Author: Anna Hartzog MD and Chinwe Unegbu MD – Children’s National Hospital
A 2-month-old infant with dilated cardiomyopathy presents for Left Ventricular Assist Device (LVAD) insertion. The surgeon implants a Levitronix CentriMag pump with Berlin Heart Excor cannulas. What is the MOST LIKELY benefit of initial placement of the CentriMag pump over initial insertion of the complete Berlin Excor system?
Correct!
Wrong!
Question of the Week 346
Approximately 20% to 30% of pediatric patients awaiting heart transplantation are bridged with a Ventricular Assist Device (VAD). This has resulted in a 50% reduction in the waitlist mortality. Candidacy for VAD implantation is often determined by serial monitoring for end-organ dysfunction (ie hepatic, renal, gastrointestinal dysfunction), nutritional status, level of inotropic support, and degree of respiratory compromise. Generally, VAD therapy should occur prior to the onset of severe end-organ dysfunction as this is an independent risk factor of mortality.
Small children and infants have limited device options. The majority of children who require a VAD are supported with either a pulsatile paracorporeal device or a continuous flow intracorporeal device. The Berlin Heart Excor VAD (Berlin Heart GmbH, Berlin, Germany) is a pulsatile paracorporeal device that is situated externally. The main continuous flow intracorporeal devices are the HeartWare HVAD (Medtronic, Minneapolis, MN) and the HeartMate 3 (Abbott Corporation, Abbott Park, IL) which have pumps that are implanted internally. The HeartWare HVAD and HeartMate 3 are currently US Food and Drug Administration-approved for the therapy of advanced heart failure in adults. However, both devices have been safely and successfully used in patients as small as twenty kilograms and body surface area of 0.6 m2. Continuous flow VADs have a 92% survival rate at 6 months, which is superior to the survival rates in pediatric patients with pulsatile devices.
The Berlin Heart Excor VAD is a pneumatically-driven, pulsatile pump with a fixed volume chamber ranging from 10 to 80 milliliters. During systole the pump moves compressed air into the pneumatic chamber causing ejection. In diastole negative pressure is applied to the pneumatic chamber to aid filling. Cardiac output is dependent on the size of the chamber and the pump rate. Unfortunately, complications such as stroke, bleeding, and infection are more common with the Berlin Heart EXCOR in comparison to continuous flow devices.
In addition to durable long-term VADs, temporary or short-term VADs also exist. Temporary circulatory support devices are traditionally defined as those providing support for two to four weeks as a “bridge to recovery” or “bridge to decision” in patients with an acute process. Temporary circulatory support devices now account for 19% of VAD implants. In 2018 Lorts et al used data from the Pediatric Interagency Registry for Mechanical Circulatory Support (PediMACS) to investigate outcomes in patients temporarily supported by VADs. The authors found that 71% had a positive outcome (ie bridge to recovery, bridge to transplant, bridge to a durable device, or alive with a device). Additionally, the authors also discovered that “temporary” devices were utilized for a wide variety of indications and for durations of time greater than six weeks.
The CentriMag/PediMag (Levitronix LLC, Waltham, MA) is a third generation paracorporeal continuous flow device that is being used with increasing frequency for temporary circulatory support. The CentriMag is driven with a bearingless motor, enabling the spinning component within the pump to be magnetically levitated and rotated without contact or wear. By eliminating the bearings, shafts, and seals associated with a conventional centrifugal pump, the incidence of thrombus accumulation and the degree of hemolysis are greatly reduced, which decreases the risk of adverse events. As there is low risk of thromboembolic events, many centers use minimal anticoagulation. This is advantageous after VAD implantation as a significant percentage of patients require re-exploration due to bleeding. In contrast, the Berlin Heart Excor system requires early initiation of anticoagulation therapy.
The need for minimal anticoagulation and lower hospital-related costs have made the CentriMag pump in combination with the Berlin Heart Excor cannulas a logical choice in some centers. This combination allows the CentriMag pump to stabilize the patient over a period of several weeks. Then once stabilized, the Berlin Heart Excor pump and drive unit can replace the CentriMag. The pump exchange can be accomplished in one to two minutes. The CentriMag pump is less expensive with a cost of $10,000 to $13,000 per pump. In comparison, the Berlin Heart Excor pump costs $39,000 and the driver monthly rental is approximately $10,000. Immediately following VAD implantation, there is considerable inflammation leading to fibrin and clot build up that may necessitate several pump exchanges. Pump exchange is quite expensive, especially with use of the Berlin Excor system. The combined use of both systems can be viewed as a cost effective “bridge to a bridge”.
Choice C is the correct answer as perioperative costs are reduced with the CentriMag. Choice A, B and D are incorrect as the Centrimag is not intended for long-term support, requires some form of anticoagulation, and is not associated with improved myocardial recovery.
References
1. Navaratnam M, Maeda K, Hollander SA. Pediatric ventricular assist devices: Bridge to a new era of perioperative care. Pediatric Anesthesia. 2019; 29: 506–518. doi:10.1111/pan.13609.
