Shunt Blood Flow Research Articles

An alternative instrumental method for studying the morphofunctional state of eyelids in chronic blepharitis

Background: To date, the assessment of morphofunctional changes within eyelids is performed using laser scanning confocal microscopy, which has extensive diagnostic capabilities. Identification of the indicators equivalence of this method and laser Doppler flowmetry will confirm the existence of an alternative, objective and economical method of eyelid examination in chronic blepharitis. Aim: To prove the possibility of laser Doppler flowmetry application as an alternative method of eyelid morphofunctional state assessment. Materials and methods: The study included 62 patients (124 eyes) with an established diagnosis of chronic mixed demodecticosis blepharitis, including 46 women and 16 men, mean age 65.8 ± 3.2 years, randomly assigned into two groups with identical age and gender composition. Group 1 patients (31 patients, 62 eyes) were treated with cosmeceuticals containing terpenes and terpenoids 2 times a day and tear substitute 3 times a day for 1.5 months. Group 2 patients (31 patients, 62 eyes) used an eyelid care gel containing sulphur medicaments 2 times a day and a tear substitute 3 times a day for 1.5 months. In addition to standard ophthalmological examination, laser Doppler flowmetry and laser scanning confocal microscopy were performed. Dynamic follow-up was performed after 1.5 and 3 months. Results: The analysis of laser scanning confocal microscopy and laser Doppler flowmetry parameters revealed a high inverse correlation between the density of inflammatory cells of the eyelids tarsal conjunctiva and neurogenic oscillations of blood flow, as well as high direct correlation with the index of blood flow shunting. A marked direct correlation between the density index of meibomian gland acinuses and the parameters of myogenic oscillations of blood flow and neurogenic oscillations of lymph flow was established. Conclusions: Pearson’s correlation analysis performed on laser scanning confocal microscopy and laser Doppler flowmetry parameters assessing the morphofunctional state of the eyelids demonstrated the presence of equivalence in both study groups with high statistical reliability. The obtained data confirm the possibility of using laser Doppler flowmetry method for objective assessment of eyelid condition and allow the parameters of this method to serve as criteria for choosing pathogenetically oriented therapy of chronic blepharitis with evaluation of its effectiveness.

Surgical management of aorto-right atrial fistula induced by Stanford type A aortic dissection: a case report

BackgroundThe occurrence of aorto-right atrial fistula in a patient with Stanford type A aortic dissection is exceedingly rare, and the treatment has not been established.Case presentationA 60-year-old male presented to the emergency department with acute lumbar pain and, based on contrast-enhanced computed tomography, was diagnosed with Stanford type A aortic dissection. Emergency surgery was performed. Transesophageal echocardiography during the surgery did not reveal an aorto-right atrial fistula. After establishing cardiopulmonary bypass, circulatory arrest was induced, and the primary entry in the proximal ascending aorta for the aortic dissection was identified. The aorta was dissected between the right brachiocephalic artery and the left common carotid artery, and an artificial conduit was anastomosed. After re-establishing circulation, venous blood flow from the dissected area at the base of the aortic root was observed, indicating communication between the aorta and the right atrium. Circulatory arrest was induced again, and the ruptured outer aortic adventitia was repaired by continuous suturing using 5–0 prolene. The atrial fistula was repaired from within the right atrium using 5–0 prolene with felt reinforcement. Thus, successful closure was achieved. Proximal anastomosis and right brachiocephalic artery reconstruction were subsequently performed. Postoperative transesophageal echocardiography revealed no shunt flow and no bleeding from the aortic root. The patient recovered smoothly and was discharged without significant complications.ConclusionsAorto-right atrial fistula associated with Stanford type A aortic dissection is rare, and in this case, the shunt blood flow was low, making preoperative diagnosis difficult. However, after intraoperative diagnosis, direct suture was used to complete the treatment, which was a simple and effective method.

