Clinical Experience of HeartMate II to HeartWare Left Ventricular Assist Device Exchange: A Multicenter Experience.

BACKGROUND: Despite improvements in pump design and durability, left ventricular assist device patients still suffer from life-threatening complications such as pump thrombosis (PT) and infection, often necessitating device exchange. Surgical exchange from HeartMate II (HM2; Abbott, Pleasanton, CA) to another HM2 is safe and associated with low mortality, but recurrent device thrombosis rates are high. Switching from axial-flow to centrifugal-flow pump, such as the HeartWare ventricular assist device (HVAD; Medtronic, Framingham, MA) may offer certain advantages due to it being a smaller, newer generation device, although there are limited data to support this strategy. Herein, we aimed to assess the surgical approach and feasibility, safety, and outcomes of surgical exchange from HM2 to HVAD. METHODS: We evaluated HM2 patients who underwent device exchange to HVAD due to PT or infection at 4 large-volume left ventricular assist device implant centers. RESULTS: Twenty-four patients underwent HM2 to HVAD exchange due to PT (92%) and refractory infection (8%). Patients were male (75%), white (88%), with ischemic cardiomyopathy (54%), Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) scale level 1-3 (90%), and destination therapy (62%). The majority underwent redo-sternotomy (79%) and the remainder underwent minimally invasive thoracotomy with subcostal approach. The existing HM2 outflow graft was maintained in 79% of cases. Recurrent PT was noted in 9% of patients. Mortality was 8% at 30 days and 33% at 1 year. CONCLUSIONS: The surgical exchange from a HM2 to HVAD is safe and feasible, despite the differences in device specifications and surgical adaptation required. Newer-generation pumps are increasingly considered for exchange in the setting of HM2 device complication, and increasing experience with modified surgical approaches may be valuable in the current era.

Organ-mounted robot localization via function approximation.

BACKGROUND: Organ-mounted robots adhere to the surface of a mobile organ as a platform for minimally invasive interventions, providing passive compensation of physiological motion. This approach is beneficial during surgery on the beating heart. Accurate localization in such applications requires accounting for the heartbeat and respiratory motion. Previous work has described methods for modeling quasi-periodic motion of a point and registering to a static preoperative map. The existing techniques, while accurate, require several respiratory cycles to converge. METHODS: This paper presents a general localization technique for this application, involving function approximation using radial basis function (RBF) interpolation. RESULTS: In an experiment in the porcine model in vivo, the technique yields mean localization accuracy of 1.25 mm with a 95% confidence interval of 0.22 mm. CONCLUSIONS: The RBF approximation provides accurate estimates of robot location instantaneously.

Combined carotid endarterectomy and transcatheter aortic valve replacement: Technique and outcomes.

BACKGROUND: Stroke and transient ischemic attack after transcatheter aortic valve replacement results in significantly higher morbidity and mortality. Severe carotid artery disease may be a contributing factor to this increased risk. We report our technique and outcomes of combined carotid endarterectomy (CEA) with transcatheter aortic valve replacement (TAVR). METHODS: From March 2013 to November 2017 a total of 753 TAVRs were performed at our institution for symptomatic severe aortic stenosis. Of this group, 16 patients underwent concomitant TAVR and CEA. A retrospective review was performed to assess risk, outcomes, and short-term survival. RESULTS: Sixteen patients underwent concomitant CEA/TAVR procedures for severe carotid and severe aortic stenosis. The mean Society of Thoracic Surgeons (STS) Risk Score was 7.0 ± 4.7. All patients had severe carotid artery stenosis and aortic stenosis. Nine patients had a transfemoral TAVR approach and eight patients had a transapical TAVR approach. The mean length of stay was 6.4 ± 3.7 days. At 30 days there were no cerebrovascular events and no mortalities. CONCLUSIONS: The use of concomitant CEA and TAVR in patients with severe aortic stenosis and severe carotid stenosis can be done safely without increased risk of complications. This approach may reduce the risk of stroke associated with TAVR in appropriately selected patients.

