The total artificial heart: where have we been, where are we now, where are we going?

The incidence and prevalence of end-stage heart failure continue to rise; however, the number of donor hearts available for transplantation continues to be limited. Therefore, alternatives to transplantation, such as the use of total artificial hearts (TAH), are necessary. The long and winding road to the development and implantation of the ideal TAH remains under construction. Although efforts have been ongoing for almost a century, researchers and clinicians continue to improve currently available TAHs and design and construct new models. With mortality and morbidity rates decreasing, particularly at high-volume centers with a dedicated team and carefully selected patients, the use of TAHs as a bridge to transplantation, and even destination therapy in clinical trials, the future of TAHs is bright.

Total artificial heart: surgical technique in the patient with normal cardiac anatomy.

Heart failure is a complex, growing problem with significant morbidity and mortality. Though heart transplantation remains the gold standard treatment for end-stage heart failure, there remains a national shortage of donor hearts. Mechanical circulatory support has provided an additional option for clinicians to support patients for the purposes of bridging patients to transplantation or to be used for destination therapy purposes. Despite generally favorable outcomes with univentricular support, in a subset of patients with biventricular heart failure, an isolated left ventricular assist device is not sufficient. Right ventricular failure has a negative impact on patient survival if not identified and treated promptly. The Total Artificial Heart (TAH) is the only Food and Drug Administration (FDA) approved artificial heart used for bridging patients to transplantation. Outcomes in patients who undergo implantation of the TAH at experienced centers have been good and reproducible.

Role of Methadone in Extracorporeal Membrane Oxygenation: Two Case Reports.

Extracorporeal membrane oxygenation (ECMO) affects pharmacokinetics/dynamics of drugs in unpredictable ways. Anecdotally, ECMO patients require high doses of opioids and sedatives, leading to concerns of tolerance. Methadone is a long-acting synthetic opioid with antagonist properties at the n-methyl-d-aspartate (NMDA) receptor. It has been shown to improve spontaneous breathing trials and weaning from mechanical ventilation; however, there is no literature describing its use in ECMO. We describe two patients from the cardiac surgery intensive care unit at Cedars Sinai (Los Angeles, CA) on ECMO for over 30 days maintained on methadone.

High Molecular Weight von Willebrand Factor Multimer Loss and Bleeding in Patients with Short-Term Mechanical Circulatory Support Devices: A Case Series.

Acquired von Willebrand syndrome (VWS) due to loss of high-molecular-weight multimers (HMWMs) has been reported with longer term mechanical devices and is associated with mucosal bleeding, a primary hemostasis type of bleeding. However, little is known whether a similar defect occurs in patients with short-term mechanical circulatory support (STMCS) devices. We reviewed von Willebrand factor (VWF) profiles in patients with STMCS devices who underwent VWS workup from December 2015 to March 2017 at an academic quaternary care hospital. There were a total of 18 patients (57.0 ± 12.7 years old; 83.3% male) including nine with mucosal bleeding and nine with decreasing hemoglobin. The STMCS devices included Impella (n = 11), Impella and right ventricular assist device (n = 2), and an extracorporeal membrane oxygenator (n = 5). The mean HMWM by quantitative VWF multimer analysis was 3.6% ± 1.3% (normal cutoff: 18-34%). In all 10 cases in which VWF activity, fibrinogen, factor VIII, or VWF antigen level were obtained, they were either normal or elevated. All cases demonstrated high normal or elevated levels of low molecular weight multimers (LMWMs). These findings are consistent with type 2 VWS (qualitative defect). This is the first study that quantitatively describes STMCS device-associated HMWM loss, which may contribute to mucosal bleeding. This finding may have implications for intraoperative management during implantation of longer term devices or heart transplantation or other surgery while on STMCS.

Characterizing Predictors and Severity of Vasoplegia Syndrome After Heart Transplantation.

