Yoshiya Toyoda, Jnanesh Thacker, Ricardo Santos, Duc Nguyen, Jay Bhama, Christian Bermudez, Robert Kormos, Bruce Johnson, Maria Crespo, Joseph Pilewski, Jeffrey Teuteberg, Rene Alvarez, Michael Mathier, Dennis McNamara, Kenneth McCurry, Marco Zenati, and Brack Hattler. 2008. “Long-term outcome of lung and heart-lung transplantation for idiopathic pulmonary arterial hypertension.” Ann Thorac Surg, 86, 4, Pp. 1116-22.Abstract
BACKGROUND: The survival after lung and heart-lung transplantation for idiopathic pulmonary arterial hypertension has been reportedly the lowest among the major diagnostic categories of lung transplant recipients. METHODS: Retrospective analysis was performed for lung and heart-lung transplant recipients for idiopathic pulmonary arterial hypertension from 1982 to 2006. The patients were divided into 2 groups, based on the era; group 1: 1982 to 1993, and group 2: 1994 to 2006. Since 1994, we have introduced our current protocols including prostaglandin E1 and nitroglycerin for donor lung preservation, and lung protection with cold and terminal warm blood pneumoplegia as well as immunosuppression with alemtuzumab induction. These modifications were introduced in different years over a wide span of time (1994 to 2003). RESULTS: Group 1 had 59 patients (35 +/- 1 years old, ranging 15 to 53, 20 male and 39 female) with 7 single lung, 11 double lung, and 41 heart-lung, whereas group 2 had 30 (43 +/- 2 years old, ranging 17 to 65, 9 male and 21 female) with 2 single, 20 double, and 8 heart-lung transplantations. The recipient age was significantly (p = 0.004) higher in group 2, and group 2 had significantly older (35 +/- 3 vs 26 +/- 1, p = 0.002) and more female donors (73% vs 41%, p = 0.007) compared with group 1. The actuarial survival was significantly (p = 0.004) better in group 2 with 86% at 1 year, 75% at 5 years, and 66% at 10 years compared with group 1 with 58% at 1 year, 39% at 5 years, and 27% at 10 years. CONCLUSIONS: With our current pulmonary protection and immunosuppression, the long-term outcome of lung and heart-lung transplantation for idiopathic pulmonary arterial hypertension is excellent.
Takeyoshi Ota, Nicholas A Patronik, David Schwartzman, Cameron N Riviere, and Marco A Zenati. 2008. “Minimally invasive epicardial injections using a novel semiautonomous robotic device.” Circulation, 118, 14 Suppl, Pp. S115-20.Abstract
BACKGROUND: We have developed a novel miniature robotic device (HeartLander) that can navigate on the surface of the beating heart through a subxiphoid approach. This study investigates the ability of HeartLander to perform in vivo semiautonomous epicardial injections on the beating heart. METHODS AND RESULTS: The inchworm-like locomotion of HeartLander is generated using vacuum pressure for prehension of the epicardium and drive wires for actuation. The control system enables semiautonomous target acquisition by combining the joystick input with real-time 3-dimensional localization of the robot provided by an electromagnetic tracking system. In 12 porcine preparations, the device was inserted into the intrapericardial space through a subxiphoid approach. Ventricular epicardial injections of dye were performed with a custom injection system through HeartLander's working channel. HeartLander successfully navigated to designated targets located around the circumference of the ventricles (mean path length=51+/-25 mm; mean speed=38+/-26 mm/min). Injections were successfully accomplished following the precise acquisition of target patterns on the left ventricle (mean injection depth=3.0+/-0.5 mm). Semiautonomous target acquisition was achieved within 1.0+/-0.9 mm relative to the reference frame of the tracking system. No fatal arrhythmia or bleeding was noted. There were no histological injuries to the heart due to the robot prehension, locomotion, or injection. CONCLUSIONS: In this proof-of-concept study, HeartLander demonstrated semiautonomous, precise, and safe target acquisition and epicardial injection on a beating porcine heart through a subxiphoid approach. This technique may facilitate minimally invasive cardiac cell transplantation or polymer therapy in patients with heart failure.
