Bridging Segment Research Articles

Phenylboronic Ester-Bridged Chitosan/Myricetin Nanomicelle for Penetrating the Endothelial Barrier and Regulating Macrophage Polarization and Inflammation against Ischemic Diseases.

The brain and liver are more susceptible to ischemia and reperfusion (IR) injury (IRI), which triggers the reactive oxygen species (ROS) burst and inflammatory cascade and results in severe neuronal damage or hepatic injury. Moreover, the damaged endothelial barrier contributes to proinflammatory activity and limits the delivery of therapeutic agents such as some macromolecules and nanomedicine despite the integrity being disrupted after IRI. Herein, we constructed a phenylboronic-decorated chitosan-based nanoplatform to deliver myricetin, a multifunctional polyphenol molecule for the treatment of cerebral and hepatic ischemia. The chitosan-based nanostructures are widely studied cationic carriers for endothelium penetration such as the blood-brain barrier (BBB) and sinusoidal endothelial barrier (SEB). The phenylboronic ester was chosen as the ROS-responsive bridging segment for conjugation and selective release of myricetin molecules, which meanwhile scavenged the overexpressed ROS in the inflammatory environment. The released myricetin molecules fulfill a variety of roles including antioxidation through multiple phenolic hydroxyl groups, inhibition of the inflammatory cascade by regulation of the macrophage polarization from M1 to M2, and endothelial injury repairment. Taken together, our present study provides valuable insight into the development of efficient antioxidant and anti-inflammatory platforms for potential application against ischemic disease.

Age-related changes in the completeness of the circle of Willis in children.

The circle of Willis is a circulatory anastomosis that supplies blood to the brain. If any of the bridging segments arehypoplastic or absent, the capacity for collateral flow in the setting of large vessel occlusion may be decreased. Outside of the neonatal period, the prevalence of a complete circle of Willis (CoW) in the pediatric population has not been well described. Our objectives include determining the prevalence of a complete CoW in children and identifying if there is an age-related "loss" of arterial segments. Following IRB approval, angiograms of the CoW performed on a 3-T MR platform from 2016 to 2020 on patients 21years or younger were retrospectively reviewed. Any patient with underlying arterial pathology that may affect the CoW was excluded. Patient age and gender at the time of imaging were obtained. In total, 592 pediatric CoW were assessed. Frequencies of completeness were calculated in two different fashions: scenario 1 where a CoW was characterized as complete even if it contained hypoplastic vessels (88.8%), and scenario 2 where it was characterized as complete after excluding hypoplastic vessels (44.0%). In both scenarios, our data showed that older age was more associated with an incomplete CoW (p < 0.0001). In addition, we found a higher percentage of males with an incomplete CoW compared with females (p < 0.0001). The presence of a complete CoW is greater in our pediatric population than what has been reported in adults. The prevalence of an incomplete circle of Willis also increases significantly with age.

Effect of Block Number and Weight Fraction on the Structure and Properties of Poly(butylene terephthalate)-block-Poly(tetramethylene oxide) Multiblock Copolymers

We report here the influence of block number and polyester weight fraction on the properties of a series of poly(ether ester) multiblock copolymers (mBCPs), poly(butylene terephthalate)-block-poly(tetramethylene oxide) (PBT-b-PTMO-b-PBT)n, with the same PTMO segment length. These mBCPs are double-crystalline polymers, where the melting temperature and crystallinity of PBT increase with the polyester weight fraction. The PBT and PTMO blocks undergo phase separation at room temperature to form a plausible bicontinuous disordered structure. With the increment of the block number, the phase-separation-domain size decreased. As a result, the crystallinity of PBT and PTMO decreases, while the strength and elongation at break of mBCPs increase significantly due to the enhancement of bridging segments between different domains. The increment of the polyester weight fraction significantly enhances mBCPs’ strength and Young’s modulus but decreases their elongation at break. Our results enrich the understanding on the phase behavior of mBCPs, and the structure–property relationship revealed here would be useful for the design of poly(ether ester) elastomers with desired properties.

Evaluation of the morphological and clinical features of left anterior descending myocardial bridging with multi-detector computed tomography.