BACKGROUND: Vasoplegia is characterized as a severe vasodilatory shock after cardiac surgery, and can be associated with substantial morbidity. Increased systemic inflammation and endothelial dysfunction, often related to prolonged cardiopulmonary bypass times, anesthesia, or mechanical circulatory support have been shown to be associated with the development of vasoplegia. We sought to identify risk factors and the impact of various degrees of vasoplegia after heart transplantation. METHODS: A retrospective review was conducted of 244 consecutive patients who underwent heart transplantation over a 3-year period. Patients were divided into three groups: no vasoplegia, mild vasoplegia (requiring one vasopressor), and moderate/severe vasoplegia (more than two vasopressors). One-year survival, freedom from rejection, and postoperative complication rates were assessed. Risk factors for vasoplegia subgroups were retrospectively identified. RESULTS: Vasoplegia syndrome was observed in 34.3% of patients after heart transplantation (mild, 74.1%; moderate/severe, 25.9%). Cardiopulmonary bypass time was significantly longer and pretransplant creatinine was significantly higher in the moderate/severe vasoplegia group. There was a strong trend toward greater use of mechanical circulatory support among moderate/severe vasoplegia patients compared with mild and no vasoplegia patients. After heart transplantation, 1-year survival, freedom from rejection, and need for hemodialysis were not significantly different between groups. CONCLUSIONS: Vasoplegia syndrome is common after heart transplantation. Risk factors for increased severity include longer cardiopulmonary bypass times and elevated preoperative creatinine. Although higher rates of mortality or graft rejection were not detected, vasoplegia was associated with prolonged intubation, greater blood product usage, and lengthened hospital stay. Further studies involving larger cohorts are warranted.

Acute Cor Pulmonale in Veno-Venous Extracorporeal Membrane Oxygenation: Three Case Reports.

A retrospective review of three patients with acute respiratory distress syndrome (ARDS) and normal baseline right ventricular function admitted to the Cardiac Surgery Intensive Care Unit whom developed acute cor pulmonale while on veno-venous extracorporeal membrane oxygenation. These patients were diagnosed with ARDS using Berlin Criteria definitions and cannulated with a dual lumen (Avalon) cannula. Despite variations in history, presentation, and course, findings of acute cor pulmonale were encountered 4 to 6 weeks after extracorporeal membrane oxygenation cannulation. The potential mechanisms include thromboembolic burden to the pulmonary vasculature, hypoxemia, acidosis, the pathologic progression of ARDS, and chronic nonphysiologic flow to the right heart.

Biventricular Support With Intracorporeal, Continuous Flow, Centrifugal Ventricular Assist Devices.

BACKGROUND: The incidence of right ventricular dysfunction requiring right ventricular assist device after left ventricular assist device placement has been reported between 10% to 30%. The mortality rate is higher compared with patients who require left ventricular assist device only; the most effective and safest biventricular assist device remains unknown. We aimed to determine the survival outcomes and frequency of adverse events in patients with two durable, intracorporeal, continuous flow centrifugal pumps for support. METHODS: Between November 2012 and June 2015, 38 patients were identified from INTERMACS received durable, intracorporeal continuous flow centrifugal pumps for biventricular support. Pediatric patients were excluded. Mean age was 47 years, and 74% of patients were male. The common primary diagnoses in this cohort were dilated myopathy, idiopathic (37%) and ischemic (16%). RESULTS: Nineteen participating centers implanted devices in 38 patients; 11 patients died with device in place, 9 patients received a heart transplant, and 18 were alive on support with the right ventricular assist device in place. Survival outcomes were 68% at 6 months and 62% at 12 months. The left ventricular assist device was placed in the left ventricle apex in 91% of cases, and in 9%, the location was not specified. The right ventricular assist device was placed in the right ventricle in 50%, right atrium in 37%, and not specified in 13%. The adverse events included infection 50%, bleeding 44%, respiratory failure 31.6%, and malfunction 26.3%; neurologic dysfunction 26.3%; renal dysfunction 18.4%; and arrhythmia 18.4%. CONCLUSIONS: The use of durable, intracorporeal, continuous flow centrifugal pumps for management of advanced biventricular heart failure is associated with high morbidity and mortality. Further investigation of this device configuration is warranted.

Vasoplegia after heart transplantation: outcomes at 1 year.