2. VanderPluym CJ, Adachi I, Niebler R, et al. Outcomes of children supported with an intracorporeal continuous-flow left ventricular assist system. J Heart Lung Transplant. 2019; 38(4): 385-393.
3. Chatterjee A, Feldmann C, Hanke JS, et al. The momentum of HeartMate 3: a novel active magnetically levitated centrifugal left ventricular assist device (LVAD). J Thorac Dis. 2018; 10(Suppl 15): S1790-S1793.
4. O’Connor MJ, Lorts A, Davies RR, et al. Early experience with the HeartMate 3 continuous flow ventricular assist device in pediatric patients and patients with congenital heart disease: A multicenter registry analysis. J Heart Lung Transplant. 2020; 39: 573-579.
5. 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. doi: 10.1161/CIRCULATIONAHA.112.000685.
6. Blume ED, VanderPluym C, Lorts A, et al. Second annual Pediatric Interagency Registry for Mechanical Circulatory Support (Pedimacs) report: Pre‐implant characteristics and outcomes. J Heart Lung Transplant. 2018; 37(1): 38‐45. doi: 10.1016/j.healun.2017.06.017.
7. Lorts A, Eghtesady P, Mehegan M, et al. Outcomes of children supported with devices labeled as “temporary” or short term: A report from the Pediatric Interagency Registry For Mechanical Circulatory Support. J Heart Lung Transplant. 2018; 37(1): 54‐60. doi:10.1016/j.healun.2017.10.023.
8. Stiller B, Lemmer J, Schubert S, et al. Management of pediatric patients after implantation of the Berlin Heart EXCOR ventricular assist device. ASAIO J. 2006; 52(5): 497-500. PMID: 16966844.
9. De Rita F, Hasan A, Haynes S, et al. Outcome of mechanical cardiac support in children using more than one modality as a bridge to heart transplantation. Eur J Cardiothorac Surg. 2015; 48: 917-922. doi:10.1093/ejcts/ezu544.
10. Conway J, Al-Aklabi M, Granoski D, et al. Supporting pediatric patients with short-term continuous-flow devices. J Heart Lung Transplant. 2016; 35: 603-609. doi:10.1016/j.healun.2016.01.1224.
11. Maat A.P, van Thiel R.J, Dalinqhaus M, Bogers A.J. Connecting the CentriMag Levitronix pump to Berlin Heart Excor cannula. J Heart Lung Transplant. 2008; 27: 112-115. doi: 10.1016/j.healun.2007.10.010
12. Loforte A, Potapov E, Krabatsch T, et al. Levitronix CentriMag to Berlin Heart Excor: A “Bridge to Bridge” Solution in Refractory Cardiogenic Shock. ASAIO J. 2009; 55(5): 465-468. doi: 10.1097/MAT.0b013e3181b58c50
13. John R, Long J, Massey T, et al. Outcomes of a multicenter trial of the Levitronix CentriMag ventricular assist system for short-term circulatory support. Mechanical Circulatory Support. 2008; 27(1): 112-115. doi:https://doi.org/10.1016/j.jtcvs.2010.03.046
Small children and infants have limited device options. The majority of children who require a VAD are supported with either a pulsatile paracorporeal device or a continuous flow intracorporeal device. The Berlin Heart Excor VAD (Berlin Heart GmbH, Berlin, Germany) is a pulsatile paracorporeal device that is situated externally. The main continuous flow intracorporeal devices are the HeartWare HVAD (Medtronic, Minneapolis, MN) and the HeartMate 3 (Abbott Corporation, Abbott Park, IL) which have pumps that are implanted internally. The HeartWare HVAD and HeartMate 3 are currently US Food and Drug Administration-approved for the therapy of advanced heart failure in adults. However, both devices have been safely and successfully used in patients as small as twenty kilograms and body surface area of 0.6 m2. Continuous flow VADs have a 92% survival rate at 6 months, which is superior to the survival rates in pediatric patients with pulsatile devices.
The Berlin Heart Excor VAD is a pneumatically-driven, pulsatile pump with a fixed volume chamber ranging from 10 to 80 milliliters. During systole the pump moves compressed air into the pneumatic chamber causing ejection. In diastole negative pressure is applied to the pneumatic chamber to aid filling. Cardiac output is dependent on the size of the chamber and the pump rate. Unfortunately, complications such as stroke, bleeding, and infection are more common with the Berlin Heart EXCOR in comparison to continuous flow devices.
In addition to durable long-term VADs, temporary or short-term VADs also exist. Temporary circulatory support devices are traditionally defined as those providing support for two to four weeks as a “bridge to recovery” or “bridge to decision” in patients with an acute process. Temporary circulatory support devices now account for 19% of VAD implants. In 2018 Lorts et al used data from the Pediatric Interagency Registry for Mechanical Circulatory Support (PediMACS) to investigate outcomes in patients temporarily supported by VADs. The authors found that 71% had a positive outcome (ie bridge to recovery, bridge to transplant, bridge to a durable device, or alive with a device). Additionally, the authors also discovered that “temporary” devices were utilized for a wide variety of indications and for durations of time greater than six weeks.