AimThe aim of the study was to assess the incidence, localization, depth, length of myocardial bridging (MB) with left anterior descending (LAD), systolic compression ratio, atherosclerotic plaque localization and degree of stenosis by 256-slice multi-detector computed tomography (MDCT).Material and methodsComputed tomography (CT) scans from a total of 3947 patients who underwent MDCT were reviewed retrospectively for LAD MB. A diastolic and systolic dataset with the best image quality was selected. Myocardial bridge was defined as a coronary artery with an intra-myocardial course. Myocardial bridging was divided into “deep” or “superficial”. The length and depth of the bridging segment were calculated. For each bridging segment, the presence of atherosclerosis was saved in a 2-cm-long segment proximal to the entry of the bridging segment. The degree of stenosis made by atherosclerotic plaques was determined.ResultsLAD myocardial bridging was detected in 410 (10.4%) patients. Among these, 97 (23.7%) patients had a deep and 313 (76.3%) patients had a superficial course. The mean LAD MB length was 20.28 ±9.63 mm and the depth was 1.72 ±1.11 mm. The systolic and diastolic mean diameter difference was 0.193 mm and the average compression ratio was 9.44%. Atherosclerotic plaques were found in 167 (40.7%) of 410 LAD MB. Atherosclerotic plaques were found in 50.5% of deep MB and 37.7% of superficial MB.Conclusions256-slice MDCT coronary angiography has a high sensitivity to show myocardial bridging in LAD localization, to determine length, depth, compression ratio, atherosclerotic plaque localization and degree of stenosis.

Design Strategies and Applications of ROS-Responsive Phenylborate Ester-Based Nanomedicine.

Reactive oxygen species (ROS)-responsive nanomedicine has been extensively developed to improve the therapeutic effects while reducing the systemic toxicity. ROS, as important biological metabolites and signaling molecules, are known to overexpress in most of tumors and inflammations. Among various ROS-sensitive moieties, phenylborate ester (PBAE) with easy modifiable structure and excellent biocompatibility, represents one of the most ROS-sensitive structures. To harness it as a switch, the past several years had witnessed a booming of ROS-sensitive PBAE-based nanomedicine for various medical purposes. Much of the efforts were devoted to exploiting the potential in the management of antitumor and anti-inflammation. This review first summarizes the design strategies of PBAE in the construction of nanomedicine, with PBAE acting as not only the ROS-responsive unit, but also the roles of hydrophobic backbone or bridging segment in the macromolecular structures. The ROS-responsive mechanisms are then briefly discussed. Afterward, we focus on the introduction of the state-of-the-art research on ROS-responsive PBAE-based nanomedicine for antitumor and anti-inflammation applications. The conclusion and future perspectives of ROS-responsive nanomedicine are also provided.

Structure of the ALS Mutation Target Annexin A11 Reveals a Stabilising N-Terminal Segment.

The functions of the annexin family of proteins involve binding to Ca2+, lipid membranes, other proteins, and RNA, and the annexins share a common folded core structure at the C terminus. Annexin A11 (AnxA11) has a long N-terminal region, which is predicted to be disordered, binds RNA, and forms membraneless organelles involved in neuronal transport. Mutations in AnxA11 have been linked to amyotrophic lateral sclerosis (ALS). We studied the structure and stability of AnxA11 and identified a short stabilising segment in the N-terminal end of the folded core, which links domains I and IV. The crystal structure of the AnxA11 core highlights main-chain hydrogen bonding interactions formed through this bridging segment, which are likely conserved in most annexins. The structure was also used to study the currently known ALS mutations in AnxA11. Three of these mutations correspond to buried Arg residues highly conserved in the annexin family, indicating central roles in annexin folding. The structural data provide starting points for detailed structure–function studies of both full-length AnxA11 and the disease variants being identified in ALS.

Sphenoparietal sinus transposition technique: optimization of the surgical corridor with preservation of prominent bridging veins between the brain and the cranial base during aneurysm clipping via the pterional approach.

