Pediatric Ventricular Assist Devices
Appropriate selection of a device is of critical importance to achieve the best outcome. The following needs to be taken into account: etiology of heart failure and anticipated duration of support, type of support (LVAD or BiVAD), the destination of support, and the availability of devices. In particular, attention should be paid to the etiology of cardiac dysfunction because this dominates decision making in terms of device selection. A general guideline for the device selection is depicted in Figure 6.
(Enlarge Image)
Figure 6.
An algorithm of device selection for pediatric mechanical circulatory support at Texas Children's Hospital. BSA = body surface area, BTB = bridge-to-bridge, BTD = bridge-to-destination, BTR = bridge-to-recovery, BTT = bridge-to-transplant, ECMO = extracorporeal membrane oxygenation, MCS = mechanical circulatory support, VAD = ventricular assist device.
Short-term VAD support is indicated when the etiology of heart failure is deemed temporary (e.g., acute myocarditis or acute cardiac graft rejection), where recovery of cardiac function is expected to occur within 2 weeks, aiming to achieve bridge-to-recovery. Short-term VAD support is also useful when there are uncertainties regarding candidacy for longterm VAD placement (e.g., transplant candidacy, unclear etiology of heart failure, uncertain neurological status, etc). The short-term VAD also can be used for acute exacerbations of chronic heart failure with the primary aim of bridging the patient to a long-term device.
Short-term VAD support is achieved with an extracorporeal centrifugal device (e.g., CentriMag or PediMag) in the ICU setting, with or without chest closure. It is usually established with central cannulation and thus requires sternotomy in pediatric patients. Exceptions are the devices specifically designed for peripheral cannulation such as TandemHeart (CardiacAssist, Pittsburgh, PA) and Impella (Abiomed, Danvers, MA). Despite very limited experience in the pediatric population, these percutaneous VAD technologies would be useful for very short-term assistance in certain situations (e.g., unstable hemodynamics after catheter intervention). The necessity of sternotomy for short-term VAD support is a major disadvantage compared with ECMO. Conversely, this feature allows the use of bigger cannulas and direct drainage of the left heart, resulting in decompression of the failing systemic ventricle. The same level of decompression is not achievable with peripheral ECMO where a smaller inflow cannula is inserted into the right side of the heart. This is particularly true when there is increased cardiac return (e.g., systemic pulmonary collaterals), which is common in the pediatric population. Adequate decompression of the systemic ventricle is of critical importance for myocardial recovery.
When the etiology of heart failure is chronic, myocardial recovery is unlikely to occur. Most of the reported cases of bridge-to-recovery in pediatric patients are with acute processes. There are only a few sporadic reports regarding "true" myocardial recovery in children with chronic heart failure treated with a long-term VAD. Therefore, long-term VAD support is a more suitable mode of therapy for chronic heart failure. Selection of long-term devices is mainly guided by patient size. For smaller patients (BSA <0.7), a pneumatic paracorporeal device (i.e., Berlin EXCOR or Medos) is the only option. Currently, there are no intracorporeal devices with FDA approval or CE mark available for small children, although small internal devices (e.g., Jarvik infant) are under development. In fact, the Jarvik infant has already been implanted in a few patients in Europe on a compassionate use basis. For older adolescents (BSA >1.3 m), adult intracorporeal devices (e.g., HeartMateII) are available. Although intermediate size patients (0.7< BSA <1.3 m) were historically treated with pneumatic devices, the newer generation of intracorporeal devices such as HeartWare would be suitable in this group of patients.
VAD Selection
Appropriate selection of a device is of critical importance to achieve the best outcome. The following needs to be taken into account: etiology of heart failure and anticipated duration of support, type of support (LVAD or BiVAD), the destination of support, and the availability of devices. In particular, attention should be paid to the etiology of cardiac dysfunction because this dominates decision making in terms of device selection. A general guideline for the device selection is depicted in Figure 6.
(Enlarge Image)
Figure 6.
An algorithm of device selection for pediatric mechanical circulatory support at Texas Children's Hospital. BSA = body surface area, BTB = bridge-to-bridge, BTD = bridge-to-destination, BTR = bridge-to-recovery, BTT = bridge-to-transplant, ECMO = extracorporeal membrane oxygenation, MCS = mechanical circulatory support, VAD = ventricular assist device.
Short-term VAD Support
Short-term VAD support is indicated when the etiology of heart failure is deemed temporary (e.g., acute myocarditis or acute cardiac graft rejection), where recovery of cardiac function is expected to occur within 2 weeks, aiming to achieve bridge-to-recovery. Short-term VAD support is also useful when there are uncertainties regarding candidacy for longterm VAD placement (e.g., transplant candidacy, unclear etiology of heart failure, uncertain neurological status, etc). The short-term VAD also can be used for acute exacerbations of chronic heart failure with the primary aim of bridging the patient to a long-term device.
Short-term VAD support is achieved with an extracorporeal centrifugal device (e.g., CentriMag or PediMag) in the ICU setting, with or without chest closure. It is usually established with central cannulation and thus requires sternotomy in pediatric patients. Exceptions are the devices specifically designed for peripheral cannulation such as TandemHeart (CardiacAssist, Pittsburgh, PA) and Impella (Abiomed, Danvers, MA). Despite very limited experience in the pediatric population, these percutaneous VAD technologies would be useful for very short-term assistance in certain situations (e.g., unstable hemodynamics after catheter intervention). The necessity of sternotomy for short-term VAD support is a major disadvantage compared with ECMO. Conversely, this feature allows the use of bigger cannulas and direct drainage of the left heart, resulting in decompression of the failing systemic ventricle. The same level of decompression is not achievable with peripheral ECMO where a smaller inflow cannula is inserted into the right side of the heart. This is particularly true when there is increased cardiac return (e.g., systemic pulmonary collaterals), which is common in the pediatric population. Adequate decompression of the systemic ventricle is of critical importance for myocardial recovery.
Long-term VAD Support
When the etiology of heart failure is chronic, myocardial recovery is unlikely to occur. Most of the reported cases of bridge-to-recovery in pediatric patients are with acute processes. There are only a few sporadic reports regarding "true" myocardial recovery in children with chronic heart failure treated with a long-term VAD. Therefore, long-term VAD support is a more suitable mode of therapy for chronic heart failure. Selection of long-term devices is mainly guided by patient size. For smaller patients (BSA <0.7), a pneumatic paracorporeal device (i.e., Berlin EXCOR or Medos) is the only option. Currently, there are no intracorporeal devices with FDA approval or CE mark available for small children, although small internal devices (e.g., Jarvik infant) are under development. In fact, the Jarvik infant has already been implanted in a few patients in Europe on a compassionate use basis. For older adolescents (BSA >1.3 m), adult intracorporeal devices (e.g., HeartMateII) are available. Although intermediate size patients (0.7< BSA <1.3 m) were historically treated with pneumatic devices, the newer generation of intracorporeal devices such as HeartWare would be suitable in this group of patients.