The future of ischemic stroke: flow from prehospital neuroprotection to definitive reperfusion.

Recent advances in ischemic stroke enable a seamless transition of the patient flow from the prehospital setting to definitive reperfusion, without the arbitrary separation of therapeutic phases of ischemia based on time alone. In 2013, the framework to understand and directly address the pathophysiology of cerebral blood flow that determines the timeline or evolution of ischemia in an individual case is given. This continuum of flow and the homeostasis of brain perfusion balanced by collaterals may be captured with serial imaging. Ongoing imaging core laboratory activities permit large-scale measurement of angiographic and tissue biomarkers of ischemia. Prehospital neuroprotection has become a reality and may be combined with revascularization therapies. Recent studies confirm that image-guided thrombolysis may be achieved without restrictive time windows. Baseline imaging patterns may be used to predict response to therapy and serial imaging may discern recanalization and reperfusion. Advanced techniques, such as arterial spin-labeled MRI, may also report hyperperfusion associated with hemorrhagic transformation. Endovascular therapies, including novel stent retriever devices, may augment revascularization and angiographic core laboratories may define optimal reperfusion. Serial evaluation of collaterals and reperfusion may identify definitive reperfusion linked with good clinical outcome rather than imposing arbitrary definitions of effective recanalization. Reperfusion injury and hemorrhagic transformation of various types may be detailed to explain clinical outcomes. Similar approaches may be used in intracranial atherosclerosis where flow, and not the degree of luminal stenosis, is paramount. Fractional flow may now be measured with computational fluid dynamics to identify high-risk lesions that require revascularization to restore the equilibrium of antegrade and collateral perfusion. Serial perfusion imaging of such cases may also illustrate inadequate cerebral blood volume gradients that may be more informative than blood flow delay alone. In sum, the growing understanding of collateral perfusion throughout all stages of ischemic stroke provides a framework for the future of ischemic stroke

Angioplasty, Various Techniques and Challenges in Treatment of Congenital and Acquired Vascular Stenoses

The field of performing transcatheter interventions to treat vascular lesions has exploded over the past 20 years. Not only has the technology changed, especially in the arena of balloon/stent devices, but the techniques of approaching complex lesions has evolved over the past decade. Lesions that no one would have imagined treating back in the 1990's are now being done routinely in the catheterization suite. This book provides an update on the current techniques and devices used to treat a wide variety of lesions. Though, at first, the outward appearance of the topics appears to be varied, they are all related by the common thread of treating vascular lesions. We hope, by publishing this book, to accomplish two things: First, to offer insight from experts in their field to treat, both medically and procedurally, complex vascular lesions that we frequently encounter. Secondly, we hope to promote increased communication between areas of medicine that frequently don't communicate, between adult interventional cardiologists, pediatric interventional cardiologists, interventional radiologists, and neurosurgeons. Much can be learned from our respective colleagues in these areas which can further our own world of interventions

Computational Analysis of Hybrid Norwood Circulation with Distal Aortic Arch Obstruction and Reverse Blalock-Taussig Shunt

BACKGROUND: The hemodynamics characteristics of the hybrid Norwood (HN) procedure differ from those of the conventional Norwood and are not fully understood. We present a multi-scale model of HN circulation to understand local hemodynamics and effects of aortic arch stenosis and a reverse Blalock-Taussig shunt (RBTS) on coronary and carotid perfusion. METHODS: Four 3-dimensional models of four HN anatomic variants were developed, with and without 90% distal preductal arch stenosis and with and without a 4-mm RBTS. A lumped parameter model of the circulation was coupled to a local 3-dimensional computational fluid dynamics model. Outputs from the lumped parameter model provided waveform boundary conditions for the computational fluid dynamics model. RESULTS: A 90% distal arch stenosis reduced pressure and net flow-rate through the coronary and carotid arteries by 30%. Addition of the RBTS completely restored pressure and flow rate to baseline in these vessels. Zones of flow stagnation, flow reversal, and recirculation in the presence of stenosis were rendered more orderly by addition of the RBTS. In the absence of stenosis, presence of the shunt resulted in extensive zones of disturbed flow within the RBTS and arch. CONCLUSIONS: We found that a 4-mm × 21-mm RBTS completely compensated for the effects of a 90% discrete stenosis of the distal aortic arch in the HN. Placed preventatively, the RBTS and arch displayed zones with thrombogenic potential showing recirculation and stagnation that persist for a substantial fraction of the cardiac cycle, indicating that anticoagulation should be considered with a prophylactic RBTS

A Coupled CFD-Lumped Parameter Model of the Human Circulation: Elucidating the Hemodynamics of the Hybrid Norwood Palliative Treatment and Effects of the Reverse Blalock-Taussic Shunt Placement and Diameter

