Effects of transdermal nitroglycerin in children with congestive heart failure: a Doppler echocardiographic study

The aim of this study was to evaluate by Doppler echocardiography whether administration of transdermal nitroglycerin (NTG) to children with congestive heart failure could modify mitral flow velocity profile with redistribution of left ventricular filling to late diastole, suggesting preload reduction of the left ventricle. Twelve children with congestive heart failure, aged from 6 months to 6 years (2.83 +/- 2.24 years; mean +/- SD), were recruited. Patients were randomly allocated either a NTG patch (study group; n = 6) or a placebo patch (control group; n = 6) in a double-blind procedure. The NTG patch was a 10-cm(2) patch releasing 5 mg of NTG per day. NTG patches were adjusted to a dose of 1 cm(2)/kg/day (0.5 mg/kg/day). Peak velocity and time--velocity integral (TVI) of E and A waves of transmitral flow, the ratio of the velocities of the A wave and E wave, and the ratio of the TVI of the A wave to the TVI of the E wave were measured. Doppler measurements were determined before treatment (H0) and 4 hours (H4) and 23 hours (H23) after the patch application. Relative changes of these parameters were not significantly different between these two groups. In the NTG group, mean NTG plasma concentration was 1.08 +/- 0.47 microg Liter(-1) at H4 (n = 5) and 1.18 +/- 0.81 microg Liter(-1) at H23 (n = 5). No patient had a NTG plasma concentration greater than 2 microg Liter(-1) either at H3 or at H24. These data suggest that 1 cm(2)/kg transdermal doses of NTG may have a limited bioavailability or a higher clearance and minimal hemodynamic effects in children with congestive heart failure already receiving other medications, implying that higher doses should be used.