This paper presents preliminary work toward localizing on a surface which undergoes periodic deformation, as an aspect of research on HeartLander, a miniature epicardial crawling robot. Using only position measurements from the robot, the aim of this work is to use the nonuniform movements of the heart as features to aid in localization. Using a particle filter, with motion and observation models which accurately model the robotic system, registration and localization parameters can be quickly and accurately identified. The presented framework is demonstrated in simulation on dynamic 2-D models which approximate the deformation of the surface of the heart.

OBJECTIVES/HYPOTHESIS: Organ preservation surgery is a major focus in head and neck oncology. Current approaches are aimed toward improving quality of life and decreasing treatment-related morbidity. Transoral robotic surgery was developed to overcome the limitations of traditional surgical approaches. The most widely used robotic system is the da Vinci Surgical System. Although the da Vinci offers clear surgical advantages over traditional approaches, its rigid operative arms prevent complex maneuverability in three-dimensional space. The ideal surgical robot would configure to the anatomy of the patient and maneuver in narrow spaces. We present the first cadaveric trials of the use of a highly flexible robot able to traverse the nonlinear upper aerodigestive tract and gain physical and visual access to important anatomical landmarks without laryngeal suspension. STUDY DESIGN: Feasibility. METHODS: Using human cadavers, we investigated the feasibility of visualizing the endolarynx transorally with a highly flexible robot without performing suspension of the larynx. Two fresh and four preserved human specimens were used. RESULTS: Unhampered visualization of the endolarynx was achieved in all specimens without performing laryngeal suspension. Standard mouth retractors facilitated the delivery of the robot into the endolarynx. CONCLUSIONS: The flexible robot technology mitigates laryngeal suspension and the limitations of current robotic surgery with rigid line-of-sight-directed instruments. Having demonstrated the feasibility of physical and visual access to the endolarynx, future work will study the feasibility of using the highly flexible robot in transoral robotic procedures with flexible instrumentation placed in the robot's available working ports.

HeartLander is a small mobile robot which adheres to and navigates over the surface of the heart to provide therapies in a minimally invasive manner. HeartLander's ability to efficiently operate in this dynamic environment is greatly affected by physiological motion, namely the cardiac and respiration cycles. Synchronization of robot motion with minimal intrapericardial pressure results in safer and more efficient travel. The work presented models the physiological components of motion using Fourier series and estimates their parameters using an Extended Kalman Filter. Using the Fourier series parameters, estimates of physiological phase values are calculated to be used for step synchronization. The proposed methods are demonstrated on data from a HeartLander animal study for four locations on the heart. Mean respiration phase estimates are shown to be within 5% of the true respiration phases, while mean cardiac phase estimates are shown to have a minimum error of 11%.

OBJECTIVE: In the Randomized On/Off Bypass (ROOBY) Trial, the efficacy of on-pump versus off-pump coronary artery bypass grafting was evaluated. This ROOBY Trial planned subanalysis compared the effects on postbypass patient clinical outcomes and graft patency of endoscopic vein harvesting and open vein harvesting. METHODS: From April 2003 to April 2007, the technique used for saphenous vein graft harvesting was recorded in 1471 cases. Of these, 894 patients (341 endoscopic harvest and 553 open harvest) also underwent coronary angiography 1 year after coronary artery bypass grafting. Univariate and multivariable analyses were used to compare patient outcomes in the endoscopic and open groups. RESULTS: Preoperative patient characteristics were statistically similar between the endoscopic and open groups. Endoscopic vein harvest was used in 38% of the cases. There were no significant differences in both short-term and 1-year composite outcomes between the endoscopic and open groups. For patients with 1-year catheterization follow-up (n=894), the saphenous vein graft patency rate for the endoscopic group was lower than that in the open harvest group (74.5% vs 85.2%, P<.0001), and the repeat revascularization rate was significantly higher (6.7% vs 3.4%, P<.05). Multivariable regression documented no interaction effect between endoscopic approach and off-pump treatment. CONCLUSIONS: In the ROOBY Trial, endoscopic vein harvest was associated with lower 1-year saphenous vein graft patency and higher 1-year revascularization rates, independent of the use of off-pump or on-pump cardiac surgical approach.

