Variants of normal electrocardiogram

Variants of normal electrocardiogram

T inversion in anterior leads may be seen as a normal variant, especially in younger individuals, usually called juvenile T inversion. Occasionally similar changes can occur in arrhythmogenic right ventricular dysplasia as well. Some cases of pulmonary embolism may manifest with only anterior T inversion due to right ventricular strain.

Technical errors like arm lead inversion, often called ‘technical dextrocardia’, should be kept in mind if all the complexes in lead I are negative. Normal precordial R wave pattern is one of gradual increase in R wave amplitude from V1 to V5. V6 usually has R wave amplitude less than in V5. Tall R wave in V1 with gradual regression of QRS amplitude towards V6 can be seen in true dextrocardia. This will differentiate ‘technical dextrocardia’ from true dextrocardia.

J point elevation due to early repolarization can occur in younger individuals as a normal variant. But presence of early repolarization does not rule out the presence of underlying coronary artery disease in a person with risk factors and typical angina pectoris. Though early repolarization has been conventionally considered as a normal variant, sudden cardiac arrest associated with early repolarization has been reported [1].

Reference

1. Michel Haïssaguerre, Nicolas Derval, Frederic Sacher, Laurence Jesel, Isabel Deisenhofer, Luc de Roy, Jean-Luc Pasquié, Akihiko Nogami, Dominique Babuty, Sinikka Yli-Mayry, Christian De Chillou, Patrice Scanu, Philippe Mabo, Seiichiro Matsuo, Vincent Probst, Solena Le Scouarnec, Pascal Defaye, Juerg Schlaepfer, Thomas Rostock, Dominique Lacroix, Dominique Lamaison, Thomas Lavergne, Yoshifusa Aizawa, Anders Englund, Frederic Anselme, Mark O’Neill, Meleze Hocini, Kang Teng Lim, Sebastien Knecht, George D Veenhuyzen, Pierre Bordachar, Michel Chauvin, Pierre Jais, Gaelle Coureau, Genevieve Chene, George J Klein, Jacques Clémenty. Sudden cardiac arrest associated with early repolarization. N Engl J Med. 2008 May 8;358(19):2016-23.