Incidence and Variables Predictive of Pressure Injuries in Patients Undergoing Ventricular Assist Device and Total Artificial Heart Surgeries: An 8-Year Retrospective Cohort Study.

OBJECTIVE: To investigate the incidence and risk factors of pressure injury (PI) development after ventricular assist device (VAD) or total artificial heart (TAH) surgery. METHODS: The investigator reviewed all VAD-TAH surgeries performed between 2010 and 2018 in a large academic health system. The PIs were reported by case incidence, patient incidence, and incidence density for each of the respective 1,000 patient days during the study period. Statistics on four different VAD-TAH devices were assessed; variables significant in bivariate analysis were entered into a stepwise logistic regression model to identify significant predictors of PI. RESULTS: The sample included 292 independent VAD-TAH surgeries among 265 patients. Thirty-two patients developed 45 PIs. The PI incidence was 11% (32/292), with a PI incidence per patient of 12% (32/265). Incidence density was 10 per 1,000 patient days (1%) for 2010-2012, 12 per 1,000 patient days (1.2%) for 2013-2015, and 10 per 920 patient days (1.1%) for 2016-2018. Logistic regression revealed that significant predictor variables for PI were age, mechanical ventilation time, and preoperative Braden Scale score. The mean time to PI was 23 days after admission and over 14 days after surgery, indicating a low rate of intraoperative and ICU-associated PI. CONCLUSIONS: The incidence of PI was lower than anticipated given historic rates. Potential mechanisms by which these patients were protected from PI are discussed. Prospective studies to further investigate significant risk factors and effective prevention measures are warranted.

Analysis of Cleveland Clinic continuous-flow total artificial heart performance using the Virtual Mock Loop: Comparison with an in vivo study.

The Virtual Mock Loop (VML) is a mathematical model designed to simulate mechanism of the human cardiovascular system interacting with mechanical circulatory support devices. Here, we aimed to mimic the hemodynamic performance of Cleveland Clinic's self-regulating continuous-flow total artificial heart (CFTAH) via VML and evaluate the accuracy of the VML compared with an in vivo acute animal study. The VML reproduced 124 hemodynamic conditions from three acute in vivo experiments in calves. Systemic/pulmonary vascular resistances, pump rotational speed, pulsatility, and pulse rate were set for the VML from in vivo data. We compared outputs (pump flow, left and right pump pressure rises, and atrial pressure difference) between the two systems. The pump performance curves all fell in the designed range. There was a strong correlation between the VML and the in vivo study in the left pump flow (r2 = 0.84) and pressure rise (r2 = 0.80), and a moderate correlation in right pressure rise (r2 = 0.52) and atrial pressure difference (r2 = 0.59). Although there is room for improvement in simulating right-sided pump performance of self-regulating CFTAH, the VML acceptably simulated the hemodynamics observed in an in vivo study. These results indicate that pump flow and pressure rise can be estimated from vascular resistances and pump settings.

Results of primary biventricular support: an analysis of data from the EUROMACS registry.

OBJECTIVES: The purpose of this study was to describe pre- and postoperative data from the EUROMACS registry with regard to indications, for and survival and complication rates of patients with primary continuous flow and pulsatile biventricular long-term assist devices (BiVADs) versus total artificial hearts (TAHs) or left ventricular assist devices (LVADs) + short-term right ventricular assist device (RVAD) implants. METHODS: We investigated patients who received implants between 1 January 2011 and 21 October 2017. Clinical baseline information about comorbidities, laboratory results, medical and device therapies and echocardiographic, haemodynamic and right ventricle (RV) parameters were evaluated along with the rates of deaths and complications. RESULTS: A total of 413 of 3282 patients (12.5%) needed a biventricular pump. We investigated 37 long-term BiVADs, 342 LVAD + short-term RVAD implants and 34 TAHs. Minor differences were found in the baseline characteristics of our population, which had an overall high morbidity profile. The 1-year survival rate was 55% for patients with a continuous flow BiVAD; 52% for patients with an LVAD + short-term RVAD; 37% for patients with pulsatile BiVADs; and 36% for patients with a TAH. No statistical difference was observed among the groups. Over 50% of patients with BiVAD support were classified as INTERMACS profiles 1 and 2. The percent of patients with ambulatory heart failure (INTERMACS 4‒7) undergoing BiVAD implants was modest at <15%. No patients with a pulsatile BiVAD (n = 15) or a TAH (n = 34) were implanted as destination therapy, but 27% of the patients with continuous flow BiVADs (n = 6) and 23% of the patients with LVAD + short-term RVAD (n = 342) were implanted as 'destination'. The adverse events profile remained high, with no significant difference among pump types. The right ventricular stroke work index and right heart failure scores indicated poor RV function in all groups. After 3 months of LVAD + short-term RVAD support, 46.7% still required ongoing support, and only 18.5% were weaned from RVAD support; 33.1% died. CONCLUSIONS: The mortality rate after BiVAD support was high. Survival rates and adverse events were statistically not different among the investigated groups. In the future, composite study end points examining quality of life and adverse events beyond survival may help in shared decision-making prior to general mechanical circulatory support, particularly in patients with BiVAD implants.

