John W. Entwistle

The AbioCor implantable replacement heart

The AbioCor implantable replacement heart (IRH) is the first available totally implantable artificial heart. We recently initiated a multicenter trial of this device in patients with severe, irreversible biventricular failure. Patients who were not candidates for other therapies, including transplantation, were evaluated. All candidates were adults with inotrope-dependent biventricular failure, whose 30-day predicted mortality was higher than 70%. A three-dimensional computerized fit study predicted fit of the AbioCor thoracic unit in all recipients. At operation, the internal battery controller and transcutaneous energy transfer unit were placed. The AbioCor thoracic unit was placed in an orthotopic position after incision of the ventricals. There were 2 intraoperative deaths (due to intraoperative bleeding or aprotinin reaction). Four late deaths were recorded, 1 from multisystem organ failure and 3 cerebrovascular accidents. Autopsy revealed thrombus on the atrial struts of the 3 patients with cerebrovascular accident. Blood pumps and valves were clean on all patients. Significant morbidity was observed, primarily related to preexisting severity of illness. However, 3 patients recovered to the point of being able to take multiple trips outside of the hospital. Two patients were discharged from the hospital, with 1 patient being discharged home for more than 7 months. No significant device malfunctions or multi-system organ failure device-related infections were noted. The AbioCor IRH may be effective therapy for patients with end-stage heart failure. Many milestones have been achieved in the initial trial in humans, including the successful discharge of a patient to home and no significant device malfunctions. The occurrence of stroke is likely related to the presence of thrombus on the atrial struts and may be decreased as these atrial struts have been removed for future clinical implants.

PREVENtion of HeartMate II Pump Thrombosis Through Clinical Management: The PREVENT multi-center study

BACKGROUND Recommended structured clinical practices including implant technique, anti-coagulation strategy, and pump speed management (PREVENT [PREVENtion of HeartMate II Pump Thrombosis Through Clinical Management] recommendations) were developed to address risk of early (<3 months) pump thrombosis (PT) risk with HeartMate II (HMII; St. Jude Medical, Inc. [Thoratec Corporation], Pleasanton, CA). We prospectively assessed the HMII PT rate in the current era when participating centers adhered to the PREVENT recommendations. METHODS PREVENT was a prospective, multi-center, single-arm, non-randomized study of 300 patients implanted with HMII at 24 participating sites. Confirmed PT (any suspected PT confirmed visually and/or adjudicated by an independent assessor) was evaluated at 3 months (primary end-point) and at 6 months after implantation. RESULTS The population included 83% men (age 57 years ± 13), 78% destination therapy, and 83% Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) Profile 1-3. Primary end-point analysis showed a confirmed PT of 2.9% at 3 months and 4.8% at 6 months. Adherence to key recommendations included 78% to surgical recommendations, 95% to heparin bridging, and 79% to pump speeds ≥9,000 RPMs (92% >8,600 RPMs). Full adherence to implant techniques, heparin bridging, and pump speeds ≥9,000 RPMs resulted in a significantly lower risk of PT (1.9% vs 8.9%; p < 0.01) and lower composite risk of suspected thrombosis, hemolysis, and ischemic stroke (5.7% vs 17.7%; p < 0.01) at 6 months. CONCLUSIONS Adoption of all components of a structured surgical implant technique and clinical management strategy (PREVENT recommendations) is associated with low rates of confirmed PT.

Ethical considerations for ventricular assist device support: a 10-point model.

The potential for long-term support on a ventricular assist device (VAD) in the bridge-to-transplant (BTT) and destination therapy (DT) settings has created unprecedented ethical challenges for patients and caregivers. Concerns include the patients adaptation to life on a device and the ethical, clinical, and practical issues associated with living on mechanical support. On the basis of our experience treating 175 consecutive VAD patients, we have developed a model to address the ethical and psychosocial needs of patients undergoing VAD implantation. Patient preparation for VAD implantation encompasses three phases: 1) initial information regarding the physical events involved in implantation, risks and benefits of current device technology, and the use of VAD as a rescue device; 2) preimplant preparation including completion of advance directives specific to BTT/DT, competency determination, and identifying a patient spokesperson, multidisciplinary consultants, and cultural preferences regarding device withdrawal; and 3) VAD-specific end-of-life issues including plans for device replacement and palliative care with hospice or device withdrawal. This three-phase 10-point model addresses the ethical and psychosocial issues that should be discussed with patients undergoing VAD support.

Multimodality therapy for resectable cancer of the thoracic esophagus.

The frequency of esophageal carcinoma continues to increase in North America primarily because of the increased incidence of Barretts epithelium in the distal esophagus and its malignant potential. Aggressive treatments involving multimodality therapies have been offered to improve overall poor survival rates. A review of this experience follows, to explain the rationale and to compare results of therapies. Although preoperative chemoradiation therapy is commonly used for locally advanced disease, few data support its superiority over surgical resection alone, followed by adjuvant therapy when appropriate. Hence this regimen should be limited to patients enrolled in controlled, randomized studies until the data support its widespread use.

The ethics of mechanical support: the need for new guidelines.