OBJECTIVE: Functional ischemic mitral regurgitation is a complication of ventricular remodeling; standard therapy is reduction annuloplasty and coronary artery bypass grafting. Unfortunately, outcomes are retrospective and contradictory. We report a multicenter study that documents the outcomes of reduction annuloplasty for functional ischemic mitral regurgitation. METHODS: Twenty-one centers randomized 75 patients to the coronary artery bypass grafting + reduction annuloplasty subgroup that was the control arm of the Randomized Evaluation of a Surgical Treatment for Off-pump Repair of the Mitral Valve trial. Entry criteria included patients requiring revascularization, patients with severe or symptomatic moderate functional ischemic mitral regurgitation, an ejection fraction 25% or greater, a left ventricular end-diastolic dimension 7.0 cm or less, and more than 30 days since acute myocardial infarction. All echocardiograms were independently scored by a core laboratory. Reduction annuloplasty was achieved by device annuloplasty. Two patients underwent immediate intraoperative conversion to a valve replacement because reduction annuloplasty was unable to correct mitral regurgitation; as-treated results are presented. RESULTS: Thirty-day mortality was 4.1% (3/73). Patients received an average of 2.8 bypass grafts. Mean follow-up was 24.6 months. Mitral regurgitation was reduced from 2.6 ± 0.8 preoperatively to 0.3 ± 0.6 at 2 years. Freedom from death or valve reoperation was 78% ± 5% at 2 years. There was significant improvement in ejection fraction and New York Heart Association class with reduction of left ventricular end-diastolic dimension. Cox regression analyses suggested that increasing age (P = .001; hazard ratio, 1.16 per year; 95% confidence interval, 1.06-1.26) and renal disease (P = .018; hazard ratio, 3.48; 95% confidence interval, 1.25-9.72) were associated with decreased survival. CONCLUSIONS: Coronary artery bypass grafting + reduction annuloplasty for functional ischemic mitral regurgitation predictably reduces mitral regurgitation and relieves symptoms. This treatment of moderate to severe mitral regurgitation is associated with improved indices of ventricular function, improved New York Heart Association class, and excellent freedom from recurrent mitral insufficiency. Although long-term prognosis remains guarded, this multicenter study delineates the intermediate-term benefits of such an approach.

HeartLander, a small mobile robot designed to provide treatments to the surface of the beating heart, overcomes a major difficulty of minimally invasive cardiac surgery, providing a stable operating platform. This is achieved inherently in the way the robot adheres to and crawls over the surface of the heart. This mode of operation does not require physiological motion compensation to provide this stable environment; however, modeling of physiological motion is advantageous in providing more accurate position estimation as well as synchronization of motion to the physiological cycles. The work presented uses an Extended Kalman Filter framework to estimate parameters of non-stationary Fourier series models of the motion of the heart due to the respiratory and cardiac cycles as well as the position of the robot as it moves over the surface of the heart. The proposed method is demonstrated in the laboratory with HeartLander operating on a physiological motion simulator. Improved performance is demonstrated in comparison to the filtering methods previously used with HeartLander. The use of detected physiological cycle phases to synchronize locomotion of HeartLander is also described.

We propose a new snake-like robot for use in single-port minimally invasive surgery. The snake robot is made of a concentric tube robot and a highly articulated robotic probe. The probe operates as a stiff shield for the concentric tube robot. Consequently, the snake robot provides simultaneously high tip stiffness and dexterity that cannot be obtained by the single use of any of two robots. A critical design challenge is achieving a small radius of curvature for the hybrid snake. A mechanic model is presented for computing the minimum achievable radius of curvature for the hybrid snake. Experiments validate the mechanic model.

The injection of a mechanical bulking agent into the left ventricular (LV) wall of the heart has shown promise as a therapy for maladaptive remodeling of the myocardium after myocardial infarct (MI). The HeartLander robotic crawler presented itself as an ideal vehicle for minimally-invasive, highly accurate epicardial injection of such an agent. Use of the optimal bulking agent, a thermosetting hydrogel developed by our group, presents a number of engineering obstacles, including cooling of the miniaturized injection system while the robot is navigating in the warm environment of a living patient. We present herein a demonstration of an integrated miniature cooling and injection system in the HeartLander crawling robot, that is fully biocompatible and capable of multiple injections of a thermosetting hydrogel into dense animal tissue while the entire system is immersed in a 37°C water bath.

HeartLander is a small, mobile robot designed to assist surgical procedures on the surface of the heart. It crawls within the pericardial sac surrounding the heart. Numerous potential clinical uses for HeartLander involve injections or other interventions at multiple locations on the epicardial surface. To minimize treatment time, we have developed an algorithm that optimizes a plan for reaching a given set of treatment targets. Results from in vitro evaluation on a beating heart model show improvement over a greedy technique.

