There is a growing interest in the use of percutaneously delivered axial-flow ventricular assist devices (PVAD) in the pediatric patient population.1 , 2 Historically, durable surgically implanted mechanical circulatory support devices in children have focused on left ventricular (LV) support in the perioperative period and in the rescue of failing hearts with acquired and congenital heart disease.3 In rare instances, biventricular pulsatile VADs have been utilized in cases of acute biventricular failure or for severe right ventricular (RV) failure after left VAD implantation.4 The Impella CP LVAD (Abiomed, Inc., Danvers, MA) is currently Food and Drug Administration approved as a short-term percutaneously delivered axial-flow VAD for up to 6 hours although longer term support has been reported.1 , 2 , 5 Right ventricular support is also offered via the Impella RP which is Food and Drug Administration indicated for providing circulatory assistance for up to 14 days in pediatric patients who develop acute right heart failure or decompensation after left VAD implantation, heart transplant, or open-heart surgery. Current sheath size and device dimensions are capable of supporting older children although simultaneous use of CP and RP has not been reported in the pediatric population.
A 16 year old, 52.3 kg (Body surface area 1.54 m2) female with a remote history of familial LV noncompaction cardiomyopathy underwent orthotopic heart transplantation 9 months before presenting at a tertiary-care pediatric cardiovascular intensive care unit (CVICU) with 3 days of nausea and vomiting. The patient’s interim history after transplantation was without graft rejection or dysfunction, coronary allograft vasculopathy, or medication noncompliance.
Initial evaluation revealed tachycardia, an S3 gallop, and hepatomegaly without evidence of respiratory distress or altered mental status. Electrocardiography revealed sinus tachycardia with global voltage attenuation and new-onset T wave flattening/inversion throughout the anterolateral distribution. Transthoracic echocardiography revealed new-onset moderate tricuspid regurgitation and severe systolic dysfunction with a LV ejection fraction of 38% by bullet method. She underwent hemodynamic catheterization with endomyocardial biopsies on hospital day #1 which revealed low mixed venous oxygen saturations (MVO2) of 36%, elevated central venous pressure (CVP) of 21 mm Hg with corresponding elevation in pulmonary artery wedge pressure (PAWP) of 32 mm Hg. She experienced hemodynamic instability during the procedure and required intubation and initiation of inotropic support before transfer back to the CVICU. Biopsy results demonstrated cellular and antibody-mediated rejection (grade 2R, C4d positive) with elevated titers of donor-specific antibodies requiring aggressive immunosuppression with steroids, antithymocyte globulin infusion, and plasmapheresis in the subsequent days. Early in recovery from the procedure, the patient developed ventricular tachycardia (VT) degrading into ventricular fibrillation (VF) requiring defibrillation and ultimately lidocaine and amiodarone infusions to control episodes of nonsustained monomorphic VT. Over the ensuing week, she failed to respond to immunosuppressive regimens and required continued inotropic support along with antiarrhythmic infusions. Due to concerns for worsening ventricular dysfunction on echocardiography (see Video 1, Supplemental Digital Content, http://links.lww.com/ASAIO/A226), oliguric acute kidney injury, rising CVP and liver enzymes, she was taken back to the cardiac catheterization on hospital day #12, where intracardiac pressures were found to be elevated (CVP 24 mm Hg, PAWP 31 mm Hg) along with low MVO2 (30%). She developed ventricular fibrillation and due to concern for evolving acute graft rejection and dysfunction, an Impella CP LVAD was deployed via right femoral artery. The support level was increased to P8 generating flows from 3.1 to 3.4 L/min with corresponding drop in pulmonary capillary wedge pressure (PCWP) to 22 mm Hg.