Jeremy R McGarvey, David Schwartzman, Takeyoshi Ota, and Marco A Zenati. 2008. “Minimally invasive epicardial left atrial ablation and appendectomy for refractory atrial tachycardia.” Ann Thorac Surg, 86, 4, Pp. 1375-7.Abstract
Surgical removal or epicardial radiofrequency ablation of the left atrial appendage (LAA) is occasionally required when endocardial ablations fail. We report a modified minimally invasive surgical approach for elimination of recurrent atrial arrhythmias arising from the LAA, including both radiofrequency ablation and appendectomy. Ablation of the LAA base was performed using the Medtronic Cardioblate bipolar radiofrequency device (Medtronic, Minneapolis, MN), and left atrial appendectomy was then completed using the EndoGIA stapling system (US Surgical, Norwalk, CT). This procedure successfully isolated and removed the tachycardia focus, and normal sinus rhythm was restored. Elimination of LAA arrhythmias using a combination of epicardial radiofrequency ablation and appendectomy ensures electrical isolation while minimizing surgical invasiveness.
Takeyoshi Ota, Amir Degani, David Schwartzman, Brett Zubiate, Jeremy McGarvey, Howie Choset, and Marco A Zenati. 2008. “A novel highly articulated robotic surgical system for epicardial ablation.” Annu Int Conf IEEE Eng Med Biol Soc, 2008, Pp. 250-3.Abstract
We have developed a novel, highly articulated robotic surgical system to enable minimally invasive intrapericardial interventions through a subxiphoid approach and have performed preliminary tests of epicardial left atrial ablation in porcine (N=3) and human cadaver (N=2) preparations. In this study, the novel highly articulated robotic surgical system successfully provided safe epicardial ablations to the left atrium in porcine beating heart models via a subxiphoid approach. We have also performed complex guidance of the robot and subsequent ablation in a cadaveric preparation for successful pulmonary vein isolation.
Takeyoshi Ota, Thomas W Gilbert, Stephen F Badylak, David Schwartzman, and Marco A Zenati. 2007. “Electromechanical characterization of a tissue-engineered myocardial patch derived from extracellular matrix.” J Thorac Cardiovasc Surg, 133, 4, Pp. 979-85.Abstract
OBJECTIVE: Extracellular matrix scaffolds have been successfully used for myocardial wall repair. However, regional functional evaluation (ie, contractility, electrical conductivity) of the extracellular matrix scaffold during the course of remodeling has been limited. In the present study, we evaluated the remodeled scaffold for evidence of electrical activation. METHODS: The extracellular matrix patch was implanted into the porcine right ventricular wall (n = 5) to repair an experimentally produced defect. Electromechanical mapping was performed with the NOGA system (Biosense Webster Inc, Diamond Bar, Calif) 60 days after implantation. Linear local shortening was recorded to assess regional contractility. After sacrifice, detailed histologic examinations were performed. RESULTS: Histologic examinations showed repopulation of the scaffold with cells, including a monolayer of factor VIII-positive cells in the endocardial surface and multilayered alpha-smooth muscle actin-positive cells beneath the monolayer cells. The alpha-smooth muscle actin-positive cells tended to be present at the endocardial aspect of the remodeled scaffold and at the border between the remodeled scaffold and the normal myocardium. Electromechanical mapping demonstrated that the patch had low-level electrical activity (0.56 +/- 0.37 mV; P < .0001) in most areas and moderate activity (2.20 +/- 0.70 mV; P < .0001) in the margin between the patch and the normal myocardium (7.58 +/- 2.23 mV). CONCLUSIONS: The extracellular matrix scaffolds were repopulated by alpha-smooth muscle actin-positive cells 60 days after implantation into the porcine heart. The presence of the cells corresponded to areas of the remodeling scaffold that showed early signs of electrical conductivity.
Marco A Zenati, Alaa Shalaby, Gregory Eisenman, John Nosbisch, Jeremy McGarvey, and Takeyoshi Ota. 2007. “Epicardial left ventricular mapping using subxiphoid video pericardioscopy.” Ann Thorac Surg, 84, 6, Pp. 2106-7.Abstract
We report a novel subxiphoid video pericardioscopy approach for epicardial mapping that allows direct visualization of the epicardium with minimal use of fluoroscopy. The FLEXview system (Boston Scientific Cardiac Surgery, Santa Clara, CA), which is capable of a free navigation around the heart owing to its flexible neck, was inserted into the pericardial space through a small subxiphoid incision. A commercially available mapping catheter advanced through the working port of the device could be navigated around virtually the entire biventricular epicardial surface. The subxiphoid video pericardioscopy approach using the FLEXview system provided adequate visualization and access to the epicardium of both ventricles for electroanatomic mapping while minimizing surgical invasiveness.