OBJECTIVE: Single-port subxiphoid videopericardioscopy with a rigid shaft is useful for left atrial exclusion, left ventricular pacing lead implantation, and epicardial mapping, but it may interfere with the cardiac rhythm and adversely alter hemodynamics. We examined the impact of this technique on hemodynamic indices in a porcine model. METHODS: The videopericardioscopy device was introduced into the pericardial space of 5 pigs (35-45 kg) via a subxiphoid approach and navigated to 6 anatomical targets (right atrial appendage, superior vena cava, ascending aorta, left atrial appendage (anterior and posterior approaches), transverse sinus, and atrioventricular groove). After successful target acquisition, the device was withdrawn through the subxiphoid port. When the hemodynamics stabilized, the device was navigated to another target. The heart rate, arterial blood pressure, central venous pressure, pulmonary arterial pressure, and mixed venous oxygen saturation were measured at every pre-target (subxiphoid incision) and target point. After the navigation trials, the animals were sacrificed and the mediastinum space was examined for procedure-related injuries. RESULTS: The device afforded a good view, and the navigation trials were successfully performed on the beating heart. Four animals tolerated the procedures, while 1 died of device-induced ventricular fibrillation after the trials. Hemodynamics were severely compromised at all anatomical targets except the left atrial appendage (anterior approach). CONCLUSIONS: Subxiphoid videopericardioscopy significantly interferes with the cardiac rhythm, causing life-threatening arrhythmia and hemodynamic compromise, when the target is located deep and far from the pericardiotomy. A flexible or highly articulated device would enable intrapericardial navigation without hemodynamic compromise.

OBJECTIVES: we sought to determine whether patients with functional mitral regurgitation (FMR) would benefit from ventricular reshaping by the Coapsys device (Myocor, Inc., Maple Grove, Minnesota). BACKGROUND: FMR occurs when ventricular remodeling impairs valve function. Coapsys is a ventricular shape change device placed without cardiopulmonary bypass to reduce FMR. It compresses the mitral annulus and reshapes the ventricle. We hypothesized that Coapsys for FMR would improve clinical outcomes compared with standard therapies. METHODS: RESTOR-MV (Randomized Evaluation of a Surgical Treatment for Off-Pump Repair of the Mitral Valve) was a randomized, prospective, multicenter study of patients with FMR and coronary disease with core laboratory analysis. After enrollment, patients were stratified to the standard indicated surgery: either coronary artery bypass graft alone or coronary artery bypass graft with mitral valve repair. In each stratum, randomization was to either control (indicated surgery) or treatment (coronary artery bypass graft with Coapsys ventricular reshaping). RESULTS: the study was terminated when the sponsor failed to secure ongoing funding; 165 patients were randomized. Control and Coapsys both produced decreases in left ventricular (LV) end-diastolic dimension and MR at 2 years (p < 0.001); Coapsys provided a greater decrease in LV end-diastolic dimension (p = 0.021). Control had lower MR grades during follow-up (p = 0.01). Coapsys showed a survival advantage compared with control at 2 years (87% vs. 77%) (hazard ratio: 0.421; 95% confidence interval: 0.200 to 0.886; stratified log-rank test; p = 0.038). Complication-free survival (including death, stroke, myocardial infarction, and valve reoperation) was significantly greater with Coapsys at 2 years (85% vs. 71%) (hazard ratio: 0.372; 95% confidence interval: 0.185 to 0.749; adjusted log-rank test; p = 0.019). CONCLUSIONS: analysis of RESTOR-MV indicates that patients with FMR requiring revascularization treated with ventricular reshaping rather than standard surgery had improved survival and a significant decrease in major adverse outcomes. This trial validates the concept of the ventricular reshaping strategy in this subset of patients with heart failure. (Randomized Evaluation of a Surgical Treatment for Off-Pump Repair of the Mitral Valve [RESTOR-MV]; NCT00120276).

Functional mitral regurgitation or functional tricuspid regurgitation most commonly result from maladaptive remodeling due to ischemic heart disease or idiopathic dilatative cardiomyopathy. We report a case of significant functional mitral regurgitation and functional tricuspid regurgitation arising from isolated annular dilatation secondary to atrial fibrillation and associated atrial remodeling. The patient underwent successful mitral and tricuspid valve repair and a bi-atrial Maze procedure.

PURPOSE: We developed a novel, highly articulated robotic surgical system (CardioARM) to enable minimally invasive intrapericardial therapeutic delivery through a subxiphoid approach. We performed preliminary proof of concept studies in a porcine preparation by performing epicardial ablation. DESCRIPTION: CardioARM is a robotic surgical system having an articulated design to provide unlimited but controllable flexibility. The CardioARM consists of serially connected, rigid cyclindrical links housing flexible working ports through which catheter-based tools for therapy and imaging can be advanced. The CardioARM is controlled by a computer-driven, user interface, which is operated outside the operative field. EVALUATION: In six experimental subjects, the CardioARM was introduced percutaneously through a subxiphoid access. A commercial 5-French radiofrequency ablation catheter was introduced through the working port, which was then used to guide deployment. In all subjects, regional ("linear") left atrial ablation was successfully achieved without complications. CONCLUSIONS: Based on these preliminary studies, we believe that the CardioARM promises to enable deployment of a number of epicardium-based therapies. Improvements in imaging techniques will likely facilitate increasingly complex procedures.