Beating-heart registration for organ-mounted robots.

BACKGROUND: Organ-mounted robots address the problem of beating-heart surgery by adhering to the heart, passively providing a platform that approaches zero relative motion. Because of the quasi-periodic deformation of the heart due to heartbeat and respiration, registration must address not only spatial registration but also temporal registration. METHODS: Motion data were collected in the porcine model in vivo (N = 6). Fourier series models of heart motion were developed. By comparing registrations generated using an iterative closest-point approach at different phases of respiration, the phase corresponding to minimum registration distance is identified. RESULTS: The spatiotemporal registration technique presented here reduces registration error by an average of 4.2 mm over the 6 trials, in comparison with a more simplistic static registration that merely averages out the physiological motion. CONCLUSIONS: An empirical metric for spatiotemporal registration of organ-mounted robots is defined and demonstrated using data from animal models in vivo.

Significance of Residual Mitral Regurgitation After Continuous Flow Left Ventricular Assist Device Implantation.

OBJECTIVES: This study hypothesized that the presence of residual mitral regurgitation (MR) post-continuous flow (CF) left ventricular assist device (LVAD) implantation based on quantitative assessment would be negatively associated with right ventricular (RV) size and function and clinical outcomes. BACKGROUND: MR is associated with elevated left atrial pressure, secondary pulmonary hypertension and RV dysfunction. Implantation of a LVAD leads to mechanical unloading of the left ventricle and generally improves MR. The clinical significance of residual MR in patients supported with CF LVADs is uncertain. Most studies evaluating the presence of MR in LVAD patients have utilized predominantly qualitative assessments of MR. METHODS: We retrospectively identified patients implanted with CF LVADs at our institution from 2007 to 2013 who had a pre-operative transthoracic echocardiogram (TTE) within 3 months of LVAD implant and who had a post-operative TTE at least 1 month post-LVAD. MR was assessed quantitatively using the ratio of MR color jet area (CJA)/left atrial area (LAA) in apical views. We also compared quantitative RV metrics, hospitalizations, and mortality in patients with and without significant residual MR (defined as MR CJA/LAA >0.2) on post-implantation TTE. RESULTS: Sixty-nine patients were included in this study. Post-LVAD implantation, 55 patients (80%) had mild or less MR (mean MR CJA/LAA 0.08) but 14 (20%) had significant residual MR (mean MR CJA/LAA 0.34). Patients with residual MR had significantly larger RV size (right ventricular end diastolic dimension 49 mm vs. 45 mm; p = 0.04) and worse RV function (tricuspid annular plane systolic excursion 10 mm vs. 12 mm; p = 0.02; and right ventricular fractional area change 29% vs. 34%; p = 0.02). Post-implantation pulmonary artery pressures were higher in patients with residual MR (pulmonary artery systolic 43 mm Hg vs. 35 mm Hg; p = 0.05). In patients with residual MR there was slightly greater posterior displacement of the mitral coaptation point on pre-operative TTE (28 mm vs. 26 mm; p = 0.16) but this difference was not significant. Time from LVAD implantation to first hospitalization was shorter in patients with residual MR (62 days vs. 103 days; p = 0.05) as was time from LVAD implantation to death (80 days vs. 421 days; p = 0.03). CONCLUSIONS: Significant residual MR post-LVAD implantation assessed by a quantitative measure is associated with persistent pulmonary hypertension, worse RV function, and significantly shorter time to hospitalization and death. MR post-LVAD implantation may serve as a surrogate for adverse outcomes post-LVAD implantation.

Parallel Force/Position Control of an Epicardial Parallel Wire Robot.

