An Incessant Tachycardia with Alternating QRS Complexes: What Is the Mechanism?

Prognostic Role of Electrocardiographic Alternans in Ischemic Heart Disease

Background/Objectives: Noninvasive arrhythmic risk stratification in patients with ischemic heart disease is poor nowadays, and further investigations are needed. The most correct approach is based on the use of electrocardiogram (ECG) with the extraction of indices such as ECG alternans (ECGA). The aim of this study is to monitor the ECG evidence of ischemic coronary artery occlusion by the ECGA and to verify its ability to monitor the time course of balloon inflation, with the final goal of contributing to the exploration of the prognostic role of ECGA in ischemic heart disease. Methods: The ECGA amplitude and magnitude were computed by the correlation method (CM) on the STAFF III database, where ischemic coronary artery occlusion was induced in a controlled manner through coronary artery blockage by balloon inflation. ECGA computed during balloon inflation was also compared with periods before and after the inflation. Results: ECGA values became statistically higher during inflation than in the pre-inflation period and increased as inflation time increased, although not always in a statistically significant manner. ECGA went from values in the range 4-7 µV and 169-396 µV·beat before inflation to values in the range 5-9 µV and 208-573 µV·beat during 5 min of inflation (resulting statistically higher than before inflation), returning towards values in the range 4-8 µV and 182-360 µV·beat after inflation for amplitude and magnitude, respectively. Conclusions: CM-based ECGA detection was able to track the balloon inflation period. Our ECGA investigation represents a contribution in the field of research exploring its prognostic role as a noninvasive electrical risk index in ischemic heart disease.

The Initial Part of Polymorphic Ventricular Tachycardia as a Clue for the Sustainability of Tachycardia and Ablation Success: A Varying Degree of Purkinje-Myocardial Complicity?

The cardiac Purkinje system is capable of very rapid burst activity suggestive of its potential role in being a driver of polymorphic ventricular tachycardia (VT) (PMVT) or ventricular fibrillation (VF). It plays a pivotal role, however, not only in the triggering of but also the perpetuation of ventricular arrhythmias. A varying degree of Purkinje-myocardial complicity has been blamed in determining not only the sustained or non-sustained nature of PMVT but also the pleomorphism of the non-sustained runs. The initial part of PMVT before cascading to the whole ventricle to establish disorganized VF can give important clues for ablation of PMVT and VF. We present a case of an electrical storm after acute myocardial infarction that was successfully ablated after identifying Purkinje potentials that triggered polymorphic, monomorphic, and pleiomorphic VTs and VF.

Widening of the QRS complex during the wide complex tachycardia: What is the mechanism?

Tachycardia-induced tachycardia, or so-called double tachycardia, appears to be a relatively rare condition. This article is protected by copyright. All rights reserved.

Simultaneous narrow and wide QRS complex tachycardia: Misdiagnosis or Missed diagnosis?

Tachycardia-induced tachycardia, or so-called double tachycardia, appears to be a relatively rare condition. Regardless of the mechanism, this case illustrates the importance of assessing the response to multiple different pacing maneuvers in determining the mechanism of narrow and wide QRS complex tachycardias, rather than relying upon a single maneuver, even one that is believed to be diagnostic. This article is protected by copyright. All rights reserved.

Transition from Two Wide to A Narrow QRS Complex Tachycardia: What is the mechanism of tachycardia and transition?

Spontaneous transition from one tachycardia to another tachycardia poses a challenge to the electrophysiologists and most likely occurs by multiple mechanisms. This article is protected by copyright. All rights reserved.