Robotic assistance enhances conventional endoscopy; yet, limitations have hindered its mainstream adoption for cardiac surgery. HeartLander is a miniature mobile robot that addresses several of these limitations by providing precise and stable access over the surface of the beating heart in a less-invasive manner. The robot adheres to the heart and navigates to any desired target in a semiautonomous fashion. The initial therapies considered for HeartLander generally require precise navigation to multiple surface targets for treatment. To balance speed and precision, we decompose any general target acquisition into navigation to the target region followed by fine positioning to each target. In closed-chest, beating-heart animal studies, we demonstrated navigation to targets located around the circumference of the heart, as well as acquisition of target patterns on the anterior and posterior surfaces with an average error of 1.7 mm. The average drift encountered during station-keeping was 0.7 mm. These preclinical results demonstrate the feasibility of precise semiautonomous delivery of therapy to the surface of the beating heart using HeartLander.

OBJECTIVE: Minimally invasive repair of mitral valve prolapse (MVP) causing severe mitral regurgitation (MR) should reduce MR and have chronic durability. Our ex vivo, acute in vivo, and chronic in vivo studies suggest that direct application of radiofrequency ablation (RFA) to mitral leaflets and chordae can effect these repair goals to decrease MR. METHODS: A total of seven canines were studied to assess the effects of RFA on mitral valve structure and function. RFA was applied ex vivo (n = 1), acutely in vivo using a right lateral thoracotomy and cardiopulmonary bypass (n = 3), and chronically in vivo using percutaneous access to the heart (n = 3). RFA was applied to the mitral valve and its associated chordae. Mitral valve structure and function (in vivo preparations) were then assessed. RESULTS: Ex vivo application of RFA resulted in qualitative reduction in mitral leaflet surface area and chordal length. Acute in vivo application of RFA to canines found to have MVP causing severe MR demonstrated a 43.7-60.7% statistically significant (P = 0.039) reduction in postablation MR. Chronic, in vivo, percutaneous application of RFA was found to be feasible and the engendered alterations durable. CONCLUSION: These data suggest that myxomatous mitral valve repair using radiofrequency energy delivered via catheter is feasible.

OBJECTIVE: We sought to promote myocardial repair using urinary bladder matrix incorporated with a fusion protein that combined hepatocyte growth factor and fibronectin collagen-binding domain in a porcine model. Collagen-binding domain acted as an intermediary to promote hepatocyte growth factor binding and enhance hepatocyte growth factor stability within urinary bladder matrix. METHODS: Urinary bladder matrix incorporated with collagen-binding domain and hepatocyte growth factor was implanted into the porcine right ventricular wall (F group) to repair a surgically created defect. Untreated urinary bladder matrix patches (U group) and Dacron patches (D group) served as controls (N = 5/group). Electromechanical mapping was performed 60 days after surgery. Linear local shortening was used to assess regional contractility, and electrical activity was recorded. RESULTS: Linear local shortening was significantly improved in the F group compared with controls (F: 0.51% +/- 1.57% [P < .05], U: -1.06% +/- 1.84%, D: -2.72% +/- 2.59%), whereas it was inferior to the normal myocardium (13.7% +/- 4.3%; P < .05). Mean electrical activity was 1.49 +/- 0.82 mV in the F group, which was statistically greater than in the control groups (U: 0.93 +/- 0.71 mV; D: 0.30 +/- 0.22 mV; P < .05) and less than the normal myocardium (8.24 +/- 2.49 mV; P < .05). Histologic examination showed predominant alpha-smooth muscle actin positive cells with the F group showing the thickest layer and the D group showing the thinnest layer, with an endocardial endothelial monolayer. Scattered isolated islands of alpha-actinin positive cells were observed only in the F group, but not in the controls, suggesting the presence of cardiomyocytes. CONCLUSION: The collagen-binding domain/hepatocyte growth factor/urinary bladder matrix patch demonstrated increased contractility and electrical activity compared with urinary bladder matrix alone or Dacron and facilitated a homogeneous repopulation of host cells. Urinary bladder matrix incorporated with collagen-binding domain and hepatocyte growth factor may contribute to constructive myocardial remodeling.

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.

A patient presenting with a history of transient ischemic attacks was initially diagnosed with a large secundum-type atrial septal defect by transesophageal echocardiography. Subsequent attempts to percutaneously repair the defect using an Amplatzer septal occlude device (AGA Medical, Plymouth, MN) failed to position correctly on multiple attempts. At the time of surgery, a largely deficient and highly fenestrated septum primum was found, which was likely the cause of the Amplatzer device (AGA Medical) failure. The defect was then definitively repaired using a bovine pericardial patch without incident.