The sylvian bridging veins between the brain and the dura on the inner surface of the sphenoid wing can restrict brain retraction for widening of the lateral retrocarotid space during clipping surgery for internal carotid artery (ICA)-posterior communicating artery (PCoA) and basilar apex (BX) aneurysms. In such cases, the authors perform extradural anterior clinoidectomy with peeling of the temporal dura propria from the periosteal dura and inner cavernous membrane around the superior orbital fissure, with the incision of the dura mater stretching from the base of the temporal side to just before the distal dural ring of the ICA (termed by the authors as the sphenoparietal sinus transposition [SPST] technique). This technique displaces the bridging segment of the sylvian vein posteriorly and enables widening of the surgical space without venous injury. In this study, the authors observed the operative nuances and investigated the usefulness of this technique. The authors retrospectively reviewed the medical charts of 66 consecutive patients with ICA-PCoA and BX aneurysms between January 2016 and July 2018. This technique was performed in 8 patients (5 patients with PCoA aneurysms and 3 with BX aneurysms) in whom the bridging segments of the sylvian veins between the brain and the skull base restricted brain retraction for widening of the surgical space. The surface areas of the lateral retrocarotid space and the aneurysm were measured at the most visible working angle before and after the SPST technique was performed. With the use of the SPST technique, an adequate surgical space for aneurysm clipping was obtained with preservation of the bridging veins in all patients. The mean surface areas of the lateral retrocarotid space (p = 0.002) and aneurysm (p = 0.001) were significantly increased from 18.3 ± 18.8 and 2.8 ± 2.5 cm2 before to 64.2 ± 21.1 and 20.9 ± 20.6 cm2, respectively, after the SPST technique was performed. The SPST technique enables displacement of the bridging segments of the sylvian veins without venous injury and enables widening of the surgical space around the lateral retrocarotid area.

Equilibrium configurations of drops or bubbles in an eccentric annulus

The purpose of this paper is to find the zero-gravity equilibrium configurations of liquid drops or bubbles that have sufficient volume to form large-aspect-ratio bridging segments or occluding slugs in the eccentric annulus between two cylinders. In zero gravity, the static problem depends on the contact angle of the fluid segment on the solid support, and two geometric parameters: the radius ratio and the dimensionless distance between the cylinder centres. For both non-wetting and wetting liquids, we find regions of geometric parameter space where only occluding configurations occur, a bistable region where either configuration can occur, and a region where only the non-occluding bridging configuration can occur. For the non-occluding cases, we applied a large-aspect-ratio free-energy minimization approach to predict the cross-sectional shape of the liquid, and a finite element method was used to compute the interface shape of the occluding cases. A Surface Evolver model was used to simulate the three-dimensional shape of both occluding and non-occluding configurations. The simulation results support the theoretical predictions well. The fractional open area of the conduit was determined for both highly wetting and highly non-wetting minority phases. Optimization of the geometric parameters for a given wetting condition could facilitate the segregation and transport of two fluid phases in applications involving large aspect ratios and small pressure driving forces.

Myocardial bridging ‘a double-edged sword’: Analysis and significance

IntroductionMyocardial bridging (MB) in coronary artery exhibits a role of a double-edged sword in coronary artery disease (CAD). The objectives under study were to validate the prevalence and segments of coronaries with myocardial bridging, length and diameter of bridging segments and cardiac dominance patterns among a west coastal population of Kerala and Karnataka, India from coronary angiogram reports. The co-relation of bridged segments and cardiac dominance patterns in diseased and non-diseased coronary arteries were assessed to find out the significance of both in CAD. Materials and MethodsThe angiograms were obtained from K.S Hegde Medical Academy and Hospital, Karnataka after procuring the ethical clearance. 1000 cases with clinical symptoms, ECG abnormalities were studied prospectively. Recanalized normal looking coronary arteries were excluded. ResultsMyocardial bridging were seen in 50 cases with majority involvement of mid-segment of the left anterior descending artery (LAD). Mean±S.D for the length of bridged segments can be expressed as 17.96±9.79mm for upper limit (U.L) and 14.51±7.56mm for lower limit (L.L) respectively. Cardiac dominance was seen as right in 863 cases, left in 77 cases, co-dominant in 60 cases. 629 patients had diseased coronaries among the study group. Out of the 50 bridged coronaries, eleven cases had stenosis among bridged segments Discussion and conclusionSignificant association (p<0.001) which indicated a chance of occurrence of stenosis in the bridged segment or in the artery were bridging is present; if bridge involvement percentage is less than 15% in a coronary artery.

Multimodality Imaging in the Assessment of the Physiological Significance of Myocardial Bridging.

