Andersons pediatric cardiology 1723

Functionally univentricular physiology with a systemic-to-pulmonary artery shunt Acute myocarditis Acute decompensation of chronic cardiac failure ECMO/VAD ECMO Single VAD for VAD Shunt restriction can be considered With left atrial decompression Unless cardiac arrest or poor lung function BIVAD, Biventricular assist device; CPR, cardiopulmonary resuscitation; ECMO, extracorporeal membrane oxygenation; VAD, ventricular assist device In the following section, description is given of some of the available mechanical support devices for children and a review of the available evidence for their use in children is provided For extra clarification, the devices have been separated into complete and partial systems based on the amount of support they provide Complete Mechanical Support Extracorporeal Membrane Oxygenation Venoarterial ECMO provides circulatory support and gas exchange by draining the systemic venous blood, passing it through an oxygenator that functions as a highly efficient lung, and returning oxygenated blood to the systemic arterial circulation ECMO can provide total cardiopulmonary rest for the heart with poor intrinsic function, or can provide partial support for a borderline, or recovering circulation (Video 64.1) Cannulation for ECMO can be through a sternotomy, or the peripheral route (neck or femoral vessels) The route for cannulation is dictated by the underlying pathophysiology and the age or size of the patient Cannulation for peripheral ECMO in infants and small children is generally via the carotid artery and jugular vein, whereas for older children is typically via the femoral route (Table 64.5).43,44 Table 64.5 Routes of Cannulation for Extracorporeal Membrane Oxygenation Indication Cannulation Acute circulatory Neck cannulation failure, not (carotid artery– postoperative jugular vein) Femoro-femoral (femoral artery– femoral vein) Comments Neck cannulation for infants and younger children Reasons Morbidity related to carotid cannulation greater in older patients Femoro-femoral for older children: consider in children >20 kg Peripheral circulatory problems related to femoral cannulation greater in younger patients Open chest cannulation (right atrium—aorta) Postoperative Open chest circulatory failure (sternotomy) Consider for overwhelming sepsis with supranormal flow requirements If early postoperative phase High flows achievable with larger cannula Easily accessible for rapid cannulation or conversion from cardiopulmonary bypass Most centers use centrifugal pumps and modern hollow fiber oxygenators to provide temporary ECMO support, and these have been significantly refined over recent years to minimize circuit volume, turbulence, and potential for shear stress, and to be sufficiently miniaturized to enable patient transport (Videos 64.2 and 64.3) One commonly used pump is the RotaFlow centrifugal continuous flow pump (Maquet Cardiopulmonary AG) It is relatively compact and can generally provide up to 10 L/min of blood flow It employs a magnetically stabilized rotor on a sapphire bearing radial shaft, resulting in gentle blood handling by reducing friction.45 Another recent addition has been the Cardiohelp (Maquet Cardiopulmonary AG) This is a miniaturized ECMO system, weighs approximately 10 kg, and can deliver up to 7 liters per minute of flow The system also contains an integrated sensor technology for measurement of venous oxygen saturation, hemoglobin, hematocrit, and arterial blood temperature.46 In addition, the compact design of the Cardiohelp makes it particularly appealing for transporting patients on ECMO Ventricular Assist Devices Temporary VADs provide support to one or both ventricles, but do not support the lungs, and are most often used to support a failing ventricle in the setting of acute myocarditis, or early after cardiac surgery Long-term VAD will be discussed elsewhere in this book The basic circuitry for temporary VAD support includes cannulation, typically through a median sternotomy, for venous drainage, and arterial return This can be right atrial drainage and pulmonary arterial return, for patients requiring RV support, or left atrial drainage and aortic return, for patients requiring LV support In its simplest form, the external features of a VAD circuit resemble that used for ECMO without an oxygenator, and many centers use the same centrifugal pumps (e.g., the RotaFlow pump) for temporary VAD as they do for ECMO The CentriMag and PediMag (Thoratec) systems are continuous extracorporeal centrifugal pumps The motor has no bearings and magnetically levitates the rotor, thus minimizing friction The CentriMag can generate flows up to 10 liters per minute, whereas the PediMag is capable of delivering flows up to 1.5 liters per minute and is ideal for infants and smaller children These systems are implanted via standard median sternotomy with or without cardiopulmonary bypass and uses any commercially available cannulas.47,48 A recent systematic review of 53 studies in 999 adults and children showed that the CentriMag was used as a VAD in 72% of the cases and in 25% of the cases as part of ECMO circuit The range duration of support was 8.8 to 25 days, and the survival on support was 82% (95% CI 70 to 92).49 These systems have also been implanted in single-ventricle children for RV support with promising results.47 CentriMag and PediMag have become an effective technology for temporary support of patients with cardiac and cardiorespiratory support Partial Mechanical Circulatory Support Although ECMO or VAD are more commonly used in acute circulatory failure to provide mechanical circulatory support, there are instances in which complete support is not required or warranted The use of partial mechanical circulatory support limits itself to those systems providing partial unloading of the circulatory system by assisting one of the two ventricles These systems are the percutaneous implantable intraaortic balloon pumps (IABPs), left-sided Impella devices, and TandemHeart Impella The Impella (Abiomed) is a percutaneous VAD utilized to maintain cardiac output during the management of cardiogenic shock, high-risk cardiac catheterization procedures, and potentially LV unloading in the absence of an appropriate left atrial vent or septostomy It is inserted percutaneously into an artery and placed in a retrograde fashion into the LV across the aortic valve, enabling continuous blood flow up to 5.0 L/min The Impella percutaneous system is composed of a miniature rotary blood pump mounted to pass through a 13 Fr or 21 Fr sheath, depending on the chosen device Pediatric insertion of the Impella percutaneous systems has been reported either alone or in conjunction with ECMO to decompress the left ventricle A recently published case series from Texas Children's Hospital demonstrated promising results in high-risk children and adolescents with cardiac disease.50 The authors reported augmentation of the native cardiac output and LV unloading concomitant to V-A ... system is composed of a miniature rotary blood pump mounted to pass through a 13 Fr or 21 Fr sheath, depending on the chosen device Pediatric insertion of the Impella percutaneous systems has been reported either alone or in conjunction