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Functional and pathologic effects of multiple echocardiographic contrast injections on the myocardium, brain and
Insights
Myocardial contrast echocardiography (MCE) can assess heart damage after coronary occlusion but requires safety evaluation. This study found MCE caused transient hemodynamic changes and wall motion depression, but no lasting organ damage, indicating its potential safety.
Area of Science:
- Cardiovascular Imaging
- Diagnostic Echocardiography
- Contrast Agent Toxicology
Background:
- Myocardial contrast echocardiography (MCE) is a valuable tool for assessing the area at risk for necrosis following coronary occlusion.
- The clinical utility of MCE is contingent upon its intrinsic safety, ensuring no toxic effects on the heart or other vital organs.
Purpose of the Study:
- To evaluate the functional and pathological effects of a commonly used contrast agent during MCE.
- To determine the safety profile of MCE when administered via intracoronary, intrarenal, and intracarotid routes.
Main Methods:
- Five dogs underwent intracoronary, intrarenal, and intracarotid injections of an agitated Renografin-saline solution.
- Hemodynamic parameters (heart rate, blood pressure, LVEDP, dP/dt) and electrocardiograms were monitored during and after injections.
- Left ventricular wall motion analysis and light microscopic examination of the heart, brain, and kidneys were performed.
Main Results:
- Intracoronary injections caused transient decreases in blood pressure and increases in left ventricular end-diastolic pressure.
- A depression in wall motion within contrast-enhanced regions and ECG ST-T changes were observed.
- No significant changes in heart rate or left ventricular dP/dt were noted, and all measured variables normalized.
- Light microscopy revealed no myocardial or cerebral pathological changes attributable to the contrast agent.
Conclusions:
- Myocardial contrast echocardiography with the tested agent induces transient, reversible hemodynamic and functional changes.
- The contrast agent demonstrated no significant intrinsic toxicity to the myocardium, brain, or kidneys at the tested doses and administration routes.
- These findings support the potential safety of MCE for in vivo assessment of the area at risk in coronary occlusion models.
Abstract:
Myocardial contrast echocardiography can define in vivo the area at risk for necrosis after coronary occlusion. However, if this technique is to be used, it cannot be intrinsically toxic to the heart or other critical organs. To determine the functional and pathologic effects of contrast echocardiography, six intracoronary, six intrarenal and six intracarotid artery injections of 2 to 6 cc of a commonly employed contrast agent (agitated Renografin-saline solution) were performed in five dogs. A sixth dog served as a sham to assess any deleterious effects of the model preparation. Two-dimensional echocardiographic images and electrocardiograms were recorded during intracoronary injections, and heart rate, blood pressure, left ventricular end-diastolic pressure and rate of rise of left ventricular pressure (dP/dt) were continuously monitored. At 24 hours, echocardiographic and hemodynamic measurements were repeated, the dogs were killed and the heart, brain and kidneys were removed and prepared for light microscopic examination. Quantitative analysis of left ventricular wall motion was performed on control, peak contrast, post-contrast and 24 hour studies. With each intracoronary injection, there were transient decreases in blood pressure (p = 0.05 versus control) and increases in left ventricular end-diastolic pressure (p = 0.04 versus control). These were associated with depression of wall motion in contrast-enhanced regions (p = 0.01 versus control) and ST-T segment changes on the electrocardiogram. No significant change in heart rate or left ventricular dP/dt was noted. All variables normalized with the clearance of the contrast effect and remained normal to 24 hours. Light microscopic examination revealed no myocardial or cerebral changes attributable to the contrast agent injections.(ABSTRACT TRUNCATED AT 250 WORDS)