Each generation of physicians has been faced with new therapies or technologies that have dramatically changed the way medicine is practiced. Usually, mainstream adoption of such medical advances has been an uncomplicated process. Occasionally, these advances require a thorough reexamination of the way that we approach medical care because they represent such a change in patient management that our conventional assumptions no longer apply. New-generation ventricular assist devices (VADs) represent such a technology. VADs have been used in humans for nearly 50 years, but they have only recently seen widespread adoption to the point that they present todays clinicians with ethical challenges on a large scale. In many cases, these issues arise from patient non-compliance or other disruptive behaviors. Similar issues have been seen with organ transplantation, but guidelines and protocols for patient selection and organ allocation have been established, making psychosocial considerations, such as non-compliance and anti-social behavior, part of the selection process. In this way, the ethical issues surrounding organ transplantation have been mitigated, if not solved. To address the growing ethical problems generated by VAD implantation, similar guidelines are necessary. In the 1990s, VADs were used primarily in patients awaiting transplantation who needed interim support until a suitable organ could be identified. For the most part, they were implanted only in transplant centers as a bridge to transplantation (BTT), and VAD candidates were judged by the same criteria used to evaluate patients for transplantation. Thus, if patients were not candidates for transplantation, they were not candidates for VAD insertion. The decision to exclude certain candidates from VAD therapy was made easier because of the linkage of VADs to organs for transplantation, which are a scarce resource, was widely believed to justify limiting their use to situations in which the chance of success was good.

Short- and long-term mechanical ventricular assistance towards myocardial recovery.

Long-term LVADs are primarily used as a bridge to transplantation because cardiac transplantation currently offers a better long-term outlook for most patients. Some patients will not get the opportunity for transplantation due to organ shortages and long waiting lists, however, and alternate care strategies must be considered. LVAD weaning and explantation may be an appropriate course of action for patients who have IDC and in whom transplantation is not the optimal therapy. The data demonstrate that LVAD weaning may be performed successfully in selected patients with IDC, and that transplantation may be delayed or avoided altogether; however, VAD weaning is not without its risks. Many of the patients have demonstrated recurrence of heart failure at various times after undergoing device removal. Through proper monitoring, most of these patients can be identified early enough to be relisted for transplantation, although some will require reinsertion of an LVAD while waiting. The critical steps in establishing a successful VAD weaning program are proper patient selection, ventricular unloading in the early stages, the institution of heart failure medications, frequent monitoring for ventricular recovery, and a period of ventricular retraining before explantation. In addition, the surgeons must be able to perform the explantation procedure with a low operative mortality. As experience with LVAD weaning and explantation grows, we may be able to better predict which patients may be successfully treated without resorting to transplantation. Explantation may eliminate, or safely delay, the need for cardiac transplantation. Although it is unlikely that these patients will be studied in a randomized fashion, the collection of accurate and complete data may allow us to establish a database that can answer many of todays questions.

Long-term mechanical ventricular assistance toward myocardial recovery

Myocardial recovery after VAD support provides a perfect example of reverse remodeling. It also establishes that heart failure may not be an end of the road situation. Although post-LVAD myocardial recovery has become a distinct entity, basis of reversal of the dedifferentiation process will need to be further explored. With this objective, several centers in the United States have formed the LVAD Working Group to: determine the incidence of myocardial recovery; obtain serial studies to determine the response of the LVAD-supported heart to stress; and study the tissue and serological changes as they relate to the recovery process. Patients enrolled in this study will receive anti-heart failure therapy and serial examinations after implantation and explanation. Stress evaluations will include dobutamine stress echocardiograms as well as bicycle exercise with right heart catheterization. A large database of prospectively collected data will likely result in a greater understanding of myocardial recovery and the LVAD weaning process.

Superior Vena Cava Rupture during Balloon Angioplasty and Stent Placement to Relieve Superior Vena Cava Syndrome: A Case Report

Percutaneous stenting of the superior vena cava (SVC) has been an accepted therapy for SVC syndrome for more than a decade. Complications are uncommon and usually of minor consequence. Three previous reports have described ruptures of the SVC during venoplasty with death on one occasion. We report a fourth case of SVC rupture during angioplasty and stenting that required immediate pericardiocentesis followed by open surgical repair via sternotomy for direct control and repair. An algorithm for rapid recognition and prompt intervention is described.

Postoperative Nesiritide Use following High-Risk Mitral Valve Replacement

Nesiritide is primarily used in the treatment of acutely decompensated chronic heart failure. It may also be useful in the postoperative management of patients with an exacerbation of heart failure after cardiac surgery. The management of a patient with cardiogenic shock after acute papillary muscle rupture is described. The patient exhibited signs of postoperative heart failure, and nesiritide therapy was instituted to lower filling pressures and achieve diuresis. This drug may be useful when patients with heart failure undergo cardiac surgery and continue to show evidence of heart failure in the postoperative period.

Three-dimensional echocardiography of post-myocardial infarction cardiac rupture.

Ventricular septal defects and pseudoaneurysms are two serious complications of acute myocardial infarction and are associated with a high mortality if not surgically treated. Two‐dimensional echocardiography provides excellent diagnostic information in such cases, but three‐dimensional echocardiography may provide superior anatomic data of these potentially fatal complications. We describe two cases in which three‐dimensional echocardiography provided incremental morphological information. (ECHOCARDIOGRAPHY, Volume 21, April 2004)