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An Innovative Ventricular Assist Device Strategy as a Bridge-to-Recovery in an Infant with Glenn Physiology

Boston, Umar; Sun, John X.; Kumar, T. K. Susheel; Knott-Craig, Christopher

doi: 10.1097/MAT.0000000000000836
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Mechanical circulatory support for infants with single ventricle physiology remains challenging. Utilization of a ventricular assist device (VAD) has potential advantages over extracorporeal circulatory membrane oxygenation. As such, VAD utilization in single ventricle patients with refractory heart failure continues to be explored. Herein, we describe a novel VAD strategy to support an infant with Glenn physiology who presented in cardiogenic shock related to myocardial depression of unknown etiology. This VAD configuration supported the systemic circulation independent of the Glenn circulation. Seven days of VAD support resulted in recovery of myocardial and end-organ function leading to VAD removal. The patient remains alive and free from transplantation 16 months post VAD explantation.

From the Division of Pediatric Cardiothoracic Surgery, Department of Surgery, University of Tennessee Health Science Center, Le Bonheur Children’s Hospital, Memphis, Tennessee.

Submitted for consideration December 2017; accepted for publication in revised form April 2018.

Disclosure: The authors have no conflicts of interest to report.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text, and links to the digital files are provided in the HTML and PDF versions of this article on the journal’s Web site (www.asaiojournal.com).

Correspondence: Umar Boston, Division of Pediatric Cardiothoracic Surgery, University of Tennessee Health Science Center, Le Bonheur Children’s Hospital, Memphis, TN. Email: uboston@uthsc.edu.

Infants with single ventricle (SV) physiology have an ongoing risk of developing heart failure and may ultimately require a heart transplant (HT). Mechanical circulatory support (MCS) can be challenging especially in infants with bidirectional Glenn (BDG) anatomy. Extracorporeal circulatory membrane oxygenation (ECMO) support for SV patients as a bridge-to-recovery or transplant results in poor survival.1 This perhaps is because of the inability of ECMO to support the systemic circulation and decompress the systemic ventricle adequately. This is compounded by the high incidence of adverse events and the inability to rehabilitate the patient.1 Studies have demonstrated the effectiveness of a ventricular assist device (VAD) in pediatric patients with biventricular physiology as a bridge-to-transplantation.2–6 However, VAD support for SV patients continues to evolve. Herein, we describe a novel VAD strategy to successfully support an SV infant with a BDG to recovery.

This is a 7 month-old infant with segmental anatomy {S,L,D}, double outlet right ventricle with hypoplastic aortic arch, common atrioventricular (AV) canal, and hypoplastic right ventricle. As a neonate, arch reconstruction with pulmonary artery band (PAB) was performed for stage 1 palliation. At 4 months of age, the patient underwent stage II palliation with a BDG and division of the main pulmonary artery.

The patient presented in cardiogenic shock 2 months following BDG, presumably because of an acute viral illness; however, no microbial cultures were positive. Echocardiogram showed that the systemic left ventricle was severely dilated with an ejection fraction of 10%. By day 2 of admission, there was escalation of inotropic support with epinephrine 0.1 μg/kg/min, milrinone 0.5 mg/kg/min, and calcium infusion 10 mg/kg/hr and need for mechanical ventilation. There was progressive worsening of renal and liver function as reflected in Figure 1. The patient became obtunded from poor cardiac output. The brain naturetic peptide (BNP) measured 18,211 pg/ml and a troponin-1 level measured 3.0 ng/ml. Herein, we describe a novel VAD strategy to provide support to the systemic circulation as a bridge-to-decision.

Figure 1

Figure 1

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Materials and Methods

The paracorporeal VAD design was that of an atrial-to-aortic configuration. The operation was conducted via a redo median sternotomy without the aid of cardiopulmonary bypass (see Video 1, Video 2, and Video 3 Supplemental Digital Content, http://links.lww.com/ASAIO/A328, http://links.lww.com/ASAIO/A329, and http://links.lww.com/ASAIO/A331). A 6 mm Berlin Heart Excor aortic cannula was anastomosed to the right atrium as the inflow limb. For the outflow limb, an 8 mm Hemashield graft, 5 mm in length was attached to a 6 mm Berlin Heart Excor aortic cannula. The Hemashield graft was then anastomosed to the ascending aorta. Cannulas were then tunneled through the subcostal abdominal wall and attached to a Thoratec PediMag pump. superior vena cava (SVC) and pulmonary artery were not cannulated. Inotropes were immediately discontinued and chest closure was accomplished. Anticoagulation in the postoperative period consisted of intravenous heparin infusion to achieve an anti-Xa level of 0.6–0.8 IU/ml and acetylsalicylic acid 5 mg/kg per day.

