Related Experiment Videos
Myocardial infarction and thrombolysis. Electrocardiographic short term and long term results using precordial
Insights
Successful reperfusion after myocardial infarction significantly reduces ST segment shifts and improves R wave amplitude. This indicates salvaged heart muscle, suggesting ST changes may not always signify irreversible damage.
Area of Science:
- Cardiology
- Medical Imaging
- Biomedical Engineering
Background:
- Acute myocardial infarction (AMI) requires prompt assessment of coronary artery patency and myocardial salvage.
- Electrocardiographic (ECG) changes, specifically ST segment shifts and precordial R waves, are key indicators of cardiac events.
- Assessing the effectiveness of thrombolysis and reperfusion therapies is crucial for patient outcomes.
Purpose of the Study:
- To evaluate the correlation between ST segment changes in limb leads and precordial R wave mapping with angiographic findings in acute myocardial infarction.
- To determine the non-invasive assessment of myocardial salvage and damage following reperfusion or reocclusion therapies.
Main Methods:
- Summation of ST segment depression/elevation in limb leads (I, II, III) before and after intracoronary streptokinase in 56 AMI patients.
- Analysis of precordial R and Q waves using a 48-electrode mapping system in 54 anterior AMI patients over 4-6 months.
- Comparison of ECG findings with repeat angiographic results to assess vessel patency and reperfusion.
Main Results:
- Forty-three patients with confirmed reperfusion showed significant ST shift decrease and normalization, often with T wave inversion.
- Thirteen patients without reperfusion exhibited no significant change in summated ST segment shift.
- Patent infarct-related vessels in 36 patients correlated with increased R wave amplitude and fewer leads without R waves; reocclusion led to decreased R waves.
Conclusions:
- Summated ST segment shift in limb leads effectively reflects reperfusion status after thrombolysis.
- Precordial R wave mapping is a valuable non-invasive tool for assessing myocardial salvage post-reperfusion and damage from reocclusion.
- Loss of R waves in acute myocardial infarction does not definitively indicate irreversible myocardial damage.
Abstract:
In a consecutive series of 56 patients with acute myocardial infarction, ST segment depression and elevation in the electrocardiographic limb leads I, II, and III were summated for each patient before and immediately after intracoronary streptokinase infusion and the results compared with the angiographic findings. Forty three patients had angiographically confirmed reperfusion of an initially occluded vessel and showed a significant decrease in summated ST shift. The ST segment changes in the limb leads virtually returned to normal in all 43 patients, and in most, inverted T waves developed. Thrombolysis was unsuccessful in 10 patients, and the infarct related coronary artery was already patent in three. When these two groups are combined, all 13 patients without reperfusion showed no significant change in summated ST segment shift. During percutaneous transluminal angioplasty inflation of the balloon in the vessel that was previously occluded simulated reocclusion and was followed by new ST elevation if the artery supplied viable myocardium. In a further consecutive study of 54 patients with anterior myocardial infarction, the precordial R waves and Q waves were studied over the four to six months following infarction using a standardised 48 electrode mapping system. All patients underwent a repeat angiogram after four to six months. In 36 patients the infarct related vessel was patent. They showed a significant mean increase in summated precordial R wave amplitude and a reduction in the mean number of precordial leads without R waves. In 18 patients with unsuccessful thrombolysis or reocclusion there was a further reduction in mean summated R wave amplitude and an increased number of precordial leads not showing R waves. Precordial R wave mapping seems to be a valuable non-invasive method of assessing the salvage of myocardium after reperfusion and the damage caused by reocclusion. Loss of R waves in the acute phase of myocardial infarction does not necessarily mean an irreversibly damaged myocardium.