Successful heart transplantation in patients with total artificial heart infections.

BACKGROUND: Data are limited on clinical outcomes in patients awaiting heart transplant (HT) with total artificial heart (TAH) infections. METHODS: We retrospectively reviewed all TAH recipients at our center. TAH infection was classified as definite if a microorganism was isolated in cultures from the exit site or deep tissues around the TAH; as probable in patients without surgical or microbiologic evidence of infection but no other explanation for persistent or recurrent bloodstream infection (BSI); or possible in patients with clinical suspicion and radiographic findings suggestive of TAH infection, but without surgical intervention or microbiologic evidence. RESULTS: From 2012 to 2015, a total of 13 patients received a TAH, with a median age at implantation of 52 years (range: 28-60). TAH infection occurred in nine patients (seven definite, one probable, one possible) a median of 41 days after implant (range: 17-475). The majority of TAH infections were caused by Staphylococcus species. Seven of nine patients underwent HT (four had pre-HT mediastinal washout, and five had positive HT operative cultures). Three patients had an active BSI caused by the same pathogen causing TAH infection at the time of HT, with one developing a post-HT BSI with the same bacteria. No patient developed post-HT surgical site infection caused by the TAH infection pathogen. No deaths among HT recipients were attributed to infection. CONCLUSION: TAH infection is frequently associated with BSI and mediastinitis and Staphylococcus was the most common pathogen. A multimodal approach of appropriate pre- and post-HT antimicrobial therapy, surgical drainage, and heart transplantation with radical mediastinal debridement was successful in curing infection.

Ethical Analysis of Withdrawing Total Artificial Heart Support.

OBJECTIVES: To describe the characteristics of patients who undergo withdrawal of total artificial heart support and to explore the ethical aspects of withdrawing this life-sustaining treatment. PATIENTS AND METHODS: We retrospectively reviewed the medical records of all adult recipients of a total artificial heart at Mayo Clinic from the program's inception in 2007 through June 30, 2015. Management of other life-sustaining therapies, approach to end-of-life decision making, engagement of ethics and palliative care consultation, and causes of death were analyzed. RESULTS: Of 47 total artificial heart recipients, 14 patients or their surrogates (30%) requested withdrawal of total artificial heart support. No request was denied by treatment teams. All 14 patients were supported with at least 1 other life-sustaining therapy. Only 1 patient was able to participate in decision making. CONCLUSION: It is widely held to be ethically permissible to withdraw a life-sustaining treatment when the treatment no longer meets the patient's health care-related goals (ie, the burdens outweigh the benefits). These data suggest that some patients, surrogates, physicians, and other care providers believe that this principle extends to the withdrawal of total artificial heart support.

Use of mechanical circulatory support devices in end-stage heart failure patients.

BACKGROUND: Mechanical circulatory support (MCS) is the standard therapy for the management of acute or chronic end-stage heart failure. We report on our two-center experience with MCS therapy. METHODS: Between January 2000 and December 2012, 116 adult patients (mean age 56.8 ± 9.9 years, range: 31 to 76 years) were primarily supported on temporary or long-term ventricular assist devices (VADs) or total artificial hearts (TAHs) at our institutions. Temporary extracorporeal radial VAD support was established in 50 patients (43.1%) (Group A) whereas 66 (56.8%) patients received long-term paracorporeal and intracorporeal VAD or TAH (Group B). LVAD support was established in 63 patients (54.3%), with BVAD/TAH support in 29 (25%). A temporary CentriMag was the only device adopted as an isolated RVAD support, being placed in 24 patients (20.6%). RESULTS: In Group A, the overall mean support time was 10.2 ± 6.6 days (range: 3 to 43 days) and the overall success rate was 55.1% (27 patients). The mean LVAD support time was 357 ± 352.3 days (range: 1 to 902 days) in Group B and 98 ± 82.6 days (range: 8 to 832 days) in BVAD/TAH patients, with success rates of 72.5% (37 patients) and 46.6% (seven patients), respectively. The heart transplantation (Htx) rate for both groups combined was 25.8% (n = 30). The overall one- and five-year survival rates after Htx were 73.3% and 60%, respectively. CONCLUSIONS: When a decision to treat with VAD or TAH is made early, either modality can be used as an alternative to Htx, affording comparable early to mid-term outcomes.

