Intraaortic balloon pumping in children

Pediatric Mechanical Circulatory Support

Over the past two decades clinicians and researchers have sought to bring mechanical circulatory support (MCS) to pediatric patients with heart failure. ECMO, IABPs, and VADs have all been used in infants and children as a bridge to myocardial recovery or as a bridge to transplant. However, until recently, a commitment by industry, government, and researchers towards the development of pediatric MCS has not been present, especially in the United States. Advancements in adult VAD design to smaller, quieter, and fully implantable pumps capable of complete outpatient support have sparked curiosity in the application of this technology to children. Also, the increasing success of palliating congenital heart disease is creating an ever-growing cohort of children and adolescents with heart failure. These changing demographics and technological advances have caused a refocus of attention. This is most clearly demonstrated by the international use of several established MCS pediatric and neonatal systems, by the FDA's increasing proclivity to allow the use of international pediatric VADs in the USA, and by the recent National Heart, Lung, and Blood Institute funding of several institutions to develop pediatric VADs. This review describes the different aspects of pediatric MCS including indications, the features of the various VADs, and their current application in children worldwide.

Partial mechanical circulatory support in children

Partial mechanical support devices are capable of partially unloading only one ventricle, often the systemic one, in the setting of acute circulatory failure. They are rarely used in the pediatric population, as the mode of circulatory failure in patients with congenital heart disease often involves biventricular or a predominantly right ventricular component. The devices include intra-aortic balloon pumping, Impella, TandemHeart, and CentriMag. They are rarely used as a bridge-to-recovery, but more often as a bridge-to-decision, or bridge-to-conversion to full mechanical support systems, such as extracorporeal membrane oxygenation or ventricular assist devices. Currently, lack of availability of more complete support devices, cost issues, or lack of infrastructure and personnel may still be indications to continue using partial mechanical support as opposed to more complete forms of biventricular circulatory support.

Perioperative mechanical circulatory support in children with critical heart disease

OPINION STATEMENT

The treatment of cardiovascular failure in the perioperative period with the use of mechanical circulatory support is a well-recognized, well-developed, and commonly utilized treatment modality. Regardless of the exact circumstances of initiation, the use of a support device is a "bridge." Where there has been an acute myocardial insult, short-term assist devices can serve as a "bridge to immediate survival," a "bridge to recovery," or even a "bridge to the next decision." Mechanical circulatory support can serve as a treatment of cardiovascular decompensation caused by myocarditis, acute myocardial insult, low cardiac output following surgery, and congenital heart disease. The utilization of such support carries significant risks such as bleeding, infection, and thrombosis. However, these can be minimized in order to allow for the safe and effective deployment of this therapeutic strategy. One specific therapeutic domain in which these devices provide immediate impact is during cardiac arrest. Although outcomes of cardiac arrest remain poor, use of a mechanical device as an intervention has allowed salvage of otherwise certain mortality. However, it is important to note that the utility of support was most pronounced in patients that were not on either extreme of the survival prediction curve. This can be best summarized by the concept of "not too early, not too late." Therefore, it is the responsibility of the entire care team to find the appropriate patient population in which to "pull the trigger" on mechanical support as a therapy. This decision point is supported by a monitoring strategy that can be utilized to predict deterioration and intervene adequately. Most importantly, an effective monitoring strategy allows the practitioner to judge the effectiveness of treatment and support strategies and make adjustments in a timely manner, potentially with mechanical support in the perioperative period.

Mechanical circulatory support of the critically ill child awaiting heart transplantation

The majority of children awaiting heart transplantation require inotropic support, mechanical ventilation, and/or extracorporeal membrane oxygenation (ECMO) support. Unfortunately, due to the limited pool of organs, many of these children do not survive to transplant. Mechanical circulatory support of the failing heart in pediatrics is a new and rapidly developing field world-wide. It is utilized in children with acute congestive heart failure associated with congenital heart disease, cardiomyopathy, and myocarditis, both as a bridge to transplantation and as a bridge to myocardial recovery. The current arsenal of mechanical assist devices available for children is limited to ECMO, intra-aortic balloon counterpulsation, centrifugal pump ventricular assist devices, the DeBakey ventricular assist device Child; the Thoratec ventricular assist device; and the Berlin Heart. In the spring of 2004, five contracts were awarded by the National Heart, Lung and Blood Institute to support preclinical development for a range of pediatric ventricular assist devices and similar circulatory support systems. The support of early development efforts provided by this program is expected to yield several devices that will be ready for clinical trials within the next few years. Our work reviews the current international experience with mechanical circulatory support in children and summarizes our own experience since 2005 with the Berlin Heart, comparing the indications for use, length of support, and outcome between these modalities.

