Related Experiment Video
Updated: Jun 1, 2026
09:23
Confirmation of Myocardial Ischemia and Reperfusion Injury in Mice Using Surface Pad Electrocardiography
Published on: November 24, 2016
The delayed activation wave in non-ST-elevation myocardial infarction
Tiesheng Niu1, Peng Fu, Chenhong Jia
1Department of Cardiology, Shengjing Hospital of China Medical University, Shenyang 110004, China. niuts@sj-hospital.org
International Journal of Cardiology
|June 14, 2011
Summary
A new ECG finding, the "N wave," can help identify left circumflex artery occlusions in non-ST-elevation myocardial infarction (NSTEMI) patients. This specific QRS complex abnormality shows high sensitivity and specificity for diagnosing culprit LCX artery in NSTEMI.
Area of Science:
- Cardiology
- Electrocardiography
- Medical Diagnostics
Background:
- The relationship between electrocardiographic (ECG) findings and infarct-related arteries (IRAs) in non-ST-elevation myocardial infarction (NSTEMI) is not well understood.
- A novel ECG phenomenon, a notch or deflection in the terminal QRS complex (termed 'N wave'), was observed in NSTEMI patients with acute left circumflex artery (LCX) occlusion.
Purpose of the Study:
- To investigate whether the identified 'N wave' ECG phenomenon can accurately identify the culprit artery in NSTEMI patients.
- To determine the diagnostic performance of the 'N wave' for detecting LCX artery as the IRA in NSTEMI.
Main Methods:
- A study included 218 NSTEMI patients undergoing coronary angiography within 24 hours of admission.
- The 'N wave' was defined as a notch or deflection in the terminal QRS complex of the surface ECG.
- Correlations between the presence of 'N waves' in specific ECG leads and the IRA were analyzed.
Main Results:
- Patients with 'N waves' had a significantly prolonged QRS duration (121 ± 12 ms) compared to those without (106 ± 11 ms).
- The 'N wave' in leads II, III, and aVF was present in 77% of LCX patients, versus 6% in LAD and 18% in RCA patients (P<0.001).
- The 'N wave' in leads I and aVL also showed a higher prevalence in the LCX group (P<0.001), with 77% sensitivity and 89% specificity for leads II, III, aVF, and 64% sensitivity and 96% specificity for leads I, aVL.
Conclusions:
- The 'N wave' represents a delayed activation wave from the left ventricular basal region, supplied by the LCX artery.
- This ECG pattern demonstrates high sensitivity and specificity for identifying the LCX as the culprit artery in NSTEMI.
- The 'N wave' is proposed as a new electrocardiographic pattern indicative of myocardial ischemia.
More Related Videos
Related Concept Videos
01:19Acute Coronary Syndrome II: Pathophysiology and Clinical Manifestations
The pathophysiology of Acute Coronary Syndrome [ACD] involves several key processes:The main underlying cause of ACD is atherosclerosis, a chronic inflammatory disease characterized by the buildup of lipid-laden plaques within the coronary arteries.As the atherosclerotic plaque grows in the coronary artery, it may become unstable due to the formation of a lipid-rich core and a thin fibrous cap. Inflammatory cells within the plaque, such as macrophages, secrete enzymes that degrade the...
01:30Acute Coronary Syndrome I: Introduction
Acute Coronary Syndrome (ACS) encompasses a spectrum of heart conditions caused by sudden obstruction of coronary arteries, typically resulting from the rupture of an atherosclerotic plaque and subsequent thrombus (blood clot) formation. This obstruction can lead to partial or complete blockage of blood flow, causing varying degrees of myocardial ischemia or infarction.ACS includes the following clinical entities:Unstable Angina (UA)Non-ST-Elevation Myocardial Infarction (NSTEMI)ST-Elevation...
01:30Cardiac Action Potential
Cardiac action potentials are essential for proper heart function, enabling the rhythmic contractions needed for adequate blood circulation. Nodal cells and Purkinje fibers, specialized for electrical conduction, generate these action potentials.
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
01:30Acute Coronary Syndrome III: Diagnostic Studies
Diagnosing acute coronary syndrome or ACS begins with a thorough patient history. Notable symptoms include central, crushing chest pain radiating to the left arm, neck, jaw, or back, along with shortness of breath, sweating (diaphoresis), nausea, vomiting, dizziness, and palpitations.It is crucial to note any history of cardiac illnesses and assess risk factors, including age, gender, smoking, hypertension, diabetes, hyperlipidemia, and a sedentary lifestyle.During physical examination, vital...
01:25Correlation between ECG and Cardiac Cycle
The electrical signals recorded on an electrocardiogram (ECG) occur before the mechanical processes of contraction and relaxation during the cardiac cycle.
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...
01:15Ischemic Stroke ll: Pathophysiology
An ischemic stroke occurs when a cerebral blood vessel becomes obstructed, most often by a thrombus or embolus, interrupting the delivery of oxygen and glucose to brain tissue. Because neurons rely on continuous aerobic metabolism, energy failure begins within minutes of reduced perfusion. The region receiving the least blood flow becomes the infarct core, an area of irreversible cellular death. Surrounding this core lies the penumbra, a zone of hypoperfused but still viable tissue that is...