Takeyoshi Ota, David Schwartzman, David Francischelli, Douglas A Hettrick, and Marco A Zenati. 2007. “Impact of beating heart left atrial ablation on left-sided heart mechanics.” J Thorac Cardiovasc Surg, 134, 4, Pp. 982-8.Abstract
OBJECTIVE: The cut-and-sew Cox-Maze procedure is the gold standard for surgical treatment of atrial fibrillation, but it is associated with long-term impairment of left atrial mechanical function. We developed a bipolar, irrigated radiofrequency ablation device. We hypothesized that beating heart radiofrequency left atrial ablation would result in minimal acute changes in left atrial hemodynamics. METHODS: Six healthy subjects were studied. Combination pressure-conductance catheters were inserted into the left atrium and ventricle. With the use of the device, atrial ablation was performed on the beating heart without cardiopulmonary bypass, including electrical isolation of the posterior left atrium and atrial appendage myocardium. Simultaneous left-sided heart pressure-volume and intracardiac echocardiography data were acquired before ablation, after left atrial appendage ablation alone, and after all ablation (with and without appendage occlusion). The derived indices of left-sided heart mechanical function were examined. RESULTS: Relative to baseline, no significant diminishment in pressure-volume or intracardiac echocardiography-derived indices of global left-sided heart mechanical function were observed after ablation, with or without appendage occlusion. Mitral valve morphology and function were not significantly altered. A significant diminishment of atrial appendage systolic flow was noted after appendage ablation in association with spontaneous echocardiographic contrast in this region. CONCLUSIONS: In this model, ablation does not seem to compromise global left-sided heart mechanical function. However, these findings mask regional diminishment in atrial appendage systolic function. This observation demonstrates that electrical isolation of the appendage should be accompanied by its occlusion or excision. Appendage occlusion after ablation does not seem to compromise left-sided heart mechanical function.
Takeyoshi Ota, Amir Degani, Brett Zubiate, Alon Wolf, Howie Choset, David Schwartzman, and Marco A Zenati. 2006. “Epicardial Atrial Ablation Using a Novel Articulated Robotic Medical Probe Via a Percutaneous Subxiphoid Approach.” Innovations (Phila), 1, 6, Pp. 335-340.Abstract
OBJECTIVE: Minimally invasive epicardial atrial ablation to cure atrial fibrillation through the use of a percutaneous subxiphoid approach currently has a lack of dedicated technology for intrapericardial navigation around the beating heart. We have developed a novel articulated robotic medical probe and performed preliminary experiments in a porcine preparation. METHODS: In five large, healthy pigs, the teleoperated robotic system was introduced inside the pericardial space through a percutaneous subxiphoid approach. Secondary visualization of the left atrium and left atrial appendage was achieved with the use of a 5-mm scope inserted through a left thoracic port. The operator actively controlled the path of the robot by using a master manipulator. The catheter, with an irrigated radiofrequency tip, was guided through the working port of the robot to achieve epicardial ablation of the left atrium. RESULTS: Access to the pericardial space and progression around the left atrium was successful in all cases, with no interference with the beating heart such as a fatal arrhythmia, unexpected bleeding, and hypotension. Epicardial ablation was successfully performed in all five cases. No adverse hemodynamic or electrophysiological events were noted during the trials. When the animals were killed, there was no visually detected injury on the surrounding mediastinal structures caused by ablation. Transmural ablation was confirmed by histopathology of the left atrium. CONCLUSIONS: We have developed a dedicated articulated robotic medical probe and successfully performed epicardial left atrial radiofrequency ablation. Based on the feedback from these preliminary experiments, the radius of curvature and proper visualization of the device are being improved in the next generation prototype.
Amir Degani, Howie Choset, Brett Zubiate, Takeyoshi Ota, and Marco Zenati. 2006. “Highly Articulated Robotic Probe for Minimally Invasive Surgery.” Conf Proc IEEE Eng Med Biol Soc, 2006, 1642343, Pp. 4167-4172.Abstract
We have developed a novel highly articulated robotic probe (HARP) that can thread through tightly packed volumes without disturbing the surrounding tissues and organs. We use cardiac surgery as the focal application of this work. As such, we have designed the HARP to enter the pericardial cavity through a subxiphoid port. The surgeon can effectively reach remote intrapericardial locations on the epicardium and deliver therapeutic interventions under direct control. Our device differs from others in that we use conventional actuation and still have great maneuverability. We have performed proof-of-concept clinical experiments to give us preliminary validation of the ideas presented here.