In myocardial bridging (MB) a segment of the coronary artery is covered by the myocardium. MB can be seen as a systolic compression by invasive coronary angiography (ICA) or as an intramural course by computed tomography angiography (CTA). Intramural course is a common incidental finding in CTA studies. Only minority of the bridging segments are associated with systolic compression causing a possible impairment of myocardial perfusion. The relationship between myocardial blood flow and MB is complex and poorly evaluated by anatomic imaging. Furthermore, provocation tests are frequently needed to uncover systolic compression. Fractional flow reserve can be used to assess the hemodynamic significance of MB. Nuclear perfusion imaging can demonstrate flow abnormalities associated with MB. Stress echocardiography can demonstrate ischemic wall motion abnormalities. They can be complemented by hybrid imaging with CTA to distinguish epicardial coronary artery disease and MB. This article will review different imaging modalities for the evaluation of the physiologic significance of MB.

The Functional Effects of Intramural Course of Coronary Arteries and its Relation to Coronary Atherosclerosis

ObjectivesThis study observed hemodynamic consequences of myocardial bridging and its relation to coronary atherosclerosis. BackgroundMyocardial bridging is seen as intramural course by computed tomography angiography (CTA) or systolic compression by invasive coronary angiography. Segments with myocardial bridging are in previous studies closely associated with proximal atherosclerotic plaques. MethodsWe prospectively studied 100 patients 63 ± 7 years of age with intermediate likelihood of coronary artery disease. Segments with superficial (>1 mm) or deep (>2 mm) intramural course were identified using CTA. Myocardial perfusion was studied by 15-Oxygen water positron emission tomography and systolic compression by invasive coronary angiography. ResultsMyocardial bridging was detected in 34 (34%) patients in 48 different vascular segments. Of these, 24 (50%) were deep and systolic compression was present in 14 (29%). In patients without obstructive coronary artery disease, myocardial stress perfusion distal to myocardial bridging was comparable with remote control regions (3.3 ± 0.9 ml/g/min vs. 3.3 ± 0.7 ml/g/min, n = 24, p = 0.88). Stress perfusion was comparable in segments with and without systolic compression (3.0 ± 0.9 vs. 2.7 ± 1.0 ml/g/min, p = 0.43). Atherosclerotic plaques were more frequent in proximal (71%) than myocardial bridging (7%) or distal (21%) segments. The presence of atherosclerosis and the average number of plaques were comparable in coronary arteries with and without myocardial bridging (73% vs. 60%, p = 0.14 and 2.0 ± 1.7 vs. 1.5 ± 1.6, p = 0.06). Median Agatston coronary calcium score was not elevated in vessels with myocardial bridge (15 [interquartile range: 0, 129] vs. 50 [interquartile range: 0, 241], p = 0.21). ConclusionsMyocardial bridging of coronary arteries is common on CTA, but only approximately one-third of these show systolic compression. Myocardial bridging is not associated with reduced myocardial perfusion during vasodilator stress. Atherosclerosis is located predominantly proximal to myocardial bridging but atherosclerotic burden and presence of vulnerable plaques were comparable.

Quantum dot-modified aptamer probe for chemiluminescence detection of carcino-embryonic antigen using capillary electrophoresis

A new method is proposed for determination of carcino-embryonic antigen (CEA) based on quantum dot (QD)-modified aptamer probe by capillary electrophoresis-chemiluminescence (CE-CL) detection system. An oligonucleotide sequence A contains two parts, one is CEA aptamer and the other is bridging segment. Horseradish peroxidase (HRP) conjugates with sequence A (HRP-DNAA) and then mixes with QD labeling complementary bridging segment (QD-DNAB), forming HRP-DNAA-B-QD probe. When CEA exists, the specific combination of the aptamer in sequence A and CEA can form CEA/HRP-DNAA-B-QD complex. After separation of CEA/HRP-DNAA-B-QD complex and HRP-DNAA-B-QD probe by capillary electrophoresis (CE), the chemiluminescence (CL) catalyzed by CEA/HRP-DNAA-B-QD complex can be detected without any interference, and the content of CEA can be estimated by the CL intensity. It has been proved that the separation efficiency of HRP-DNAA-B-QD and CEA/HRP-DNAA-B-QD complex is improved greatly after QD modification, then the interference issue resulted from free HRP-DNAA-B-QD probe is solved well; and the specific combination of HRP-DNAA-B-QD and CEA leads to a closer distance of HRP and QD, then chemiluminescent resonance energy transfer (CRET) occurs, which confirms the validity of the strategy. Results show that the CL intensity has a linear relationship with the concentration of CEA in the range from 0.0654 to 6.54ng/mL, and the limit of detection is approximately 8pg/mL (S/N=3). This proposed method with high specificity has been applied for the accurate analysis of content of CEA in patient's serum.

