Mechanical heart support at the Deutsches Herzzentrum Berlin: Recent developments (2011)

Since the inception of the mechanical circulatory support (MCS) program at the Deutsches Herzzentrum Berlin (DHZB) in 1987, more than 1600 patients have received support with 18 different designs of technical blood pump systems, in accordance with the respective state of the art. At the beginning, pulsatile pneumatic extracorporeal ventricular assist devices (VAD) and implantable pneumatic total artificial hearts (TAH) were available, followed by pulsatile electromechanical implantable devices. At this time the assist program was based on three objectives: bridging to recovery, bridging to heart transplantation (HTx) and for permanent support. Very soon (in 1995) patients of advanced age – over 65 years – were included in the program. In 1998 rotary blood pumps with continuous flow entered the program, from 2006 edging out step by step the pulsatile systems. Today the implantable pulsatile systems have disappeared from the DHZB program, with the exception of the extracorporeal uni‐ or biventricular pneumatic EXCOR systems (Berlin Heart GmbH), which are the only systems available for newborns and children. The only approved total artificial heart is the CardioWest device, implanted in rare cases after explantation of the natural heart. Miniaturized rotary blood pumps, axial flow turbines or centrifugal radial flow pumps are leading today's market. The size and configuration of one of these pumps, the hydrodynamically and magnetically levitated HeartWare HVAD, allowed its application as a biventricular implantable assist device. The worldwide first clinical implantation of this system was performed at the DHZB in 2009. With the increasing number of patients needing immediate circulatory support and the stagnating or even decreasing number of donor hearts available for HTx, the extreme discrepancy means that other therapies are gaining increasing importance. The objectives of the MCS program therefore had to focus on permanent VADs, thus creating a growing population of long‐term outpatients with implanted systems, living with their families a near‐normal life. Within a quarter century VAD implantation has grown from an experimental procedure into an established and generally accepted therapy. Facing the rapidly increasing population of patients with end‐stage heart failure and the stagnating number of heart transplants, the use of VAD technology may represent the most advanced progress in cardiac care in the coming years. Further minaturization of the devices will allow the treatment of patients with a wide age spectrum, from newborn children to the elderly, even with biventricular support. The ultimate goal will be the development of a durable total artificial heart, based on the rotary blood pump technology, with transcutaneous energy transfer through the intact skin, guaranteeing the patients optimal quality of life for many years of support.     

Ventricular assist device as a bridge to heart transplantation in adults

Background

Because of the shortage of donor hearts, various ventricular asist devices (VAD) have been used in decompensated patients to prolong patient survival until a suitable heart becomes available. In this paper, we present our single-center report of adult patients in whom bridging was used with VAD.

Methods

We performed a retrospective review of 14 adult patients who underwent heart transplantation after insertion of a long-term VAD. The study spans from February 2006 until September 2010. The mean patient age was 44.28 ± 11.06 years. We used the Berlin Heart EXCOR VADs (n = 11; Berlin Heart AG Berlin, Germany), or the Berlin Heart Incor (n = 2), or the Abiomed AB500 (n = 1). Preimplantation status of the subjects were critical cardiogenic shock (n = 6), deterioration on inotropes (n = 3), or stable but inotrope-dependent (n = 5).

Results

Mean VAD support time was 153.71 days (range, 25-517). Major adverse events during VAD support included reexploration for bleeding (n = 3; 21.4%), neurologic events (n = 2; 14.3%), left VAD-related infection (n = 2; 14.3%), pneumonia (n = 1; 14.3%), or primary device failure (n = 1; 7.1%). One (7.1%) patient showed evidence of human leukocyte antigen sensitization. There were 2 deaths (14.3%) over a mean of 324 days follow-up after heart transplantation: One due to biventricular failure in the early postoperative period and the other, at 69 days from pneumonia. Rejection was observed in 2 patients who had International Society for Heart and Lung Transplantation grade 2R without hemodynamic deterioration. In our series, the 1-year mortality was 14.4% among heart transplantations without VAD implantation and 14.2% among the bridge-to-transplantation group.

Conclusion

We conclude that VAD implantation improved end-organ function before heart transplantation in critically ill patients.     

Pneumatic pulsatile ventricular assist devices in children under 1 year of age.