The Hybrid Norwood (HN) is a relatively new first stage procedure for neonates with Hypoplastic Left Heart Syndrome (HLHS), in which a sustainable univentricular circulation is established in a less invasive manner than with the standard procedure. A computational multiscale model of such HLHS circulation following the HN procedure was used to obtain detailed hemodynamics. Implementation of a reverse-BT shunt (RBTS), a synthetic bypass from the main pulmonary to the innominate artery placed to counteract aortic arch stenosis, and its effects on local and global hemodynamics were studied. A synthetic and a 3D reconstructed, patient derived anatomy after the HN procedure were utilized, with varying degrees of distal arch obstruction, or stenosis, (nominal and 90% reduction in lumen) and varying RBTS diameters (3.0, 3.5, 4.0 mm). A closed lumped parameter model (LPM) for the peripheral or distal circulation coupled to a 3D Computational Fluid Dynamics (CFD) model that allows detailed description of the local hemodynamics was created for each anatomy. The implementation of the RBTS in any of the chosen diameters under severe stenosis resulted in a restoration of arterial perfusion to near-nominal levels. Shunt flow velocity, vorticity, and overall wall shear stress levels are inverse functions of shunt diameter, while shunt perfusion and systemic oxygen delivery correlates positively with diameter. No correlation of shunt diameter with helicity was recorded. In the setting of the hybrid Norwood circulation, our results suggest: (1) the 4.0mm RBTS may be more thrombogenic when implemented in the absence of severe arch stenosis and (2) the 3.0mm and 3.5mm RBTS may be a more suitable alternative, with preference to the latter since it provides similar hemodynamics at lower levels of wall shear stress

New techniques and principles in acute aortic pathologies requiring emergency surgical interventions

Aortic surgery, especially for pathologies requiring urgent surgical intervention has undergone significant changes in the past twenty years, leading to major improvement in short- and long-term outcomes. This thesis aims to provide a comprehensive, up-to-date overview on clinical characteristics of acute aortic syndrome, with special emphasis on current operative treatment possibilities, including well-established and novel, innovative surgical approaches. Within this scheme, further specific goals are to analyse different cannulation and perfusion options, the role of core temperature management during hypothermic circulatory arrest and impact of age-related differences in surgical approach of AAS. Ultrasound-guided direct cannulation on the concavity of aortic arch applying Seldinger technique is a reliable method in dissection repairs. Prompt antegrade perfusion provides not only cerebral, but also peripheral organ and tissue protection, which is an advantage in this high-risk group of patients. This alternative arterial inflow technique can be applied for prompt establishment of cardiopulmonary bypass in type A dissections or other aortic emergencies, especially during haemodynamic instability. We have proven that tympanic temperature measurements correlate with arterial blood temperature monitoring during aortic surgery applying hypothermic circulatory arrest, therefore, should replace bladder and rectal measurements. Early diagnosis and aggressive surgical approach without delay is a key factor in effective treatment for aortooesophageal fitulas. Endovascular treatment is essential to save the patient, but as a standalone procedure often ends-up with life threatening mid-term graft infection. Eliminating the source of bleeding as an emergency, resecting the oesophagus urgently to prevent sepsis and reconstructing the gastrointestinal continuity as an elective case after having the inflammatory processes settled seems to justify the sequence of endovascular aortic repair and subtotal oesophageal resection, followed by a gastro-oesophageal reconstruction, as an effective surgical approach. More frequent proximal and distal progression of the dissection flap occurs in younger patients with acute type A aortic dissection. Older age is associated with a lower probability of an intimal tear at the level of sinus of Valsalva. These findings, associated with prognostic implications, account for the choice of more radical proximal procedures for repair of aortic dissection in younger patients

Diagnosis of Symptomatic Intracranial Atherosclerotic Disease

Intracranial atherosclerotic stroke differs from extracranial atherosclerotic stroke in many aspects, including risk factors and stroke patterns. It occurs in association with in situ thrombotic occlusion, artery-to-artery embolism, branch occlusion, and hemodynamic insufficiency. Intracranial atherosclerotic stenosis (ICAS) could have only been diagnosed by transcranial Doppler (TCD) and transcranial color-coded sonography (TCCS), which are burdened by a risk of bias, or catheter angiography (DSA), which, on the contrary, is very precise, but rarely it is done in clinical practice due to its invasiveness. Computed tomography angiography (CT-A) and magnetic resonance imaging angiography (MR-A) have increased the identification of ICAS in a wider stroke population

Technical advances improved outcome in patients undergoing surgery of the ascending aorta and/or aortic arch: ten years experience

Background: Several technical advances in thoracic aortic surgery, such as the use of antegrade cerebral perfusion, avoidance of cross-clamping and the application of glue, have beneficially influenced postoperative outcome. The aim of the present study was to analyse the impact of these developments on outcome of patients undergoing surgery of the thoracic aorta. Methods and results: Between January 1996 and December 2005, 835 patients (37.6%) out of 2215 aortic patients underwent surgery on the thoracic ascending aorta or the aortic arch at our institution. All in-hospital data were assessed. Two hundred and forty-one patients (28.8%) suffered from acute type A dissection (AADA). Overall aortic caseload increased from 41 patients in 1996 to 141 in 2005 (+339%). The increase was more pronounced for thoracic aortic aneurysms (TAA) (+367.9%), than for acute type A aortic dissections (+276.9%). Especially in TAA, combined procedures increased and the amount of patients with impaired left ventricular function (EF <50%) raised up from 14% in 1996 to 24% in 2005. Average age remained stable. Logistic regression curve revealed a significant decrease in mortality (AADA) and in the overall incidence of neurological deficits. Conclusions: Technical advances in the field of thoracic aortic surgery lead to a decrease of mortality and morbidity, especially in the incidence of adverse neurological events, in a large collective of patients. Long-term outcome and quality of life are better, since antegrade cerebral perfusion has been introduce