Percutaneous intervention of sequential coronary venous graft.

We present a case with coronary bypass grafts in which venous graft was anastomosed to obtuse marginal (OM) 1 and OM2 branches sequentially. We performed percutaneous intervention to the proximal circumflex (CX), OM1, and bridging segment of the venous graft. Finally, bridging segment of the venous graft began to function as a CX body extending between the OM1 and OM2.

Frequency and Significance of Myocardial Bridging and Recurrent Segment of the Left Anterior Descending Coronary Artery in Patients With Takotsubo Cardiomyopathy

Despite intensive research efforts, the causative mechanisms of takotsubo cardiomyopathy (TC) are still unknown. Recently, morphologic characteristics of the left anterior descending coronary artery (LAD) have been proposed as a potential pathophysiological substrate. Hence, the aim of the present study was to evaluate the prevalence of myocardial bridging and LAD recurrent segments in a large cohort of patients with TC. A total of 161 patients with TC were matched for age and gender with 161 controls without coronary artery or valvular heart disease. Myocardial bridging was diagnosed according to indirect signs in coronary angiography. Furthermore, the LAD was evaluated regarding parts of the vessel outreaching the left ventricular apex (LAD recurrent segment). The prevalence of myocardial bridging was similar in the TC and control groups (11.8% vs 6.8%, p = 0.18). Any part of the LAD outreaching the left ventricular apex was observed in 55.6% of patients with TC compared with 35.4% in the control population (p <0.001). Moreover, the LAD supplied ≥ 25% of the inferior myocardial wall in 21 patients with TC (13.1%), whereas patients in the control group did not show this pattern of coronary circulation at all (p <0.001). Patients with TC with typical apical ballooning compared with those with atypical ballooning patterns demonstrated a higher prevalence of myocardial bridging (p = 0.04) but not LAD recurrent segments (p = 0.28). In conclusion, the prevalence of myocardial bridging in patients with TC is low and comparable with that in a matched control group. In contrast, LAD recurrent segments are significantly more frequent in patients with TC.

Late Gadolinium Enhancement on Cardiac Magnetic Resonance Imaging in Acute Myocardial Infarction Due to Myocardial Bridging: A Clinical Dilemma

A 51-year-old male with a family history of premature coronary artery disease (CAD) presented with acute myocardial infarction (AMI) with coronary angiography demonstrating no angiographic disease and a mid -left anterior descending (LAD) myocardial bridging (MB) segment with 71% mean lumen diameter (MLD) compression. Due to continually rising biomarkers and recurrent angina, cardiac magnetic resonance imaging(CMR) was obtained demonstrating late gadolinium enh ancement (LGE) involving the mid-distal LAD territory. Patient subsequently underwent successful percutaneous coronary intervention (PCI) with drugeluting stent (DES) to the MB segment with resolution of symptoms, which persisted over a year. MBis defined as an intramuscular segment resulting in overlying bands of myocardium, also called

Oritavancin: Mechanism of Action

Oritavancin is a semisynthetic lipoglycopeptide analogue of vancomycin that contains the heptapeptide core common to all glycopeptides. It differs from vancomycin by the presence of a hydrophobic N-4-(4-chlorophenyl)benzyl (also referred to as 4'-chlorobiphenylmethyl) substituent on the disaccharide sugar, the addition of a 4-epi-vancosamine monosaccharide to the amino acid residue in ring 6, and the replacement of the vancosamine moiety by 4-epi-vancosamine. One mechanism of action of oritavancin is inhibition of transglycosylation (important in peptidoglycan synthesis) by binding to D-alanyl-D-alanine stem termini in Gram-positive bacteria. The inhibition of peptidoglycan synthesis via inhibition of transglycosylation is common to all glycopeptides (vancomycin) and lipoglycopeptides. Secondary binding of oritavancin to the pentaglycyl (Asp/Asn) bridging segment in peptidoglycan also occurs, which distinguishes it from vancomycin and contributes to oritavancin's activity versus vancomycin-resistant organisms. The presence of the hydrophobic 4'-chlorobiphenylmethyl group allows for interaction and disruption of the cell membrane, resulting in depolarization, permeabilization, and concentration-dependent, rapid cell death. This mechanism is shared with telavancin but not vancomycin and results in activity against daptomycin-nonsusceptible organisms. In conclusion, oritavancin's mechanism of action involves at least 3 known mechanisms: inhibition of transglycosylation, inhibition of transpeptidation, and cell membrane interaction/disruption. Oritavancin's multiple mechanisms of action confer activity against vancomycin-susceptible and -resistant organisms, as well as rapid, concentration-dependent killing versus actively growing, stationary phase, and biofilm-producing Gram-positive bacteria.

