Related Experiment Videos
Intracardiac electrode detection of early or subendocardial ischemia
Insights
Intracardiac electrograms detect myocardial ischemia earlier and more sensitively than surface ECG, even with masked changes. This improved detection method aids in diagnosing critical cardiac events.
Area of Science:
- Cardiology
- Biomedical Engineering
Background:
- Subendocardial and early transmural ischemia can have serious clinical effects but may show minimal electrocardiogram (ECG) changes.
- Detecting early-stage ischemia is crucial for timely intervention and improved patient outcomes.
Purpose of the Study:
- To evaluate the sensitivity and timing of intracardiac electrograms (IC EGM) compared to surface ECG for detecting myocardial ischemia.
- To assess the utility of IC EGM in challenging diagnostic scenarios, such as the presence of intraventricular conduction defects.
Main Methods:
- Developed modified intracavitary electrodes for transvenous (right ventricle, coronary sinus) and transarterial (left ventricle) insertion, avoiding endocardial contact.
- Recorded simultaneous IC EGM and surface ECG in 22 dogs during graded coronary artery stenoses (circumflex and left anterior descending).
- Analyzed EGM for specific ischemic changes in response to stenosis and reperfusion.
Main Results:
- IC EGM detected specific ischemic changes in 100% of left ventricle (LV), 60% of right ventricle (RV), and 89% of coronary sinus (CS) recordings, even with nonspecific ECG changes.
- Specific ischemic changes were identified in 29% of LV, 10% of RV, and 19% of CS recordings when the surface ECG showed no changes.
- IC EGM demonstrated changes earlier than surface ECG and could detect ischemia despite intraventricular conduction defects and other masking conditions.
Conclusions:
- Intracardiac electrograms offer superior sensitivity and earlier detection of myocardial ischemia compared to surface ECG.
- This technique holds significant potential for diagnosing ischemia in complex clinical situations where standard ECG may be unreliable.
Abstract:
Subendocardial and early transmural ischemia may have significant clinical consequences while manifesting few ECG changes. Catheters were designed to be introduced transvenously into the right ventricle (RV), and coronary sinus (CS) and transarterially into the left ventricle (LV). The intracavitary electrodes were modified so that the electrodes would not contact the endocardium. In twenty-two dogs ninety-eight graded stenoses of the circumflex and left anterior descending coronary arteries were performed while electrograms (EGM) were recorded simultaneously from the intracardiac (IC) electrodes and surface ECG. Of those stenoses resulting in only nonspecific ECG changes, there were specific ischemic changes on 100% of LV, 60% of RV, and 89% of CS electrograms. Of those stenoses which resulted in no ECG change, there were specific ischemic changes in the 9/31 (29%) of LV, 3/31 (10%) of RV, and 6/31 (19%) of CS electrograms. Recognizable patterns of change occur on the intracardiac electrograms in response to both stenosis and reperfusion, earlier than any change on the ECG. Besides being more sensitive, intracardiac electrodes allowed for the detection of ischemia even in the presence of intraventricular conduction defects, strain patterns, and possibly other situations which might otherwise mask ischemic changes on the ECG.