Conducting tissue of the heart in kwashiorkor

Electrocardiographic and echocardiographic findings in malnourished children

OBJECTIVE

To compare heart abnormalities in a group of malnourished children with a control group and to describe their predictive variables.

METHODS

Thirty children with malnutrition were matched with thirty healthy children. Anthropometry, plasma levels of albumin and electrolytes were determined. Among others, corrected QT interval (QTc) and QT dispersion (QTd: difference between the maximum and the minimum QT) were measured in 12-lead electrocardiogram; and left ventricular mass (LVm) and left ventricular mass index (LVmi) were measured by echocardiography. Regression analyses were performed with cardiac findings as dependent variables and anthropometric and biochemical data as independent variables.

RESULTS

Plasma levels of albumin, potassium and calcium were lower in malnourished children. QTc and QTd were significantly greater in patients with malnutrition than in controls (QTc: 445.9 +/- 31.4 vs. 400.9 +/- 17.7 ms, p = 0.000; QTd: 76.4 +/- 34.1 vs. 47.9 +/- 10.2 ms, p = 0.000). LVm and LVmi were significantly lower in malnourished children (LVm: 55.3 +/- 10.3 vs. 71.4 +/- 6.9 g, p = 0.000; LVmi: 46.5 +/- 6.6 vs. 60.5 +/- 4.9 g/m2, p = 0.000). The body mass index (kg/m2) was the most powerful predictor of the variability in QTc (39.1%), LVm (48.1%) and LVmi (51.2%).

CONCLUSIONS

Important electrocardiographic and echocardiographic abnormalities have been found in malnourished children associated with their nutritional status. Special precaution must be taken about the possibility of occurrence of arrhythmias and sudden death related with malnutrition.

Cardiac function in malnourished children

The cardiovascular status of severely malnourished children was characterized before, during, and after nutritional rehabilitation. In most children with third-degree malnutrition, cardiac mass was decreased on admission to the hospital and recovered subsequent to nutritional therapy. All children had echocardiographic and Doppler measurements indicative of impaired ventricular function which significantly improved during the course of hospitalization, as evidenced in part by the change in fractional shortening (P = 0.015), mean velocity of circumferential fiber shortening (P = 0.038), and systolic time interval (P = 0.030). We conclude that children with primary third-degree malnutrition not only have cardiac muscle wasting, but also have inherent ventricular dysfunction as the result of severe malnutrition that responds to nutritional therapy. Particular care with fluid administration is imperative in the first week of therapy, when heart function is the most compromised.

Selective morphologic alterations of the cardiac conduction system in calves deficient in vitamin E and selenium

Vitamin E and selenium (E-Se) deficiency causes necrosis of the contractile myocardium in many species but does not usually affect the cells of the conduction system. In the present study, experimental E-Se deficiency in cattle produced preferential degeneration and necrosis of Purkinje cardiocytes. Calves fed deficient diets for 127-137 days had sublethal damage characterized histologically by sarcoplasmic accumulation of lipopigment granules; ultrastructurally, these granules corresponded to cytolysosomes that had a heterogeneous ultrastructure. Alterations in necrotic cells included mitochondrial mineralization, sarcoplasmic condensation, and plasmalemmal fragmentation. Necrosis of Purkinje cells was followed by macrophagic penetration of the external lamina, phagocytosis of necrotic sarcoplasm, and repair by fibrosis. Furthermore, E-Se depletion of calves resulted in only minimal alterations in the contractile myocardium. In contrast, feeding supplements of polyunsaturated fatty acids to E-Se-deficient calves intensified the Purkinje cell damage but also resulted in widespread degeneration and necrosis of the contractile myocardium. Accumulation of lipopigment supports a pathogenetic role for lipoperoxidation in development of the cardiac lesions of E-Se deficiency. These lesions constitute a unique example of preferential damage to Purkinje cardiocytes. This model offers an attractive method of studying damage and repair to the cardiac conduction system.

Cardiovascular complications during prolonged starvation

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