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.

Electrocardiogram: his bundle potentials can be recorded noninvasively beat by beat on surface electrocardiogram.

BACKGROUND: The micro waveform of His bundle potential can't be recorded beat-to-beat on surface electrocardiogram yet. We have found that the micro-wavelets before QRS complex may be related to atrioventricular conduction system potentials. This study is to explore the possibility of His bundle potential can be noninvasively recorded on surface electrocardiogram. METHODS: We randomized 65 patients undergoing radiofrequency catheter ablation of paroxysmal superventricular tachycardia (exclude overt Wolff-Parkinson-White syndrome) to receive "conventional electrocardiogram" and "new electrocardiogram" before the procedure. His bundle electrogram was collected during the procedure. Comparative analysis of PAs (PA interval recorded on surface electrocardiogram), AHs (AH interval recorded on surface electrocardiogram) and HVs (HV interval recorded on surface electrocardiogram) interval recorded on surface "new electrocardiogram" and PA, AH, HV interval recorded on His bundle electrogram was investigated. RESULTS: There was no difference (P > 0.05) between groups in HVs interval (49.63 ± 6.19 ms) and HV interval (49.35 ± 6.49 ms). Results of correlational analysis found that HVS interval was significantly positively associated with HV interval (r = 0.929; P < 0.01). CONCLUSIONS: His bundle potentials can be noninvasively recorded on surface electrocardiogram. Noninvasive His bundle potential tracing might represent a new method for locating the site of atrioventricular block and identifying the origin of a wide QRS complex.

Effects of Antegrade Accessory Pathway Conduction on QRS Terminal Vector in Patients with Preexcitation Syndrome.

BACKGROUND: Ventricle preexcitation through accessory pathway changes QRS initial vector, and manifests as delta wave on electrocardiogram (ECG). However, QRS terminal vector can also be affected. METHODS: A total of 158 patients who had single accessory pathway (AP) with antegrade conduction capacity were included and divided into two groups according to the ECG with or without delta wave. Note that 150 patients had delta wave (overt AP group) on ECG; classical preexcitation syndrome was diagnosed before radiofrequency ablation. Eight patients had no delta wave on ECG (unapparent AP group); preexcitation was induced by transesophageal atrial pacing. ECGs and intracardiac electrogram (IEGM) before and after ablation and during atrioventricular reentrant tachycardia were analyzed. RESULTS: (1) In the overt AP group: QRS terminal vector amplitude and polarity changes were observed in all the 150 patients, and were related to AP location and delta wave polarity. (2) In the unapparent AP group: QRS terminal vector changes were found in two out of eight patients, and the initial activation of ventricle myocardium via AP on IEGM was almost simultaneous with the onset of QRS complex on ECG. CONCLUSIONS: It is not only the QRS initial vector, but also the QRS terminal vector that can be changed by the antegrade accessory pathway conduction in patients with preexcitation syndrome. The change of QRS terminal vector is valuable for the diagnosis of atypical preexcitation.

Prediction of Pulmonary Arterial Hypertension in Chronic Obstructive Lung Disease from Three-Dimensional Vectorcardiographic Parameters.

AIM: The objective of our study was to assess diagnostic value of three-dimensional (3D) vectorcardiographic (VCG) parameters in detecting pulmonary arterial hypertension (PAH) in chronic obstructive lung disease (COLD) with and without right ventricular hypertrophy (RVH). METHODS: The study group of 62 patients with COPD was stratified on the basis of color Doppler echocardiographic findings into three subgroups: non-PAH (n = 23), PAH without RVH (n = 22), and PAH with RVH (n = 17). Pairwise differences between the subgroups were evaluated by one-way analysis of variance, and Pearson correlation analysis was used to evaluate the significance of the correlations between pulmonary arterial systolic pressure (PASP) and various VCG parameters. RESULTS: The azimuth of the QRS vector decreased from -24° in the non-PAH group to -62° in PAH without RVH and to -140° in PAH with RVH (P < 0.01 for pairwise differences between all three groups). Similar significant decrease was observed for the azimuth of the ventricular gradient (VG) vector. Spatial QRS/T angle increased from 69° in the non-PAH group to 115° in PAH without RVH (P < 0.01). In the PAH group with RVH, QRS/T angle was 94° (P < 0.05 for difference from the non-PAH group). There was a significant correlation between PASP and QRS/T angle (r = 0.89, P < 0.05) and between PASP and the azimuth of the VG vector (r = 0.86, P < 0.05). PASP increase from linear regression model was 0.8 mmHg for a QRS/T angle increase by 10° and 1.3 mmHg for each 10° increase in the azimuth of the VG vector. CONCLUSION: 3DVCG parameters are potentially useful for predicting PASP in COLD patients, and possibly also for differentiation between COLD patients with PAH and RVH from those without RVH.