NA Patronik, T Ota, MA Zenati, and CN Riviere. 2006. “Improved traction for a mobile robot traveling on the heart.” Conf Proc IEEE Eng Med Biol Soc, 2006, Pp. 339-42.Abstract
This document describes the effects of several design parameters on the traction generated by the suction pads of a mobile robot that walks on the surface of the heart. HeartLander is a miniature mobile robot that adheres to the epicardial surface of the heart using suction, and can travel to any desired location on the heart to administer therapeutic applications. To maximize the effectiveness of locomotion, the gripper pads must provide sufficient traction to avoid slipping. Our testing setup measured the force applied to the gripper pad adhering to ovine epicardial tissue, and recorded overhead video for tracking of the pad and tissue during an extension. By synchronizing the force and video data, we were able to determine the point at which the pad lost traction and slipped during the extension. Of the pads tested, the pad with no suction grate achieved maximum traction. Increasing the extension speed up to 20 mm/s resulted in a corresponding increase in traction. Increasing the vacuum pressure also improved the traction, but the magnitude of the effect was less than the improvement gained from increasing extension speed.
Marco A Zenati, Ali Sonel, Brack Hattler, Laurie A Shroyer, Joseph Collins, John Messenger, Janet H Baltz, Lisa M Mohr, Jennifer M Gabany, Dimitri Novitsky, and Frederick Grover. 2006. “Patency outcomes of aortic connectors.” Innovations (Phila), 1, 5, Pp. 255-7.Abstract
OBJECTIVE: : Controlled outcome analysis of mechanical aortic connectors for proximal saphenous vein bypass graft anastomosis is lacking. We report the clinical and angiographic outcome of patients receiving the Symmetry aortic connector (St. Jude Medical, Inc St. Paul, MN, US) within a multicenter, prospective, randomized study. METHODS: : Twenty-five patients at 3 study sites received aortic connectors at the time of coronary artery bypass surgery. Protocol-defined angiographic follow-up was completed in 19 of 25 patients (76%) at time-points up to 14 months postoperatively; 32 connector anastomoses were evaluated in these 19 patients. Beating heart surgery was performed in 17 patients, and 2 were performed with cardiopulmonary bypass. Age was 69.7 ± 8.1 year; all patients were males. RESULTS: : The connector anastomosis patency rate was 15.6% (5/32). There were no deaths during the follow-up period. Four patients (21%) suffered myocardial infarction and 2 additional patients (10.5%) required percutaneous coronary interventions; one of who required 3 percutaneous coronary interventions, the other received one percutaneous coronary intervention. CONCLUSIONS: : In this nonrandomized cohort of patients, occlusion rate with Symmetry connectors was significantly greater than anticipated. Patients who have received these connectors during coronary artery bypass surgery may require closer follow-up and evaluation. While the manufacturer has stopped producing this device, there has been no recall of the product, clinical support remains ongoing, and next generation connectors have now been marketed. Consideration should be given to discontinuation of the clinical use of Symmetry connectors.
Takeyoshi Ota, Nicholas A Patronik, Cameron N Riviere, and Marco A Zenati. 2006. “Percutaneous subxiphoid access to the epicardium using a miniature crawling robotic device.” Innovations (Phila), 1, 5, Pp. 227-31.Abstract
BACKGROUND: : To expand minimally invasive beating-heart surgery, we have developed a miniature 2-footed crawling robot (HeartLander) that navigates on the epicardium. This paradigm obviates mechanical stabilization and lung deflation, and avoids the access limitations of current approaches. We tested the locomotion of the device on a beating porcine heart accessed through a closed-chest subxiphoid approach. METHODS: : HeartLander consists of 2 modules that are connected by an extensible midsection. It adheres to the epicardium using suction pads. Locomotion and turning are accomplished by moving the 2 modules in an alternating fashion using wires that run through the midsection between them. After a preliminary test with a plastic beating-heart model, we performed a porcine study in vivo. The device was inserted into the pericardial space through a subxiphoid incision, while the test was observed using a left thoracoscopy. The blood pressure and electrocardiogram were monitored, and vacuum pressure and driving forces on the wires were recorded. RESULTS: : HeartLander traveled across the anterior and lateral surfaces of the beating heart without restriction, including locomotion forward, backward, and turning. The vacuum pressure was kept below 450 mm Hg at all times. The average maximum force during elongation was 1.86 ± 0.97 N, and during retraction was 1.24 ± 0.33 N. No adverse hemodynamic or electrophysiologic events were noted during the trial. No epicardial damage was found on the excised heart after the porcine trial. CONCLUSIONS: : The current HeartLander prototype demonstrated safe and successful locomotion on a beating porcine heart through a closed-chest subxiphoid approach.
