Unusual Tachycardia in a Patient With Chest Pain and Bradycardia.

This case report describes a patient in their 50s who presented with squeezing chest pain for 4 hours and an initial electrocardiogram showing acute inferior wall and right ventricular infarction with third-degree atrioventricular block.

An Interesting Wide QRS Complex Tachycardia.

This case report describes a patient in their 70s who presented to the emergency department with sudden-onset tachycardia that had been going on for more than 1 day after experiencing recurrent palpitations for the past 20 years.

Noteworthy P Waves in an Elderly Woman.

This case report describes a patient in their 70s who was referred to the emergency department for worsening shortness of breath, chest tightness, and episodes of palpitations. What is your diagnosis?

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 V2-6, J point depression with upsloping ST-segment depression. However, the coronary angiogram demonstrated a 100% occlusion of midshaft LAD artery. CONCLUSIONS: Recognition of this atypical electrocardiogram (ECG) pattern can ensure immediate reperfusion therapy regarding acute myocardial infarction.

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. Sensing and stimulating electrode catheters were placed in the high right atrium and along epicardial surface of atrioventricular groove of the left ventricular anterior wall, respectively. Programmed premature stimulation S2 was synchronized with P wave and utilized to stimulate the ventricle. The ECG recorded the electrical activity of the heart. As compared with the QRS complex during sinus rhythm, paced QRS was assessed regarding the initial, maximal and terminal vector. PS2 interval and PR interval were also measured and analyzed. RESULTS: Preexcitation was successfully simulated by ventricular pacing in the rabbits, including (1) Complete preexcitation: PS2 interval was less than PR interval; the difference was more than or equal to 47.00 ± 7.53 ms. (2) Incomplete preexcitation: PS2 interval was less than PR interval; the difference was less than 47.00 ± 7.53 ms. (3) Incomplete latent preexcitation: PS2 interval was more than or equal to PR interval; the difference was less than or equal to 13.00 ± 3.50 ms. (4) Complete latent preexcitation: PS2 interval was more than or equal to PR interval; the difference was more than 13.00 ± 3.50 ms. CONCLUSIONS: The difference in the relative conduction velocity of the atrioventricular node versus the AP pathways determines the degree of preexcitation and different manifestation on ECG. The QRS terminal vector also reflects the ventricle preexcitation, indicating a valuable sign for the diagnosis of atypical or latent 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." METHODS: We randomized 100 healthy volunteers (50 females and 50 males; mean age 25.12±1.62 years) to receive "conventional 12-lead ECG" and "Saah ECG," which were recorded by the "Saah ECG" machine. We recorded and further analyzed "conventional 12-lead ECG" and "Saah ECG." According to the microwavelets before the QRS complex, the PR interval was the sum of three intervals: PAs interval (PA interval recorded on surface ECG), AHs interval (AH interval recorded on surface ECG), and HVs interval (HV interval recorded on surface ECG). The PR interval, PAs interval, AHs interval, and HVs interval were measured. RESULTS: Not only the P-QRS-T waves but also the microwavelets before the P wave, before the QRS complex, and after the QRS complex were recorded in 100 healthy volunteers. The PAs interval, AHs interval, and HVs interval were 22-37 (31.23±2.93) ms, 60-103 (76.07±13.43) ms, and 39-55 (49.29±4.44) ms, respectively. The PAs interval, AHs interval, and HVs interval were consistent with the intracardiac measurements (PA, AH, and HV intervals) obtained in previous studies. Compared with female volunteers, male volunteers had a longer AHs interval (p<0.05). CONCLUSION: Not only the P-QRS-T waves but also the microwavelets before the P wave, before the QRS complex, and after the QRS complex were recorded on surface ECG. The wavelets before the QRS complex may be related to atrioventricular nodal, His bundle (bundle branch) potentials.