Alternating anterior and posterior fascicular block and left septal fascicular block.

Electrocardiogram of a patient affected by hypertensive cardiomyopathy showed an anterior fascicular block pattern and in right precordial leads an anterior displacement of QRS complex, characterised by a well evident jump of r wave from V1 to V2. Lead V2 showed qR morphology with embryonic q wave and very tall R wave. Septal q waves were not present in leads I and aVL. A subsequent electrocardiogram showed a posterior fascicular block pattern and the same findings in right precordial leads. Septal q waves were not present in inferior leads. Other causes of anterior displacement of QRS complex were ruled out by clinical/instrumental investigation. These findings are highly suggestive of left septal (middle) fascicular block coexisting with anterior and posterior fascicular block.

Different degrees of anterior displacement of QRS complex.

Electrocardiogram of a patient affected by hypertrophic cardiomyopathy showed normal PR and QRS intervals and signs of left ventricular hypertrophy. In leads I,V5 and V6 the initial q waves were absent. A subsequent electrocardiogram revealed the appearance of prominent anterior QRS forces expressed by a change from rS to R pattern in leads V2 and V3 with a tall R wave in V2. PR and QRS intervals and QRS axis remained substantially unchanged. Other electrocardiograms showed day-to-day variations of the anterior displacement of QRS complex. The different degrees of anterior displacement appear to be an expression of an underlying left septal fascicular block, but a diagnosis cannot be made with certainty.

Incomplete (partial) left anterior hemiblock.

This report describes two electrocardiograms (ECGs) showing unusual manifestations of left anterior hemiblock (LAH). One revealed different degrees of incomplete LAH and the other documented the occurrence of 2:1 LAH. Understanding different degrees of LAH helps to interpret the ECG with regard to intraventricular conduction disorders and other ECG abnormalities.

Intermittent isolated anterior displacement of QRS complex - Differential diagnosis.

BACKGROUND: The proposed criteria for diagnosis of left septal (middle) fascicular block (LSFB) appear to be conflicting. Moreover, it has been claimed that isolated anterior displacement (AD) of QRS complex could be a manifestation of a conduction delay of the right bundle branch, besides of LSFB. The purpose of the present study was to better define the etiology of AD through an analysis of the case reports dealing with intermittent AD, published up to now. METHODS: PubMed search was performed to include all case reports dealing with intermittent AD occurring spontaneously, with an available 12­lead electrocardiographic recording. Pertinent data were extracted from the papers for further analysis. RESULTS: Eighteen case reports were found in the literature; in all cases intermittent AD was attributed to LSFB. In all cases AD was associated to changes of initial QRS forces, characterized by disappearance of septal q waves (in I and V6) and/or appearance of a small q wave in leads V1-V3. Morphology of terminal QRS forces, analysed for the first time, was unchanged in 90% of cases. Some Isolated ADs observed during induction of premature atrial extra-stimuli and recorded by vectorcardiographic tracing and some electrocardiographic leads were attributed to a conduction delay of the right bundle branch. In this case, initial QRS forces did not change and terminal QRS forces shifted to the right. CONCLUSIONS: In the presence of intermittent isolated AD, a differential diagnosis between LSFB and a conduction delay of the right bundle branch appears to be possible by the analysis of initial and terminal QRS forces. Instead, the diagnosis of permanent LSFB remains a challenge.

Left septal fascicular block: Evidence, causes, and diagnostic criteria.

The existence of a tetrafascicular intraventricular conduction system is widely accepted by researchers. In this review, we have updated the criteria for left septal fascicular block (LSFB) and the differential diagnosis of prominent anterior QRS forces. More and more evidence points to the fact that the main cause of LSFB is critical proximal stenosis of the left anterior descending coronary artery before its first septal perforator branch. The most important characteristic of LSFB that has been incorporated in the corresponding diagnostic electrocardiographic criteria is its transient/intermittent nature mostly observed in clinical scenarios of acute (ie, acute coronary syndrome including vasospastic angina) or chronic (ie, exercise-induced ischemia) ischemic coronary artery disease. In addition, the phenomenon proved to be phase 4 bradycardia rate dependent and induced by early atrial extrastimulus. Finally, we believe that intermittent LSFB has the same clinical significance as "Wellens syndrome" and the "de Winter pattern" in the acute coronary syndrome scenario.

Transient P' waves in a hyperkalemic cat: artifact or dissociation?

A 15-year-old Sphynx cat was referred for cervical ventroflexion, ataxia, and lethargy associated with hypokalemia. After administration of supplemental potassium, the cat became severely hyperkalemic. Transient P' (vs. pseudo P' waves) were detected on the electrocardiogram. Over the course of hospitalization, the cat's potassium normalized, and the abnormal P' waves did not recur. These images are presented to highlight the differential diagnoses for this type of electrocardiogram. Diagnostic considerations included complete or transient atrial dissociation (as a rare consequence of hyperkalemia), atrial parasystole, and various electrocardiographic artifacts. Definitive diagnosis of atrial dissociation requires an electrophysiologic study or echocardiographic documentation of two independent atrial rhythms with associated mechanical activity, but these were unavailable in this case.