OBJECTIVE: Although considerable progress has been made on ventricular assist devices (VAD) for adults, pneumatic pulsatile circulatory support in young infants is still limited. There is a need for long-term ventricular assist devices to bridge the failing myocardium of young children until recovery or transplantation. Miniaturized devices and innovative modalities need to be optimized. We report on our experience. METHODS: From 1/1992 to 6/2004, 18 infants (6 male/12 female) under 1 year of age were treated with the Berlin Heart Excor VAD. The infants were divided into two groups, depending on the year of treatment. Group A consists of eight infants resuscitated and supported with a pulsatile pneumatic ventricular assist device between 1992 and 1998 and group B consists of 10 infants treated between 1999 and 6/2004. With the pediatric-sized Berlin Heart we used miniaturized extracorporeal pneumatically driven blood pumps, the lowest stroke volume being 10 ml. RESULTS: In 18 children, age 3-345 (median 147) days, artificial replacement of heart function was applied for long-term support (1-64, median 10 days) as a life-saving measure in our hospital. Nine had LVAD and nine BVAD support. All were in cardiogenic shock with multiorgan failure; three had fulminant myocarditis, four cardiomyopathy, and one chronic stage of congenital heart disease. Five children were weaned from the system, three reached heart transplantation, and 10 died on the VAD. There were no differences between groups A and B regarding age, body weight or diagnosis, but the duration of mechanical support differed: Group A, median 2, range 1-16 days; group B, median 12, range 1-100 days. Since 1999 (group B), the survival rate of our small infants has increased to 70% whereas none of the infants in group A survived to be discharged. CONCLUSIONS: The outcome of VAD support in small infants is no longer inferior to that of adult support, now optimized cannulas, modified anticoagulation and optimized surgical and intensive care management have been established.     

Fundus Fluorescein Angiographic Findings in Patients Who Underwent Ventricular Assist Device Implantation

Disruption of microcirculation in various tissues as a result of deformed blood rheology due to ventricular assist device (VAD) implantation causes novel arteriovenous malformations. Capillary disturbances and related vascular leakage in the retina and choroidea may also be seen in patients supported by VADs. We aimed to evaluate retinal vasculature deteriorations after VAD implantation. The charts of 17 patients who underwent VAD implantation surgery for the treatment of end‐stage heart failure were retrospectively reviewed. Eight cases (47.1%) underwent pulsatile pump implantation (Berlin Heart EXCOR, Berlin Heart Mediprodukt GmbH, Berlin, Germany); however, nine cases (52.9%) had continuous‐flow pump using centrifugal design (HeartWare, HeartWare Inc., Miramar, FL, USA). Study participants were selected among the patients who had survived with a VAD for at least 6 months, and results of detailed ophthalmologic examinations including optic coherence tomography (OCT) and fundus fluorescein angiography (FA) were documented. All of the 17 patients were male, with a mean age of 48.5 ± 14.8 years (15–67 years). Detailed ophthalmologic examinations including the evaluation of retinal vascular deteriorations via FA were performed at a mean of 11.8 ± 3.7 months of follow‐up (6–18 months). Mean best‐corrected visual acuity and intraocular pressure were found as logMAR 0.02 ± 0.08 and 14.6 ± 1.9 mm Hg, respectively in the study population. Dilated fundoscopy revealed severe focal arteriolar narrowing in two patients (11.8%), and arteriovenous crossing changes in four patients (23.5%); however, no pathological alteration was present in macular OCT scans. In patients with continuous‐flow blood pumps, mean arm‐retina circulation time (ARCT) and arteriovenous transit time (AVTT) were found to be 16.8 ± 3.0 and 12.4 ± 6.2 s, respectively; whereas those with pulsatile‐flow blood pumps were found to be 17.4 ± 3.6 and 14.0 ± 2.1 s in patients (P = 0.526 and P = 0.356, respectively). FA also revealed a tendency for increased frequency of dye leakage from the optic disc in our study population. Except for remarkable delays in both ARCT and AVTT as well as a tendency for increased frequency of dye leakage from the optic disc, ophthalmologic evaluations revealed no other significant pathology or vascular deterioration in the retina that could be attributed to artificial heart systems.     

