Planarity of the spatial QRS loop. Comparative analysis in normals, infarcts, ventricular hypertrophies, and intraventricular conduction defects.
An almost perfect planarity of the spatial QRS loop is known as a characteristic of normal hearts. The Lyon VCG program routinely computes an original planarity index based on the relative magnitude of a so-called geometrical area vector (GAV%). It provides an indirect assessment of any kind of loop distortion (distorted segments lying outside the preferential plane, concavities, figures of eight, narrow configuration). Mean intraindividual variations of GAV%, studied in three different conditions, showed its relatively good stability. Eleven groups totaling 1,435 subjects were investigated. The highest GAV% values (mean, 88%) and the smallest scatter (sigma = 7) were found in normal tracings. GAV% was lower in right (mean, 82%) and left (76-82%) ventricular hypertrophies, in inferior (82%) and anterior (61%) myocardial infarctions, and in right (55%) and left (49%) bundle branch blocks. The diagnostic value of this index was tested for the normal-abnormal discrimination. Using a threshold of 80%, specificity was 89.6%, sensitivity was 78.6% for anterior myocardial infarction, right BBB was 86.6%, left BBB was 91.0% and other groups had unsatisfactory sensitivity. Poor correlations were observed with six other structural parameters, demonstrating that GAV% is relatively independent and may provide new diagnostic information.
Arnaud
P
P
National Institute of Health Medical Research, Cardiovascular Hospital, Lyon, France.
Morlet
D
D
Rubel
P
P
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D002037:Bundle-Branch Block / Q000503:physiopathology*; D006332:Cardiomegaly / Q000503:physiopathology*; D003627:Data Interpretation, Statistical; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000503:physiopathology*; D012016:Reference Values; D014672:Vectorcardiography