Cardiopulmonary Bypass Blood Flow Rates and Major Adverse Kidney Events in Cardiac Surgery: A Propensity Score-adjusted Before–After Study

ObjectiveCardiac surgery associated-acute kidney injury (CSA-AKI) is a common and serious postoperative complication of cardiac surgery, which is associated with increased postoperative morbidity and mortality. This study aimed to explore the association between CPB blood flow rate (CPB-BFR) and major adverse kidney events at day 30 (MAKE30). DesignRetrospective single-center before-after observational study. Patients were divided in two groups according to CPB flow rates: a first group with an institutional protocol targeting a CPB-BFR >2.2 L/min/m² (low CPB-BFR group), and a second group with a modified institutional protocol targeting a CPB-BFR >2.4 L/min/m² (high CPB-BFR group). The primary outcome was MAKE 30, defined as the composite of death, renal replacement therapy or persistent renal dysfunction. SettingThe data were collected from clinical routines in university hospital. ParticipantsAdult patients who underwent elective and urgent cardiac surgery without severe chronic renal failure, for whom CPB duration was ≥90 minutes. Interventions533 patients were included (low CPB-BFR group n=270, high CPB-BFR group n=263). Measurements and Main ResultsA significant decrease in MAKE 30 was observed in the high CPB-BFR group (3% vs. 8%; OR 0.779, 95% CI [0.661;0.919]; P<0.001) mainly mediated by a lower 30-day mortality in the high CPB-BFR group (1% vs. 5%; OR 0.697, 95% CI [0.595;0.817]; P= 0.001), as was renal replacement therapy (1% vs. 4%; OR 0.739, 95% CI [0.604;0.904]; P=0.016). ConclusionsIn patients undergoing cardiac surgery, increased CPB-BFR was associated with a reduction in MAKE 30 including mortality and renal replacement therapy.

Liposomal Phenylephrine Nanoparticles Enhance the Antitumor Activity of Intratumoral Chemotherapy in a Preclinical Model of Melanoma.

Intratumoral injection of anticancer agents has limited efficacy and is not routinely used for most cancers. In this study, we aimed to improve the efficacy of intratumoral chemotherapy using a novel approach comprising peri-tumoral injection of sustained-release liposomal nanoparticles containing phenylephrine, which is a potent vasoconstrictor. Using a preclinical model of melanoma, we have previously shown that systemically administered (intravenous) phenylephrine could transiently shunt blood flow to the tumor at the time of drug delivery, which in turn improved antitumor responses. This approach was called dynamic control of tumor-associated vessels. Herein, we used liposomal phenylephrine nanoparticles as a "local" dynamic control strategy for the B16 melanoma. Local dynamic control was shown to increase the retention and exposure time of tumors to intratumorally injected chemotherapy (melphalan). C57BL/6 mice bearing B16 tumors were treated with intratumoral melphalan and peri-tumoral injection of sustained-release liposomal phenylephrine nanoparticles (i.e., the local dynamic control protocol). These mice had statistically significantly improved antitumor responses compared to melphalan alone (p = 0.0011), whereby 58.3% obtained long-term complete clinical response. Our novel approach of local dynamic control demonstrated significantly enhanced antitumor efficacy and is the subject of future clinical trials being designed by our group.

A Case of Aortopulmonary Fistula with Post-Operative Aortic Pseudoaneurysm Diagnosed by Transesophageal Echocardiography.

Tracheobronchial or esophageal fistula after aortic surgery has been reported sporadically in the literature, however, reports of an aortopulmonary fistula associated with a post-operative aortic pseudoaneurysm are rare. We experienced a case of refractory heart failure due to an aortopulmonary fistula associated with a post-operative aortic pseudoaneurysm. A 60-year-old man who had undergone aortic surgery 2 years earlier was hospitalized for congestive heart failure. He was diagnosed with refractory heart failure after 10 days of diuretic therapy failed to improve his condition. He underwent a contrast-enhanced computed tomography (CT) scan and was suspected to have pulmonary artery perforation of an aortic pseudoaneurysm at the anastomotic site of the ascending aortic surgery. Transesophageal echocardiography showed shunt blood flow from the aortic aneurysm into the right pulmonary artery, leading to a definitive diagnosis of aortopulmonary fistula with post-operative aortic pseudoaneurysm. Computed tomography angiography is commonly used to diagnose an aortic fistula; however, diagnosis is often difficult because of the subtle imaging findings. We highlight the usefulness of transesophageal echocardiography in providing a definitive diagnosis and detailed morphologic information on this pathophysiology.

