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Hemodynamic effects of hydralazine in infants with a large ventricular septal defect
Insights
Hydralazine effectively reduced the left-to-right shunt in infants with large ventricular septal defects (VSD) by increasing systemic blood flow. This afterload reduction may benefit VSD management.
Area of Science:
- Pediatric Cardiology
- Cardiovascular Pharmacology
Background:
- Large ventricular septal defects (VSD) in infants can lead to significant hemodynamic challenges.
- Effective management strategies for VSDs are crucial for improving patient outcomes.
Purpose of the Study:
- To evaluate the acute hemodynamic effects of hydralazine as an afterload-reducing agent in infants with large VSDs.
- To determine if hydralazine can decrease the left-to-right shunt in this population.
Main Methods:
- Seven infants with large VSDs received a single dose of hydralazine (0.2 mg/kg) during cardiac catheterization.
- Hemodynamic parameters, including pressures, saturations, and flows, were measured before and at multiple time points after hydralazine administration.
Main Results:
- Hydralazine significantly increased systemic blood flow and decreased systemic vascular resistance.
- The pulmonary-to-systemic flow ratio and the absolute left-to-right shunt were significantly reduced.
- Pulmonary resistance, pressures, heart rate, and oxygen consumption remained unchanged.
Conclusions:
- Acute administration of hydralazine effectively reduces the left-to-right shunt in infants with large VSDs.
- The observed benefits are attributed to hydralazine's afterload-reducing effects, specifically the decrease in systemic resistance.
- These findings suggest hydralazine may be a valuable therapeutic option for managing infants with large VSDs.
Abstract:
To evaluate the effects of acute afterload reduction, hydralazine, 0.2 mg/kg, was administered at cardiac catheterization to seven infants who had a large ventricular septal defect (VSD). The infants were 2.5 - 11 months old (mean 5.1 months). Before and 5, 15, 25 and 35 minutes after hydralazine, aortic, pulmonary capillary wedge, pulmonary artery, right atrial and superior vena caval pressures and saturations, heart rate and oxygen consumption were measured. Hemodynamic effects were noted after 5 minutes but were most pronounced 35 minutes after hydralazine. Prehydralazine baseline data were therefore compared with values 35 minutes after hydralazine. Pulmonary flow did not changes, but systemic flow increased significantly (4.5 +/- 0.2 to 6.7 +/- 0.5 liters/min/m2 [mean +/- SEM], p less than 0.001). The pulmonary-to-systemic flow ratio decreased by 32% (3.4 +/- 0.4 to 2.3 +/- 0.2, p less than 0.001) and the absolute left-to-right shunt decreased by 24% (10.8 +/- 1.3 to 8.2 +/- 1.2 liters/min/m2, p less than 0.01). Hydralazine caused a significant decrease in systemic resistance (13.9 +/- 0.7 to 9.5 +/- 0.7 U, p less than 0.001). Pulmonary resistance, aortic, pulmonary artery and pulmonary capillary wedge pressures, heart rate and oxygen consumption did not change after hydralazine. Right atrial pressure decreased slightly (4.0 +/- 0.6 to 2.4 +/- 0.6 mm Hg, p less than 0.05). In conclusion, hydralazine caused a significant increase in systemic blood flow and a significant decrease in both pulmonary-to-systemic flow ratio and absolute left-to-right shunt in seven infants with a large VSD. These effects appear to be related to the decrease in systemic resistance that occurred with hydralazine. Although limited to the acute setting, these findings suggest that hydralazine may be beneficial in the management of infants with a large VSD.