Neurological Complications During Pulsatile Ventricular Assistance With the Berlin Heart EXCOR in Children: Incidence and Risk Factors

The aim of this study is to describe the incidence of brain injury (BI) in children with end‐stage cardiac failure who were supported with the Berlin Heart EXCOR ventricular assist device (VAD) as a bridge to heart transplantation. Between January 2002 and January 2012, all patients <18 years of age who underwent the implantation of the Berlin Heart EXCOR at Bambino Gesú Children's Hospital were included. A total of 25 patients were included in this study. Median age and weight at implantation were 22.4 months (range 3.6–154.2) and 10 kg (range 4.5–36), respectively. Diagnosis included cardiomyopathy (n = 20) and congenital heart disease (n = 5). Eleven patients received atrial cannulation. Nine patients underwent biventricular assist device support. Seven patients underwent extracorporeal membrane oxygenation before the implantation of the EXCOR VAD. Median duration of VAD support was 51 days (range 2–167). Nine patients had evidence of acute BI including intracranial hemorrhage (n = 5) and cerebral ischemia (n = 4). Freedom from BI at 30, 60, and 90 days from VAD implantation was 80.7, 69.9, and 43.3%, respectively. Weight <10 kg at implantation was significantly associated with BI. BI is a frequent complication among children supported with EXCOR VAD and is associated with lower weight at implantation. However, our data do not support the association between size and BI. Future prospective multicenter studies are warranted to further help understand the etiology and the impact of BI and to improve functional outcomes for children undergoing EXCOR VAD mechanical support.     

The Berlin Heart EXCOR Pediatrics—The SickKids Experience 2004–2008

The ventricular assist device (VAD) Berlin Heart EXCOR Pediatrics was utilized at our institution since 2004 for bridging pediatric patients to cardiac transplantation or myocardial recovery. The present study reviewed our results following VAD implantation. We retrospectively reviewed patients that underwent implantation of a VAD between October 2004 and October 2008. Data collected included age at implantation, gender, weight, underlying disease, pre‐ and postdevice clinical status, complications, and outcome. Fifteen patients were identified (9 female and 6 male, average age: 8.8 years, range 0.3–14.8; average weight 31.1 kg, range 5.2–86.4). Indications for VAD support were dilated cardiomyopathy in 14 patients and progressing heart failure with a single ventricle physiology (bidirectional Glenn shunt) in one patient. Three patients (20%) were bridged from extracorporeal membrane oxygenation to VAD. Average support was 29 (1–108) days. Fourteen patients were on a bi‐VAD, one patient (single ventricle) had single VAD support. Three patients developed mediastinal/pericardial fluid collections, requiring surgical exploration in two, and drain insertion in one. Three patients presented with neurological symptoms. In two patients, a total of three blood pumps were exchanged due to thrombus formation. No patient was weaned off the VAD; two patients (13%) died on the VAD. All surviving patients are neurologically intact at follow‐up. In our experience, VAD support provides an effective means of bridging children with advanced dilated cardiomyopathy or heart failure to transplantation with a relatively small number of complications and deaths given the complexity of the patient population.     

Changing face of heart failure surgery

Background

Heart failure is a serious disease ending with death if untreated. Although heart transplantation is the best therapy for end-stage heart failure, most candidates die in the waiting period due to the lack of donor organs. This condition represent a new era of heart failure surgery.

Methods

We retrospectively investigated 159 patients from 1998 to 2011 with a mean age of 40.0 years (range = 5-65), who were mostly diagnosed as dilated cardiomyopathy (n = 113). After April 2007, 67 patients underwent vascular assist device (VAD) implantation surgery for acute or chronic end-stage heart failure. We performed 69 heart transplantation with 27 on VAD systems before transplantation.

Results

Early mortality was 13.3% with 21 patients after the heart transplantation. The 67 patients supported with VAD did not experience an intraoperative death. The mean support time was 214 days (range = 3-1035). Twenty-four patients (35.8%) are still on pump support. The overall survival until transplantation or weaning was 77.6% at mean of 250.7 days survival reached 90% with Heartware (Hartware Inc, Miramar, Fla, USA) continuous flow pumps.

Conclusion

After the introduction of VAD in 2007, the overall picture has been restructured radically for heart failure surgery, reducing patient loss on the waiting list. Especially, since 2009 nearly 80% of donor hearts were used for patients on mechanical circulatory support.     

