 Hi, my name is Jennifer Cozard, I'm a cardiovascular surgeon here at THI, and I want to thank the perfusion department for inviting me to speak today. It's been my honor to work with so many THI perfusion staff, members and trainees over the past 13 years I've been at Texas Heart, and I'm happy to have the opportunity to speak to you today. I'll be speaking about atrial fibrillation and the surgical management options of this common disease. Atrial fibrillation is the most common cardiac arrhythmia affecting more than 33 million people worldwide. In the U.S. alone over 3 million people have ephib. It's associated with increased risk of thromboembolic events like stroke and peripheral ischemia from embolus, reduced quality of life, and also increased mortality. Persistent ephib is often a treatment challenge due to the electrical and anatomic differences among patients. There can be variable scar burden, different locations, and they can have left atrial enlargement as well as many other comorbidities. So what is ephib? Ephib or atrial fibrillation is a superventricular arrhythmia with chaotic rapid contraction of the atrium. On the EKG shown here on the top, normal rhythm, you see that there's, for every QRS complex, it's preceded by a P wave at regular intervals. Below is a patient in ephib that has low amplitude baseline oscillations and fibrillatory or F waves with an irregularly irregular ventricular rhythm. The F waves can have a rate of 300 to 600 beats per minute, and then the ventricular rate during ephib is typically 100 to 160 beats per minute. So this is kind of a busy slide, but it briefly shows that basically there's many different mechanisms of ephib, which is a heterogeneous disease, and it can have a variety of different electrical abnormalities. There can be single or multiple foci of abnormality, multiple re-entrant circuits or multiple wavelets. The majority of these abnormalities are found in the left atrium and near the pulmonary veins, but they can also rise in other areas of the heart. So there's several different types of ephib, and these are just some definitions. So an ephib episode is considered at least 30 seconds of ephib on an EKG tracing. Paroxysmal ephib is ephib that resolves within 70s of its onset. It's considered persistent if it continues beyond seven days, and it's considered long-standing persistent ephib if it's continuous ephib for greater than 12 months. Ephib's the most common cardiac arrhythmia, as I said. It affects nearly 2% of the worldwide population. The incidence and prevalence increases with age, and patients 80 and above have an over 8% incidence, and men are affected more than women. As I said, ephib is less common in women, but when women experience ephib, they usually have many more symptoms, more complications, and a worse overall quality of life compared to men. There are many different causes and risk factors for ephib, and some of those are included here, like ischemic heart disease, acute myocardial infarction, hypertension, valvular heart disease, cardiomyopathies, also diabetes and hyperthyroidism, obesity and sleep apnea are also causes, and temporary causes are alcohol and also post-op patients, specifically after open heart or thoracic surgery. This is an important slide because it sums up most of everything we need to know about ephib. So the ephib risk factors shown here on the left are those that induce structural changes in the atrium, and then that leads to fibrosis of the tissue, inflammation, and cellular changes in the atrium. These changes then increase the susceptibility to ephib. Persistent ephib then further induces electrical and structural remodeling, and that promotes more ephib. So the term ephib begets ephib is a very common thing you may hear because the longer people are in ephib, then the more likely they're to continue in ephib. Ephib also leads to development of many other risk factors that then further damage to the atrium. And then finally, ephib is associated with several adverse clinical outcomes, which we're all familiar with, specifically stroke, myocardial infarction, dementia, heart failure, and thromboembolism. Ephib clinically leads to decreased atrial output, ventricular tachycardia, decreased cardiac output, increased thrombus formation, and an increased stroke risk, and ephib produces about 25% of all known stroke, and it also increases thromboembolism. Common symptoms with ephib are shown in the picture with palpitations, shortness of breath, fatigue, and decreased quality of life and decreased exercise tolerance. But some patients have no symptoms at all. So ephib causes the atria to beat irregularly, which causes stasis of the blood in the atria and then formation of thrombus. The most common place of thrombus formation is in the left atrial appendage, which is shown in this picture. The clot can then embolize into the bloodstream, leaving the heart, and end up lodged in the cerebral