Effects of Preexcitation Syndrome on Terminal QRS Vector Observed in Spatial Vector.

BACKGROUND: Preexcitation syndrome could affect terminal QRS vector, which is not emphasized in clinic. In this study, we made a comparison between vectorcardiogram (VCG) before and after ablation to observe the change of terminal QRS vector. Furthermore, the relationship between the change of terminal QRS vector and accessory pathway (AP) as well as the change of initial QRS vector (delta vector) was analyzed. METHODS: Thirty patients who were proved to have a single AP by ablation were included. All patients were divided into seven groups based on the AP location. Comparison between VCG before and after ablation was made to observe the change of terminal and delta vector. The relationship between the change of terminal QRS vector and AP location as well as delta vector was analyzed. RESULTS: (1) All 30 patients had a change in terminal QRS vector (elevation and/or azimuth) in comparison to postablation VCG. (2) The change of terminal QRS vector was related to delta vector and AP location. The agreement and consistency between the change of terminal QRS vector and delta vector were 91.65% and 0.856 (P < 0.01), respectively. CONCLUSIONS: (1) Both initial and terminal QRS vector are affected by the antegrade conduction of AP. The change of terminal QRS vector is related to the AP location and delta vector. (2) The effect of preexcitation syndrome on QRS terminal vector is shown as more intuitive and easy in spatial vector by comparison with electrocardiogram, which is helpful for the diagnosis of atypical preexcitation and localization of AP.

Very early recurrence of Takotsubo syndrome.

An 82-year-old female presented lasting chest pain for stimulation and the ECG revealed ventricular fibrillation and ST segment elevation, so we considered acute myocardial infarction. However, after the clinical condition of the patient improved, symptoms recurred for stimulation again on day 4. An echocardiogram showed left ventricular apical ballooning, so, we diagnosed her as Takotsubo syndrome.

Hyperkalemia-induced Brugada pattern with electrical alternans.

The Brugada syndrome is a genetic disease (mutation of the SCN5A gene) that predisposes to syncope and life-threatening sudden cardiac death. The case highlights the importance of recognizing hyperkalemia, as potential triggers of the acquired Brugada sign with electrical alternans.

Preexcitation syndrome with myocardial infarction complicated by atrioventricular block in both normal and accessory pathways?

The preexcitation syndrome may either simulate myocardial infarction (MI) or mask it. The rapid anterograde conduction through accessory pathway may obscure atrioventricular (AV) block of the normal AV-nodal tract. To our knowledge, the case of various degree AV-nodal and bypass tract block after MI in a patient with preexcitation syndrome has been infrequently reported. We report a complex case of preexcitation syndrome presenting with first-degree and transient third-degree AV blocks in both normal and accessory pathways after acute MI. Subsequently, we further discuss the diagnosis of MI in preexcitation syndrome and analyze the electrocardiographic character of AV block in preexcitation syndrome.

Pre-excitation syndrome with a change in terminal QRS vector.

Most accessory pathways in pre-excitation syndrome are capable of antegrade conduction from atrium to ventricle, and identified by characteristic ECG abnormalities such as a delta wave (ventricular pre-excitation) and a shortened PR interval.Therefore, the traditional diagnosis method is to detect the initial changes of the QRS complex. Here we report a patient initially mistaken as having atrioventricular re-entrant tachycardia (AVRT) and concealed pre-excitation syndrome. A diagnosis of incomplete latent pre-excitation syndrome was established on the basis of differences between the ECGs during sinus rhythm and AVRT in terminal QRS vectors, demonstrated by intracardiac electrophysiological radiofrequency catheter ablation.

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.