Clinical outcome and bridge to transplant rate of left ventricular assist device recipient patients: comparison between continuous-flow and pulsatile-flow devices

BACKGROUND: Long-term implantable continuous axial-flow pumps are increasingly used in bridging heart failure patients to heart transplant. Compared to pulsatile left ventricular assist devices (LVADs), they offer smaller dimensions, less surgical trauma and less thromboembolisms. However concerns still remain about the long-term effects of continuous-flow on patients' outcome. The aim of this study was to review our mechanical bridge to transplant experience to compare pre- and post-transplant outcomes between pulsatile and continuous-flow LVAD recipients. METHODS: Thirty-six patients with a continuous-flow device (Micromed DeBakey, Houston, TX or InCor Berlin Heart, Berlin, Germany--group A) were compared with 41 patients supported with a pulsatile device (Novacor, WorldHeart, Oakland, CA--group B). RESULTS: Mean age (48.6+/-12.4 vs 47.2+/-12.5) and LVAD duration (119.3+/-115.4 vs 128.3+/-198.3) were similar in the two groups. Group A recipients were smaller compared to group B (mean body surface area=1.77+/-0.18 vs 1.93+/-0.16; p<0.001). Idiopathic dilated cardiomyopathy was not significantly greater between the two groups (78% vs 58.3%; p=0.085). Successful bridging to transplantation was similar in group A compared to group B (52.8% vs 63.4%; p=non significant). On-VAD mortality was similar between the two groups (A vs B=33.3% vs 36.6%; p=non significant). Thirty-day mortality after HTx in group A was 10.5% compared to 7.7% in group B (p=non significant). First year post-transplant incidence of treated rejections (36.8% vs 46%; p=non significant) as the mean number of rejection/patient (0.38+/-0.5 vs 0.53+/-0.83; p=non significant) were similar in group A compared to group B. CONCLUSIONS: In our experience, when compared to pulsatile LVAD, continuous-flow pumps are similarly effective in transplant rate and post-transplant outcome.     

Ventricular assist devices as a bridge to heart transplantation or as destination therapy in pediatric patients

Purpose

Despite the remarkable advances with the use of ventricular assist devices (VAD) in adults, pneumatic pulsatile support in children is still limited. We report on our experience in the pediatric population.

Methods

Retrospective review of 27 consecutive children offered mechanical support with Berlin Heart as a bridge to heart transplant, and Jarvik 2000 as a destination therapy from February 2002 to October 2011.

Results

The median patient age was 4.8 years (range = 75 days to 20.5 years). The median patient weight was 18.6 kg (range = 2.9-63 kg). We divided the patients in two groups, including in group I patients assisted for bridging to heart transplantation and in group II patients with Duchenne's dystrophy assisted as destination therapy. In the group I, 11 patients required biventricular mechanical support (BVAD), but in all other cases, a single left VAD proved sufficient (56%). The median duration of VAD support was 48 days (1 to 192 days). The median pre-VAD pulmonary vascular resistance index (Rpi) was 5.7 WU/m² (3.5 to 14.4 WU/m²). Twelve patients (48%) were successfully bridged to heart transplantation after a median duration of mechanical support of 63 days (range = 2-168 days). Ten deaths occurred (40%), three for neurological complications, two for sepsis, two for multiorgan failure, and three other for device malfunctioning. Since 2007, the survival rate of our patients has increased from 33% to 75%, and the need for BVAD has decreased from 89% to 23%. In the group II, two patients with mean age of 15.3 years were assisted with Jarvik 2000, and both of them are alive in a follow-up of 10.4 months. In two patients with Rpi > 10 WU/m², unresponsive to pulmonary vasodilatator therapy, Rpi dropped to 2.2 and 2 WU/m² after 40 and 23 days of BVAD support, respectively. Six patients (32%) required at least one pump change. Of 12 patients undergoing heart transplantation, five developed an extremely elevated (>60%) panel-reactive antibody by enzyme-linked immunosorbent assay, confirmed by Luminex. All of them experienced at least one acute episode of rejection in the first month after heart transplant, needing plasmapheresis. The survival rate after heart transplantation was 100% with a median follow-up of 34.4 months (45 days to 8.7 years).

Conclusions

Mechanical support in children with end-stage heart failure is an effective strategy as a bridge to heart transplantation with a reasonable morbidity and mortality. BVAD support may offer an additional means to reverse extremely elevated pulmonary vascular resistance. The total implantable system opens a future scenarios for patients not eligible for heart transplantation.     

Surgical therapy of end-stage heart failure in pediatric patients

Objective

We herein review our experience with ventricular assist device (VAD) implantation and heart transplantation in children with end-stage heart failure.

Methods

We performed a retrospective nonrandomized review of all patients who underwent insertion of a Berlin Heart Excor VAD or heart transplantation in our clinic. The study spans from July 2005 to July 2010. We transplanted 11 patients of mean age 11.8 ± 4.49 years, 3 of whom with critical hemodynamic situations were bridged to heart transplantation by VAD implantation. Despite the poor right ventricular systolic functions, they did not require right rVAD. In addition, 2 patients who underwent VAD implantation are still awaiting a donor heart. The mean follow-up was 825.27 ± 630.23 days (range, 21-1,888 days).

