 Our next speaker is Dr. Jacob Labus. Dr. Labus is a cardiovascular anesthesiologist at Cologne University, where he works at the University Hospital and is part of the medical faculty there. Dr. Labus completed his medical training at the University of Cologne and University of Zurich and committed his residency in anesthesiology and intensive care medicine at the University Hospital of Düsseldorf in 2015. He's a member of the German Society of Anesthesiology and Intensive Care Medicine, the German Cardiac Anesthesia Scientific Working Group, and the European Association of Cardiothoracic Anesthesiology and Intensive Care, YAC-YAC, Sub-Specially Committee for ECHO, and is also a member of the ASC. Dr. Labus will be speaking to us about assessing fiber motion with strain. Dr. Labus. Thank you for the kind introduction. Can everyone hear me? Yes, we can hear you. Okay. Should I try to share my screen? Okay. So I go ahead. Okay. So once again, thank you for the kind introduction. Dear colleagues, dear ladies and gentlemen, first of all, I would like to thank the Arts and Committees for inviting me to Toronto Perioperative Echocymposium. It is my pleasure to talk today about left ventricle fiber motion and strain analysis. I have no disclosures to declare, and my presentation will contain the concept of myocardous strain analysis first, including some technical aspects and advantages and disadvantages of this technique. And I'll give a brief summary about myocardous fiber structure and especially in motion, since it's enormously important to understand in order to perform and interpret pyrrole per myocardous strain. After this, I'll show clinical examples of intraoperative strain analysis and show how results can be interpreted in this context. Since my time is limited to 25 minutes, this talk will focus on two-dimensional assessment since it's the most available technique at software at the moment. And I would like to begin with a question. What is myocardial strain? Strain is the dimensionless measurement described in a deformation of a structure, typically lengthening or shortening, between two time points, for example, and systole and end diastole. And this deformation is expressed in percent of initial length. In the early days of echocardiography strain analysis, color Doppler and T-C Doppler were used to measure myocardial velocity gradients along a scan line, which were then integrated to deformation values as displacement or strain, and this at an individual defined point of the myocardium. And this one-dimensional assessment has a very good temporal resolution, allows fast assessment and direct display of measured data. At a certain point, without regulatory algorithms over software, and therefore, there's no cosmetics of measured values. But mainly, this technique is not used today since it is extremely time-consuming because of dedicated image acquisition and has a lot of limitations as angle dependency and it is prone to artifacts. And therefore, difficult to interpret. Currently, speckle tracking echocardiography is used to measure myocardial strain. This technique has unique properties. It is a non-Doppler measurement assessing the regional and global deformation and it is nearly angle-independent. Moreover, this technique is less prone to artifacts compared to T-C Doppler imaging. But what is speckle tracking? Speckles are these bright and dark pixels in a usually 2 dB mode view and they are just acoustic reflections and their relations to each other is like a fingerprint of the myocardium. Speckles can be tracked in blocks through the complete cardiac cycle given an estimate of myocardial deformation in any direction. And this process is highly automated and highly reproducible by available software for all the great manufacturers of echocardiographic machines. So, to answer the question, what is myocardial strain? It is a change of myocardial length over time by measuring the movement of typical acoustic reflections of the myocardium, the so-called speckles, that can be tracked during the entire cardiac cycle. Therefore, the underlying technology for strain alers today is called speckle tracking echocardiography. And the assessment of myocardial strain is not restricted to a certain point in myocardium or part of the myocardium by this technique. The entire myocardial wall can be evaluated using different but similar 2 dB views. Similar in terms of configuration and heart rate since left ventricle movement is reconstructed from different loops by the analyzing software. But this technique has limitations too. Temporal and resolution is lower compared to tissue Doppler imaging. And it depends on good image quality. And there are differences between vendors. Moreover, there's some influence of post-processing on strain values. Last, not least, using two-dimensional evaluation, there's for sure out of plain motion of the speckles since left ventricle is not a two-dimensional but a three-dimensional structure. Speckle tracking echocardiography can be performed out of 3D full-volume data sets too and has the potential to overcome the limitations of 2D assessment, like out of plain motion. It doesn't rely on geometric assumptions and is able to evaluate the complex left ventricle-contractive pattern from a single heartbeat. But 3D speckle tracking has specific limitations providing a wide application in the claim to practice at the moment. Among them, one of the main factors is the low spatial and temporal resolution as well as intervendor differences. Another aspect is that 3D analysis software is not available for trans-ozophial echocardiography for all manufacturers. And there's limited period operative data at the moment. So to summarize the advantage of strain analysis with speckle tracking echocardiography, I would like to say that there's a potential of this technique. It's a differentiated evaluation of the complete myocardium