CineECG illustrating the ventricular activation sequence in progressive AV-junctional conduction block.

We present the use of CineECG in visualizing abnormal ventricular activation in a case of a complex conduction disorder. CineECG combines the standard 12­lead surface ECG with a 3D anatomical model of the heart. It projects the location and direction of the average ventricular activation and recovery on the heart model over time. In this case, CineECG was able to visualize the different type of fascicular conduction in this progressive conduction block. This novel imaging technique was able to provide additional insight in this complex case, and might be of use in other complex ECG patterns.

Is narrowest QRS the best? A case of cardiac resynchronization therapy in a patient with left anterior fascicular block.

The efficacy of cardiac resynchronization therapy (CRT) in patients with a narrow QRS duration has not been established. We present a patient with a narrow QRS duration and left anterior fascicular block in which CRT was effective. Left ventricular lead implantation at the optimal site and appropriately-timed left ventricular pacing (LVP) resulted in left ventricle reverse remodeling. Left ventricular dyssynchrony did not improve with LVP at a timing that resulted in narrower QRS than an intrinsic QRS duration. The optimization of LVP timing in CRT for patients with a narrow QRS duration is discussed.

Group beating bradycardia due to two level AV junctional conduction block including combined Wenckebach and Mobitz 2 fascicular block.

A case of a complex advanced two level AV junctional conduction block is described with electrocardiographic features consistent with the combination of incompletely concealed Wenckebach in the left anterior fascicle of the left bundle branch, and most probably in the right bundle branch and with Mobitz type II in the left posterior fascicle of the left bundle branch, resulting in intermittent trifascicular block.

Transitory R wave growth in the midst of ST-segment elevation myocardial infarction: A case of left septal fascicular block with atypical electrocardiographic presentation.

We report the case of a patient who presented with angina and ST-segment elevation in the precordial leads owing to a proximal occlusion of the left anterior descending coronary artery. Serial electrocardiography (ECG) showed signs consistent with the left septal fascicular block (LSFB). The latter was observed in conjunction with a pre-existing left anterior fascicular block and presented atypical ECG features, such as intermittent prominent anterior QRS forces (prominent R wave) in V2 only and preserved septal q waves in I and aVL. In the discussion, we present an overview of the electrocardiographic criteria for the diagnosis of the LSFB together with reasons for which LSFB may present with an atypical ECG picture.

Patient With Presyncope and Variable PR Interval and QRS Morphology.

We describe the case of a 72-year-old female patient, presenting with presyncope and variable PR Interval and changing QRS morphology on the electrocardiogram. Differential diagnosis is discussed. (Level of Difficulty: Beginner.).

Exercise-induced left fascicular block: A forgotten sign of coronary disease.

A 55-year-old patient presented with stable angina pectoris with normal physical examination on rest electrocardiogram and cardiac echocardiogram. Treadmill test revealed exercise-induced left posterior fascicular block, which is an uncommon and easily unnoticed marker of coronary artery disease. A dobutamine stress echocardiogram was performed, with a clearly positive result. Coronary angiography revealed critical stenosis in the right coronary artery.

Electrocardiographic Recognition of Unprotected Left Main ST-Segment Elevation Myocardial Infarction: Looking Beyond aVR.

ST-segment elevation in aVR has traditionally been used for electrocardiographic identification of left main coronary artery (LM) myocardial infarction. We present two ST-segment elevation myocardial infarction (STEMI) cases with acute total occlusion of the LM without aVR ST-segment elevation. This report reviews the different electrocardiographic discriminators suggestive of unprotected LM STEMI. (Level of Difficulty: Intermediate.).

Left Anterior Fascicular Block After Transcatheter Closure of Ventricular Septal Defect in Children.

Background: Arrhythmia is the most common complication after transcatheter closure of a ventricular septal defect (VSD). However, the effects of postprocedural left anterior fascicular block are not clear. This study presents the clinical characteristics, prognosis, and related risk factors of left anterior fascicular block after transcatheter closure of a VSD in children. Methods: The clinical and follow-up data of the patients in the Heart Center of Children's Hospital of Chongqing Medical University from June 2009 to October 2018 were reviewed. And 30 cases were eligible out of all 1,371 cases. Results: An electrocardiogram showed a left anterior fascicular block within 3 days, and most patients gradually returned to normal within 1-2 years, showing a dynamic change. Left ventricular end-diastolic dimension Z-score ranged from -2 to 2 in all children, and no decrease of left ventricular ejection fraction was found in all children. The high ratio between VSD size and body surface area [p < 0.05, odds ratio (OR) 2.6, 95% CI: 1.136-6.113] and large diameter difference between the occluder size and VSD size (p < 0.05, OR 2.1, 95% CI: 1.036-4.609) were independent risk factors for postprocedural left anterior fascicular block. Conclusions: The incidence of postprocedural left anterior fascicular block is not that low, and the overall prognosis is quite good at the current follow-up stage. No progressive severity has been found, such as complete left bundle branch block, double (triple) bundle branch block, and atrioventricular block, to have an influence on cardiac systolic and diastolic function.