Results

There was no serious complication during VAD support. The overall heart transplantation mortality rate was 9.1% (1/11). In all patients, impaired end-organ functions were improved by VAD implantation before the heart transplantation. Cardiac biopsies revealed 4 grade 2R rejection episodes, which were successfully controlled in 3 patients.

Conclusion

Heart transplantation is highly effective therapy for pediatric patients with end-stage heart failure. Pediatric VAD implantation provided satisfactory safe circulatory support for small children in poor condition on the waiting list. This option should be considered for all pediatric candidates who show a poor hemodynamic status.     

Anesthetic management of children with in situ Berlin Heart EXCOR™

Modern mechanical devices can support children with severely impaired cardiac function until a donor heart is found for transplantation or native function recovers. Pediatric heart transplantation offers a good chance of survival with a high quality of life to individuals with limited life expectancy and/or severe limitation to daily activities, but many die on the transplant list or are not listed because of a shortage of donor organs. In recent cohorts, there is better outcome when ventricular assist devices (VADs) rather than extracorporeal membrane oxygenation are used as a ‘bridge’ to transplantation. Anesthesiologists working in centers where VADs are available may increasingly be asked to provide anesthesia to children with such devices in situ, including procedures outside the cardiac surgical operating room. The Berlin Heart EXCOR? device is a VAD system with increasing popularity in pediatric practice and has system components available in sizes suitable even for neonates. Postimplantation considerations include hemodynamics, thromboembolic complications and their prevention by anticoagulation, antimicrobial therapy, and the rehabilitation and mobilization of recipients. VAD‐specific emergencies must be recognized and managed appropriately by anesthesiologists looking after Berlin Heart recipients. These include malignant dysrhythmias, sudden loss of VAD output, air or clot embolism, and sudden cyanosis. Provision of anesthesia for patients with an in situ Berlin Heart requires attention to particular considerations in preoperative assessment, induction, maintenance, and postoperative care.     

Circulatory support with a centrifugal pump as a bridge to cardiac transplantation

Since January 1985, the Heart Transplant Program at Washington University Medical Center, St. Louis, has performed 89 heart transplantations in 86 patients. Twenty patients (23%) have required preoperative mechanical support of circulation or respiration prior to transplantation. The Bio-Medicus centrifugal pump (Bio-Pump) formed the basis of our circulatory support system during the period of this report. Nine patients were placed on the Bio-Pump with the intention of bridging them to transplantation. Six patients required left ventricular assistance; in 2, the device was inserted because they could not be weaned from cardiopulmonary bypass. Two patients required biventricular assistance, 1 because she could not be weaned from cardiopulmonary bypass at the end of a cardiac operation. Extracorporeal membrane oxygenation was necessary in 1 patient for right ventricular decompensation and cardiac arrest four hours after orthotopic cardiac transplantation. One of these 9 patients died on circulatory support, and in another, a complication developed that precluded transplantation. The remaining 7 patients (78%) underwent a successful transplant procedure after an average of 1.6 days of circulatory support (range, 0.5 to three days), and all are long-term survivors of transplantation. There has been 1 late death at 17 months from a cerebrovascular hemorrhage. In summary, the centrifugal pump provides excellent short-term circulatory support for individuals who would otherwise die before cardiac transplantation.     

Comparison of Continuous‐Flow and Pulsatile‐Flow Blood Pumps on Reducing Pulmonary Artery Pressure in Patients With Fixed Pulmonary Hypertension