Gene therapies for heart failure have emerged in recent years, yet they lack an effective method for minimally invasive, uniform delivery. To address this need we developed a minimally invasive parallel wire robot for epicardial interventions. Accurate and safe interventions using this device require control of force in addition to injector position. Accounting for the nonidealities of the device design, however, yields nonlinear and underconstrained statics. This work solves these equations and demonstrates the efficacy of using this information in a parallel control scheme, which is shown to provide superior positioning compared to a position-only controller.

Successful treatment of acute left ventricular assist device thrombosis and cardiogenic shock with intraventricular thrombolysis and a tandem heart.

Management for continuous flow left ventricular assist device (LVAD) thrombosis often relies on speculation of individual clinical risk factors and integration of indirect evidence for device dysfunction. There are no comprehensive guidelines for treatment of this serious complication, and most of our current knowledge comes from anecdotal experience or observational study. More data on effective treatment, both with aggressive pharmacologic and device-based interventions, are needed for improving our understanding of mechanisms driving device thrombosis and for preventing future events. We present a case of LVAD thrombosis with emphasis on recognition and treatment of acute pump thrombosis, and discuss a potentially novel strategy using percutaneous mechanical circulatory support for pump salvage.

A parallel wire robot for epicardial interventions.

This paper describes the design and preliminary testing of a planar parallel wire robot that adheres to the surface of the beating heart and provides a stable platform for minimally invasive epicardial therapies. The device is deployed through a small subxiphoid skin incision and attaches to the heart using suction. This methodology obviates mechanical stabilization and lung deflation, which are typically required during minimally invasive beating-heart surgery. The prototype design involves three vacuum chambers connected by two flexible arms. The chambers adhere to the epicardium, forming the vertices of a triangular base structure. Three cables connect a movable end-effector head to the three bases; the cables then pass out of the body to external actuators. The surgical tool moves within the triangular workspace to perform injections, ablation, or other tasks on the beating heart. Tests in vitro and in vivo were conducted to demonstrate the capabilities of the system. Tests in vivo successfully demonstrated the ability to deploy through a subxiphoid incision, adhere to the surface of the beating heart, move the surgical tool head within the robot's workspace, and perform injections into the myocardium.

Use of Extracorporeal Membrane Oxygenation to Stabilize a Polytrauma Patient During Intramedullary Nailing of a Femoral Fracture: A Case Report.

CASE: An eighteen-year-old polytrauma patient sustained multiple nonorthopaedic and orthopaedic injuries, including a closed femoral shaft fracture. She was started on extracorporeal membrane oxygenation (ECMO) for respiratory failure. After added resuscitation and stabilization, she underwent intramedullary nailing of the femoral fracture while on ECMO on the third day after the injury. She remained stable throughout the case and recovered after a prolonged hospital course. At the most recent clinical follow-up, she was walking without assistance and had union of the fracture. CONCLUSIONS: ECMO successfully stabilized and mitigated any potential pulmonary complications during intramedullary nailing of a femoral shaft fracture in an unstable patient with polytrauma.

Insertion of an Abiomed Impella® left ventricular assist device following bioprosthetic aortic valve placement.

BACKGROUND: Post-cardiotomy cardiogenic shock is an infrequent devastating complication with few options for support. MATERIALS AND METHODS: We present a case highlighting use of the Impella 5.0 (ABIOMED; Danvers, MA) for postcardiotomy cardiogenic shock after coronary artery bypass and bioprosthetic aortic valve replacement. RESULTS: Support was maintained for 7 days before being successfully weaned with myocardial recovery and no damage to the bioprosthetic aortic valve. CONCLUSIONS: This is the first published report of successful use of an Impella 5.0 (ABIOMED; Danvers, MA) for post-cardiotomy cardiogenic shock through a new implanted bioprosthetic aortic valve.

Use of extracorporeal membrane oxygenation support during an emergent decompression of a thoracic epidural abscess.

