Feasibility of Coronary Access Following Redo-TAVR for Evolut Failure: A Computed Tomography Simulation Study.

BACKGROUND: Coronary accessibility following redo-transcatheter aortic valve replacement (redo-TAVR) is increasingly important, particularly in younger low-risk patients. This study aimed to predict coronary accessibility after simulated Sapien-3 balloon-expandable valve implantation within an Evolut supra-annular, self-expanding valve using pre-TAVR computed tomography (CT) imaging. METHODS: A total of 219 pre-TAVR CT scans from the Evolut Low-Risk CT substudy were analyzed. Virtual Evolut and Sapien-3 valves were sized using CT-based diameters. Two initial Evolut implant depths were analyzed, 3 and 5 mm. Coronary accessibility was evaluated for 2 Sapien-3 in Evolut implant positions: Sapien-3 outflow at Evolut node 4 and Evolut node 5. RESULTS: With a 3-mm initial Evolut implant depth, suitable coronary access was predicted in 84% of patients with the Sapien-3 outflow at Evolut node 4, and in 31% of cases with the Sapien-3 outflow at Evolut node 5 (P<0.001). Coronary accessibility improved with a 5-mm Evolut implant depth: 97% at node 4 and 65% at node 5 (P<0.001). When comparing 3- to 5-mm Evolut implant depth, sinus sequestration was the lowest with Sapien-3 outflow at Evolut node 4 (13% versus 2%; P<0.001), and the highest at Evolut node 5 (61% versus 32%; P<0.001). CONCLUSIONS: Coronary accessibility after Sapien-3 in Evolut redo-TAVR relates to the initial Evolut implant depth, the Sapien-3 outflow position within the Evolut, and the native annular anatomy. This CT-based quantitative analysis may provide useful information to inform and refine individualized preprocedural CT planning of the initial TAVR and guide lifetime management for future coronary access after redo-TAVR. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02701283.

Feasibility of redo-TAVI in self-expanding Evolut valves: a CT analysis from the Evolut Low Risk Trial substudy.

BACKGROUND: Transcatheter aortic valve implantation in an existing transcatheter valve (redo-TAVI) pins the index valve leaflets in the open position (neoskirt), which can cause coronary flow compromise and limit access. Whether anatomy may preclude redo-TAVI in self-expanding Evolut valves is unknown. AIMS: We aimed to evaluate the anatomical feasibility of redo-TAVI by simulating implantation of a balloon-expandable SAPIEN 3 (S3) within an Evolut or an Evolut within an Evolut. METHODS: A total of 204 post-TAVI computed tomography (CT) scans from the Evolut Low Risk CT substudy were analysed. Five redo-TAVI positions were evaluated: S3-in-Evolut inflow-to-inflow, S3 outflow at Evolut nodes 4, 5, and 6, and Evolut-in-Evolut inflow-to-inflow. Univariable modelling identified pre-TAVI clinical characteristics, CT anatomical parameters, and procedural variables associated with coronary flow compromise using the neoskirt height and post-TAVI aortic root dimensions. RESULTS: The risk of coronary flow compromise was lowest when the S3 outflow was at Evolut node 4 (20%) and highest when at Evolut node 6 (75%). The highest likelihood of preserving coronary accessibility occurred with the S3 outflow at Evolut node 4. Female sex and higher body mass index were associated with a higher risk of coronary flow compromise, as were a smaller annulus diameter, lower sinus of Valsalva height and width, shorter coronary height, smaller sinotubular junction diameter, and shallower Evolut implant depth. CONCLUSIONS: The feasibility of redo-TAVI after Evolut failure is multifactorial and relates to the native annular anatomy, as well as the implantation depth of the index and second bioprostheses. Placement of an S3 at a lower Evolut position may reduce the risk of coronary flow compromise while preserving coronary access. CLINICALTRIALS: gov: NCT02701283.

Impact of generator replacement on the risk of Fidelis lead fracture.

BACKGROUND: A dilemma arises about the merits of conservative management vs lead replacement and/or extraction when patients with a Medtronic Sprint Fidelis lead undergo generator replacement. Conflicting reports suggest that the fracture rate may increase after generator change. OBJECTIVE: The purpose of this study was to investigate the effect of generator replacement on Fidelis lead performance. METHODS: The Carelink PLUS cohort is composed of 21,500 Fidelis leads (model 6949) implanted in 1,006 centers. The survival rate for leads that remained active after the first generator replacement was compared with that for a control group with matched lead implant duration, patient age, patient sex, and generator type using the Kaplan-Meier method. The control group's starting point was adjusted to match the implant duration of each lead in the replacement group to allow for the comparison of similarly aged leads. RESULTS: Of the 2,988 implanted leads in each group, there was no statistical difference in the number of lead fractures between cases and controls (replacement, n = 227; no replacement, n = 257; Fisher exact, P = .169). Lead survival analysis demonstrated that lead performance since the first replacement procedure did not differ from that of the matched control group. CONCLUSION: The Fidelis lead survival rate after generator replacement does not differ from that of the Fidelis leads that have not had replacement. In the event of generator replacement with no manifestation of lead fracture, the lead model, patient age and life expectancy, ejection fraction, comorbidities, ease of extraction, local extraction expertise, and patient preference should be considered to determine the best course of action.