The effectiveness of photodynamic effects on the clinical and functional state of periodontal tissues in periodontitis

A clinical and functional study and treatment of chronic generalized periodontitis of moderate degree were conducted in 56 people (22 men and 34 women) aged 37 to 55 years. The patients were divided into 2 groups depending on the type of treatment: group 1 (main) - 28 people (11 men and 17 women, the average age of the group was 43.5±2.8 years, photodynamic therapy (PDT) with 1% dimegin gel using an AFS Spectrum LED emitter with a wavelength of 660 nm and an energy density of 95 J/cm2), in group 2 (control) - 28 people. (9 men and 19 women, the average age of the group was 45.0±3.1 years) standard treatment was performed without PDT. The level of tissue blood flow, its activity and vasomotor activity of microvessels, as well as the blood flow bypass index were determined by laser Doppler flowmetry. The study of oxygenation was carried out by optical tissue oximetry with determination of the index of oxygenation, specific oxygen consumption and perfusion oxygen saturation. After PDT, the periodontal tissues showed an increase in blood flow by 65.5% after 3 months, the level of oxygen metabolism increased by 51%, which increased after 6 months. The use of PDT in the complex treatment of chronic generalized periodontitis of moderate severity has an activating effect on the microcirculation system and the level of oxygen metabolism in periodontal tissues both in the near and long-term follow-up periods. The use of PDT with 1% dimegin gel has an effective effect on the state of microhemodynamics and oxygenation in periodontal tissues.

Occipital Steal Syndrome with Carotid Artery Occlusion–A Physiologic Study with Transcranial Doppler

Occipital or posterior steal syndrome is a constellation of signs and symptoms that arise from abnormal shunting of blood flow from the posterior cerebral circulation into its anterior counterpart leading to transient episodes of neurological deficits due to posterior circulation ischemia. A 45-year-old woman who experienced transient visual phenomena during breath holding was evaluated by transcranial Doppler sonography (TCD) for changes in cerebral blood flow. TCD revealed that the anterior cerebral vascular system was shunting blood away from its posterior counterpart in the setting of hypercapnia, resulting in visual symptoms. Using permissive blood pressure control, the steal phenomenon was resolved.

The Advantages of Non-Adhesive Gel-like Embolic Materials in the Endovascular Treatment of Benign Hypervascularized Lesions of the Head and Neck.