circulation, causing a stroke. Ephib increases stroke risk on average five-fold. The strokes that are caused by ephib are typically more severe than those not related to ephib, and ephib increases mortality and linked to sudden death. This is just an echo, which shows the left atrial appendage there on the right of the screen and thrombus within it, and that's what we typically see on an echo. Now we'll get into the procedural treatments for ephib. Most procedures for ephib target treatment of the left atrial wall because it's a critical part of initiating and maintaining persistent ephib. Endocardial ablation is done by an AP cardiologist, and it is effective, but it's difficult for treating persistent and long-standing persistent ephib. Patients can require repeat ablations, and these can lead to complications like esophageal and frenic nerve injury. The techniques all cover specifically coming up are surgical techniques, which they're invasive, of course have a longer recovery versus endocardial ablations. This specifically cocks maize is the gold standard surgical treatment for ephib. It's technically challenging, can be complex, requires sternotomy and cardiopulmonary bypass. Other techniques like mini maize is a mix of different approaches and lesions. Pulmonary vein isolation is another technique, but it only treats part of the left atrial wall. The convergent procedure or the hybrid approach to ephib is a newer technique where a multidisciplinary team with EP cardiologists and surgeons do a combination of endocardial and epicardial ablation, and this provides maximal treatment to the left atrial tissue. So surgical treatment of ephib was first performed over 25 years ago by Dr. James Cox in 1987 at Barnes Hospital in St. Louis. Since then, the full Cox maize lesion set has proved to be highly effective and result in a high cure rate for ephib. The maize pattern of lesions was chosen to prevent the multiple erratic impulses from propagating through the heart, but also of leaving behind the ability of activating both atria by normal sinus rhythm. This diagram shows what's called the cut and sew Cox maize three procedure. The Cox maize has changed in iterations three time and this is the third design by Dr. Cox. And so this technique actually involved making multiple incisions in the right and left atria, which then when you sewed it back together formed a set of scars, which isolated the pulmonary veins, the posterior left atrium, right atrial incisions are also made. These lesions are meant to direct the sinus impulse from the sinoatrial node to the AV node along a specified route. In theory, this allows coordinated electrical activation of the entire atrial myocardium. This pattern shown, the Cox maize three was first used in April 1992 and served as a basis for all subsequent minimally invasive approaches or the so-called Cox maize four procedure. This is what's known as the Cox maize four technique. It basically goes along the same type of lines that were done with a cut and sew Cox maize three, but it uses a combination of alternate energy sources like bipolar radio frequency and cryo ablation to complete the full lesion set instead of all incisions. This makes for an easier, quicker and safer operation with the same end goal instead of using all incisions. So the Cox maize four replaces, as I said, most of the cut and sew Cox maize three lesions with radio frequency or cryo ablation. The images shown here kind of go over what that looks like in the operating room. So this can be performed with sternotomy or also minimally invasive through a right mini thoracotomy. The diagrams show what you would see through a sternotomy. We would do bicable cannulation, use initially normal thermic cardiopulmonary bypass. And then we could use a bipolar clamp to isolate a cuff of left atrial tissue surrounding the right and left pulmonary veins. And that creates the pulmonary vein isolation lesion lines. Then you can cool the patient to 34 degrees Celsius and perform the right atrial lesions while the heart's still beating without an aortic clamp. Then you could cool the patient down, apply the aortic clamp and arrest the heart to perform the left atrial lesions. The left atrial appendage is also closed. This can be done from the inside of the heart with sutures, or also the outside of the heart through different techniques, so I'll go over. Cryo ablation or cryothermy is an excellent energy source because you can use this near valves and also directly over the coronary sinus. Because it actually preserves the fibrous skeleton of the heart and maintains valve competency without damage. These pictures just show the setup for a right mini thoracotomy. The coxamase four lesion set can also be performed very well through a right mini thoracotomy using femoral cannulation for bypass. We use a lot more of the energy sources with a bipolar radio frequency clamp as well as the cryoprobe. So