through the entire cardiac cycle. And it is highly reproducible and highly automated and perhaps even completely automated in the future. I will show you later. So to understand myocardial strain, which describes fiber motion, it is enormously important to understand myocardial fiber structure. And the myocardium of the left ventricle is not a homogenous mass, as often shown in schematic figures, for example, in this wall stress scheme. That's forced too short in describing the left ventricle. The left ventricle of myocardium has a complex shape with a differentiated fiber architecture converting a 10 to 50% shortening of the myocytes into a reduction of intracavitory volume of more than 50%, which is normal left ventricular ejection friction. And to summarize the complex structure briefly, since there's not a talk about left ventricle anatomy, but on fiber motion strain, I would like to first look at the cross-section of the left ventricle of myocardial wall. Endo and epicardial orientation of myocardial fibers is longitudinal, where fibers are oblique orientated in the middle wall. And there's a transmural continuum ranging from an angle of minus 60 degrees to plus 60 degrees. And this is because of the double helical structure of the left ventricle of myocardium. Let's have a look on the long axis of the left ventricle. Myocardial fibers begin in this basal subendocardium, descend to the apex, turn around, and descend as subepical fibers back to the base. Between both helices lies the oblique fiber layer in the middle wall. And that's a change from right-handed descending fibers in the subendocardium into a left-handed ascending helical geometry in a subepicalium. And therefore, left ventricle contraction is a complex sequence. And because of time, I'm not going too much into details, since we could talk about fiber orientation and motions for hours. But for clinically purpose, left ventricle contraction can be simplified in four dimensions of motion. First, there's a longitudinal shortening. And second, there's circumferential contraction during systole. And third aspect is a radial thickening of myocardium. And because of the helical structure of the left ventricle, the base rotates counterclockwise, while the apex rotates clockwise during systole, bringing the left ventricle like a towel. And this is the first component of contraction, the so-called left ventricle torsion or twist. And all of the components of contraction can be evaluated by strain analysts using speckled tracking echocardiography, since it's able to measure deformation in any direction. Moreover, while strain describes left ventricle contraction during the systole, strain and strain rate describes relaxation and filling during the diastole. In the next few slides, I will show how this is performed. And first of all, you have to acquire the software. And it depends on the manufacturer of an eco-machine. But irrespectively which vendor you use, or if you use vendor-independent software, mostly these applications need to be prepared separately. And be aware, values generated from different software solutions are not interchangeable. They are similar, but not the same. So as next step, you need the required loops. And for global longitudinal strain, these are the mid-as of a four-chamber, two-chamber and long-axis view. And for circumferential and regular strain, these are the transgustic short-ex views that can also be used for the evaluation of left ventricle rotation. Then the software reconstructs left-track movement from the different views. And the different loops need almost the same hard rate and configuration of left ventricle. You need high-quality images without greater artifacts and rhythm disturbances. And you need high frame rates, usually above 40 frames per second. But this depends on the software. So next, you have to open the software, whatever it is. You have to import the required views. You have to choose the patient and choose the loop. And I would recommend to start with a long-ex view first. After this, ANSYSTOL and ANT-DIOSSTOL needs to be defined. And this can be done based on ECGO by Valve events or both. Using software of our vendor in Cologne, these applications suggest ANSYSTOL and ANT-DIOSSTOL ECG-based. And you can adjust this by defining Valve events when you use the long-ex view first. As a next step, you have to define the region of interest. This is usually a semi-automated approach where the endocardial borders needs to be defined by the operator. And the software generates the region of interest, which can be adjusted manually. Here, I must be taken in to identify true myocardial borders, as, for example, inclusion of the pericardium would lower calculated strain values. Then further analysis of deformation is performed completely automated by the software. And it presents results of analysis. The software generates values for each segment evaluated, as well as averaged values, presenting the results in form of time-strain curve and as mean peak systolic strain. After this, you have to repeat for all the different views. So at the moment, it's a bit time-consuming and you need several minutes for each analysis by this approach. But as often in life, speed comes with repeated practice. And help is on its way regarding fully automated analysis, which are available, but to the best of my knowledge, not explored in the period-operative setting till now. So at the moment, you get values for each evaluated loop and the software averages them and presents results typically in a bullseye view for better orientation of the operator. All in all, it's quite a lot of work, which arise the question, is it worth the effort? So can strain aid in clinical decision-making and what's the evidence in cardiac surgery patients? Is it worth to spend all the time and all the money for additional software and have to say, at the moment, there are no published