The use of non-adhesive gel-like embolic materials (NAGLEMs) in the endovascular treatment of hypervascularized formations in the head and neck is gaining in popularity because of a number of important characteristics involved. Their primary benefits are their capacity to penetrate diseased vasculature, effectively distribute, and, most importantly, remain controllable during the process. We reviewed the literature and evaluated the results of using NAGLEMs in comparison to other embolizing substances (namely, coils, glue, and particles) as alternative embolizing agents for patients receiving care at our clinic. The process comprised evaluating the safety, effectiveness, and technological elements of endovascular therapy used to treat two categories of hypervascular pathological abnormalities that were surgically corrected between 2015 and 2023. Arteriovenous malformations (AVMs) located in the head, neck, and paragangliomas with jugular/carotid body localization are combined by intense shunting blood flow and shared requirements for the embolic agent used in endovascular treatment (such as penetration, distribution, delayed polymerization, and controllability). An analysis of the literature was also conducted. Results showed 18 patients diagnosed with neck paragangliomas of the carotid body and jugular type. Five patients with arteriovenous malformation (AVM) of the face and neck were included, consisting of sixteen females and seven males with an average age of 55 ± 13 years. Endovascular procedures were performed using NAGLEMs (ONYX (Medtronic, Irvine, CA, USA), SQUID (Balt, Montmorency, France), and PHIL (Microvention, Tustin, CA, USA)) and dimethyl sulfoxide (DMSO)-compatible balloon catheters. All patients achieved complete or partial embolization of hypervascularized formations using one or more stages of endovascular treatment. Additionally, three AVMs of the face and two paragangliomas of the neck were surgically excised following embolization. In other instances, formations were not deemed necessary to be removed. The patients' condition upon discharge was assessed by the modified Rankin Scale (mRs) and rated between 0 and 2. Currently, NAGLEMs are predominantly used to treat hypervascularized formations in the neck and head due to their fundamental properties. These properties include a lack of adhesion and a delay in predictable polymerization (after 30-40 min). NAGLEMs also exhibit excellent distribution and penetration throughout the vascular bed of the formation. Adequate controllability of the process is largely achieved through the presence of embolism forms of different viscosity, as well as excellent X-ray visualization.

Incorporation and Performance Verification of Hepatic Portal Blood Flow Shunting in Minimal and Full PBPK Models of Liver Cirrhosis.

Patho-physiological changes in liver cirrhosis create portacaval shunts that allow blood flow to bypass the hepatic portal vein into the systemic circulation affecting drug pharmacokinetics (PKs). The objectives of this work were to implement a physiologically-based pharmacokinetic (PBPK) framework describing shunted blood flows in virtual patients with differing degrees of liver cirrhosis; and to assess the minimal and full PBPK model's performance using drugs with intermediate to high hepatic extraction. Single dose concentration-time profiles and PK parameters for oral ibrutinib, midazolam, propranolol, and buspirone were simulated in healthy volunteers (HVs) and subjects with cirrhosis (Child-Pugh severity score (CP-A, CP-B, or CP-C)). Model performance was verified by comparing predicted to observed fold-changes in PK parameters between HVs and cirrhotic subjects. The verified model was used to simulate the PK changes for simvastatin in patients with cirrhosis. The predicted area under the curve ratios (AUCCirr :AUCHV ) for ibrutinib were 3.38, 6.87, and 11.46 using the minimal PBPK model with shunt and 1.61, 2.58, and 4.33 without the shunt, these compared with observed values of 4.33, 8.14, and 9.04, respectively. For ibrutinib, propranolol, and buspirone, including a shunt in the PBPK model improved the prediction of the AUCCirr :AUCHV and maximum plasma concentration ratios (CmaxCirr :CmaxHV ). For midazolam, an intermediate extraction drug, the differences were less clear. Simulated simvastatin dose adjustments in cirrhosis suggested that 20 mg in CP-A and 10 mg in CP-B could be used clinically. A mechanistic model-informed understanding of the anatomic and pathophysiology of cirrhosis will facilitate improved dose prediction and adjustment in this vulnerable population.

Changes in Microcirculation in the Brain, Heart, and Liver in Female Rats with Translational Model of Alcoholic Cardiomyopathy.

We studied some features of blood and lymph microcirculation in the brain, heart, and liver of female rats with developed alcoholic cardiomyopathy. In female rats after 24-week forced consumption of 10% ethanol solution, the size and inotropic function of the heart were measured by echocardiography. Microcirculation in the brain, myocardium, and liver was assessed by laser Doppler flowmetry using LAKK-OP2 and LAZMA-D computerized laser analyzers. Using spectral wavelet analysis, we determined the absolute and normalized to total perfusion amplitudes of microcirculation oscillations reflecting various regulatory mechanisms. Intact animals served as controls. In rats of the experimental group, alcoholic cardiomyopathy completely developed. Under these conditions, the index of microcirculation in the brain, myocardium, and liver significantly decreased. At the same time, there was a redistribution in the brain between shunting and nutritive blood flow in favor of the latter. In the myocardium and liver, this ratio did not change.