Use of Intra-Aortic Balloon Counterpulsation in an Adult Patient With Left Ventricular Failure following Repair of Tetralogy of Fallot: A Case Report

We report the case of a 26-year-old male patient who developed primary left ventricular failure with subsequent biventricular failure early following intracardiac repair of tetralogy of Fallot. The failing biventricular circulation was successfully supported using intra-aortic balloon counterpulsation. Aortic counterpulsation facilitates recovery of biventricular function and appears to be a reasonable alternative in select instances of systemic ventricular failure following repair of tetralogy of Fallot.

Mechanical support in childhood heart failure

Despite optimization of standard medical therapy, some patients with chronic heart failure will deteriorate to the point that they require hospitalization for intravenous therapies and inpatient monitoring. Once the condition is recognized, the therapeutic goals are to reverse hemodynamic derangements, correct metabolic abnormalities, and provide symptomatic relief. Achievement of these goals requires individualized care and a familiarity with the risks and benefits of particular therapies.

Mechanical support availability in pediatric cardiac surgery: program size should not matter

Intractable heart failure may require Extracorporeal Life Support (ECLS) techniques for rescue therapy. Nevertheless, in many small to middle-sized centers in Europe, this valuable resource is not available. In our University pediatric intensive care unit 0.9% of 1360 open-heart surgical patients required mechanical assistance over the latest 9 years with a survival rate of 69.2% and low residual morbidity. This favorable overall outcome suggests that regardless of the program size, it is possible to ensure the availability of efficient mechanical assistance that appears to be fundamental in a center performing surgery for complex congenital or acquired cardiac diseases.

Circulatory assistance in small infants and neonates with a hydraulically driven system: a viable option?

We have developed a new drive system for a cardiac assist system for use with newborns and infants. This study reports results of animal experiments in which this system was tested using a commercially available 25-ml ventricle. A major property of the device is its hydraulic mode, which allows not only for the conventional full-empty mode (chamber completely filled in diastole) but also for the filled-empty mode, in which the chamber is completely emptied in systole but only partially filled in systole; this mode gives full flexibility to adjust the pump frequency for any given pump flow rate. The assist device was applied in eight pigs (weight 9-14 kg) for left ventricular assistance during normal and impaired cardiac function (pacing-induced cardiac shock, mean arterial blood pressure less than 40 mmHg). Both, full-empty and filled-empty mode during normal cardiac function led to significantly decreased pulmonary capillary wedge pressure, suggesting load reduction of the right ventricle. In impaired cardiac function, circulatory assistance increased the diminished cardiac output and systolic arterial blood pressure, although only the latter was statistically significant. Neither arterial lactate concentration nor oxygen uptake was reduced during circulatory assistance for normal and impaired cardiac function. These results suggest that the cardiac ventricular assist device can be used as an effective circulatory assist device and that the function of the newly introduced filled-empty mode, which allows for a high degree of functional flexibility, is not inferior to that of the classical, but less flexible, full-empty mode.

The role of the Intra-aortic balloon pump in supporting children with acute cardiac failure

Acute heart failure occurs in children following the operative correction of a congenital anomaly, as an acute change in a child with a congenital anomaly, or in a structurally normal heart with acute myocarditis. Acute heart failure in children justifies aggressive treatment because of the high potential for complete recovery. The options for providing mechanical support to the failing heart in a child include extracorporeal membrane oxygenation, left ventricular assist devices and the use of the intra-aortic balloon pump (IABP). The principles of intra-aortic balloon pump usage are described, and the literature regarding the indications and outcome of its use in children is reviewed.