Variant Angina with Spontaneously Documented Ischemia- and Tachycardia-induced "Lambda" Waves.

In a patient with variant angina of the proximal left anterior descending coronary artery, myocardial ischemia changed the QRS-ST-T configurations without J-waves into those resembling "lambda" waves at maximal ST-segment elevation, and couplets or triplets of supraventricular extrasystole (SVE) changed the ischemia-induced "lambda" waves into QRS-ST-T configurations resembling a "tombstone" morphology or "monophasic QRS-ST complex." At the resolution phase of coronary spasm, the QRS-ST-T configurations returned to those without J-waves and were changed by SVE into "lambda" waves. Interestingly, neither ischemia- nor SVE-induced "lambda" waves or SVE-induced "tombstone" morphology or "monophasic QRS-ST complex" were complicated by ventricular tachyarrhythmia.

A rare combination of atrial and intraventricular conduction disturbances: Atypical type I advanced interatrial block, left posterior fascicular block and transient right bundle branch block.

According to the first 2012 consensus report about interatrial block, the diagnosis of advanced interatrial block (A-IAB) consists of a P-wave duration ≥120 ms with biphasic "plus-minus" (±) polarity in the three leads of the inferior wall in the electrocardiogram. At the end of 2018, a new concept was introduced: the atypical A-IAB due to changes in the polarity or duration of the P-wave. The prevalence of these atypical patterns in different scenarios is currently unknown, but the patterns should be considered as risk factors of embolic stroke of undetermined source. When the A-IAB pattern is associated with clinical arrhythmic manifestations, it is known as the Bayés' Syndrome. We present a characteristic case of atypical A-IAB, and the rare left posterior fascicular block and transient right bundle branch block.

Stimulation and propagation of activation in conduction tissue: Implications for left bundle branch area pacing.

BACKGROUND: Characterizing wavefront generation and impulse conduction in left bundle (LB) has implications for left bundle branch area pacing (LBBAP). OBJECTIVES: The purpose of this study was to describe the pacing characteristics of LB and to study the role of pacing pulse width (PW) in overcoming left bundle branch block. METHODS: Twenty fresh ovine heart slabs containing well-developed and easily identifiable tissues of the conduction system were used for the study. LB stimulation, activation, and propagation were studied under baseline conditions, simulated conduction slowing, conduction block, and fascicular block. RESULTS: The maximum radius of the LB early activation increased up to 13.4 ± 2.4 mm from the pacing stimulus, and the time from stimulus to evoked potential shortened when pacing PW was increased from 0.13 to 2 ms at baseline. Conduction slowing and block induced by cooling could be resolved by increasing pacing PW from 0.25 to 1.5 ms over a distance of 10 ± 1.5 mm from the pacing stimulus. The LB strength-duration (SD) curve was shifted to the left of the myocardial SD curve. CONCLUSION: Increasing PW resolved conduction slowing and block and bypassed the experimental model of fascicular block in LB. Precise positioning of the LB lead in left ventricular subendocardium is not mandatory in LBBAP, as the SD curve of LB was shifted to the left of the myocardium SD curve and could be captured from a distance by optimizing PW.

The Vectorcardiogram and the Main Dromotropic Disturbances.

Until the mid-1980s, it was believed that the vectorcardiogram (VCG) presented a greater specificity, sensitivity and accuracy in comparison to the 12-lead electrocardiogram (ECG), in the cardiology diagnosis. Currently, the VCG still is superior to the ECG in specific situations, such as in the evaluation of myocardial infarctions when associated with intraventricular conduction disturbances, in the identification and location of accessory pathways in ventricular preexcitation, in the differential diagnosis of patterns varying from normal of electrical axis deviation, in the evaluation of particular aspects of Brugada syndrome, Brugada phenocopies, concealed form of arrhythmogenic right ventricular cardiomyopathy and zonal or fascicular blocks of the right bundle branch on right ventricular free wall.VCG allows us to analyze the presence of left septal fascicular block more accurately than ECG and in the diagnosis of the interatrial blocks and severity of some chambers enlargements. The three-dimensional spatial orientation of both the atrial and the ventricular activity provides a far more complete observation tool than the linear ECG. We believe that the ECG/VCG binomial simultaneously obtained by the technique called electro-vectorcardiography (ECG/VCG) brought a significant gain for the differential diagnosis of several pathologies. Finally, in the field of education and research, VCG provided a better and more rational tridimensional insight into the electrical phenomena that occurs spatially, and represented an important impact on the progress of electrocardiography.