A Bridge Too Far: A LISS Non-Union

A non-union of the tibia developed after the use of a LISS with a long bridging segment as a pure relative stability device for a comminuted tibial fracture. It was treated primarily by stiffening the construct which led to union. It is suggested that the non-union developed because of strain concentration and healed when this was neutralised. The case illustrates an interesting failure mode, perhaps adds light to the biomechanical features of a LISS plate and suggests the role of strain in the process of bony healing.

Myocardial Bridging in an Adult Patient with d-Transposition of the Great Arteries

Myocardial bridging is characterized by intra-myocardial course of a segment of an epicardial coronary artery, leading to systolic compression. In most cases, it is considered a benign condition but rarely has been associated with serious cardiac events like myocardial infarction and sudden death. We describe a 25-year-old man with known d-transposition of the great arteries (d-TGA) status post-Mustard procedure who presented with palpitations and chest pain. Cardiac catheterization revealed complete systolic compression of a myocardial bridging segment of the left anterior descending artery and also complete compression of the first septal perforator during episodes of ectopic atrial tachycardia. No percutaneous or surgical interventions were performed. Symptoms improved after cautious use of beta-blockers. This appears to be the first report of symptomatic myocardial bridging in an adult patient with d-TGA.

The role of myocardial perfusion imaging in evaluating patients with myocardial bridging

BackgroundMyocardial bridging (MB) is a common, congenital coronary-abnormality that is found on average in one out of every three adults at autopsy (Moehlenkamp et al in Circulation, 106:2616-2622, 2002; Erbel et al in Circulation, 120:357-359, 2009). However, its clinical significance and impact on myocardial ischemia remains controversial and unclear. Myocardial perfusion imaging (MPI) is widely used to assess myocardial ischemia in patients with known or suspected coronary artery disease, and is frequently performed to evaluate the hemodynamic significance of MB. This study was undertaken to determine the use of MPI in evaluating MB and to identify the characteristics of MB associated with perfusion defects using MPI. Methods and ResultsThirty-nine patients with MB of the left anterior descending (LAD) artery as documented by coronary angiography (CA) were enrolled for this study. None of the patients exhibited other forms of heart disease as determined by both CA and stress-rest MPI, no later than 1 month prior to the study. Using MPI, eight patients (20.5%) were found to have perfusion defects in the corresponding myocardial areas. This frequency was significantly higher when compared with results obtained by stress electrocardiogram. The difference in the mean systolic narrowing of bridging segments was statistically significant between patients with and without ischemia. The positive rate of reversible defects in patients with severe systolic narrowing was significantly higher than in patients with mild-to-moderate systolic narrowing. However, there was no significant difference either between the mean length of the tunneled artery in patients with and without abnormal MPI or the positive rate of abnormal MPI in patients with different locations of the tunneled artery. ConclusionsMPI is an effective, noninvasive technique for the evaluation of patients with MB. The myocardial ischemia that resulted from bridging is associated more closely with the degree of systolic narrowing than with the length of tunneled artery or the location of MB.

Hemodynamic and intravascular ultrasound assessment of myocardial bridging: Fractional flow reserve paradox with dobutamine versus adenosine

Compared to coronary angiography, both intravascular ultrasound (IVUS) and CT-angiography provide important information with respect to the morphological aspects of myocardial bridging (MB). However, these modalities are limited in defining the hemodynamic and clinical significance of MB. Intracoronary Doppler studies demonstrate a peculiar abnormal Doppler flow profile associated with MB. Fractional flow reserve (FFR) after adenosine infusion has been used to assess the hemodynamic significance of MB, but FFR after adenosine induced hyperemia underestimates the significance of MB. On the other hand, high-dose dobutamine by increasing the contractility of the bridging segment unmasks ischemia induced by MB. This review outlines the role of flow velocity measurement by intracoronary Doppler, FFR, and IVUS for assessment of patients with MB. In addition, we compared FFR measurements after adenosine versus dobutamine infusions for the hemodynamic assessment of MB in two patients.