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[Study of congenital cardiopathies with left-right shunt using gamma-angiocardiography]
Insights
Radioactive Technetium-labeled red blood cells track cardio-pulmonary blood flow. This study identifies prolonged lung activity in patients with left-to-right shunts, aiding diagnosis and monitoring.
Area of Science:
- Nuclear Medicine
- Cardiology
- Pulmonary Medicine
Context:
- Assessing cardio-pulmonary circulation is crucial for diagnosing and managing various cardiac conditions.
- Left-to-right shunts represent a significant group of congenital heart defects requiring accurate evaluation.
- Non-invasive imaging techniques are essential for monitoring shunt flow and treatment efficacy.
Purpose:
- To evaluate the utility of radioactive Technetium-labeled red blood cells in assessing cardio-pulmonary transit and diagnosing left-to-right shunts.
- To correlate quantitative parameters derived from radionuclide imaging with established methods like oximetry and dye dilution curves.
- To establish the safety and indications for this investigation in pediatric cardiology.
Summary:
- Red blood cells labeled with radioactive Technetium were intravenously injected and tracked using a scintillation camera to visualize cardio-pulmonary blood flow in 58 patients with left-to-right shunts and 40 controls.
- Analysis of intensity-duration curves revealed abnormally prolonged lung activity and early recirculation peaks in patients with shunts, with a numerical ratio (C2/C1) correlating with pulmonary-to-systemic flow ratios.
- The study demonstrated a strong correlation between radionuclide findings and oximetry/dye dilution curves, enabling localization of shunts to atrial or ventricular levels and confirming surgical closure of septal defects.
Impact:
- Provides a safe and effective method for diagnosing and monitoring left-to-right shunts in children.
- Offers crucial data for confirming the success of surgical interventions for septal defects.
- Aids in clarifying complex conditions such as infundibulo-pulmonary syndromes through detailed flow analysis.
Abstract:
Red blood cells labelled with radioactive Technetium were injected intravenously, and the passage of the tracer through the cardio-pulmonary system recorded using a scintillation camera coupled with a numerical dosimeter. The results are presented as serial analoque pictures taken at the rate of two per second, as numerical tracings which are later processed, and as flow charts from predetermined areas of interest: the chambers of the heart, the lung parenchyma, and the aorta. This study is concerned with 58 patients with a left-to-right shunt, and about 40 normal examinations were used as a baseline for comparison. In cases of left-to-right shunt, the finding on the tracings is of abnormally prolonged activity in the lungs after a normal passage through the right side. The intensity-duration curves highlight this finding, and show an early recirculation peak in the right side of the heart and a slowing of pulmonary emptying, which can be evaluated numerically from the ratio C2/C1. A correlation has been found between this value and the ratio of pulmonary to systemic flow as calculated by oximetry. The correlation is even closer if a comparison is made between the curves of pulmonary radioactivity and the dye dilution curves. In certain cases, the shunt can be localised to the atrial or ventricular level. There are many indications for this safe investigation: --the diagnosis and monitoring of the flow through a left-to-right shunt in a child; --confirmation of the closure of septal defects after surgery; --clarification of an infudibulo-pulmonary syndrome.