Alaa Shalaby, Mahesh S Sharma, and Marco A Zenati. 2006. “Robotic implantation of a multichamber cardiac resynchronization therapy defibrillator.” Pacing Clin Electrophysiol, 29, 8, Pp. 906-9.Abstract
Transvenous implantation of a cardiac resynchronization therapy defibrillator (CRT-D) may not be feasible due to anatomic constraints. One of the most notable advances in minimal-access heart surgery has been the introduction of robotic telemanipulation systems. We present a challenging case in which a CRT-D system was implanted using a robotic approach. Feasibility of such an approach expands the horizons for delivery of CRT-D therapy.
NA Patronik, MA Zenati, and CN Riviere. 2005. “A miniature cable-driven robot for crawling on the heart.” Conf Proc IEEE Eng Med Biol Soc, 2005, Pp. 5771-4.Abstract
This document describes the design and preliminary testing of a cable-driven robot for the purpose of traveling on the surface of the beating heart to administer therapy. This methodology obviates mechanical stabilization and lung deflation, which are typically required during minimally invasive cardiac surgery. Previous versions of the robot have been remotely actuated through push-pull wires, while visual feedback was provided by fiber optic transmission. Although these early models were able to perform locomotion in vivo on porcine hearts, the stiffness of the wire-driven transmission and fiber optic camera limited the mobility of the robots. The new prototype described in this document is actuated by two antagonistic cable pairs, and contains a color CCD camera located in the front section of the device. These modifications have resulted in superior mobility and visual feedback. The cable-driven prototype has successfully demonstrated prehension, locomotion, and tissue dye injection during in vitro testing with a poultry model.
NA Patronik, MA Zenati, and CN Riviere. 2005. “Preliminary evaluation of a mobile robotic device for navigation and intervention on the beating heart.” Comput Aided Surg, 10, 4, Pp. 225-32.Abstract
This article describes the development and preliminary testing of a mobile robotic device to facilitate minimally invasive beating-heart intrapericardial intervention. The HeartLander robot will be introduced beneath the pericardium via subxiphoid incision, adhere to the epicardium, navigate to any location, and administer therapy under the control of the physician. As compared to current robotic cardiac surgical techniques, this novel paradigm obviates immobilization of the heart and eliminates access limitations. Furthermore, it does not require lung deflation and differential ventilation and thus could enable outpatient cardiac surgery. The current HeartLander prototypes use suction to maintain prehension of the epicardium and wire actuation to perform locomotion. A fiber optic videoscope displays visual feedback to the physician, who controls the device through a joystick interface. The initial prototype demonstrated successful prehension, turning, and locomotion on open-chest, beating-heart porcine models where the pericardium was removed (N = 3). A smaller second-generation prototype with an injection system demonstrated locomotion and myocardial injection of dye, both performed with the pericardium intact (N = 3). These trials illustrate the feasibility of using a miniature mobile robot to navigate upon the beating heart and perform intrapericardial therapy.
Kaoru Dohi, Matthew Suffoletto, Leonard Ganz, Marco Zenati, and John Gorcsan. 2005. “Utility of echocardiographic tissue synchronization imaging to redirect left ventricular lead placement for improved cardiac resynchronization therapy.” Pacing Clin Electrophysiol, 28, 5, Pp. 461-5.Abstract
An 80-year-old woman with severe symptomatic heart failure (ejection fraction of 13%), and left bundle branch block (QRS duration of 160 ms) underwent cardiac resynchronization therapy (CRT). She had significant baseline dyssynchrony with a septal to posterior wall delay of 160 ms by echocardiographic tissue synchronization imaging (TSI). Despite exhaustive efforts, a stable posterior-lateral coronary vein lead position could not be achieved with the standard percutaneous approach, resulting in anterior coronary vein lead placement. This resulted in no improvement in the patient's symptoms or ventricular function. Follow-up TSI revealed earlier activation of the anteroseptal site and worsened dyssynchrony with septal to posterior wall delay of now 290 ms. This information prompted surgical revision of the left ventricular (LV) lead position via limited thoracotomy and posterior-lateral epicardial lead implantation. Pacing at the new lead site resulted in a 30% increase in stroke volume and symptomatic improvement. TSI in this case redirected lead position in a clinical nonresponder, resulting in a favorable response to CRT.