Transient Left MCA Syndrome Triggered by a Diagnostic Lumbar Puncture in a Case of Atypical Moyamoya Syndrome (P12-5.017)

<h3>Objective:</h3> Case report <h3>Background:</h3> No reported cases of transient ischemia are triggered by diagnostic lumbar puncture (LP). Here we present a suspected moyamoya syndrome with reversible ischemic event shortly following LP. <h3>Design/Methods:</h3> N/A <h3>Results:</h3> 48-year-old Asian woman presented to the emergency department after two weeks of gradually worsening left leg weakness &amp; numbness. She was diagnosed with subacute right MCA-ACA border-zone infarct on clinical assessment and MRI. Vessel imaging with CTA suggested widespread obstructive arteriopathy involving bilateral ACA and MCA while sparing the terminal ICA and posterior circulation, with extensive collateral development in lenticulostriate vasculature. Cerebral angiogram confirmed the CTA findings with no signs of diffuse atherosclerosis or inflammation, raising concern for Moyamoya syndrome despite the lack of ICA termini involvement. To rule out inflammatory etiology of arteriopathy, she underwent a diagnostic LP, and 24cc of clear fluid was collected, which was non-inflammatory. Towards the end of the procedure, she developed global aphasia, left-sided gaze deviation, right-sided hemiplegia &amp; homonymous hemianopsia, suggestive of left MCA syndrome, while being normotensive and in a supine position. CT perfusion map showed 131 mL of left MCA/ACA territory penumbra with no core infarct. She was placed in Trendelenburg position and resuscitated with fluids and phenylephrine to maintain high MAP goal. This was followed by rapid resolution of her left MCA syndrome within one hour. <h3>Conclusions:</h3> The proposed mechanism for transient left MCA syndrome during LP in our patient with likely atypical Moyamoya syndrome was likely due to a steal phenomenon characterized by shunting blood flow away from severely narrowed left MCA due to global intracranial vascular dilation secondary to ICP drop during LP. This is supported by complete resolution of symptoms within one hour, mainly due to repletion of drained CSF and position change, which restored ICP to exert resistance on other less stenosed intracranial vessels while supporting MAP. <b>Disclosure:</b> Dr. Bareja has nothing to disclose. Dr. Al Gburi has nothing to disclose. Dr. Shnawa has nothing to disclose.

Abnormal movement of the pulmonary valve in dogs diagnosed with patent ductus arteriosus.

In the typical left-to-right patent ductus arteriosus (PDA), the shunt flows from the ductus arteriosus towards the pulmonary valve. Although hemodynamic changes have been carefully studied in dogs with PDA, there is very little information on the outcomes of the pulmonary valve after surgical correction of PDA. This study aimed to visualize the pulmonary valve by transthoracic echocardiography in dogs with PDA before and after surgical ligation. Prior to surgery, the movement of the anterior semilunar cusp of the pulmonary valve was obstructed by the shunted blood flow during systole in all nine dogs with PDA in this study. M-mode echocardiography revealed a continuous trajectory of the cusp, because the cusp was pushed towards the right ventricle during the whole cardiac cycle by the shunted flow. Epicardial echocardiography performed in one dog during surgical ligation of the ductus arteriosus revealed that the movement of the anterior semilunar cusp normalized immediately after ligation. B- and M-mode echocardiography may be used to support the diagnosis of PDA through observation of the pulmonary valve when color Doppler echography is not available. The findings in this study may be of importance in distinguishing PDA from PDA-mimicking diseases worth considering before the treatment process (e.g. aorticopulmonary fistulas or aberrant arteriovenous shunts).

MR vessel-encoded arterial spin labeling with the placement of metallic items to visualize the territorial blood flow after extracranial-intracranial bypass surgery: a proof-of-concept study.