Pulmonary hypertension (PH) is considered as a risk factor for morbidity and mortality in patients undergoing heart transplantation. Recently, left ventricular assist device (LVAD) implantation has been increasingly used in reducing pulmonary artery pressure (PAP) in patients with PH unresponsive to medical therapy. Herein, we aimed to compare the efficacy of continuous‐flow and pulsatile‐flow blood pumps on the improvement of PH in mechanical circulatory support patients. Twenty‐seven patients with end‐stage heart failure who underwent LVAD implantation surgery were enrolled. Fifteen of them (55.6%) had continuous‐flow pump (HeartWare Ventricular Assist System, HeartWare, Inc., Miramar, FL, USA), and 12 of them (44.4%) had pulsatile pump (Berlin Heart EXCOR ventricular assist device, Berlin Heart AG, Berlin, Germany). The efficacy of LVADs on the improvement of PH was compared between continuous‐flow and pulsatile pumps by the evaluation of systolic PAP, tricuspid annular plane systolic excursion (TAPSE), right ventricular systolic motion (RVSM), right ventricular ejection fraction (RVEF), and grade of tricuspid insufficiency (TI) for each of the study participants. All of the 15 patients who underwent continuous‐flow blood pump implantation surgery (Group 1) were male with a mean age of 46.9 ± 11.7 years, and in pulsatile‐flow blood pump implanted participants (Group 2), the mean age was 40.6 ± 16.8 years, all of whom were also male (P = 0.259). Mean follow‐up was 313.7 ± 241.3 days in Group 1 and 448.7 ± 120.7 days in Group 2 (P = 0.139). In Group 1, mean preoperative and postoperative systolic PAP were measured as 51.7 ± 12.2 mm Hg and 22.2 ± 3.4 mm Hg, respectively, while those in Group 2 were 54.5 ± 7.5 mm Hg and 33.9 ± 6.4 mm Hg, respectively. A significantly greater decrease in systolic PAP was noticed in patients with continuous‐flow blood pumps (P = 0.023); however, no statistically significant difference was found when we considered the change in TAPSE between study groups (P = 0.112). A statistical significance in the alteration of RVEF, RVSM, and the grade of TI during study visits was not found between the study groups (P = 0.472, P = 0.887, and P = 0.237, respectively). Although the two studied types of LVADs were found to be effective in reducing PAP in heart transplantation candidates with PH, lesser postoperative systolic PAP values were achieved in patients who underwent continuous‐flow pump implantation surgery.     

Pneumatic pulsatile ventricular assist device as a bridge to heart transplantation in pediatric patients

Despite the remarkable advances with the use of ventricular assist devices (VAD) in adults, pneumatic pulsatile support in children is still limited. We report on our experience in the pediatric population. A retrospective review of 17 consecutive children offered mechanical support with Berlin Heart as a bridge to heart transplant from February 2002 to April 2010 was conducted. The median patient age was 3.9 years (75 days to 13.3 years). The median patient weight was 14.1 kg (2.9–43 kg). Before VAD implantation, all children were managed by multiple intravenous inotropes and mechanical ventilation (14) or extracorporeal membrane oxygenation (3). All patients had right ventricular dysfunction. Nine patients required biventricular mechanical support (BVAD), but in all other cases a single left ventricular assist device proved sufficient (47%). The median duration of VAD support was 47 days (1–168 days). The median pre‐VAD pulmonary vascular resistance index (Rpi) was 5.7 WU/m² (3.5 to 14.4 WU/m²). Eleven patients (65%) were successfully bridged to heart transplantation after a median duration of mechanical support of 68 days (6–168 days). Six deaths occurred (35%), three for neurological complications, one for sepsis, and two others for device malfunctioning. Since 2007, the survival rate of our patients has increased from 43% to 80%, and the need for BVAD has decreased from 86% to 30%. In two patients with Rpi >10 WU/m², unresponsive to pulmonary vasodilatator therapy, Rpi dropped to 2.2 and 2 WU/m² after 40 and 23 days of BVAD support, respectively. Seven patients (41%) required at least one pump change. Of 11 patients undergoing heart transplant, four developed an extremely elevated (>60%) panel reactive antibody by enzyme‐linked immunosorbent assay, confirmed by Luminex. All of them experienced at least one acute episode of rejection in the first month after heart transplant, needing plasmapheresis. The survival rate after heart transplantation was 100% with a median follow‐up of 25.4 months (6 days to 7.7 years). Mechanical support in children with end‐stage heart failure is an effective strategy as a bridge to heart transplantation with a reasonable morbidity and mortality. BVAD support may offer an additional means to reverse extremely elevated pulmonary vascular resistance.     