guidelines or recommendations for the period-operative strain analysis. And the application of this technique is still in its infancy in the period-operative setting, which is even more true for the intra-operative assessment. But there is some evidence and I would like to present you some clinical cases and a brief summary of existing literature. Most data on strain come from trans-traffic echocardiography in a wake and spontaneous breathing patients inside the operative setting in steady state of their disease and mainly global longitudinal strain was explored. There are recommendations for normal and abnormal values for the different strain measures, mainly for the evaluation of healthy individuals. But these are not the conditions of our patients. I think that all of us are faced with a different environment every day during echocardiography. The effects of general anesthesia, positive pressure ventilation, change of loading conditions, vasoplegia and different period-procedural aspects all having influence of more cordial function and therefore potentially on strain. All the strain is supposed to be less low dependent, which was mainly explored in animal studies. This is poorly understanding humans, which is even more true for the period-operative setting. So I come to my case presentation number one, which was a patient skater for isolated on pump cabbage surgery with three vessels disease with preoperative preserve left and right ventricle function without higher grade of diastolic dysfunction and without more than mild viral heart disease and without pulmonary hypertension. And you see the initial mid-asophageal loops of the patient after uncomplicated induction of anesthesia and ventilation without any vasoactive therapy or pacing. 3D volumetry supports the diagnosis of normal left ventricle action friction, which was calculated to be about 55%. But I think having a closer look on the contractile pattern, only seeing both loops, you can see by eyeballing the impairment of longitudinal function, which becomes obvious assessing longitudinal strain in both loops, which is reduced. By completing strain analysis by mid-asophageal long-access views, the systolic global long-distance strain was calculated to be about minus 14%, which is reduced when compared to normal values of healthy individuals. But it is also impaired for cabbage surgery patients and it's a patient at risk for unfavorable outcome. So what do we know about strain in our patients? First, I would like to present you a study from Tenaclan colleagues from 2013, and they analyzed retrospectively more than 400 patients scaled for different cardiac surgery procedures, among them 155 having cabbage surgery, and all of the patients had normal left ventricle action friction assessed preoperatively by transtherapeutic echocardiography. And they found that 40% of their patients had impaired global longitudinal strain. And in these patients, rate of postoperative heart failure, needs for inotropes and mortality was increased, with the ISF facts observed in cabbage surgery patients with a cutoff of minus 16%. Another recent published study from Korea confirmed their results, including almost 1000 patients scaled for cabbage surgery with preserved left ventricle action action friction using also preoperative transtherapeutic echocardiography. They found that in their patient, impaired global longitudinal strain increased long-term mortality with a cutoff of minus 50.5%. And there's far less data for interoperative trans esophageal assessed strain. But I would like to present you the study by Amabilian colleagues who found impaired global longitudinal strain to increase the risk of post bypass low cardiac output with a cutoff of minus 17% in a retrospective trial, including almost 300 patients were scaled for different cardiac surgery procedures. Although there was concern about correlation between preoperative transtherapeutic assessed strain and interoperative trans esophageal assessed strain in the past, we could not find a difference in our own data, which was a study performed by my dear friend Jens Fassel in Dresden, Germany, in cabbage surgery patients with preserved left ventricle action friction without any of us active therapy or pacing. Global longitudinal strain remained unchanged between pre and post anaesthesia induction. So in our opinion, preoperative global longitudinal strain values are comparable to interoperative pre bypass values in patients with uncomplicated course, at least in cabbage surgery patients. So to summarize case presentation number one, I think this patient is at risk for needs for inotropes after bypass for postoperative heart failure. And he has increased risk to die after bypass in the immediate postoperative period or in the long run, even though left ventricle action friction is preserved. And second case, I would like to present you another patient. It's a patient's schedule for isolated surgical orting valve replacement, having severe orting stenosis. And again, with preserved left and right ventricle function and without more than mild other valvular heart disease and without coronary artery disease. And again, you see the initial mid is equal to four or five chamber view and two chamber view of the patient after uncomplicated induction of anesthesia. Without any vasoactive therapy performing three volumetry of the left ventricle, left ventricle action friction was calculated this time to be above 60%. And looking again for longitudinal contraction, I think you see it by eyeballing. It seems to be reduced, which is confirmed by long to strain analysis in both loops and completing whole analysis. Systolic global long to strain was calculated to be slightly above minus 16%. So it's impaired for orting valve replacement patients and it's this patient at risk, periodically, regarding the myocardial function. And again, I show you data from tenacone colleagues