Wiedererstellung der Perfusion in den supra-aortalen Ästen durch offenen hybrid Stenting des Aortenbogens für akute Typ A Aortendissektion

Objectives: Acute type A aortic dissection is a lethal condition that requires emergent surgical repair, especially in case of cerebral malperfusion. In this setting, we aimed to investigate perfusion patterns in the aorta and in the supra-aortic vessels after implantation of the Ascyrus Medical Dissection Stent (AMDS). Methods: 16 consecutive patients presenting acute type A aortic dissection with involvement of at least one supra-aortic vessel treated with the AMDS device were retrospectively screened from our institutional database. Dissection anatomy, true and false lumen perfusion were investigated in pre- and postoperative computer tomography, using standardized centerline reconstructions. To perform an objective perfusion evaluation, the true lumen area was indexed to the entire vessel area and paired sample t-test was used to assess relevant differences prior and after surgery. Results: AMDS implantation triggered a significant improvement of true lumen perfusion in the supra-aortic vessels and descending aorta. Innominate, right and left common carotid arteries indexed true lumen increased by 72%, 112% and 30%, respectively. Device implantation induced complete resolution of every total occlusion in both common carotid arteries. After surgery, proximal- and mid-descending aorta experienced a 78% and 48% improvement in indexed true lumen area, respectively. Conclusions: hybrid arch repair using the AMDS shows promising results in terms of vascular remodeling after surgery for acute type A aortic dissection. A standardized comparison of imaging prior and after the operation demonstrated significant improvement of true lumen perfusion and complete elimination of vessel occlusions in the supra-aortic vessels. Further investigation in a larger cohort of patients is mandatory as well as the comparison with an isolated hemiarch repair.Ziele: Die akute Aortendissektion Typ A ist eine tödliche Erkrankung der Hauptschlagader, die eine sofortige chirurgische Versorgung benötigt, insbesondere im Fall einer zerebralen Malperfusion. Die vorliegende Analyse zielt darauf ab, den nicht gecoverten Ascyrus Medical Dissection Stent (AMDS) im Hinblick auf die Perfusion der supra-aortalen Gefäße nach einer Operation für akuten Aortendissektion Typ A zu untersuchen. Methode: Zwischen 2017 und 2020 wurden 16 konsekutive AMDS-Implantationen bei Patienten mit Dissektion oder Totalverschluss von mindestens einem supra-aortalen Gefäß retrospektiv analysiert. Prä- und postoperative Computertomografien wurden standardisiert hinsichtlich der wahren, falschen und gesamten Lumenfläche unter Verwendung von Mittellinienrekonstruktionen ausgewertet. Die wahre Lumenfläche wurde auf die gesamte Gefäßfläche bezogen, und ihre Veränderungen vor und nach der AMDS-Implantation wurden mit einem t-Test für gepaarte Stichproben verglichen. Ergebnisse: Die AMDS-Implantation führte zu einer signifikanten Verbesserung der wharen Lumen Perfusion in den supra-aortalen Gefäßen und in der absteigenden Aorta. Das wahre Lumen der Arteria Anonima, der rechten und linken Arteria Carotis communis nahm jeweils um 72 %, 112 % bzw. 30 % zu. Die Implantation des Stents führte zu einer vollständigen Auflösung jedes Totalverschlusses in beiden Karotisarterien. Nach der Operation verbesserte sich das indizierte wahre Lumen der proximalen und der mittleren Aorta descendens um 78 % bzw. 48 %. Schlussfolgerungen: Die Hybridbogenreparatur mit dem AMDS-Device führt zu günstigen Ergebnissen bei der chirurgischen Behandlung akuten Aortendissektionen Typ A. Nach einem standardisierten Vergleich der Bildgebung vor und nach der Operation konnte eine signifikante Vergrößerung der wahren Lumenfläche und eine vollständige Rückbildung der total verschlossenen supra-aortalen Äste nachgewiesen werden. Diese vorläufigen Ergebnisse zur positiven Gefäß-Remodelling nach AMDS-Implantation müssen in zahlreicheren Kohorten bestätigt werden, möglicherweise nach einem Vergleich mit einer Teilbogen-Reparatur allein

Intracranial vascular anastomosis using the microanastomotic system

Journal ArticleThe authors describe the use of a microanastomotic device to perform intracranial end-to-end vascular anastomoses. Direct end-to-end anastomosis was performed between the superficial temporal artery and branches of the middle cerebral artery (MCA) in three patients. Two patients had moyamoya disease, with severe proximal MCA disease, and one suffered an internal carotid artery occlusion with poor collateral flow. All patients reported a history of recent ischemic symptoms. Each anastomosis was accomplished in less than 15 minutes with technically satisfactory results. Postoperative angiographic studies demonstrated patency of the bypasses in all patients