Effect of intravenous nitroglycerin on hemodynamics in infants and children with congestive heart failure

Objective To understand the effect of intravenous nitroglycerin (NTG) on hemodynamics in infants and small children with congestive heart failure secondary to congenital cardiac defect of left to right shunt. Methods Heart rate, blood pressure and total peripheral resistance were monitored continuously. Echocardiography was used to measure ejection fraction, fractional shortening, end-diastolic volume index of left ventricle, pulmonary capillary wedge pressure, pulmonary artery mean pressure and left ventricular wall stress before uhe use and during 0.5, 1.0, 1.5, 2.5, and 5.0 mu g kg(-1).min(-1) dosages of nitroglycerin (NTG). Results There was no significant difference in the indexes of heart rate, blood pressure, ejection fraction and fractional shortening of left ventricle, stroke volume index, cardiac output index, end-diastolic volume index before the use and after the use of NTG. Pulmonary capillary wedge pressure decreased from 15.5 +/- 2.3 mm Hg before the use of NTG to 14.3 +/- 2.2 mm Hg after the use of 0.5 mu g.kg(-1) min(-1) NTG ( P < 0.05), minimum to 12.3 +/- 2.4 mm Hg; left ventricular wall stress I, II and III decreased from 407 +/- 65 dyn.cm(-2).10(3), 166 +/- 48 dyn.cm(-2).10(3), 255 +/- 52 dyn.cm(-2).10(3) to 357 +/- 75 dyn.cm(-2).10(3), 136 +/- 48 dyn.cm(-2) 10(3), 218 +/- 52 dyn.cm(-2) 10(3) (P < 0.05), minimum to 321 + 50 dyn.cm(-2).10(3), 114 +/- 42 dyn.cm(-2).10(3), 187 +/- 42 dyn.cm(-2).10(3), respectively. Total peripheral resistance and pulmonary artery mean pressure were decreased when the dosage of intravenous NTG was increased to above 2.5 mu g.kg(-1).min(-1) (P < 0.05). There was no statistical difference in the above indexes of the different dosages. Conclusion Congestive heart failure secondary to congenital cardiac defect of left to right shunt in infants and small children is the indication of using intravenous NTG which could improve hemodynamics. There was different selectivity in dosage between arterial and venous vasodilatation. and the change in hemodynamics was independent of dosage. The dosages of 0.5-1.0 mu g.kg(-1).min(-1) NTG are recommended when the decrease of cardiac preload is the main point of therapy of heart failure.