Dr. Ralph Domino at all did a review of coxamase three and coxamase four studies in 2017, comparing these two treatments and their results for AFib. The coxamase four has similar results at one year, but actually lower freedom from AFib at five years compared to the coxamase three. One explanation for this is the older studies with the coxamase three, the cut and sew, I'm sorry, the cut and sew, basically didn't really have similar follow-up methods. And so it was thought that they may not have as accurate results for their end points. However, both are still considered excellent treatment for AFib and still the gold standard. These are just some of the many energy sources that have been used for surgical ablation for the past 24 years. There are several bipolar radio frequency clamps that are currently available in cryosurgical energy sources. The majority of these like laser, microwave, and unipolar radio frequency are no longer used. The cryosurgical probe has evolved from its original Frigitronics cryo probe that was used back as early as 1973. It utilizes nitrous oxide at negative 60 degrees centigrade. And the probe is made of aluminum, so it's highly flexible to get into difficult areas and difficult shapes to get good contact with the endocardium. Pulmonary vein isolation is done using a bipolar radio frequency clamp, as you see here. It can be used in minimal access surgery, even thoracoscopic surgery or the open chest. The maximum success rate with just pulmonary vein isolation alone is about 70%. This can be used also during concomitant open heart surgery like with valves or bypasses. This illustration just shows what it would look like through an open chest. With a patient on bypass, use the clamp and place it around the right and left pulmonary veins with a little cuff of left atrial tissue to achieve complete pulmonary vein isolation. So next I want to talk about what I'm most excited about, which is the newest treatment for AFib. It's called the convergent procedure or a hybrid approach to AFib. It's a collaborative effort with both electrophysiologists and cardiac surgeons. It's basically two separate procedures, surgical endocardial ablation of the left atrium by a surgeon and also catheter directed endocardial ablation of the left atrium. This can be done on the same day or even stage four to six weeks between each procedure. Here we actually prefer delaying it at least four weeks to give the epicardial lesions time to heal and scar, which could lead to a more accurate endocardial mapping and endocardial ablation for the second stage. So there's two targeted patient groups for the convergent ablation. Longstanding persistent AFib, those that have had AFib for at least a year or more, and those with persistent atrial fibrillation who have had recurrence even after failed endocardial ablations. The contraindications to this are having prior cardiac surgery or mediastinal radiation and even pericarditis, which could lead to adhesions or scarring around the heart, which might make it difficult or impossible to safely get to the left atrium for treatment. These pictures just kind of show what we see during the surgical part. We make a small subzyphoid pericardial window at the inferior portion of the sternum, as you see on the left. And then we actually put a large trocar into that incision, into the pericardium and that goes behind the heart. This is what the ablation probe looks like. It's called the episcence coagulation device. It's made by Atrocure and it's three centimeters long. It has a coil that does the ablation and provides radio frequency ablation energy to the heart. The energy is directed directly towards the heart, so away from the esophagus, which makes this much safer. So this is a video which shows what the surgical part looks like. We make an incision at the base of the zyphoid, go under the sternum, access the pericardium through a pericardial window, and we put the trocar behind the heart. So this is a surgeon's view. We put a thoracoscope through this trocar, so we're actually looking at the back of the heart. We put the episcence device in, as you just saw, and that creates these ablation lines. And we do those sequentially, one right next to the other, until the entire left atrium is completely covered with ablation between the pulmonary veins. So approximately four to six weeks later, the endocardial ablation portion would occur, and that's done in the cath lab by EP cardiologists. They access the femoral vein, go into the heart through a transseptal approach. And then any gaps that they find through the endocardial mapping, they just touch up with endocardial ablation using either cryo or radiofrequency to complete the entire lesion set. And basically, we want to create complete isolation of the left atrium as well as complete lesions around the pulmonary veins for complete isolation. So the conversion lesion set after it's finished is shown with