OBJECTIVES: Vasoplegia syndrome is a potentially life-threatening condition that can occur following cardiopulmonary bypass. Heart transplantation is a recognized risk factor for developing this vasodilatory state. The objective of this study was to determine the effects of vasoplegia syndrome on 1-year heart transplant outcomes. METHODS: A retrospective review of orthotopic heart transplants at a single institution between November 2010 and December 2014 was performed. Of the 347 consecutive adult patients, 107 patients (30.8%) met criteria for vasoplegia syndrome. Preoperative factors and intraoperative variables were collected and compared between vasoplegia and non-vasoplegia cohorts. The incidence of postoperative complications, transplant rejection and patient survival within 1 year were evaluated. RESULTS: Demographics and preoperative medication profiles were similar in both groups, while mechanical circulatory support device use was associated with vasoplegia syndrome (30.8% vs 20.0%; P = 0.039). Perioperative characteristics such as longer cardiopulmonary bypass [165.0 (interquartile range [IQR] 74) min vs 140.0 (IQR 42.7) min; P < 0.001] and increased blood product usage (24.7 ± 17.2 units vs 17.7 ± 14.3 units; P < 0.001) were associated with vasoplegia. Non-vasoplegia patients were more likely to be extubated [42.9 (IQR 37.3) h vs 66.8 (IQR 50.2) h; P < 0.001] and discharged earlier [10.0 (IQR 6) days vs 14.0 (IQR 11.5) days; P < 0.001]. One-year patient survival (92.0% vs 88.6%; P = 0.338) and any-treated rejection rates (82.7% vs 84.3%; P = 0.569) were not significantly different between groups. CONCLUSIONS: Although vasoplegia syndrome was associated with an increase in perioperative morbidity, including greater mechanical ventilation time and hospital length of stay, no significant differences in survival or allograft rejection at 1 year was demonstrated.

Role of Thromboelastography Platelet Mapping and International Normalized Ratio in Defining "Normocoagulability" During Anticoagulation for Mechanical Circulatory Support Devices: A Pilot Retrospective Study.

Thromboembolic (TE) events and hemorrhagic complications continue to remain as frequent adverse events and causes of death after mechanical circulatory support device (MCSD) implantation. To counterbalance this postimplant multifactorial hypercoagulable state, antithrombotic therapy given postimplant must be individually tailored to keep patient adequately anticoagulated yet normocoagulable. Prior studies describing different anticoagulation protocols do not define normocoagulability for patients on MCSDs. We evaluated the role of thromboelastography platelet mapping (TEG PM) in defining "normocoagulability" for MCS patients on anticoagulant (warfarin) and antiplatelet agents. Ninety-eight MCSD patients who underwent TEG PM assay at our institution from 2012 to 2014 were included for retrospective analysis. Eleven (11.2%) subjects developed at least one TE event during the study period. Of the 13 TE events, 8 occurred in patients with total artificial heart (TAH). TEG parameters closest to the event or when patient was clinically adequately anticoagulated and corresponding international normalized ratio (INR) were measured. Thromboelastography coagulation index (CI) appears to be the single most statistically significant parameter that can be used to designate a patient as normocoagulable. Based on our results, patients with HeartMate II (HM II) and Heart Ware (HW) devices should be maintained at a CI value of less than or equal to 1.5 whereas patients with TAH devices should be maintained at a CI less than or equal to 1.2. The CI should be correlated with the degree of Vitamin K-dependent coagulation factor inhibition that is achieved using device-specific goal INR ranges. A recent modification, TEG PM assesses the effects of antiplatelet drug. Maximal amplitude arachidonic acid (MA-AA) < 50 and maximal amplitude adenosine diphosphate (MA-ADP) < 50 are desired for normocoagulable state.

Safety and Feasibility of Laparoscopic Abdominal Surgery in Patients With Mechanical Circulatory Assist Devices.

Objectives Increasing number of mechanical circulatory assist devices (MCADs) are being placed in heart failure patients. Morbidity from device placement is high and the outcome of patients who require noncardiac surgery after, is unclear. As laparoscopic interventions are associated with decreased morbidity, we examined the impact of such procedures in these patients. Methods A retrospective review was conducted on 302 patients who underwent MCAD placement from 2005 to 2012. All laparoscopic abdominal surgeries were included and impact on postoperative morbidity and mortality studied. Results Ten out of 16 procedures were laparoscopic with 1 conversion to open. Seven patients had a HeartMate II, 2 had Total Artificial Hearts, and 1 had CentriMag. Four patients had devices for ischemic cardiomyopathy and 6 cases were emergent. Surgeries included 6 laparoscopic cholecystectomies, 2 exploratory laparoscopies, 1 laparoscopic colostomy takedown, and 1 laparoscopic ventral hernia repair with mesh. Median age of the patients was 63 years (range, 29-79 years). Median operative time was 123 minutes (range, 30-380 minutes). Five of 10 patients were on preoperative anticoagulation with average intraoperative blood loss of 150 mL (range, 20-700 mL). There were 3 postoperative complications; acute respiratory failure, acute kidney injury and multisystem organ failure resulting in death not related to the surgical procedure. Conclusion The need for noncardiac surgery in post-MCAD patients is increasing due to limited donors and due to more durable and longer support from newer generation assist devices. While surgery should be approached with caution in this high-risk group, laparoscopic surgery appears to be a safe and successful treatment option.