from 2013, this time regarding orting valve replacement patients and among them, there were 150. And more than half of the patients with normal left ventricle action friction had impaired global long to strain. And also these patients had increased rate of heart failure, irotropes and increased possible mortality after bypass. And although the highest effects were observed in cabbage surgery patient, this was also significant for patients having aortic stenosis scheduled for orting valve replacement. And the results of tenacone colleagues were confirmed by a prospective single-bladed study from Baleras-Munus, I hope I pronounced it the right way. And they showed that long to strain was related to 30 days post-operative mortality and to low cardiac output. With low cardiac output patients having a mean global long to strain of about minus 14% and patients without low cardiac output of about minus 17% with almost the same standard deviation all measured by trans-terrific echocardiography. And these results are supported by a study from Cleveland assessing strain intraoperatively by trans esophageal echocardiography including almost 90 patients in a secondary analysis or randomized controlled trial showing global long to strain to predict post-bypass onotropic support with an odds ratio of about 1.8 per unit worsening in global long to strain. Interestingly, global long to strain predicted isotropic support where global circumferential and radial strain did not. So to summarize the case two, in my opinion, this patient has a reduced global long to strain as compared to healthy individuals but it's not an additional period of risk regarding his myocardial function. But coming back to the data of sang and colleagues who found that global long to strain predicted post-bypass onotropic support where circumferential and radial strain did not in their population. This is in contrast to the data of Howard Higiana from 2017 and the authors found that impaired strain predicted short and long term outcome including maze needs for onotropes and one year event free survival. And the strongest predictor for outcome was or for worse outcome was impairment of global long to run and circumferential strain. I have to emphasize that they use 3D strain and I'm sorry for this presenting 3D data although I told you I would like to focus on 2D strain but at the moment there's no good 2D strain for this. So there seems to be more than global long to strain predicted outcome in our patients which is not surprising as left vertical contraction encloses much more than just long to normal deformation. This observation supported by a recent study published only a few months ago in a non-surgic cardiac population from Budapest and others included about 350 patients and found that global circumferential strain impairment increased long term mortality even if global long to strain was preserved and again worse outcome at patients with a combination of impairment of circumferential and rate and longitudinal strain. So looking again at case number one with preserved global left ventricle function but impaired longitudinal function which writes the question which is the compensatory mechanism of preventing global function in this patient and changes of left ventricle contraction pattern through change of long standing loading conditions this is not new. This has been already described almost 15 years ago in diastolic heart failure patients as well in patients with severe aortic stenosis but to the best of my knowledge Tsang and colleagues were the first to describe a long internal circumferential and radial strain intraoperatively in anesthesized and ventilated patients scheduled for cardiac surgery but the patients had only small impairment of the different strain measures compared to normal values and healthy subjects. Regarding our own data from Cologne in anesthesized and ventilated patients scheduled for isolated on pump carriage surgery with preserved left and right ventricle function without ionotropic support or pacing global longitudinal strain was impaired while circumferential and radial strain was preserved and left ventricle rotation and twist was even increased and there was further impairment of global longitudinal strain after bypass what was expected while circumferential strain and rotation and twist improved after bypass maintaining left ventricle fracture on the other hand global radial strain remained unchanged during the same period if this observation is related to patients outcome is subject of current investigation at our department so I would like to summarize my talk and would like to say that T transassocal SS strain is feasible it is highly reproducible and automated with unique properties allowing for assessment of left ventricle deformation in any direction it allows to evaluate the entire left ventricle volume through the complete cardiac cycle and you have to be aware there are software solutions for almost every vendor of echocardial machines but there are differences between the values global longitudinal strain is the most explored strain measure today but there is more than just longitudinal deformation and I would like to leave you with future perspective since artificial intelligence is involving all parts of science and society this is also true for echocardial geography and the potential of this technique is increasingly recognized and to be honest the future has already begun fully automated global longitudinal strain analysis was described as feasible, efficient and independently associated with mortality in chronic auto regurgitation patients which is already less DNJs and for me the most important fact regarding the study it was performed with a commercially available software thank you for your attention and I'm looking forward to your questions thank you very much Dr. Levis for that excellent discussion that was quite complex topic