MRI Reconstructions of Human Phrenic Nerve Anatomy and Computational Modeling of Cryoballoon Ablative Therapy.

The primary goal of this computational modeling study was to better quantify the relative distance of the phrenic nerves to areas where cryoballoon ablations may be applied within the left atria. Phrenic nerve injury can be a significant complication of applied ablative therapies for treatment of drug refractory atrial fibrillation. To date, published reports suggest that such injuries may occur more frequently in cryoballoon ablations than in radiofrequency therapies. Ten human heart-lung blocs were prepared in an end-diastolic state, scanned with MRI, and analyzed using Mimics software as a means to make anatomical measurements. Next, generated computer models of ArticFront cryoballoons (23, 28 mm) were mated with reconstructed pulmonary vein ostias to determine relative distances between the phrenic nerves and projected balloon placements, simulating pulmonary vein isolation. The effects of deep seating balloons were also investigated. Interestingly, the relative anatomical differences in placement of 23 and 28 mm cryoballoons were quite small, e.g., the determined difference between mid spline distance to the phrenic nerves between the two cryoballoon sizes was only 1.7 ± 1.2 mm. Furthermore, the right phrenic nerves were commonly closer to the pulmonary veins than the left, and surprisingly tips of balloons were further from the nerves, yet balloon size choice did not significantly alter calculated distance to the nerves. Such computational modeling is considered as a useful tool for both clinicians and device designers to better understand these associated anatomies that, in turn, may lead to optimization of therapeutic treatments.

Left phrenic nerve anatomy relative to the coronary venous system: Implications for phrenic nerve stimulation during cardiac resynchronization therapy.

The objective of this study was to quantitatively characterize anatomy of the human phrenic nerve in relation to the coronary venous system, to reduce undesired phrenic nerve stimulation during left-sided lead implantations. We obtained CT scans while injecting contrast into coronary veins of 15 perfusion-fixed human heart-lung blocs. A radiopaque wire was glued to the phrenic nerve under CT, then we created three-dimensional models of anatomy and measured anatomical parameters. The left phrenic nerve typically coursed over the basal region of the anterior interventricular vein, mid region of left marginal veins, and apical region of inferior and middle cardiac veins. There was large variation associated with the average angle between nerve and veins. Average angle across all coronary sinus tributaries was fairly consistent (101.3°-111.1°). The phrenic nerve coursed closest to the middle cardiac vein and left marginal veins. The phrenic nerve overlapped a left marginal vein in >50% of specimens.

The relative anatomy of the coronary arterial and venous systems: implications for coronary interventions.

An anatomical understanding of human coronary arterial and venous systems is necessary for device development and therapy applications that utilize these vessels. We investigated the unique use of contrast-CT scans from perfusion-fixed human hearts for three-dimensional visualization and analysis of anatomical features of the coronary systems. The coronary arterial and venous systems of eleven perfusion-fixed human hearts were modeled using contrast-CT and Mimics software. The coronary arteries that coursed near the major coronary veins, how close coronary arteries were to coronary veins, and the size of adjacent coronary arteries were recorded and analyzed. The majority of coronary veins were within 5 mm of a coronary artery somewhere along its length. Interventricular veins elicited the largest occurrence of overlaps. There was significant variability in the percentage of each vein that coursed within 0.5, 1, 2, and 5 mm of a nearby artery. The left marginal veins and anterior interventricular vein had the largest portion of the vein that coursed near a coronary artery. The right coronary artery most often coursed near the middle cardiac vein. The inferior veins of the left ventricle elicited the most variation in adjacent arteries. The left circumflex artery and/or branches of the circumflex artery coursed near the left marginal vein in all cases where there was an artery near the marginal vein. The wide variation of measurements reinforces the importance of a precise understanding of individualized cardiac anatomy in order to provide the highest quality care to cardiac patients.

The prevalence of coronary sinus and left circumflex artery overlap in relation to the mitral valve.

OBJECTIVES: Characterize where the circumflex artery crosses between the coronary sinus and mitral valve in order to minimize the occurrence of coronary compression during percutaneous indirect mitral valve interventions. BACKGROUND: Treatment of mitral valve regurgitation using an indirect percutaneous approach via access through the coronary sinus remains under active research and development. Characterization of anatomical locations where the circumflex artery crosses between the coronary sinus and mitral valve is important for mitigation of serious ischemic complications. METHODS: Magnetic resonance images were obtained for 65 perfusion-fixed human hearts. Three-dimensional reconstructions of anatomical orientations of the coronary sinus, circumflex artery, and mitral valve annulus were generated. The prevalence and location of sites where the circumflex artery coursed between the coronary sinus and mitral valve were assessed. RESULTS: The circumflex artery coursed between the coronary sinus and mitral valve in 88% of specimens. Overlaps between the circumflex artery and coronary sinus were less prevalent more proximal to the coronary sinus ostium. The coronary sinus did not lie in the same plane as the mitral annulus in roughly 20% of the hearts. CONCLUSION: The prevalence of circumflex overlap between the coronary sinus and mitral valve was common across the sample size. The large variability in anatomy confirms the value of imaging individual patient cardiac anatomy prior to performing indirect percutaneous mitral valve annuloplasty to avoid impairment to the circumflex artery. This novel database can be utilized in the development of additional cardiac therapies that require access to the coronary sinus, such as therapeutic ablations.

