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We studied neurohormonal, clinical and invasively measured hemodynamic data of 47 infants with left-to-right shunts and varying degrees of congestive failure. When referred to a clinical heart failure score, plasma renin activities (r=0.71) and norepinephrine levels (r=0.43) are significantly increased. Arterial hypotension seems to be the hemodynamic trigger of renin release (r=-0.72), but not decreased systemic cardiac index (r=-0.43), the magnitude of the left-to-right shunt (r=0.33) or a reduced ejection fraction (r=0.12). These data indicate neurohormonal activation in infants with left-to-right shunts with preserved myocardial function is similar to the activation in adults with heart failure secondary to myocardial pump failure. These findings have to be considered for optimal medical treatment of these infants with angiotensin-converting enzyme inhibitors or beta-blockers.

To evaluate the therapeutical effects of the angiotensin converting enzyme inhibitor Captopril to the beta-blocker Propranolol in infants with congestive failure due to pulmonary overcirculation, we retrospectively analysed clinical, neurohormonal and hemodynamic data in 22 infants, 11 of whom were treated with Captopril (Group 1), 11 with Propranolol (Group 2). Age, weight, number of palliative operations, plasma renin activities and pulmonary to systemic flow ratios (3.5 vs. 3.5) were not significantly different prior to Captopril or Propranolol therapy. If treatment with digoxin and diuretics did not succeed, the infants were additionally treated with Captopril (1 mg/kg) for a mean of 7.4 months, or with 1.9 mg/kg Propranolol for 9.2 months. Results: 1 mg/kg Captopril did not effectively suppress angiotensin converting enzyme in the steady state at trough level (92±52 vs. 87±50 nmol/min/ml). In the Propranolol group, the clinical heart failure score (2.6±1.5 vs. 7.4±2.5) and plasma renin activities (14±10 vs. 101±70 ng/ml/h) were significantly lower, compared to the Captopril group. Length of hospital stay (23±9 vs. 52±24 days) was lower and weight gain (126±38 vs. 86±84 g/week) was higher within 3 months after starting Propranolol therapy. Significantly lower left atrial pressures (6.2±2.2 vs. 13.4±9.2 mmHg) and lower endiastolic ventricular pressures (7.6±2.5 vs. 12.6±4.0 mmHg) during pre-operative cardiac catheterization indicated a better diastolic ventricular function under chronic Propranolol treatment. Conclusion: Although high dose Captopril was not evaluated in this study, when compared to patients on low Captopril dosages, infants who received Propranolol treatment showed improvement in heart failure scores, shorter lengths of hospital stay, lower plasma renin activities and better diastolic ventricular functions.