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.

Unusual ventricular activation produced by temporary transvenous cardiac pacing: electrovectorcardiographic findings / Activación ventricular inusual producida por estimulación cardíaca transvenosa temporal: hallazgos electrovectorcardiográficos

Abstract Complete heart block (CHB) results from dysfunction of the cardiac conduction system, which results in complete electrical dissociation. The ventricular escape rhythm can have its origin anywhere from the atrioventricular node to the bundle branch-Purkinje system. CHB typically results in bradycardia, hypotension, fatigue, hemodynamic instability, syncope, or even Stokes-Adams syndrome. Escape rhythm originating above the bifurcation of the His bundle (HB) produces narrow QRSs with relatively rapid heart rate (HR) (except in cases of His system disease). We present a middle-aged man with an HR of 34 bpm, progressive fatigue, in whom a temporary pacemaker was implanted in the subtricuspid region. The post-intervention electrocardiogram had unusual features.

Resumen El bloqueo cardíaco completo (BCC) resulta de la disfunción del sistema de conducción cardíaco, lo que ocasiona una disociación eléctrica completa entre aurículas y ventrículos. El ritmo de escape resultante puede tener su origen en cualquier lugar desde el nodo auriculoventricular hasta el sistema His Purkinje. El BCC generalmente produce bradicardia, hipotensión, fatiga, inestabilidad hemodinámica, síncope o incluso el síndrome de Stokes-Adams. El ritmo de escape que se origina por encima de la bifurcación del haz de His produce intervalos QRS estrechos con frecuencia cardíaca no muy lenta (excepto en casos de enfermedad del sistema Hisiano). Presentamos a un hombre de mediana edad con una frecuencia cardíaca de 34 lpm, fatiga progresiva, en el que se implantó un marcapasos temporario en la región subtricuspídea. El electrocardiograma resultante a la intervención presentó características inusuales.

Unusual ventricular activation produced by temporary transvenous cardiac pacing: electrovectorcardiographic findings.

Complete heart block (CHB) results from dysfunction of the cardiac conduction system, which results in complete electrical dissociation. The ventricular escape rhythm can have its origin anywhere from the atrioventricular node to the bundle branch-Purkinje system. CHB typically results in bradycardia, hypotension, fatigue, hemodynamic instability, syncope, or even Stokes-Adams syndrome. Escape rhythm originating above the bifurcation of the His bundle (HB) produces narrow QRSs with relatively rapid heart rate (HR) (except in cases of His system disease). We present a middle-aged man with an HR of 34 bpm, progressive fatigue, in whom a temporary pacemaker was implanted in the subtricuspid region. The post-intervention electrocardiogram had unusual features.

El bloqueo cardíaco completo (BCC) resulta de la disfunción del sistema de conducción cardíaco, lo que ocasiona una disociación eléctrica completa entre aurículas y ventrículos. El ritmo de escape resultante puede tener su origen en cualquier lugar desde el nodo auriculoventricular hasta el sistema His Purkinje. El BCC generalmente produce bradicardia, hipotensión, fatiga, inestabilidad hemodinámica, síncope o incluso el síndrome de Stokes-Adams. El ritmo de escape que se origina por encima de la bifurcación del haz de His produce intervalos QRS estrechos con frecuencia cardíaca no muy lenta (excepto en casos de enfermedad del sistema Hisiano). Presentamos a un hombre de mediana edad con una frecuencia cardíaca de 34 lpm, fatiga progresiva, en el que se implantó un marcapasos temporario en la región subtricuspídea. El electrocardiograma resultante a la intervención presentó características inusuales.

The tetrafascicular nature of the intraventricular conduction system.

The existence of a tetrafascicular intraventricular conduction system remains debatable. A consensus statement ended up with some discrepancies and, despite agreeing on the possible existence of an anatomical left septal fascicle, the electrocardiographic and vectorcardiographic characteristics of left septal fascicular block (LSFB) were not universally accepted. The most important criteria requested to confirm the existence of LSFB is its intermittent nature. So far, our group has published cases of transient ischemia-induced LSFB and phase 4 or bradycardia-dependent LSFB. Finally, anatomical, anatomopathological, histological, histopathological, electrocardiographic, vectorcardiographic, body surface potential mapping, and electrophysiology studies support the fact that the left bundle branch divides into three fascicles or a "fan-like interconnected network."

Transient left septal fascicular block and left anterior fascicular block as a consequence of proximal subocclusion of the left anterior descending coronary artery.

The association of left anterior fascicular block (LAFB) with left septal fascicular block (LSFB) characterizes a left bifascicular block subtype rarely described in the literature, probably due to the fact that most researchers are not aware of the existence of the left septal fascicle. We describe a case with this transient intraventricular dromotropic disturbance due to left anterior descending coronary artery subocclusion.

Transient left anterior and septal fascicular blocks after self-expandable percutaneous transcatheter aortic valve implantation.

Transcatheter aortic valve implantation (TAVI) is indicated in severe symptomatic aortic stenosis, when there is intermediate-high surgical risk, or a condition considered inoperable, as in the case of "porcelain aorta" that could turn clamping or cannulation of the ascending aorta hazardous in open-heart surgery. Among the complications of this less invasive procedure, intraventricular conduction disorders subsequent to the procedure stand out. TAVI causes worsening of intraventricular dromotropic disorders in more than 75% of the cases, with the presence of preexisting right bundle branch block and first-degree atrioventricular block, deep prosthesis implant, male gender, size of the aortic annulus smaller than the prosthesis, and porcelain aorta being predictive of requirement for permanent pacemaker implant.

Unusual conduction disorder: left posterior fascicular block + left septal fascicular block.

A 44-year-old man with aortic valve insufficiency and stenosis underwent aortic valve replacement depicting interesting ECG changes. This unique case is discussed, contributing to the understanding of a trifascicular left intraventricular conduction system.

The history of left septal fascicular block: chronological considerations of a reality yet to be universally accepted.

There are several papers in literature that prove in a conclusive and incontestable way, that the left branch of the His bundle, in most instances (85% of the cases) splits into three fascicles of variable morphological pattern, and not into two: left anterior fascicle (LAF), left posterior fascicle (LPF), and left septal fascicle (LSF). The abovementioned papers have anatomical, histological, anatomo-pathological, electrocardiographic, and vectocardiographic, body surface potential mapping or ECG potential mapping and electrophysiological foundation.Additionally, the mentioned papers have been performed both in animal models (dogs) and in the human heart.Several clinical papers have shown that the left septal fascicular block (LSFB) may occur intermittently or transitorily as a consequence of a temporary dromotropic alteration, constituting an aberrant ventricular conduction, rate-dependent or by the application of atrial extra-stimuli, or naturally during the acute phase of infarction when this involves the anterior descending artery, before the septal perforating artery that supplies the central portion of the septum, where the mentioned LSF runs.The ECG/VCG manifestation of LSFB consists in anterior shift of electromotive forces, known as Prominent Anterior Forces (PAF), which can hardly be diagnosed in the clinical absence of other causes capable of causing PAF, such as the normal variant by counterclockwise rotation of the heart on its longitudinal axis, in right ventricular enlargement, in the dorsal or lateral infarction of the new nomenclature, in type-A WPW, in CRBBB, and others. In this historical manuscript, we review in a sequential fashion, the main findings that confirmed the unequivocal existence of this unjustifiably "forgotten" dromotropic disorder.In the developed countries, its most important cause is coronary insufficiency, particularly the proximal involvement of the left anterior descending coronary artery, and in Latin America, Chagas disease.