G Bonanomi, D Kostov, and MA Zenati. 2004. “Emergent off-pump complete myocardial revascularization in dextrocardia.” J Cardiovasc Surg (Torino), 45, 1, Pp. 31-3.Abstract
Dextrocardia is a rare condition not spared by coronary artery disease. We report the case of a 72-year-old patient with dextrocardia associated with situs inversus totalis who presented to our Institution with acute myocardial infarction complicated by congestive heart failure. Due to the severe general conditions of the patient, an emergent off-pump complete myocardial revascularization was undertaken. The patient tolerated the procedure well and was asymptomatic at discharge. The technical aspects encountered in the setting of mirror-image anatomy and the advantages of off-pump myocardial revascularization in the critically ill patient are discussed.
Cameron N Riviere, Nicholas A Patronik, and Marco A Zenati. 2004. “Prototype epicardial crawling device for intrapericardial intervention on the beating heart.” Heart Surg Forum, 7, 6, Pp. E639-43.Abstract
The development and preliminary testing of a device for facilitating minimally invasive beating-heart intrapericardial interventions are described. We propose the concept of an endoscopic robotic device that adheres to the epicardium by suction and navigates by crawling like an inchworm to any position on the surface under the control of a surgeon. This approach obviates cardiac stabilization, lung deflation, differential lung ventilation, and reinsertion of laparoscopic tools for accessing different treatment sites, thus offering the possibility of reduced trauma to the patient. The device has a working channel through which various tools can be introduced for treatment. The current prototype demonstrated successful prehension, turning, and locomotion on beating hearts in a limited number of trials in a porcine model.
Harpreet Singh Grewal, Marco A Zenati, Robert Kormos, Srinivas Murali, and William E Katz. 2004. “Serial dobutamine stress echocardiography with Doppler assessment of the left internal thoracic artery graft after minimally invasive bypass for a patient with an orthotopic heart transplant.” J Heart Lung Transplant, 23, 2, Pp. 256-9.Abstract
Select patients who have undergone orthotopic heart transplantation with proximal left anterior disease may be candidates for minimally invasive direct coronary artery bypass surgery. Combining left internal thoracic artery transthoracic Doppler flow assessment with wall motion assessment during dobutamine stress echocardiography adds to the utility of this test by focusing attention on the graft's status as well as detecting ischemia due to cardiac allograft vasculopathy.
David Schwartzman, Gianluca Bonanomi, and Marco A Zenati. 2003. “Epicardium-based left atrial ablation: impact on electromechanical properties.” J Cardiovasc Electrophysiol, 14, 10, Pp. 1087-92.Abstract
UNLABELLED: Epicardium-Based LA Ablation. INTRODUCTION: An important developmental task for surgical ablation of atrial fibrillation is simplification. A significant step would be the development of tools that create satisfactory ablation lesions without necessitating cardiopulmonary bypass or atriotomy. Optimally, these lesions would have no adverse impact on atrial electromechanical properties. METHODS AND RESULTS: We sought to characterize left atrial (LA) lesions created by a bipolar ablation device without cardiopulmonary bypass or atriotomy and to assess their impact on LA electromechanical properties. In each of five pigs, lesions were delivered to the epicardium of the beating heart, and encircled and connected right and left pulmonary vein vestibules and the atrial appendage. Before and after ablation, LA electromechanical properties were assessed using endocardial electromechanical mapping and intracardiac echocardiography. Postmortem histologic analysis also was performed. Each lesion was thrombus-free and barotrauma-free, histologically transmural, and a complete conduction barrier. Although a large aggregate area (24% +/- 6%) of LA myocardium was excluded, there was no significant change in global electromechanical properties. However, marked diminishment in appendage function was observed. CONCLUSION: Epicardium-based LA ablation in a beating heart could be achieved successfully without cardiopulmonary bypass or atriotomy. Although there was no adverse impact on global electromechanical properties, there was evidence of important regional diminishment.