Ethical challenges with deactivation of durable mechanical circulatory support at the end of life: left ventricular assist devices and total artificial hearts.

Left ventricular assist devices (LVADs) and total artificial hearts (TAHs) are surgically implanted as permanent treatment of unrecoverable heart failure. Both LVADs and TAHs are durable mechanical circulatory support (MCS) devices that can prolong patient survival but also alter end-of-life trajectory. The permissibility of discontinuing assisted circulation is controversial because device deactivation is a life-ending intervention. Durable MCS is intended to successfully replace native physiological functions in heart disease. We posit that the presence of new lethal pathophysiology (ie, a self-perpetuating cascade of abnormal physiological processes causing death) is a central element in evaluating the permissibility of deactivating an LVAD or a TAH. Consensual discontinuation of durable MCS is equivalent with allowing natural death when there is an onset of new lethal pathophysiology that is unrelated to the physiological functions replaced by an LVAD or a TAH. Examples of such lethal conditions include irreversible coma, circulatory shock, overwhelming infections, multiple organ failure, refractory hypoxia, or catastrophic device failure. In all other situations, deactivating the LVAD/TAH is itself the lethal pathophysiology and the proximate cause of death. We postulate that the onset of new lethal pathophysiology is the determinant factor in judging the permissibility of the life-ending discontinuation of a durable MCS.

Device therapy and cardiac transplantation for end-stage heart failure.

The prevalence of heart failure is increasing, and the prognosis of end-stage heart failure remains dismal. The gold-standard therapy in end-stage heart failure remains cardiac transplantation at the present time, but there is a great excess of eligible candidates compared with the number of donor organs. Advances in mechanical support, the development of the left ventricular assist device (LVAD), and the total artificial heart has reduced mortality and morbidity in patients awaiting transplantation, and LVADs are now approved as an strategy for destination therapy. Miniaturization, increased device durability, and complete implantability may render LVADs an option in earlier stages of heart failure, as a bridge to myocardial recovery or even as a viable alternative to transplantation. Alternative strategies under investigation are cell therapy and xenotransplantation. In the present article, current and potential future therapeutic options in end-stage heart failure are reviewed.

Total artificial heart--concepts and clinical use.

End-stage congestive heart failure remains the leading cause of death in the United States. Despite advances in medical treatment, it also remains the most common reason for admission to the hospital. The gold standard of treatment for the failing heart, orthotopic heart transplantation, is limited by a shortage of donor hearts. There are also a significant number of patients who are not transplant candidates due to comorbid conditions and/or inability to tolerate immunosuppressive therapy. To meet the need for this latter group, the medical field has embraced ventricular assist device (VAD) therapy to extend survival and improve quality-of-life for the end-stage cardiac patient. This therapy, however, has been currently limited to the failing left ventricle and is still fraught with complications that limit long-term and widespread use. The total artificial heart, as currently available with two devices, is rapidly becoming the treatment of choice for biventricular failure.

[Artificial heart].

Artificial heart or heart transplantation are required for the treatment of profound heart failure. Total artificial heart (TAH) and ventricular assist system (VAS) were developed from late 1950s and 2 extracorporeal pneumatic Japanese VASs (Toyobo VAS and Zeon VAS) were introduced to clinical field from 1980. Now, over 850 patients were applied several types of VASs including Japanese VASs. And 80% of heart transplant recipients were supported by VASs for 714 days (mean). Small size implantable left VAS (LVAS) are required and several types of non-pulsatile pump, including 2 Japanese made centrifugal pumps, are under clinical trials. And destination therapy by using implantable pulsatile LVAS for end-stage heart failure patients has been started in United States and is performed in United States and Europe. In near future, artificial heart and heart transplantation will be selected according to the conditions of the patients with profound heart failure.

Artificial heart research and present status of clinical application in Japan.