STUDY DESIGN: Case report. OBJECTIVE: To present the first reported case of using extracorporeal membrane oxygenation (ECMO) support in an emergent decompression and evacuation of a thoracic epidural abscess. SUMMARY OF BACKGROUND DATA: Thoracic epidural abscesses with neurological deficits require surgical evaluation and intervention in most cases. We report a case of a 35-year-old patient with an acute onset of paraplegia diagnosed with a thoracic epidural abscess. The patient was emergently taken to the operating room and was unable to tolerate prone positioning secondary to cardiopulmonary collapse. ECMO was initiated for cardiopulmonary support to complete the case. METHODS: Retrospective chart review of patient case. RESULTS: The patient was stabilized with ECMO support and tolerated a T4-T8 laminectomy and decompression. The source of the patients abscess was hematogenous and at 6 months of clinical follow-up, the patient has no motor or sensory function of his bilateral lower extremities. CONCLUSION: The use of ECMO support in adult spinal surgery has not been previously reported in the literature. Therefore we describe the first reported use of ECMO to maintain cardiopulmonary support in a patient unable to tolerate prone positioning during spine surgery. ECMO support can be a viable option in adult patients who need emergent spinal surgery but are unable to tolerate prone positioning secondary to cardiopulmonary complications.

Incidence of aortic arch anomalies in patients with thoracic aortic dissections.

BACKGROUND AND AIM OF STUDY: Traditionally aortic arch anomalies have been viewed as a "normal" and clinically insignificant; therefore, they are often overlooked by radiologists and go unreported. Arch anomalies have been reported to occur in 7% to 15% of patients without thoracic aortic aneurysm or dissection. This study aims to define the incidence of aortic arch anomalies in patients with a thoracic aortic dissection (TAD). METHODS: We retrospectively reviewed all patients from 2006 to 2010 with a TAD admitted to a single institution. Thoracic computed tomography images of 176 patients with dissected thoracic aortas and 179 consecutive, unselected age-matched patients without dissection as controls were reviewed to determine the incidence of bovine arch and other arch anomalies. Statistical analysis of demographic data and clinical outcomes was performed to evaluate significant differences between the groups. RESULTS: Arch anomalies occurred in 34% of patients with TAD compared to controls (19%, p = 0.0017). The most common variant was a common origin of the innominate and left common carotid arteries ("bovine" arch) found in 31% of dissection patients compared to 15% in the control group (p = 0.0004). Overall arch anomalies occurred in 27% of all Type A dissections and 39% (p = 0.1409) of all Type B dissections. The association was statistically significant in patients ages 50 to 79 with TAD (36.4%, p = 0.0011) and in African Americans collectively (43.2%, p = 0.0033). CONCLUSIONS: Aortic arch anomalies occur frequently in patients with TAD and therefore may represent a proclivity for this life threatening condition.

Contemporary incidence and risk factors for carotid artery disease in patients referred for coronary artery bypass surgery.

BACKGROUND: In the past decade, there has been an increase in the amount of patients with medical co-morbidities referred for coronary artery bypass surgery (CABG). Significant carotid artery disease in patients undergoing CABG procedures increases the risk of neurological complications. We review the results of routine carotid screening in patients undergoing CABG to determine the contemporary incidence and risk factors for carotid artery disease. METHODS: Between 2008 through 2010, 673 patients were referred for isolated coronary artery bypass surgery at a single institution. Patients were identified through a systematic review of The Department of Cardiothoracic Surgery Society of Thoracic Surgery Outcomes Database. A retrospective analysis of prospectively collected demographic, clinical data and outcomes were performed. All patients with screening preoperative carotid duplex were reviewed. We defined the degree of carotid disease as: none to mild stenosis (<50%), moderate stenosis (50-69%), severe stenosis (70-99%). Multivariate analysis was performed to identify risk factors. RESULTS: 559 (83%) patients underwent screening preoperative carotid ultrasonography prior to CABG. The incidence of carotid artery disease (>50% stenosis) was 36% with 18% unilateral moderate disease, 10% bilateral moderate and 8% severe disease. Risk factors associated with carotid artery disease included: advanced age, renal failure, previous stroke, peripheral vascular disease, left main coronary artery disease, and previous myocardial infarction. CONCLUSIONS: There is a significant incidence of carotid artery stenosis in patients referred for CABG. Routine screening will identify patients with carotid artery disease and may reduce the risk of postoperative stroke.