Despite Impella LVAD support, she remained in refractory cardiogenic shock and the decision was made to augment her circulatory support with femoral venoarterial (VA) extracorporeal membrane oxygenation (ECMO) on hospital day #13 as additional immunosuppression regimens were being instituted. She was well supported on peripheral VA ECMO while her immunosuppression was optimized. Cardiac function recovered and she was ultimately decannulated from ECMO on hospital day #19 with Impella CP removal 2 days later (see Video 2, Supplemental Digital Content, http://links.lww.com/ASAIO/A227). She again demonstrated declining RV and LV function with worsening acute kidney injury and lactic acidosis and returned to the cardiac catheterization laboratory on hospital day #23. The hemodynamic assessment once again revealed high CVP (23 mm Hg) and PAWP (31 mm Hg). An Impella CP LVAD was reinserted via the femoral artery with appropriate transaortic valve positioning aided by transesophageal echocardiography while additional immunosuppressant strategies were considered. Although her PAWP improved to 28 mm Hg, her elevated CVP along with echocardiographic evidence of RV dysfunction were highly suggestive of RV failure. After weighing the risks and benefits of recannulating for VA ECMO, the decision was ultimately made to implant an Impella RP RVAD (Figure 1). On support of CP P8 and RP P6, her PAWP decreased to 18–20 mm Hg and CVP to 18 mm Hg.
Despite bilateral VAD support via Impella CP and RP and multiple antirejection medications, our patient continued to demonstrate multisystem organ failure with persistent lactic acidosis (>2 mmol/L), diminished MVO2 levels, anuric renal failure requiring continuous renal replacement therapy (CRRT), elevated liver enzymes, and multiple episodes of VT while on maximal antiarrhythmic medications. In light of the treatment failure, lack of other immunosuppressive options and poor prognosis for retransplantation, the decision by the family to withdraw life-sustaining therapies and she passed away on hospital day #28.
An 18 year old, 112.4 kg (BSA 2.38 m2) male with a remote history of dilated cardiomyopathy requiring LVAD implantation (HeartMate-II; Thoratec, Inc., Pleasanton, California) and subsequent orthotopic heart transplantation presented to a tertiary-care children’s hospital CVICU with 4 days of nausea, vomiting, abdominal pain, and diarrhea. He reported significant anorexia with poor adherence of immunosuppressants as a result of the intercurrent illness. His cardiac history revealed no prior episodes of graft rejection or dysfunction, coronary allograft vasculopathy, or nonadherence to his immunosuppressant regimen.
Initial assessment revealed resting tachycardia and tachypnea, normal noninvasive blood pressures, and mild hypoxia. Physical examination revealed distant heart sounds with prominent summation gallop, few crackles at bilateral lung bases, and hepatomegaly with jugular venous distension. Echocardiography revealed new-onset severe tricuspid regurgitation, moderate mitral regurgitation, severe biventricular systolic dysfunction with LV ejection fraction (EF) of 29% by bullet method (see Video 3, Supplemental Digital Content, http://links.lww.com/ASAIO/A228). Allograft dysfunction due to rejection was suspected. The patient’s clinical condition deteriorated over the first 12 hours of admission with worsening pleural effusion and pulmonary edema, acute kidney injury with oliguria, mental status changes, and progressive hypoxemic respiratory failure (Figure 2). The patient was taken emergently to the cardiac catheterization for hemodynamic assessment, endomyocardial biopsy, and for possible initiation of mechanical circulatory support.
After successful induction, intubation, and central venous catheter placement, right and left heart filling pressures were found to be elevated (CVP 20 mm Hg, LV end diastolic pressure 18 mm Hg). Ventricular fibrillation occurred during wire manipulation in the LV requiring brief chest compressions and defibrillation with return of spontaneous circulation within 1 minute. Due to concern for evolving acute graft rejection and worsening dysfunction, an Impella CP LVAD was percutaneously inserted via left femoral artery with appropriate transaortic valve positioning aided by transesophageal echocardiography.
After achieving full support with Impella CP (P8 setting and flow of ~3.4 L/min), his CVP remained persistently elevated (21 mm Hg) with concern for impaired RV systolic function. Right VAD placement was achieved using Impella RP via the right femoral vein. A decrease in CVP (12 mm Hg) and PAWP (15 mm Hg) was noted immediately after initiating biventricular support at full settings (RP at P7 and flow of ~3.4 L/min, CP at P8). Endomyocardial biopsies were performed followed by right pleural effusion drainage and pulmonary artery catheter insertion before transport to the CVICU.
