An emergency ECG sign of ST elevation myocardial infarction.

Background: The occlusion of the left anterior descending coronary artery (LAD) is usually characterized by the ST-segment elevation associated with a tall and peaked T wave in precordial leads.

Case Presentation: We reported a case who suffered from typical chest pain and tall and positively symmetrical T waves in leads V, J point depression with upsloping ST-segment depression. However, the coronary angiogram demonstrated a 100% occlusion of midshaft LAD artery.

Preexcitation syndrome: experimental study on the electrocardiogram of antegradely conducting accessory pathway.

Background: Preexcitation syndrome is characterized by a dominant delta wave on the baseline electrocardiogram (ECG), resulting from the change in QRS initial vector by the accessory pathway (AP). This study is to explore the effect of ventricular preexcitation on the QRS initial, maximal and terminal vector in an experimental rabbit with preexcitation syndrome induced by programmed electrical stimulation.

Methods: Rabbits (n = 10) were randomized for the experimental model of ventricular preexcitation.

Recurrent extensive anterior myocardial infarction with left and right bundle branch block.

The diagnosis of myocardial infarction with left bundle branch block is difficult. We report a case of 56-year-old man with old extensive anterior myocardial infarction and left bundle branch block (masked each other). The recurrent myocardial infarction indicated right bundle branch block and first-degree atrioventricular block, making a clear diagnosis of complicated and interesting ECG.

Surface electrocardiogram: Could atrioventricular nodal and His bundle potentials be recorded beat by beat on "Saah electrocardiogram"?

Objective: The P-QRS-T wave on surface electrocardiogram (ECG) reflects the changes in atrial and ventricular electrical properties. However, the atrioventricular conduction system potentials cannot be recorded to date. This study aimed to explore the possibility of micropotential of the atrioventricular conduction system recorded by surface "SAN-Atrial-AVN-His (Saah) ECG.