Chronic thromboembolic pulmonary hypertension.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a potentially life-threatening condition characterized by obstruction of pulmonary arterial vasculature by acute or recurrent thromboemboli with subsequent organization, leading to progressive pulmonary hypertension and right heart failure. Until relatively recently, CTEPH was a diagnosis made primarily at autopsy, but advances made in diagnostic modalities and surgical pulmonary endarterectomy techniques have made this disease treatable and even potentially curable. Although published guidelines are available, in the absence of randomized controlled trials regarding CTEPH there is a lack of standardization, and treatment options have to be individualized.

Salvage peripheral extracorporeal membrane oxygenation using Cobe Revolution(®) centrifugal pump as a bridge to decision for acute refractory cardiogenic shock.

OBJECTIVES: Acute refractory cardiogenic shock with early multisystem organ failure has a poor outcome without mechanical circulatory support. We review our experience with emergent peripheral cardiopulmonary support as a bridge to decision in these patients. METHODS: A retrospective review from January 2009 through December 2010 was conducted of 26 consecutive adult patients at a single institution with acute refractory cardiogenic shock who underwent salvage peripheral cardiopulmonary support. RESULTS: There were 18 men and 8 women with a mean age of 54 years (range 18 to 76). Indications for support: acute myocardial infarction (n = 16), decompensated chronic heart failure (n = 2), refractory arrhythmic arrest (n = 3), acute valvular pathology (n = 4), and unknown (n = 1). Patients with primary postcardiotomy shock were excluded. Median duration of support was 3 days (range 1 to 14). Decisions included: withdraw of support (n = 4), recovery (n = 5), and bridge to a procedure (n = 17). The procedures were percutaneous coronary intervention (n = 4), left ventricular assist device (n = 9), heart transplantation (n = 1), and miscellaneous cardiac surgery (n = 3). Overall survival to discharge was 65%. In the recovery and bridge to a procedure group, 78% were discharged from the hospital and survival at three months was 72%. CONCLUSIONS: Salvage peripheral cardiopulmonary support is a useful tool to rapidly stabilize acute refractory cardiogenic shock permitting an assessment of neurologic and end-organ viability.

Temporary mechanical circulatory support for Takotsubo cardiomyopathy secondary to primary mediastinal B-cell lymphoma.

BACKGROUND: Left heart mechanical circulatory support (MCS) through the left chest via the pulmonary vein and descending thoracic aorta is a good option for patients with an inaccessible anterior mediastinum and/or poor peripheral access. MATERIALS AND METHODS: We report the case of a 19-year-old small female with a newly discovered bulky primary mediastinal diffuse large B-cell lymphoma (PMBL) who developed refractory inverted Takotsubo cardiomyopathy (TC) with cardiogenic shock. RESULTS: Temporary MCS was implemented in order to stabilize the patient and proceed with a chemotherapy treatment. Given the patient's oncologic "frozen" mediastinum and the presence of poor peripheral arterial access, the left heart temporary MCS was successfully implanted through a left mini-thoracotomy via the left inferior pulmonary vein and descending thoracic aorta. CONCLUSIONS: This is the first report of temporary MCS to treat inverted TC and diffuse PMBL.

Aortic valve replacement in patients with systemic mastocytosis.

Systemic mastocytosis is a hematologic disorder with important perioperative implications. A variety of stimuli and medications can cause severe anaphylaxis in these patients. We report successful preoperative, intraoperative, and postoperative management of a patient with systemic mastocytosis who underwent an aortic valve replacement and review the literature pertaining to cardiac surgery in these patients.