The CentriMag/PediMag (Levitronix LLC, Waltham, MA) is a third generation paracorporeal continuous flow device that is being used with increasing frequency for temporary circulatory support. The CentriMag is driven with a bearingless motor, enabling the spinning component within the pump to be magnetically levitated and rotated without contact or wear. By eliminating the bearings, shafts, and seals associated with a conventional centrifugal pump, the incidence of thrombus accumulation and the degree of hemolysis are greatly reduced, which decreases the risk of adverse events. As there is low risk of thromboembolic events, many centers use minimal anticoagulation. This is advantageous after VAD implantation as a significant percentage of patients require re-exploration due to bleeding. In contrast, the Berlin Heart Excor system requires early initiation of anticoagulation therapy.
The need for minimal anticoagulation and lower hospital-related costs have made the CentriMag pump in combination with the Berlin Heart Excor cannulas a logical choice in some centers. This combination allows the CentriMag pump to stabilize the patient over a period of several weeks. Then once stabilized, the Berlin Heart Excor pump and drive unit can replace the CentriMag. The pump exchange can be accomplished in one to two minutes. The CentriMag pump is less expensive with a cost of $10,000 to $13,000 per pump. In comparison, the Berlin Heart Excor pump costs $39,000 and the driver monthly rental is approximately $10,000. Immediately following VAD implantation, there is considerable inflammation leading to fibrin and clot build up that may necessitate several pump exchanges. Pump exchange is quite expensive, especially with use of the Berlin Excor system. The combined use of both systems can be viewed as a cost effective “bridge to a bridge”.
Choice C is the correct answer as perioperative costs are reduced with the CentriMag. Choice A, B and D are incorrect as the Centrimag is not intended for long-term support, requires some form of anticoagulation, and is not associated with improved myocardial recovery.
References
1. Navaratnam M, Maeda K, Hollander SA. Pediatric ventricular assist devices: Bridge to a new era of perioperative care. Pediatric Anesthesia. 2019; 29: 506–518. doi:10.1111/pan.13609.
2. VanderPluym CJ, Adachi I, Niebler R, et al. Outcomes of children supported with an intracorporeal continuous-flow left ventricular assist system. J Heart Lung Transplant. 2019; 38(4): 385-393.
3. Chatterjee A, Feldmann C, Hanke JS, et al. The momentum of HeartMate 3: a novel active magnetically levitated centrifugal left ventricular assist device (LVAD). J Thorac Dis. 2018; 10(Suppl 15): S1790-S1793.
4. O’Connor MJ, Lorts A, Davies RR, et al. Early experience with the HeartMate 3 continuous flow ventricular assist device in pediatric patients and patients with congenital heart disease: A multicenter registry analysis. J Heart Lung Transplant. 2020; 39: 573-579.
5. 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. doi: 10.1161/CIRCULATIONAHA.112.000685.
6. Blume ED, VanderPluym C, Lorts A, et al. Second annual Pediatric Interagency Registry for Mechanical Circulatory Support (Pedimacs) report: Pre‐implant characteristics and outcomes. J Heart Lung Transplant. 2018; 37(1): 38‐45. doi: 10.1016/j.healun.2017.06.017.
7. Lorts A, Eghtesady P, Mehegan M, et al. Outcomes of children supported with devices labeled as “temporary” or short term: A report from the Pediatric Interagency Registry For Mechanical Circulatory Support. J Heart Lung Transplant. 2018; 37(1): 54‐60. doi:10.1016/j.healun.2017.10.023.
8. Stiller B, Lemmer J, Schubert S, et al. Management of pediatric patients after implantation of the Berlin Heart EXCOR ventricular assist device. ASAIO J. 2006; 52(5): 497-500. PMID: 16966844.
9. De Rita F, Hasan A, Haynes S, et al. Outcome of mechanical cardiac support in children using more than one modality as a bridge to heart transplantation. Eur J Cardiothorac Surg. 2015; 48: 917-922. doi:10.1093/ejcts/ezu544.
10. Conway J, Al-Aklabi M, Granoski D, et al. Supporting pediatric patients with short-term continuous-flow devices. J Heart Lung Transplant. 2016; 35: 603-609. doi:10.1016/j.healun.2016.01.1224.
11. Maat A.P, van Thiel R.J, Dalinqhaus M, Bogers A.J. Connecting the CentriMag Levitronix pump to Berlin Heart Excor cannula. J Heart Lung Transplant. 2008; 27: 112-115. doi: 10.1016/j.healun.2007.10.010
12. Loforte A, Potapov E, Krabatsch T, et al. Levitronix CentriMag to Berlin Heart Excor: A “Bridge to Bridge” Solution in Refractory Cardiogenic Shock. ASAIO J. 2009; 55(5): 465-468. doi: 10.1097/MAT.0b013e3181b58c50
13. John R, Long J, Massey T, et al. Outcomes of a multicenter trial of the Levitronix CentriMag ventricular assist system for short-term circulatory support. Mechanical Circulatory Support. 2008; 27(1): 112-115. doi:https://doi.org/10.1016/j.jtcvs.2010.03.046