Antirejection therapies were administered throughout the post-Impella placement period although biopsy results revealed grade 1R rejection and negative C4d staining. A hemodialysis catheter was placed postprocedure day #1 and plasmapheresis was performed for concern for antibody-mediated rejection followed by initiation of CRRT. The percutaneous RVAD was removed on hospital day #4 with CVP measurements remaining <10 mm Hg after removal. With improvement in LV function (EF 48%; see Video 4, Supplemental Digital Content, http://links.lww.com/ASAIO/A229) and with evidence of hemolysis and persistent bleeding at insertion site, the percutaneous LVAD was removed hospital day #5 without complication. The patient was subsequently extubated on hospital day #8 and remained on CRRT. Due to persistent graft dysfunction, he was subsequently supported with an Impella 5.0 LVAD (via an axillary artery chimney graft) which was then transitioned to a total artificial heart on hospital day #62. He was subsequently discharged home and ultimately underwent successful retransplantation.
We report the first description of percutaneous biventricular assist device implantation using Impella CP and RP devices for the treatment of acute decompensated heart failure in the pediatric population. Due to increased recognition and improvement in operative strategies for congenital heart disease, pediatric hospitalizations and readmissions for heart failure are increasing in frequency and cost.6 , 7 Furthermore, those pediatric patients whose hospitalizations are complicated by heart failure are at ≥20-fold increased risk of death.8
The opportunity to support the growing pediatric heart failure population with percutaneous mechanical circulatory support devices other than VA ECMO is highly desirable given the known morbidity and mortality associated with ECMO in the pediatric population.9 , 10 Percutaneous VADs have become established therapeutic options for cardiogenic shock in the adult population with positive outcomes described over the last decade.11 Although biventricular support with these devices, smaller children is limited by vessel patency and large sheath size; their use in the older pediatric patient is a viable option. More importantly, the recognition of right heart failure in context of advanced LV failure is critical. Although the medical management of the failing RV is similar to the LV in terms of preload/contractility/afterload manipulation, the optimal timing of mechanical circulatory support of the RV remains unclear. Recently, the Impella RP axial-flow catheter has been introduced to support the failing RV after LVAD placement or after cardiotomy or myocardial infarction. The RECOVER RIGHT trial demonstrated significant hemodynamic benefit of the Impella RP device with 30 day survival of 73% in both types of RV failure patient groups.12
It is noteworthy that our two patients, although 18 years of age or younger, were adult sized. The Impella RP system is indicated for circulatory support for a duration of as long as 14 days in pediatric and adult patients with a body surface area of ≥1.5 m2. However, despite these approved indications, before our current report, no publications were available on the use of the Impella RP system in the pediatric age population. Acknowledging the fact that our patients were adult sized, our report highlights important considerations for pediatric care providers. Pediatric centers are treating higher numbers of adolescents who have sequelae related to heart transplantation or congenital heart disease. Thus, it is vital for pediatric specialists taking care of these patients to be familiar with this potential mode of therapy, which adds to the armamentarium of options available for treating right heart failure. In addition, familiarity with this technology will hopefully allow future miniaturization of this device, making its use more applicable to smaller children.
The design and implementation of multidisciplinary mechanical support programs at pediatric centers where devices like the Impella RP or other Impella devices are infrequently utilized can be quite challenging. In addition to physician training, training of nurses in the cardiac catheterization laboratory, operating room, and intensive care units is essential. Due to less frequent use of these devices compared with adult centers, frequent refresher courses are needed, which we have personally found to be helpful. Finally, partnering with an adult facility is vital when a center decides to offer therapy such as the use of the Impella RP system. Ultimately, clinical experience with both RV and LV percutaneously implanted VADs in the pediatric cardiac critical care environment is lacking. Further investigations that provide clarity for the indications, risk/benefit ratios of implantable versus percutaneous mechanical support options in pediatric patients are warranted.
This report describes the novel use of biventricular percutaneous VADs for the support of acute decompensated biventricular heart failure as a form of mechanical support technology with potential applicability in the older pediatric heart failure population.
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