Depiction of bypass blood flow in patients who received extracranial-intracranial (EC-IC) bypass surgery is important for patient care. To develop a vessel-encoded arterial spin labeling (VE-ASL) method using surgical staples as a magnetic resonance (MR)-conditional product in patients who received EC-IC bypass surgery. Pseudo-continuous labeling was used for VE-ASL acquisition with a 3-T MR unit. First, an experimental study was conducted to determine the appropriate number of surgical staples to obtain a spatially sufficient saturation effect. Thereafter, four healthy normal volunteers underwent a VE-ASL study to confirm the sufficiency of the saturation effect to the right or left common carotid artery. Finally, VE-ASL scanning was performed in seven patients after EC-IC bypass surgery to confirm the ability of VE-ASL to visualize the territorial bypass perfusion. All qualitative evaluation was performed by two neuroradiologists using a 3-point grading system (2 = good, 1 = moderate, 0 = poor). A quantity of 200 staples was found to be appropriate for VE-ASL scanning. In healthy volunteers, one neuroradiologist rated the images of all four cases as good, while the other rated three cases as good and one case as moderate. For the seven patients after EC-IC bypass surgery, one neuroradiologist rated all seven cases as good, and the other rated six cases as good and one case as moderate. VE-ASL using surgical staples might be useful for the evaluation of territorial bypass perfusion in patients after EC-IC bypass surgery.

A curious case of confusion

A curious case of confusion

Ischemic stroke associated with patent foramen ovale: hospital database analysis

To analyze clinical and instrumental characteristics of patients with ischemic stroke (IS) due to paradoxical embolism according to the data of hospital registers of Moscow and Perm. A comprehensive study of 114 patients, aged 18 to 55 years, with IS by the mechanism of paradoxical embolism was carried out. All patients underwent clarification of the cause of IS (electrocardiography, ultrasound scanning of the brachiocephalic arteries, CT or MRI of the brain, CT or MR angiography, transthoracic and/or transesophageal echocardiography). The presence of right-left shunt blood flow (RLS) was confirmed by transcranial dopplerography with a bubble test. The clinical significance of patent foramen ovale (PFO) was assessed according to The PFO-Associated Stroke Causal Likelihood Classification System (PASCAL). Clinical and instrumental characteristics of patients with IS due to paradoxical embolism were obtained from two hospital registries. In both groups, the leading trigger for the development of IS was the Valsalva phenomen (>20%), the share of other provoking factors did not exceed 10%. Significant differences between the analyzed groups related to the ultrasonic characteristics of RLS/PFO: patients with a grade 4 shunt predominated in the Research Center of Neurology (RCN) population, while patients with a grade 3 shunt predominated in the City Clinical Hospital (CCH) №4 group. At the same time, there were twice as many patients with aneurysm of the interatrial septum in the CCH №4 group. In accordance with the PASCAL classification, in 93% of RCN patients, PFO can be considered as a probable cause of IS, while in the CCH No. 4 group, a probable causal relationship was traced only in 51% of cases, in 18% of patients, the role of an anomaly in the development of stroke was unlikely. The analysis showed that the primary screening of RLS in a regional vascular center allows classifying PFO as a probable cause of IS in only half of the patients. For a more accurate selection of patients for whom endovascular occlusion of the PFO will be most effective, an in-depth examination in a specialized hospital is recommended.

Abstract 14923: A Special Type Aortic Left Ventricular Tunnel With Bicuspid Aortic Valve: A Case Report

