Nutrition in pediatric cardiomyopathy - Children's Cardiomyopathy ...

T.L. Miller et al. / Progress in Pediatric Cardiology 24 (2007) 59–7161discovery of pneumoncystis carinii pneumonia in otherwisehealthy, but severely malnourished children in developingnations [22]. Investigators have shown that improving nutritionalstatus in malnourished and chronically ill children relates toimproved survival and decreased utilization of health careresources through lower hospitalization rates [23]. In anotherstudy evaluating cardiac outcomes in chronically ill children[24], nutritional status was a strong and independent predictor ofmortality and cardiac function. Thus, better nutritional status ofthe child (or adult) is related to the optimal functioning of theheart and other organ systems and eventual clinical outcomes[25,26].Growth failure is one of the most significant clinicalproblems of children with cardiomyopathy with nearly onethirdof children with this disorder manifesting some degree ofgrowth failure during the course of their illness. In a recentinternational study in Brazil [25], Azevedo determined thatweight z-score was positively and independently correlated withsurvival in a chart review of 165 children with idiopathic dilatedcardiomyopathy between 1979 and 2003. However, short of thisrestrospective chart review, there is a dearth of information onnutritional correlates to cardiac outcomes and function inchildren with cardiomyopathy. We have shown previously thatin other models of chronic illness in children (humanimmunodeficiency virus infection), that cardiac muscle massdoes not always waste in proportion to skeletal muscle [27].This suggests that neurohormonal influences may affect cardiacstatus to a greater extent than skeletal muscle. The underlyingcause of growth failure is usually due to persistent congestiveheart failure as a result of an overall poor response to medicaltreatment. Significant cardiac dysfunction in these children canresult in increased metabolic demands, decreased food intakeand malabsorption of important nutrients. Growth failure ormalnutrition in children can lead to problems in virtually everyorgan system, with many of the effects only partially reversible.Thus cardiomyopathy may lead to growth problems, but growthproblems can lead to further complications that may directly orindirectly impact on heart function, leading to a viciousdownward cycle (Fig. 1). These clinical manifestations indicatethat growth patterns may be an important predictor of theoutcomes among CM patients or an important indicator of theseverity of their cardiomyopathy. If this is so, then it becomesFig. 1. Vicious downward cycle of malnutrition in pediatric cardiomyopthy.apparent that clinicians should be vigilant regarding treatmentissues surrounding growth. The relationship between growthpatterns and echocardiographic findings is unknown.3. The effect of nutrients on cardiac endpoints in heartfailurePromotion of adequate nutrition begins with early detectionof children at risk for malnutrition. Optimal nutrition is criticalin providing children the means to recover from their illness andto withstand the detrimental metabolic effects of aggressivetherapies. In theory, patients with heart failure who have eitherinsufficient fat mass (BMI b10% for age and sex) or excess fatmass (BMI ≥85% for age and sex) should have pooreroutcomes than patients with a BMI in the reference range(between 10% and 95%). Although excess body fat mayincrease the risk of developing heart failure, evidence suggeststhat it may be beneficial once heart failure develops. Onemechanism may be that increased body fat provides a metabolicreserve that allows overweight and obese patients to tolerate themetabolic/catabolic stress associated with heart failure pathologyfor a longer time [28]. Another potential mechanism isrelated to the hypothesized differences in proinflammatorycytokine activity between underweight and overweight/obeseindividuals with heart failure [29]. In addition to releasingproinflammatory cytokines, adipose tissue is a source of antiinflammatorycytokines. However, it is not known whether thepotential positive effects of excess body fat in patients withheart failure vary depending on body fat distribution. Ourcurrent recommendations focus on decreasing body fataccumulation due to the known adverse effects and secondarydiseases that may develop from obesity. However, more studiesare needed in order to tease out the complex interaction betweenobesity and active heart failure with particular focus on thepediatric population that has been often difficult to study owingto limited numbers of children available to study.3.1. MacronutrientsChildren with cardiomyopathy, with varying degrees ofcongestive heart failure, need to receive adequate calories tocompensate for their heart failure (that typically increases basalenergy expenditure) as well as to provide additional calories fornormal growth. As mentioned previously, children in heartfailure often do not grow along expected standards for age andsex and poor growth may either contribute to poor cardiacfunction or be one result of it. Optimal caloric intake is usuallyestimated to be approximately 110–125% of the estimatedenergy requirement (EER) (Table 1) [30] for age and sex.However, greater or fewer calories may be required dependingon the child's growth as a response to their intake; as normalnutrition is the balance between energy intake and energyutilization. Children who are in congestive heart failure oftenhave increased metabolic rates due to the increased work ofbreathing, eating, or other routine activities of daily living. Theymay also malabsorb critical nutrients as a result of heart failureleading to gut edema. Furthermore, anorexia, due to a variety of