Intra-aortic balloon counterpulsation in a patient with the failing Fontan circulation

We report a 23-year-old patient undergoing functionally univentricular repair who developed cardiac failure due primarily to systemic ventricular dysfunction. The failing Fontan circulation was successfully re-established using intra-aortic balloon counterpulsation. Aortic counterpulsation facilitates recovery of systemic ventricular function, and appears to be a reasonable alternative in select instances of cardiac failure in patients with the Fontan circulation.

Intra-aortic balloon pumping in children undergoing cardiac surgery: an update of the Liverpool experience

OBJECTIVE

Intra-aortic balloon pumping in children remains a rarity. We report our experience in supporting pediatric cardiac surgical patients with intra-aortic balloon pumping.

METHODS

We reviewed the cases of 24 children supported with intra-aortic balloon pumping after cardiac surgery in our institution from 1994 through 2003.

RESULTS

Mean age at the time of the operation was 5.0 +/- 5.6 years (range, 7 days-17.5 years). Ten patients were infants less than 6 months old. Mean weight was 18.9 +/- 18.1 kg (range, 3.5-58.7 kg). Indications for intra-aortic balloon pump deployment were postoperative hemodynamic deterioration (n = 11, 8 survivors), failure to wean off cardiopu(n = 7, 5 survivors), and prophylaxis before weaning off cardiopulmonary bypass (n = 6, 5 survivors). The balloon was inserted through the ascending aorta in infants and through the femoral artery in children. Eighteen children (7 infants) were weaned off the intra-aortic balloon pump successfully (intra-aortic balloon pump survival, 75%). Mean duration of intra-aortic balloon pump support was 121.3 +/- 140.60 hours (range, 8-670 hours). There were 3 post-intra-aortic balloon pump in-hospital deaths (survival to hospital discharge, 62.5%). Severe intra-aortic balloon pump-related complications were mesenteric ischemia in 1 patient and lower limb ischemia requiring intra-aortic balloon pump removal in 1 patient. At a mean follow-up of 85 +/- 31 months (range, 18-124 months), all 15 long-term survivors were alive and well.

CONCLUSIONS

Use of an intra-aortic balloon pump is an effective modality of cardiac support in properly selected pediatric cardiac surgical patients with refractory low cardiac output. It can be safely used in small infants and neonates. In selected cases with known left ventricular dysfunction, there is a place for prophylactic use of an intra-aortic balloon pump.

New developments in pediatric cardiac anesthesia

As the practice of pediatric cardiac anesthesia continues to grow, anesthesiologists now routinely care for patients ranging in size from less than 2 kg to more than 100 kg. New clinical and laboratory research has enhanced our understanding of the effects of anesthetic drugs on the pediatric myocardium, and improvements in survival statistics for even the smallest and sickest infants have shifted the emphasis to evaluation of quality of life and neurological outcome in pediatric cardiac patients. The use of circulatory support in infants and children, both for rapid resuscitation and for more chronic indications such as bridge to transplantation, also continues to evolve, with the recent introduction of pulsatile and axial pumps for pediatric use. This article reviews anesthetic agents, bleeding and coagulation, neurological monitoring, and mechanical circulatory support in the treatment of infants and children.

Decision making for mechanical cardiac assist in pediatric cardiac surgery

The practice of pediatric cardiac surgery has evolved to the point where the majority of patients operated on represent the most complex end of the spectrum of congenital heart disease. Given this, the potential role for mechanical cardiac assist will continue to expand. Although extracorporeal membrane oxygenation remains the mainstay of mechanical circulatory assist, the increased use of centrifugal ventricular assist devices is changing the approach to the treatment of acute cardiac failure. A range of newly developed implantable and paracorporeal devices is beginning to make its way into the clinical practice of pediatric cardiac surgery. This article addresses the different types of support available for mechanical cardiac assist and the clinical considerations in selecting the appropriate device.

Anesthetic and perfusion issues in contemporary pediatric cardiac surgery

As the fields of pediatric cardiology and cardiac surgery advance in complexity and in accountability for clinical and economic outcomes, several issues traditionally associated with the operating room are becoming important to physicians, nurses, and respiratory therapists who take care of children after cardiac surgery. The article discusses the concepts of "fast track" cardiac surgery, regional anesthetic techniques, coagulopathies and bleeding after cardiopulmonary bypass, intraoperative ultrafiltration, and mechanical circulatory assist devices.