Introduction: Aortic-left ventricular tunnel (ALVT) is an extremely rare congenital cardiac lesion that is an abnormal passage connecting the ascending aorta to the left ventricle. ALVT can be diagnosed by the use of real-time two-dimensional and continuous-wave Doppler echocardiography. Case presentation: A two-year and seven-month-old boy with recently diagnosed influenza presented to the hospital because of severe tachypnea and fatigue after running. Physical examination revealed a grade 3/6 systolic and diastolic murmur at the second and third left intercostal space. Transthoracic echocardiography (GE E95 with a 5-MHz scanning head) demonstrated that the aortic valve was a bicuspid aortic valve (BAV) with mild-moderate insufficiency during diastole, the peak systolic velocity (PSV) and gradient of aortic valve were 1.9m/s and 14mmHg, respectively; The aortic sinotubular junction (ASJ) was stenotic, the PSV and gradient of ASJ were 2.7m/s and 29mmHg, respectively; A tubular-like structure originated in the outlet septum beneath the right coronary cusp and terminated in the ascending aorta superior to the right coronary aortic sinus (Fig. A, B), CDFI and continuous-wave Doppler showed unobstructed to-and-fro (systolic and diastolic) flow in the tunnel with a high-velocity color signal that aliased during systole (Fig. C-E). Clinical considerations for congenital heart disease: ALVT combines BAV with aortic insufficiency and supravalvar aortic stenosis. The patient was referred for possible surgical correction. Discussion: In this patient, the type of ALVT does not belong to any one of Hovaguimian’s classifications. Two-dimensional echocardiography can display the tunnel-like structure of ALVT in real-time, and CDFI can identify that two-stage bidirectional shunted blood flow, systolic ventricular ejection occurs through both the tunnel and the semilunar valve, and the diastolic flow reverses from the aorta to ventricle via ALVT.

Abstract 12774: Detecting Change in Cardiopulmonary Bypass Blood Flow Rate With a Novel, Wireless, Wearable Doppler Ultrasound Patch: A Pilot Study

Introduction: Assessing preload reserve (PR) is important when managing cardiac surgery patients. Typically, a 10% change in cardiac output is used as a reference standard to gauge PR; how this change in cardiac output translates to common carotid artery (CCA) velocity is unknown. In this pilot study, we compared known changes in cardiopulmonary bypass (CPB) flow rate to those measured by a novel wireless, wearable Doppler ultrasound placed over the CCA. Methods: A sample of 14 adult patients undergoing elective CABG was studied. While on CPB, at least two changes in blood flow (one negative, one positive) were made. The corresponding change in CCA velocity was measured by a wearable continuous wave (CW) Doppler ultrasound patch. For each subject, CPB flow changes were determined from the displayed spectrogram by the peristaltic pulsation frequency and CCA velocity changes were calculated from the automated maximum velocity trace. 5-10s windows pre- and post-CPB speed changes were selected, with sufficient signal quality to determine both relative CPB flow and CCA velocity. A “dose-response” curve was fitted to the relative changes in flow and velocity for each subject, as shown in Fig. 1, and the CCA velocity change corresponding to a 10% change in CPB flow was calculated. Results: CPB flows ranged from 0.5-6.3L/min. Mean relative flow changes were -58 and 179%, corresponding to mean CCA velocity changes of -43 and 107%. A mean CCA velocity change of 14% was found to correspond to 10% CPB flow change, ranging from 1.5-27.8%. Conclusions: CCA velocity measured with the Doppler patch successfully tracked changes in CPB flow. A CCA velocity change of &gt;14% suggests a &gt;10% change in cardiac output. Although preliminary, these results provide another important parameter for predicting the response to preload using a novel, easy-to-use, wireless Doppler device.

Computational hemodynamic analysis for optimal stent position in the transjugular intrahepatic portosystemic shunt procedure

Transjugular intrahepatic portosystemic shunt (TIPS) is an effective treatment for portal hypertension (PH). The current study aimed to investigate the effect of stent position on post-TIPS hemodynamic performance using computational fluid dynamics. Patient-specific pre- and post-TIPS models were reconstructed from CT images of two patients, then virtual TIPS models were created by shifting the portal vein (PV) entry site of the stent. Although there were marginal differences the effects of left-sided and right-sided TIPS on post-TIPS portal pressure and shunting flow, right-sided TIPS resulted in a greater proportion of superior mesenteric vein (SMV) flow diverting to stents compared to that for left-sided TIPS. The results also demonstrated that the nearer the entry site of stent to the portal venous bifurcation, the greater and more stable the shunting blood flow. These results suggest that the entry site of the stent should be as close to the portal vein bifurcation as possible during TIPS. TIPS on the right branch of the portal vein may be more likely to result in post-TIPS hepatic encephalopathy than that on the left branch.

