascular edema. GFP-labeled ECs were numerous, evenly distributed along the vascular tree and their morphology was polarized with respect to the direction of blood flow. After tamoxifen induction, ectopic Cx43 was specifically expressed in ECs. Similarly to endogenous Cx43, ectopic Cx43 was localized at the membrane contacts of ECs and it did not affect tight junction proteins. The ability to enhance gap junctions in ECs provides a precise and potentially powerful tool to treat microcirculation deficits, an early pathology in numerous diseases.

The \u201cDirect tip injection in occlusive lesions (DIOL)\u201d fashion

BackgroundThe successful intervention for peripheral artery disease is limited by complex chronic total occlusions (CTOs). During CTO wiring, without the use of intravascular or extravascular ultrasound, the guidewire position is unclear, except for calcified lesions showing the vessel path. To solve this problem, we propose a novel guidewire crossing with plaque modification method for complex occlusive lesions, named the “Direct tip Injection in Occlusive Lesions (DIOL)” fashion.Main textThe “DIOL” fashion utilizes the hydraulic pressure of tip injection with a general contrast media through a microcatheter or an over-the-wire balloon catheter within CTOs. The purposes of this technique are 1) to visualize the “vessel road” of the occlusion from expanding a microchannel, subintimal, intramedial, and periadventitial space with contrast agent and 2) to modify plaques within CTO to advance CTO devices safely and easily. This technique creates dissections by hydraulic pressure. Antegrade-DIOL may create dissections which extend to and compress a distal lumen, especially in below-the-knee arteries. A gentle tip injection with smaller contrast volume (1–2 ml) should be used to confirm the tip position which is inside or outside of a vessel. On the other hand, retrograde-DIOL is used with a forceful tip injection of moderate contrast volume up to 5-ml to visualize vessel tracks and to modify the plaques to facilitate the crossing of CTO devices. Case-1 involved a severe claudicant due to right superficial femoral artery occlusion. After the conventional bidirectional subintimal procedure failed, we performed two times of retrograde-DIOL fashion, and the bidirectional subintimal planes were successfully connected. After two stents implantation, a sufficient flow was achieved without complications and restenosis for two years. Case-2 involved multiple wounds in the heel due to ischemia caused by posterior tibial arterial occlusion. After the conventional bidirectional approach failed, retrograde-DIOL was performed and retrograde guidewire successfully crossed the CTO, and direct blood flow to the wounds was obtained after balloon angioplasty. The wounds heeled four months after the procedure without reintervention.ConclusionsThe DIOL fashion is a useful and effective method to facilitate CTO treatment.

Direction change in a distal bypass graft due to increased collateral perfusion after the free flap transfer: a case report

Distal bypass combined with a free flap is a frequent surgical option for ischemic ulcers of the lower extremities. Here, we describe a patient in whom there was a change in the direction of blood flow in a distal bypass graft. A 68-year-old male patient with an ischemic ulcer on his left heel was referred to our facility by a local dermatology clinic. Surgical revascularization was performed between the popliteal artery and the dorsalis pedis artery using an ipsilateral great saphenous vein as the graft vessel. The wound site did not heal postoperatively, so it was covered using a free latissimus dorsi muscle flap. At the same time, the thoracodorsal artery was anastomosed to the bypass graft in an end-to-side manner to serve as a nutrient vessel. Initially, blood flow into the thoracodorsal artery from the bypass graft was via the popliteal artery. However, after occlusion of the proximal anastomotic site of the bypass graft, blood flow into the thoracodorsal artery from the bypass graft was via the dorsalis pedis artery, which was the distal anastomotic site. The change in direction of blood flow might have been the result of an increase in blood flow in the collateral vessels in the ischemic lower leg, which eventually overwhelmed the blood flow in the bypass graft.