Second-degree interatrial block: A case series.

Advanced interatrial block (IAB) (P-wave ≥120 ms and biphasic P-wave in leads II, III and aVF) is a prevalent ECG pattern frequently associated with supraventricular arrhythmias and stroke, especially in patients with structural heart disease. Intermittent IAB is a much more poorly defined electrocardiographic entity with uncertain clinical significance. In this case series, we review and analyze eight cases of second degree intermittent IAB. In six cases, there is normalization of advanced IAB after a premature supraventricular or ventricular contraction, suggesting a functional block that temporarily recovers post extra-systolic pause. Recognition of intermittent IAB (second degree) may help further characterize the prognostic and clinical implications of this ECG pattern.

Ventricular tachycardia or artifact?

Electrocardiographic artifacts are extracardiac signals that may alter the electrocardiogram (ECG) generating false diagnoses. These artifacts may simulate pathologies on ECG's in healthy patients and result in long-term unnecessary or even deleterious treatments. On the other hand, to consider an arrhythmia as an artifact, may carry even worse consequences.

Premature ventricular contraction-induced concealed retrograde penetration: Electrocardiographic manifestations on anterograde ventricular preexcitation.

In patients with manifest anterograde ventricular preexcitation, the electrocardiographic manifestation of the anomalous conduction through the simultaneous conduction over the atrioventricular (AV) node and the accessory pathway ("delta wave"); depends on several factors, the most representative being the conduction velocity over one or another connection. Occasionally, ventricular ectopic beats may present with retrograde penetration over one or both conduction pathways (AV node and/or accessory pathway), impacting on the morphology of the next immediate anterogradely conducted QRS. We present a case of a young patient with WPW syndrome and ectopic ventricular beats with different manifestations on the postectopic QRS due to concealed penetration of different conduction pathways.

Ashman phenomenon dynamicity during atrial fibrillation: the critical role of the long cycles.

A case of a patient with Atrial Fibrillation and intermittent wide complex beats. What's the mechanism?

Diagnostical mistakes in ablation procedures associated with a high placement of the leads V1-V3.

The misplacement of electrodes for surface electrocardiogram (ECG) recording that we use daily as a reference for mapping precise locations in invasive procedures may, besides inducing diagnostical mistakes, greatly increase the duration of the procedure and making more feasible the incidence of complications, especially in ablation of arrhythmic substrates of ventricular outflow tracts such as premature ventricular contractions (PVC's) and accessory pathways, if the right precordial electrodes (V1-V3) are higher positioned.