The intraaortic balloon pump in cardiac surgery

The intraaortic balloon pump (IABP) has been used in cardiac operations since the late 1960s. Over the years, with refinements in technology, its use has expanded; the IABP is now the most commonly used mechanical assist device in cardiac operative procedures. This review provides an evaluation of evidence for the efficacy of IABP use in different clinical scenarios, using the American College of Cardiology/American Heart Association classification of evidence where appropriate. We evaluated complications and outcomes associated with IABP use, and attempted to draw conclusions regarding the use of the IABP in different clinical situations. We examined the trends and variation in utilization over time and across centers. We discussed the IABP in light of new cardiac assist devices and the changing patient population and management strategies. Lastly, we identified areas of future research.

Pediatric circulatory support systems

Ventricular assist devices (VADs) are a valid option for long term circulatory support in pediatric patients with postoperative myocardial failure or debilitating heart defects. Most clinical experience to date has involved the short-term support of patients weighing 6 kg and larger. For cases of VAD implementation in pediatric patients, the assist device showed tremendous promise in reversing cardiac failure and providing adequate support as a bridge to cardiac transplantation. The Medos-HIA system, Berlin Heart, Medtronic Bio-Medicus Pump, Abiomed BVS 5000, Toyobo-Zeon pumps, and Hemopumps have proven successful for short-term circulatory support for the pediatric population. The Jarvik 2000 and Pierce-Donachy pediatric system further demonstrate the potential to be used for pediatric circulatory support. The clinical and experimental success of these support systems provide encouragement to believe that long-term support is possible.

Current results with intraaortic balloon pumping in infants and children

BACKGROUND

Intraaortic balloon pumping (IABP) is useful for support in patients with moderate left ventricular dysfunction. IABP is usually timed with the R wave of the electrocardiogram. We have utilized M-mode echocardiography timed IABP in children with left-side heart failure since 1994. Electrocardiogram timing seems inappropriate for children, who have much higher heart rates. We describe our experience with children who underwent IABP therapy before and after 1994, when echocardiographic timing was instituted.

METHODS

We reviewed records of 29 children who underwent IABP for all indications at Primary Children's Medical Center since 1988.

RESULTS

Overall survival was 62.1% (18 of 29) in this series. Survival was similar for infants (odds ratio = 2.0, 95% confidence interval = 0.29 to 14.31, p = 0.43) and older children. Survival was similar in the echocardiography era when compared with the electrocardiogram era (odds ratio = 2.4, 95% confidence interval = 0.56 to 10.4, p = 0.44).

CONCLUSIONS

IABP is a useful means of support in children with left ventricular dysfunction. M-mode echocardiography is effective in triggering IABP. The sample size in this study is too small to detect a mortality rate difference.

Intra-aortic balloon pumping in children with dilated cardiomyopathy as a bridge to transplantation

Children with dilated cardiomyopathy awaiting transplantation who fail maximal pharmacologic therapy may benefit from intra-aortic balloon pumping. Between July 1993 and August 1999, a total of 4 children with dilated cardiomyopathy underwent pre-transplant balloon pumping for 6.0 +/- 5.8 (1 to 12) days. One child (pumped for 12 days) died awaiting transplant, and the remaining 3 were successfully transplanted. Intra-aortic balloon pumping timed precisely with M-mode echocardiographic markers offers a relatively simple and safe intermediate level of mechanical support for children with dilated cardiomyopathy who fail pharmacologic support.

Nonpharmacologic treatment of acute heart failure

Acute heart failure is unusual in the pediatric population, but in many situations it justifies aggressive therapy. For example, children with lymphocytic myocarditis have an overall survival rate of nearly 90%, with complete myocardial recovery for the majority. Pharmacologic agents traditionally have been the mainstay of medical therapy for acute heart failure, but, in recent years, there has been increasing interest in using measures that reduce the myocardial workload. This article highlights nonpharmacologic approaches to the management of severe heart failure in the critically ill child. It also concentrates on physiologic approaches that address the balance between oxygen demand and delivery; the manipulation of cardiopulmonary interactions to optimize ventricular function; and the use of mechanical circulatory support as a method of achieving ultimate myocardial rest.