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To improve standardization of echocardiographic left ventricular anatomic measurements, echographic left ventricular dimensions and mass were related to body size indexes, sex, age and blood pressure. Independent normal populations comprised 92 hospital-based subjects (64 women, 28 men) and 133 subjects from a population sample (55 women, 78 men). All measurements of chamber size, wall thickness and mass differed between men and women in both series (p less than 0.01 to p less than 0.001). Left ventricular mass was related most closely to body surface area among measurements of body size (r = 0.37, p less than 0.01 to r = 0.57, p less than 0.001) in all four groups. Indexation by body surface area eliminated sex differences in wall thicknesses and internal dimension, but a significant sex difference in left ventricular mass index persisted (89 +/- 21 g/m2 in men versus 69 + 19 g/m2 in women in the entire series, p less than 0.0001). The 97th percentile of left ventricular mass index was identical in both groups of men (136 and 132 g/m2) and women (112 and 109 g/m2). A highly significant difference in lean body mass, estimated from 24 hour urine creatine excretion, was observed between men and women (58 +/- 15 versus 40 +/- 13 kg, p less than 0.001) and no sex difference existed in left ventricular mass indexed by lean body mass (3.4 +/- 1.3 versus 3.5 +/- 1.5 g/kg). Weak correlations were observed between left ventricular mass/lean body mass and systolic or diastolic blood pressure (r = 0.25, p less than 0.05 and r = 0.28, p less than 0.01, respectively) but not age (18 to 72 years).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac arrest due to torsade de pointes (TdP) in the acquired form of drug-induced long-QT syndrome (LQTS) is a rare but potentially catastrophic event in hospital settings. Administration of a QT-prolonging drug to a hospitalized population may be more likely to cause TdP than administration of the same drug to an outpatient population, because hospitalized patients often have other risk factors for a proarrhythmic response. For example, hospitalized patients are often elderly people with underlying heart disease who may also have renal or hepatic dysfunction, electrolyte abnormalities, or bradycardia and to whom drugs may be administered rapidly via the intravenous route.In hospital units where patients' electrocardiograms (ECGs) are monitored continuously, the possibility of TdP may be anticipated by the detection of an increasing QT interval and other premonitory ECG signs of impending arrhythmia. If these ECG harbingers of TdP are recognized, it then becomes possible to discontinue the culprit drug and manage concomitant provocative conditions (eg, hypokalemia, bradyarrhythmias) to reduce the occurrence of cardiac arrest.The purpose of this scientific statement is to raise awareness among those who care for patients in hospital units about the risk, ECG monitoring, and management of drug-induced LQTS. Topics reviewed include the ECG characteristics of TdP and signs of impending arrhythmia, cellular mechanisms of acquired LQTS and current thinking about genetic susceptibility, drugs and drug combinations most likely to cause TdP, risk factors and exacerbating conditions, methods to monitor QT intervals in hospital settings, and immediate management of marked QT prolongation and TdP. Characteristic Pattern of TdPThe term torsade de pointes was coined by Dessertenne in 1966 as a polymorphic ventricular tachycardia characterized by a pattern of twisting points. 1 Several ECG features are characteristic of TdP and are illustrated in Figure 1. First, a change in the amplitude and morphology (twisting) of the QRS complexes around the isoelectric line is a typical feature of the arrhythmia;The American Heart Association and the American College of Cardiology Foundation make every effort to avoid any actual or potential conflicts of interest that may arise as a result of an outside relationship or a personal, professional, or business interest of a member of the writing panel. Specifically, all members of the writing group are required to complete and submit a Disclosure Questionnaire showing all such relationships that might be perceived as real or potential conflicts of interest. The American Heart Association requests that this document be cited as follows: Drew BJ, Ackerman MJ, Funk M, Gibler WB, Kligfield P, Menon V, Philippides GJ, Roden DM, Zareba W; on behalf of the American Heart Association Acute Cardiac Care Committee of the Council on Clinical Cardiology, the Council on Cardiovascular Nursing, and the American College of Cardiology Foundation. Prevention of torsade de pointes in hospital settings: a sc...

QRS duration is an independent ECG predictor of the presence of left ventricular hypertrophy, and the simple product of either Cornell voltage or 12-lead voltage and QRS duration significantly improves identification of left ventricular hypertrophy relative to other ECG criteria that use QRS duration and voltages in linear combinations.

In a previous study of 543 patients we developed, using echocardiographic left ventricular mass as the reference standard, two new sets of criteria that improve the electrocardiographic diagnosis of left ventricular hypertrophy (LVH).

To develop improved electrocardiographic criteria of left ventricular hypertrophy, individual electrocardiographic voltage measurements were compared with echocardiographic left ventricular mass in a "learning series" of 414 subjects. The strongest independent relations with left ventricular mass were exhibited by the S wave in lead V3, the R wave in lead a VL and the T wave in lead V1 (each p less than 0.001), and by age and sex. Better electrocardiographic detection of left ventricular hypertrophy was achieved by new criteria that stratified QRS voltage and repolarization findings in sex and age subsets. For men, at all ages, left ventricular hypertrophy is suggested by QRS voltage alone when the R wave in lead aVL and the S wave in lead V3 total more than 35 mm. When this voltage exceeds 22 mm, left ventricular hypertrophy is suggested in men under age 40 years when the T wave in lead V1 is positive (greater than or equal to 0 mm), and in men 40 years or older when the T wave in lead V1 is at least 2 mm. For women, at all ages, left ventricular hypertrophy is suggested when the R wave in lead a VL and the S wave in lead V3 total more than 25 mm. When this voltage exceeds 12 mm, left ventricular hypertrophy is suggested in women under 40 when the T wave in lead V1 is positive (greater than or equal to 0 mm), and in women over 40 when the T wave in lead V1 is 2 mm or greater.(ABSTRACT TRUNCATED AT 250 WORDS)