Current Status of Heart Assist and Replacement in Taiwan

Abstract: The first clinical application of intraaortic balloon pumps (IABP) in Taiwan was in 1976 to treat post-cardiotomy cardiogenic shock. It is now the most commonly used circulatory assist. From 1991 to 1995, 186 patients received IABP support with an overall mortality rate of 41.9%. The male patients had the best survival rate, 67%, after coronary artery bypass grafting. The first extracorporeal membrane oxygenation (ECMO) was in 1987 to treat intractable heart failure caused by severe acute rejection after heart transplantation. Because of poor outcome, patients only received ECMO sporadically during the past years. From November 1994 to November 1995, 30 patients received ECMO support with 50% of them eventually weaned from ECMO and 27% discharged. For short-term support or emergency rescue, ECMO was a good choice. When long-term support was required, the ventricular assist device (VAD) was a more suitable assist. One patient who received Thermedics VAD developed right heart failure and finally died of sepsis and multiple organ failure. VAD should be implanted before the secondary organ failure. The first successful clinical heart transplantation in Taiwan was performed on July 17, 1987. From 1991 to 1995, 102 patients underwent heart transplantation. The operative mortality was 3.9%, and the 1 and 5 year actuarial survival rates were 86 ± 3% and 77 ± 5%, respectively. To improve the success rate of clinical heart transplantation, organ donation should be encouraged.     

Successful Bridge‐to‐Transplant of Functionally Univentricular Patients With a Modified Continuous‐Flow Ventricular Assist Device

A continuous flow extracorporeal ventricular assist device (VAD) was modified to support functionally univentricular infants and children awaiting heart transplantation. A centrifugal VAD, designed to flow from 1.5 to 8 L/min, was used as a bridge‐to‐transplant in four patients with functionally univentricular circulation. A variable restrictive recirculation shunt permitted lower flow ranges in small patients. In hypoxic patients, an oxygenator was incorporated into the circuit. From 2012 to 2015, the modified VAD was placed in four patients with Glenn physiology. Age ranged from 0.97 to 6.98 years (median = 2.2 yrs). Body surface area ranged from 0.41 to 0.84 m² (median = 0.54 m²). One patient was on extracorporeal membrane oxygenation prior to VAD. A recirculation shunt was used in three patients. Three patients required temporary use of an oxygenator for 4, 10, and 27 days. Median time on the VAD was 32.3 days (range = 23–43 days). A decrease in the cavopulmonary pressure was noted in all patients, as was a fall in the B‐type natriuretic peptide. Three patients survived transplant and were discharged at 28–82 days post‐transplantation. One patient died after 35 days of support. Two patients experienced major bleeding events. Two patients experienced cerebrovascular accidents, one major and one minor. The centrifugal VAD successfully supported palliated functionally univentricular patients awaiting heart transplantation. The modified recirculation shunt facilitated the successful support of patients in whom optimal flows were substantially lower than that recommended by the manufacturer. The continuous‐flow VAD effectively decompressed the cavopulmonary system. The design allowed placement of an in‐line oxygenator in hypoxic patients. Further investigation is required to decrease the thromboembolic events, and associated morbidity, in patients supported with this device.     

Mechanical bridge with extracorporeal membrane oxygenation and ventricular assist device to heart transplantation

The aim of this study was to evaluate the effect of double bridges with extracorporeal membrane oxygenation (ECMO) and ventricular assist devices (VADs) in clinical heart transplantation. Between May 1994 and October 2000, 134 patients underwent heart transplantation at the National Taiwan University Hospital. Ten patients received ECMO or VAD support as bridges to transplantation. The ages ranged from 3 to 63 years. The indications included cardiac arrest under cardiopulmonary resuscitation in 2 and profound cardiogenic shock refractory to conventional therapy in 8 patients. Usually ECMO was first set up as rescue therapy. If ECMO could not be weaned off after short-term (usually 1 week) support, suitable VADs (HeartMate or Thoratec VAD) were implanted for medium-term or long-term support. Five patients received ECMO support as emergency rescue for 2 to 9 days, and then moved to Thoratec VAD for 8, 49, and 55 days, respectively, or centrifugal VAD for 31 days, or HeartMate VAD for 224 days. They all survived. The survival rate of double bridges with ECMO and VAD was 100%. In postcardiotomy cardiogenic shock, circulatory collapse from acute myocardial infarction or myocarditis, ECMO is the device of choice for short-term support. If heart transplantation is indicated, VADs should replace ECMO for their superiority as a bridge to heart transplantation. Our preliminary data of double bridges with ECMO and VAD revealed good results and were reliable and effective bridges to transplantation.     