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Results

Postoperatively, the VAD achieved flow rates of 800 ml/min or 156 ml/kg/min at 3,200 revolutions/min. There was progressive improvement of myocardial and end-organ function (Figure 1). Glenn pressures decreased from 17 to 10 mm Hg following implantation. The patient was supported on PediMag VAD for 7 days. Under similar loading conditions, the daily echocardiographic assessment showed improvement in the systemic ventricle contractility. As such, a VAD weaning process was initiated on postimplant days 6 and 7. The VAD was stopped for a period of 15 minutes. During this time, the systemic ventricular function was assessed and found to have an ejection fraction of 55–60%. There was no inotropic support required with excellent hemodynamics and saturations during these trials.

The device was explanted on postimplant day 7 supported only on milrinone. Pump-related adverse events included one pump exchange and transfusion on postimplant day 3 for hemolysis. There was no evidence of stroke, bleeding, or infection. Although not extubated before VAD explantation, the patient was weaned to minimal mechanical ventilatory settings on postimplant day 5. The patient is alive 16 months postexplantation of VAD. To date, he has had no further decompensation in his heart failure to warrant transplant evaluation.

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Discussion

This report illustrates the utilization of a novel surgical strategy for SV VAD support in an infant with Glenn physiology. To our knowledge, this is one of the first successful reports utilizing this strategy as a bridge-to-recovery in an infant with a BDG. The utilization of Berlin cannulas attached to a Thoratec CentriMag pump has been previously reported and utilized successfully in one study in infants following failed Norwood with Blalock-Taussig shunt procedure.7,9 However, the anatomical arrangement of these infants required supporting both the systemic and pulmonary circulations as such very high VAD flow rates are demanded. The VAD system we described proved to be effective from a number of perspectives. Utilization of Berlin cannulas provided sufficiently high flow rates to support the systemic circulation.8,9 Furthermore, there was effective offloading of the atria which indirectly augmented the Glenn circulation as evident by the decrease in Glenn pressure. We deemed it to be an advantage to limit cannulation sites as avoided cannulation of the SVC and pulmonary artery direct Glenn support.

Other potential benefits of this VAD configuration include avoidance of a ventriculotomy for inflow cannulation which may allow for better myocardial recovery and ease of cannula explantation. In addition, this VAD configuration is easy to implant without utilizing cardiopulmonary bypass (CPB).

One limitation, when utilizing any VAD system, is that the lungs must be functional for adequate oxygenation. However, in the presence of lung dysfunction, it is feasible to splice an oxygenator into the outflow limb of this VAD system if needed until lung recovery.

Ventricular dysfunction and/or systemic AV valve regurgitation is not infrequently seen in infants with SV physiology and is a major risk factor for death. The vexing problem is that MCS remains challenging for those who progress to decompensated heart failure. Presently, for the infant with BDG, we advocate this novel VAD strategy for MCS support over ECMO. Continued development of a durable VAD to support this circulation is needed.

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References

1. Almond CS, Singh TP, Gauvreau K, et al. Extracorporeal membrane oxygenation for bridge to heart transplantation among children in the United States: Analysis of data from the Organ Procurement and Transplant Network and Extracorporeal Life Support Organization Registry. Circulation 2011.123: 2975–2984.
2. Blume ED, Naftel DC, Bastardi HJ, et al. Outcomes of children bridged to heart transplantation with ventricular assist devices: A multi-institutional study. Circulation. 2006;113:2313–2319.
3. Brancaccio G, Gandolfo F, Carotti A, Amodeo A. Ventricular assist device in univentricular heart physiology. Interact Cardiovasc Thorac Surg 2013.16: 568–569.
4. Morales D, Zafar F, Almond C, Canter C, Fynn-Thompson F, Conway J, et al. Berlin Heart EXCOR use in patients with congenital heart disease. J Heart Lung Transplantation 2017.
5. Carlo WF, Villa CR, Lal AK, Morales DL. Ventricular assist device use in single ventricle congenital heart disease. Pediatric Transplantation 2017.21: e13031.
6. Almond CS, Morales DL, Blackstone EH, et al. Berlin Heart EXCOR pediatric ventricular assist device for bridge to heart transplantation in US children. Circulation 2013.127: 1702–1711.
    7. Gazit AZ, Petrucci O, Manning P, et al. A novel surgical approach to mechanical circulatory support in univentricular infants. Ann Thorac Surg 2017.104: 1630–1636.
      8. Maat AP, van Thiel RJ, Dalinghaus M, Bogers AJ. Connecting the Centrimag Levitronix pump to Berlin Heart Excor cannulae; a new approach to bridge to bridge. J Heart Lung Transplant 2008.27: 112–115.
        9. Mongé MC, Kulat BT, Eltayeb O, et al. Successful bridge-to-transplant of functionally univentricular patients with a modified continuousflow ventricular assist device. Artif Organs 2017.41: 25–31.
        Keywords:

        single ventricle; ventricular assist device; Glenn physiology; Berlin heart Excor cannula; mechanical circulatory support; extracorporeal membrane oxygenation

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