Advanced interatrial block: A well-defined electrocardiographic pattern with clinical arrhythmological implications

3.050 JCR (2013) Q2, 44/125 Cardiac & cardiovascular system

Lateral MI Explains the Presence of Prominent R Wave (R ≥ S) in V1.

AIMS: It is necessary to clarify if the presence of a prominent R wave in V1 , in post-myocardial infarction (MI) patients, is due to the involvement of the posterior wall (currently inferobasal segment) or the lateral wall (as has been demonstrated recently by electrocardiographic contrast-enhanced cardiac magnetic resonance [ECG-CE-CMR] correlations studies). METHODS: In 155 patients with inferolateral zone MI, as detected by CE-CMR, the following ECG parameters were evaluated and correlated with MI location according to CE-CMR: R/S ratio in V1 ≥ 1 (classic criteria for posterior MI), R/S ratio in V1 ≥ 0.5, and R in V1 ≥ 3 mm. RESULTS: R/S ≥ 1 criterion: Present in 20 cases: 3 of lateral MI, 17 of inferolateral MI, 0 of inferior MI. Absent in 135 cases, 81 of lateral/inferolateral MI (28/53), 54 of inferior MI (SE 19.8%, SP 100%). R/S ≥ 0.5 criterion: Present in 47 cases: 6 of lateral MI, 39 of inferolateral MI, 2 of inferior MI. Absent in 108 cases, 56 of lateral/inferolateral MI (25/31), 52 of inferior MI (SE 44.6%, SP 96.4%). R ≥ 3 mm criterion: Present in 30 cases: 5 of IM lateral, 23 of inferolateral MI, 2 of inferior MI. Absent in 125 cases, 73 lateral/inferolateral MI (26/47), 52 inferior MI (SE 27.7%, SP 96.4%). CONCLUSIONS: The presence of prominent the R wave in V1 is due to the lateral MI and not to the involvement of inferobasal segment of inferior wall (old posterior wall)

Electrocardiographic classification of acute coronary syndromes: a review by a committee of the International Society for Holter and Non-Invasive Electrocardiology

The electrocardiogram (ECG) remains the most immediately accessible and widely used diagnostic tool for guiding emergency treatment strategies. The ECG recorded during acute myocardial ischemia is of diagnostic, therapeutic, and prognostic significance. In patients with myocardial ischemia as a result of decreased blood supply, the initial 12-lead ECG typically shows (1) predominant ST-segment elevation (STE) as part of STE acute coronary syndrome (STE-ACS), or (2) no predominant STE, that is, non STE ACS (NSTE-ACS). Patients with predominant STE are classified as having either aborted myocardial infarction (MI) or ST-elevation MI (STEMI) based on the absence or presence of biomarkers of myocardial necrosis. The MI may be aborted either by spontaneous or therapeutic reperfusion of the ischemic myocardium before development of myocardial cell necrosis. NSTE-ACS patients are classified as having either unstable angina or NSTE-MI, based also on the absence or presence of biomarkers of mycardial necrosis. The information obtained from the 12-lead ECG at presentation should be complemented by repeated ECGs especially during symptoms indicative of ischemia and, if applicable, by comparing the findings with reference ECGs. Also, continuous ECG recording in a coronary care setting, including the comparison of ECGs with and without pain, adds to the information gained at patient presentation. In this article, mechanisms of ischemic ECG changes and the ECG patterns recorded in both STE-ACS and NSTE-ACS are described. ECG patterns of NSTE-ACS, which include ST depression, negative T wave, and even normal ECG, need to be better defined in future studies to correlate them with the severity and extent of ischemia and to explore to what extent they are explained by acute active ischemia or represent consequences of ischemia. One of the aims of this article is to propose a classification of the ECG patterns encountered in different clinical scenarios of ACS. How these patterns will aid in guiding the diagnostic and therapeutic process is discussed. (c) 2010 Elsevier Inc. All rights reserved

Universal scaling relations in food webs

The structure of ecological communities is usually represented by food webs. In these webs, we describe species by means of vertices connected by links representing the predations. We can therefore study different webs by considering the shape (topology) of these networks. Comparing food webs by searching for regularities is of fundamental importance, because universal patterns would reveal common principles underlying the organization of different ecosystems. However, features observed in small food webs are different from those found in large ones. Furthermore, food webs (except in isolated cases) do not share general features with other types of network (including the Internet, the World Wide Web and biological webs). These features are a small-world character and a scale-free (power-law) distribution of the degree (the number of links per vertex). Here we propose to describe food webs as transportation networks by extending to them the concept of allometric scaling (how branching properties change with network size). We then decompose food webs in spanning trees and loop-forming links. We show that, whereas the number of loops varies significantly across real webs, spanning trees are characterized by universal scaling relations