A detailed assessment of the human coronary venous system using contrast computed tomography of perfusion-fixed specimens.

BACKGROUND: Access to the coronary venous system is required for the delivery of several cardiac therapies including cardiac resynchronization therapy, coronary sinus ablation, and coronary drug delivery. Therefore, characterization of the coronary venous anatomy will provide insights to gain improved access to these vessels and subsequently improved therapies. For example, cardiac resynchronization therapy has a 30% nonresponder rate, partially due to suboptimal lead placement within the coronary veins. OBJECTIVE: To understand the implications of coronary venous anatomy for the development of devices deployed within these vessels. METHODS: We cannulated the coronary sinus of 121 perfusion-fixed human hearts with a venogram balloon catheter and injected contrast into the venous system while obtaining computed tomographic images. For each major coronary vein, distance to the coronary sinus, branching angle, arc length, tortuosity, number of branches, and ostial diameter were assessed from the reconstructed anatomy. RESULTS: Twenty-nine percent (35/121) specimens did not have a venous branch overlying the inferolateral side of the heart large enough to fit a 5F pacing lead. No significant differences in anatomy were found between subgroups with varying cardiac medical histories. CONCLUSION: The anatomical approach employed in this study has allowed for the development of a unique database of human coronary venous anatomy that can be used for the optimization of design and delivery of cardiac devices.

The benefits of the Atlas of Human Cardiac Anatomy website for the design of cardiac devices.

This paper describes how the Atlas of Human Cardiac Anatomy website can be used to improve cardiac device design throughout the process of development. The Atlas is a free-access website featuring novel images of both functional and fixed human cardiac anatomy from over 250 human heart specimens. This website provides numerous educational tutorials on anatomy, physiology and various imaging modalities. For instance, the 'device tutorial' provides examples of devices that were either present at the time of in vitro reanimation or were subsequently delivered, including leads, catheters, valves, annuloplasty rings and stents. Another section of the website displays 3D models of the vasculature, blood volumes and/or tissue volumes reconstructed from computed tomography and magnetic resonance images of various heart specimens. The website shares library images, video clips and computed tomography and MRI DICOM files in honor of the generous gifts received from donors and their families.

Anatomical reconstructions of the human cardiac venous system using contrast-computed tomography of perfusion-fixed specimens.

A detailed understanding of the complexity and relative variability within the human cardiac venous system is crucial for the development of cardiac devices that require access to these vessels. For example, cardiac venous anatomy is known to be one of the key limitations for the proper delivery of cardiac resynchronization therapy (CRT)(1) Therefore, the development of a database of anatomical parameters for human cardiac venous systems can aid in the design of CRT delivery devices to overcome such a limitation. In this research project, the anatomical parameters were obtained from 3D reconstructions of the venous system using contrast-computed tomography (CT) imaging and modeling software (Materialise, Leuven, Belgium). The following parameters were assessed for each vein: arc length, tortuousity, branching angle, distance to the coronary sinus ostium, and vessel diameter. CRT is a potential treatment for patients with electromechanical dyssynchrony. Approximately 10-20% of heart failure patients may benefit from CRT(2). Electromechanical dyssynchrony implies that parts of the myocardium activate and contract earlier or later than the normal conduction pathway of the heart. In CRT, dyssynchronous areas of the myocardium are treated with electrical stimulation. CRT pacing typically involves pacing leads that stimulate the right atrium (RA), right ventricle (RV), and left ventricle (LV) to produce more resynchronized rhythms. The LV lead is typically implanted within a cardiac vein, with the aim to overlay it within the site of latest myocardial activation. We believe that the models obtained and the analyses thereof will promote the anatomical education for patients, students, clinicians, and medical device designers. The methodologies employed here can also be utilized to study other anatomical features of our human heart specimens, such as the coronary arteries. To further encourage the educational value of this research, we have shared the venous models on our free access website: www.vhlab.umn.edu/atlas.

Human coronary venous anatomy: implications for interventions.

The coronary venous system is a highly variable network of veins that drain the deoxygenated blood from the myocardium. The system is made up of the greater cardiac system, which carries the majority of the deoxygenated blood to the right atrium, and the smaller cardiac system, which drains the blood directly into the heart chambers. The coronary veins are currently being used for several biomedical applications, including but not limited to cardiac resynchronization therapy, ablation therapy, defibrillation, perfusion therapy, and annuloplasty. Knowledge of the details of the coronary venous anatomy is essential for optimal development and delivery of treatments using this vasculature. This article is part of a JCTR special issue on Cardiac Anatomy.