the blue areas, which are done by the epicardial and the red areas done by the endocardial ablations. So the goal is basically reducing the substrate that causes a fib. We want entire coverage of the left posterior atrial wall as well as isolation of the pulmonary veins. The complications that we typically worry about with both of these procedures is esophageal injury. We use a temperature probe to monitor the esophageal temperature at all times. We also worry about pericarditis or effusions post-op or post-ablation. And we can help control this with steroids and also anti-inflammatories like colchicine and indison. One exciting thing is that we just had our first prospective multi-center randomized clinical trial called the Converge Trial. And this data was published just recently in March of 2021. And this basically looked at the Convergent Procedure. And it showed that it had superior effectiveness compared to endocardial ablation alone in patients with advanced a-fit. And it basically proved that a heart team approach, a collaboration with EP cardiologists and surgeons, significantly helps to improve outcomes in patients with difficult a-fit. So from the study, it enrolled a total of 153 patients. These patients were randomized to each treatment arm and treated with either the hybrid convergent procedure versus endocardial catheter ablation alone. And the convergent procedure had superior effectiveness at 12 and 18 months. In the graph here, it shows that basically the hybrid convergent patients are shown in orange and the endocardial ablation patients are shown in blue. And the convergent had better freedom from a-fib over endocardial ablation alone. And also, even if it didn't cause complete freedom from a-fib, it caused at least a greater than 90% a-fib burden reduction in the majority of patients and many more compared to endocardial ablation. We also looked at how it changed use of anti-arhythmic drugs. And across the board, it improved either just completely obliterating their need for anti-arhythmic drugs, decreasing the need for increasing anti-arhythmics or adding extra drugs. And just overall showed much more improvement over endocardial ablation alone. And then also, in the patients that got convergent, much better results there with many less patients requiring cardioversion within the 18-month period that was observed. This is, again, kind of a busy slide just showing many other studies that were done in the last 10 years looking at the convergent approach. And across the board, looking at these, basically, most patients at a year can achieve sinus rhythm approximately 86%. And we've also, at our series here at Texas Heart, we've seen excellent results with freedom from a-fib and approximately 95% of our patients at the six-month period. Whenever you're talking about a-fib, left atrial appendage management is also a very important part of the overall treatment for a-fib. We can also do this as a standalone procedure or even in addition to any kind of ablations. As I said, when you're doing open heart surgery, you can do endocardial suture closure of the appendage orifice. However, there's a high rate of failure, and so that's not done very often anymore. A laryate, which is an epicardial device or a watchman endocardial device, those are usually done by EP cardiologists. And those have excellent results. Surgically, on the right, we use a device called the attraclip. And that's a clip that's very easily and quickly placed at the base of the left atrial appendage as shown on the right. And that helps not only improve reduction of a-fib if there's any electrical signals arising from the left atrial appendage itself, but also by closing that, it greatly reduces the risk of stroke in patients with a-fib. Just very briefly, when you close off the appendage, as I said, it can help reduce the arrhythmia burden, also reduce the risk of stroke and systolic thromboembolic problems. And so any patient with a-fib closing off the appendage is a very important part of their overall treatment, whether it's done alone or with another ablation procedure. So in summary, surgical treatment of a-fib continues to be the most effective option for long-term freedom from a-fib, especially patients with very complex or long-standing persistent a-fib. Stand-alone or hybrid approaches offer excellent results, and treatment of a-fib remains an evolving field with THI at the forefront of new therapies. I actually do the convergent procedure here, along with a group of our excellent EP cardiologists. And I'm really honored to have the ability to offer this to patients. And we're continuing to look at new therapies to treat patients like this in the future. And I just want to say thank you so much for having me talk today. We love our profusionists here at Texas Heart. And I just want to say I appreciate all of you for helping us do our jobs every day. It's a pleasure working with you. Thank you.