Changing trends in abdominal surgical complications following cardiac surgery in an era of advanced procedures. A retrospective cohort study.

BACKGROUND: Abdominal complications following cardiopulmonary bypass (CPB) procedures may have mortality rates as high as 25%. Advanced procedures such as ventricular assist devices, artificial hearts and cardiac transplantation are being increasingly employed, changing the complexity of interventions. This study was undertaken to examine the changing trends in complications and the impact of cardiac surgery on emergency general surgery (EGS) coverage. METHODS: A retrospective review was conducted of all CPB procedures admitted to our ICU between Jan. 2007 and Mar. 2010. The procedures included coronary bypass (CABG), valve, combination (including adult congenital) and advanced heart failure (AHF) procedures. The records were reviewed to obtain demographics, need for EGS consult/procedure and outcomes. RESULTS: Mean age of the patients was 66 ± 8.5 years, 71% were male. There were 945 CPB procedures performed on 914 patients during this study period. Over 39 months, 23 EGS consults were obtained, resulting in 10 operations and one hospital death (10% operative mortality). CABG and valve procedures had minimal impact on EGS workload while complex cardiac and AHF procedures accounted for significantly more EGS consultations (p < 0.005) and operations (p < 0.005). The majority of consultations were for small bowel obstruction/ileus (n = 4, 17%), cholecystitis (n = 3, 13%) and to rule out ischemia (n = 2, 9%) CONCLUSIONS: In the era of modern critical care and cardiac surgery, advanced technology has increased the volume of complex CPB procedures increasing the EGS workload. Emergency general surgeons working in institutions that perform advanced procedures should be aware of the potential for general surgical complications perioperatively and the resultant nuances that are associated with operative management in this patient population.

Mechanical circulatory support in cardiogenic shock following an acute myocardial infarction: a systematic review.

The significance of the utilization of mechanical circulatory support following a myocardial infarction is not well defined. We present a systematic review of this treatment alternative and suggest guidelines to be considered in the treatment of these patients.

Left ventricular assist devices: physiologic assessment using echocardiography for management and optimization.

Left ventricular assist devices (LVAD) are being deployed increasingly in patients with severe left ventricular dysfunction and medically refractory congestive heart failure of any etiology. The United States Food and Drug Administration (FDA) recently approved the use of the Thoratec Heartmate II (Thoratec Corporation, Pleasanton, CA, USA) for outpatient use. Echocardiography is fundamental during each stage of patient management, pre-LVAD placement, during LVAD placement, for postoperative LVAD optimization and long-term follow-up. We present a pragmatic and systematic echocardiographic approach that serves as a guide for the management of left ventricular assist devices.

Antibody-mediated rejection in heart transplantation: case presentation with a review of current international guidelines.

Antibody-mediated rejection (AMR) (humoral rejection) of cardiac allografts remains difficult to diagnose and treat. Interest in AMR of cardiac allografts has increased over the last decade as it has become apparent that untreated humoral rejection threatens graft and patient survival. An international and multidisciplinary consensus group has formulated guidelines for the diagnosis and treatment of AMR and established that identification of circulating or donor-specific antibodies is not required and that asymptomatic AMR, that is, biopsy-proven AMR without cardiac dysfunction is a real entity with worsened prognosis. Strict criteria for the diagnosis of cardiac AMR have not been firmly established, although the diagnosis relies heavily on tissue pathological findings. Therapy remains largely empirical. We review an unfortunate experience with one of our patients and summarize recommended criteria for the diagnosis of AMR and potential treatment schemes with a focus on current limitations and the need for future research and innovation.