Novel experimental model of brain arteriovenous malformations using conditional Alk1 gene deletion in transgenic mice.

Hereditary hemorrhagic telangiectasia is the only condition associated with multiple inherited brain arteriovenous malformations (AVMs). Therefore, a mouse model was developed with a genetics-based approach that conditionally deleted the causative activin receptor-like kinase 1 (Acvrl1 or Alk1) gene. Radiographic and histopathological findings were correlated, and AVM stability and hemorrhagic behavior over time were examined. Alk1-floxed mice were crossed with deleter mice to generate offspring in which both copies of the Alk1 gene were deleted by Tagln-Cre to form brain AVMs in the mice. AVMs were characterized using MRI, MRA, and DSA. Brain AVMs were characterized histopathologically with latex dye perfusion, immunofluorescence, and Prussian blue staining. Brains of 55 Tagln-Cre+;Alk12f/2f mutant mice were categorized into three groups: no detectable vascular lesions (group 1; 23 of 55, 42%), arteriovenous fistulas (AVFs) with no nidus (group 2; 10 of 55, 18%), and nidal AVMs (group 3; 22 of 55, 40%). Microhemorrhage was observed on MRI or MRA in 11 AVMs (50%). AVMs had the angiographic hallmarks of early nidus opacification, a tangle of arteries and dilated draining veins, and rapid shunting of blood flow. Latex dye perfusion confirmed arteriovenous shunting in all AVMs and AVFs. Microhemorrhages were detected adjacent to AVFs and AVMs, visualized by iron deposition, Prussian blue staining, and macrophage infiltration using CD68 immunostaining. Brain AVMs were stable on serial MRI and MRA in group 3 mice (mean age at initial imaging 2.9 months; mean age at last imaging 9.5 months). Approximately 40% of transgenic mice satisfied the requirements of a stable experimental AVM model by replicating nidal anatomy, arteriovenous hemodynamics, and microhemorrhagic behavior. Transgenic mice with AVFs had a recognizable phenotype of hereditary hemorrhagic telangiectasia but were less suitable for experimental modeling. AVM pathogenesis can be understood as the combination of conditional Alk1 gene deletion during embryogenesis and angiogenesis that is hyperactive in developing and newborn mice, which translates to a congenital origin in most patients but an acquired condition in patients with a confluence of genetic and angiogenic events later in life. This study offers a novel experimental brain AVM model for future studies of AVM pathophysiology, growth, rupture, and therapeutic regression.

Review of Polymeric Biomimetic Small-Diameter Vascular Grafts to Tackle Intimal Hyperplasia.

Small-diameter artificial vascular grafts (SDAVG) are used to bypass blood flow in arterial occlusive diseases such as coronary heart or peripheral arterial disease. However, SDAVGs are plagued by restenosis after a short while due to thrombosis and the thickening of the neointimal wall known as intimal hyperplasia (IH). The specific causes of IH have not yet been deduced; however, thrombosis formation due to bioincompatibility as well as a mismatch between the biomechanical properties of the SDAVG and the native artery has been attributed to its initiation. The main challenges that have been faced in fabricating SDAVGs are facilitating rapid re-endothelialization of the luminal surface of the SDAVG and replicating the complex viscoelastic behavior of the arteries. Recent strategies to combat IH formation have been mostly based on imitating the natural structure and function of the native artery (biomimicry). Thus, most recently, developed grafts contain a multilayered structure with a designated function for each layer. This paper reviews the current polymeric, biomimetic SDAVGs in preventing the formation of IH. The materials used in fabrication, challenges, and strategies employed to tackle IH are summarized and discussed, and we focus on the multilayered structure of current SDAVGs. Additionally, the future aspects in this area are pointed out for researchers to consider in their endeavor.