Revisiting the Atrioventricular Conduction Axis for the 21st Century.

In this review, we summarise the ongoing debate surrounding the anatomy of the atrioventricular conduction axis and its relevance to pacing. We highlight previous disagreements and emphasise the importance of understanding the anatomical location of the axis. We give credit and support to the initial descriptions by His and Tawara, in particular their attention to the relationship of the atrioventricular conduction axis with the membranous septum.

Evidence for concealed fasciculo-ventricular connections as revealed by His bundle pacing.

Background: It is almost 100 years ago since Mahaim described the so-called paraspecific connections between the ventricular conduction axis and the crest of the muscular ventricular septum, believing such pathways to be ubiquitous. These pathways, however, have yet to be considered as potential pathways for septal activation during His bundle pacing.

Materials: So as to explore the hypothesis that specialised septal pathways might provide the substrate for septal activation during His bundle pacing, we compared the findings from 22 serially sectioned histological datasets and 34 different individuals undergoing His bundle pacing.

Confounding factors leading to misdiagnosing ventricular tachycardia as supraventricular in the emergency room.

Studies conducted during the last 50 years have proposed electrocardiographic criteria and algorithms to determine if a wide QRS tachycardia is ventricular or supraventricular in origin. Sustained ventricular tachycardia is an uncommon reason for consultation in the emergency room. The latter and the complexity of available electrocardiographic diagnostic criteria and algorithms result in frequent misdiagnoses.

Right Ventricle Involvement by Glycogen Storage Cardiomyopathy (PRKAG2): Standard and Advanced Echocardiography Analyses.

Background: PRKAG2 syndrome is a rare, early-onset autosomal dominant inherited disease. We aimed to describe the right ventricle (RV) echocardiographic findings using two and three-dimensional (2D and 3D) modalities including myocardial deformation indices in this cardiomyopathy. We also aimed to demonstrate whether this technique could identify changes in RV function that could distinguish any particular findings.

Mahaim Revisited.

The name Ivan Mahaim is well-known to electrophysiologists. However, alternative anatomical substrates can produce the abnormal rhythms initially interpreted on the basis of the pathways he first described. These facts have prompted suggestions that Mahaim should be deprived of his eponym.

Inferior Extensions of the Atrioventricular Node.

The pathways for excitation of the atrioventricular node enter either superiorly, as the so-called 'fast' pathway, or inferiorly as the 'slow' pathway. However, knowledge of the specific anatomical details of these pathways is limited. Most of the experimental studies that established the existence of these pathways were conducted in mammalian hearts, which have subtle differences to human hearts.

Miniseries 2-Septal and paraseptal accessory pathways-Part II: Para-Hisian accessory pathways-so-called anteroseptal pathways revisited.

Surgeons, when dividing bypass tracts adjacent to the His bundle, considered them to be 'anteroseptal'. The area was subsequently recognized to be superior and paraseptal, although this description is not entirely accurate anatomically, and conveys little about the potential risk during catheter interventions. We now describe the area as being para-Hisian, and it harbours two types of accessory pathways.

Miniseries 2-Septal and paraseptal accessory pathways-Part I: The anatomic basis for the understanding of para-Hisian accessory atrioventricular pathways.

Aims: Although the anatomy of the atrioventricular conduction axis was well described over a century ago, the precise arrangement in the regions surrounding its transition from the atrioventricular node to the so-called bundle of His remain uncertain. We aimed to clarify these relationships.

Methods And Results: We have used our various datasets to examine the development and anatomical arrangement of the atrioventricular conduction axis, paying particular attention to the regions surrounding the point of penetration of the bundle of His.

Anatomy of the conduction tissues 100 years on: what have we learned?

Knowledge of the anatomy of the 'conduction tissues' of the heart is a 20th century phenomenon. Although controversies still continue on the topic, most could have been avoided had greater attention been paid to the original descriptions. All cardiomyocytes, of course, have the capacity to conduct the cardiac impulse.

QRS alternans during right ventricular pacing while ablating a concealed left sided accessory pathway.

A 16-year-old boy was referred for an electrophysiological study for documented regular narrow complex tachycardia. A diagnosis of a concealed left lateral accessory pathway was made with an eccentric atrial activation sequence both during tachycardia and right ventricular (RV) pacing. The pathway was mapped at the left posterior mitral vestibule during RV pacing, performed through the distal tip of the His bundle catheter pushed into right ventricular outflow tract.

Critical Assessment of the Concepts and Misconceptions of the Cardiac Conduction System over the Last 100 Years: The Personal Quest of Robert H. Anderson.

Anatomical concepts regarding the conduction system of the heart have been a matter of debate since pioneering work done at the beginning of the 20th century. Robert H. Anderson was actively involved in this field for half a century.

Glycogen storage cardiomyopathy (PRKAG2): diagnostic findings of standard and advanced echocardiography techniques.

Aims: Describe the findings obtained using standard echocardiography (Echo) and deformation indices (2D and 3D speckle tracking strain) in patients (Pts) with PRKAG2 cardiomyopathy. Seek to identify any peculiar characteristics and possible strain patterns that may distinguish this condition from other causes of left ventricular hypertrophy (LVH).

Methods And Results: Thirty Pts with genetically proven PRKAG2 (R302Q and H401Q), 16 (53.

Thrombin Generation and other hemostatic parameters in patients with atrial fibrillation in use of warfarin or rivaroxaban.

Patients with atrial fibrillation (AF) present hyperactivation of both platelets and coagulation leading to a hypercoagulable state which contributes to an increased risk of thromboembolism. Therefore, one of the main strategies for treatment of AF is prevention of these events through the use of oral anticoagulants (OAC). The aim of this study was to evaluate hemostasis as a whole in patients with non-valvular AF undergoing warfarin or rivaroxaban by thrombin generation test (TGT), in addition to monocyte-platelet aggregates (MPA), glycoprotein IIb/IIIa (GPIIb/IIIa), and platelet (PMP) and endothelium (EMP) microparticles, compared to age and sex matched controls.

Unusual variants of pre-excitation: From anatomy to ablation: Part I-Understanding the anatomy of the variants of ventricular pre-excitation.

The famous quotation of Winston Churchill, made in his radio broadcast of 1939 regarding Russia's next move, specifically "A riddle wrapped up in a mystery, inside an enigma," perfectly fits the current understanding of unusual accessory atrioventricular pathways, including the variants producing ventricular pre-excitation. It was many decades after their original descriptions that we came better to begin to understand most of their structure-function relationships. Their mysterious pathophysiology was sometimes unveiled after invasive treatments, such as surgical ablation of the atrioventricular conduction axis instead of the accessory pathway itself.

An unusual ectopic ventricular rhythm in a young woman.

A case of a 22-year-old young pregnant woman with palpitations and near syncope is presented. Holter monitoring showed very frequent premature beats and runs of wide complex tachycardia, refractory to antiarrhythmic drugs. Electrophysiologic evaluation disclosed spontaneous automatism arising in an atriofascicular pathway.