Extracorporeal membrane oxygenation hybrid with various ventricular assist devices as double bridge to heart transplantation

Ventricular assist devices (VAD) have benefitted patients with end-stage heart failure as a bridge to heart transplantation (HTx). We present our experience with HTx after an extracorporeal membrane oxygenation (ECMO) hybrid with various ventricular assist devices (VAD). From May 1996 to December 2003, mechanical circulatory support with a Biopump VAD was performed in eight patients, HeartMate left VAD in eight patients, and Thoratec VAD in eight patients. Before VAD implantation, 19 patients maintained their circulation with ECMO. Half of the 24 patients were implanted with VAD to await a suitable donor for HTx. We observed that half of the patients supported by ECMO hybrid with various VAD awaited a suitable donor for HTx. In our experience, we recommend the application of ECMO for short-term support within 1 week and the Biopump VAD, Thoractec VAD, or HeartMate VAD for medium-term or long-term support as a bridge to HTx.     

Heart transplantation in children after mechanical circulatory support with pulsatile pneumatic assist device.

BACKGROUND: Mechanical support with a pulsatile pneumatic ventricular assist device (VAD) is a complex rescue procedure performed in children with untreatable cardiogenic shock. Its impact on early and long-term survival after subsequent heart transplantation (HTx) remains to be determined. METHODS: We reviewed retrospectively the course of 95 children (median age, 8 years; range, 8 days-17 years; body weight, 24 kg; range, 3-110 kg) who underwent HTx. Group A, the elective-HTx group, consists of 33 children who were treated as outpatients before transplantation. Group B, the emergency-HTx group, has 44 children who were critically ill and hospitalized before transplantation but without ventricular assist devices, whereas Group C, the VAD-HTx group, consists of 18 children resuscitated and supported with pulsatile pneumatic VADs for a median time of 20 days. RESULTS: Overall actuarial survival after cardiac transplantation was 86% at 1 month, 82% at 1 year, and 78% at 5 years, without significant differences among the 3 sub-groups. Group A had the best long-term survival rate, 88% at 1 month, 88% at 1 year, and 80% at 5 years. Group B had a survival rate of 88% at 1 month, 82% at 1 year, and 79% at 5 years. Group C had a survival rate of 72% at 1 month, 72% at 1 year, and 72% at 5 years. We found no differences in neurologic outcome, acute cardiac rejection, or transplant failure. The survival rate was significantly better in the children with cardiomyopathy compared with those with congenital heart defects (p = 0.014). CONCLUSIONS: Bridging to HTx with a pulsatile pneumatic VAD is a safe procedure in pediatric patients. After HTx, overall survival of these children is similar to that of patients who were bridged with inotropes or who were awaiting heart transplantation electively.     

Ventricular assist device support in children and adolescents with heart failure: the Children's Medical Center of Dallas experience

Children with heart failure unresponsive to medical therapy are left with few options for survival. Ventricular assist devices (VADs) are life-saving options for such patients, allowing for bridge to transplantation or cardiac recovery. Retrospective review of cases from May 2006 to October 2010 was undertaken. Fourteen patients underwent implantation of VADs for refractory heart failure. Mean age was 9 years (range 1-17 years), and weight was 41 kg (range 9.7-71 kg). Indications for support: end-stage cardiomyopathy (n = 8), myocarditis (n = 3), univentricular failure (n = 2), and congenital heart disease/postcardiotomy (n = 1). Level of limitation at time of implant included critical cardiogenic shock in six (43%) and progressive decline in eight (57%). Extracorporeal membrane oxygenation was used as a bridge to VAD in five (36%) patients. Preimplant variables: 86% of patients requiring mechanical ventilation (mean 10.3 days), hyperbilirubinemia in 75%, and acute renal insufficiency in 79%. Device selection was systemic VAD in 11 (79%) and biventricular assist device in three (21%). Berlin Heart EXCOR was used in eight patients, while six patients received a Thoratec implantable VAD or paracorporeal VAD. Mean duration of support was 68 days (range 8-363 days). Overall survival was 79%. Ten patients (71%) were successfully bridged to transplantation, three (21%) died while on a device, one remains on support, and no patients were weaned from VAD. Children supported for single ventricle heart failure had a 50% survival with none currently bridged to transplantation. Complications included bleeding requiring reoperation in 21% (n = 3), stroke in 29% (n = 4), and driveline infections in 7% (n = 1). In two patients, a total of six pump exchanges were performed for thrombus formation. Survival for pediatric patients of all ages is excellent using current device technology with a majority of patients being successfully bridged to transplantation. Morbidity is acceptably low considering the severity of illness. Significant challenges exist with long-term extracorporeal support due to lack of donor availability and the high incidence of preformed alloantibodies especially in the failing single ventricle.