Japan has a long history of research and development of the artificial heart since Atsumi began studying artificial hearts at the University of Tokyo in 1959. Since that time, the University of Tokyo group has been developing different types of artificial hearts, as well as materials, blood pumps, driving mechanisms, and control methods. Other than the University of Tokyo, there are 12 institutes involved in artificial heart research and development in Japan. As for artificial heart clinical application in Japan, four devices were approved by the government; two are domestic, two are imported. Between 1980 and 2004, 697 cases of clinical application of a ventricular assist device (VAD) have been performed, including in 38 pediatric patients under 18 years. Recently, clinical use of percutaneous cardiopulmonary support has been increasing with 600 to 800 cases being performed every year, including in 40 to 60 patients under age 20 years. Although the requirement for clinical use of pediatric VADs is increasing, there is no device, domestic or imported, currently used in Japan; therefore, there is an urgent need for development of a pediatric VAD.

[Implantable artificial heart].

Heart transplants have been decreasing globally due to the lack of available donor hearts. As a result, the increased use of artificial hearts is anticipated as an alternative therapy. Although biocompatibility issues, such as thrombus formation/thromboembolism and infection, are still the main cause of mortality associated with artificial hearts, more than 20 different types are now clinically available after a half-century of development and experimental trials. These devices range from extracorporeal pneumatic to implantable battery-powered artificial hearts. The early development of artificial hearts logically focused on volumetric pump designs incorporating functions similar to the natural heart. Today, development has shifted toward designs that are significantly different from the natural heart. These pumps utilize axial or centrifugal flow allowing for a much simpler design, which is smaller in size and has very few moving parts. With rapid advances in technology, this new generation of artificial heart pumps is beginning to emerge as an alternative to heart transplants.

Total artificial heart bridge to transplantation: a 9-year experience with 62 patients.

BACKGROUND: The SynCardia CardioWest total artificial heart (CardioWest TAH) is a biventricular, orthotopic, pneumatic, pulsatile blood pump driven by an external console. For each ventricle, the length of the blood-flow path is shorter and the inflow and outflow valves are larger than in any other bridge-to-transplant device, resulting in greater blood flow at smaller pre-load. Such a device should be optimal for bridging transplant candidates who have biventricular failure and for whom all other therapies have failed. METHODS: From January 1, 1993, to April 1, 2002, we prospectively studied 62 consecutive CardioWest TAH implant recipients to document safety and efficacy in bridge to transplantation. We used multisystem monitoring and multidrug therapy for anti-coagulation in 58 patients starting September 1, 1994. RESULTS: Before implantation, patients were critically ill with biventricular heart failure. Mortality in this group from the time of implantation until transplantation was 23%. Causes of death during device support included multi-organ failure (6), sepsis (3), and valve entrapment (2). Forty-eight patients underwent transplantation (77%). Forty-two survived to hospital discharge (68% of the total, 88% of those undergoing transplantation). Adverse events included bleeding (20%), device malfunction (5%), fit complications (3%), mediastinal infections (5%), visceral embolus (1.6%), and stroke during support (1.6%). The linearized stroke rate was 0.068 events per patient-year. CONCLUSIONS: Sixty-eight percent of critically ill transplant candidates for whom medical therapy failed were bridged to transplantation with the CardioWest TAH and survived long-term. Most deaths that occurred during device support were related to pre-implant problems. Infection and stroke were rare events. Therefore, we recommend the CardioWest TAH as the biventricular bridge-to-transplant device of choice.

Under-utilization of mechanical circulatory support in Canada: why and what can be done?

In October of 2002, a workshop was held as part of the Canadian Cardiovascular Congress in Edmonton, Canada, entitled "Under-Utilization of Mechanical Circulatory Support in Canada. Why and What Can Be Done?" The workshop examined various issues related to the use of mechanical circulatory support devices in the Canadian context. Representatives from all Canadian centers with active mechanical circulatory support programs were invited to participate and participants included surgeons and cardiologists, as well as other affiliated health professionals. Opinions were solicited from the workshop participants and a series of recommendations were formulated.

Mechanical treatment of heart failure: the growing role of LVADs and artificial hearts.

Left ventricular assist devices (LVADs) and artificial hearts are improving. These devices can prolong a patient's life while on a heart transplant list. More exciting, mechanical assistance may provide an opportunity for a damaged heart to recover some function. Still, despite the promise, the use of these devices raises some difficult cost-benefit and ethical questions.