2003, Number 2
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Arch Cardiol Mex 2003; 73 (2)
Electrical features of hypertrophied left heart
A de Micheli, GA Medrano, A Aranda
Language: Spanish
References: 17
Page: 135-142
PDF size: 104.95 Kb.
ABSTRACT
Chronological and spatial characteristics of the main resultant vectors of
the left atrial and ventricular depolarization in normal conditions and in
presence of hypertrophy, due to a sustained overload, are described. The
coexistence of interatrial, intraatrial, and intraventricular conduction
disorders can modify the orientation of these vectors. The main
electrocardiographic sign of left atrial hypertrophy is a P wave
duration > 0.10 sec in adults. In case of left ventricle hypertrophy,
the time of onset of the intrinsicoid deflection (TOID) is prolonged
in the near left unipolar leads, and the S wave voltage is increased
in opposite regions, i. e. in the right precordial or transitional leads.
It is necessary to bear in mind other useful electrocardiographic signs.
Hence, absence of the right basal vector (IIId) manifestation in a
clockwise rotating heart is probably due to an increase in the basal
electromotive forces of the left ventricle (vector IIIi) due to
hypertrophy or ipsilateral ventricular conduction disorders. For
a correct evaluation of these signs, it is mandatory to perform a
rational analysis of the tracings, not just a stereotyped electrical
exploration. Besides it is very important to determine the Q-TC
interval in the left unipolar leads to establish whether, in these
leads, the inverted T wave is of secondary type (normal Q-TC) or of
primary type (prolonged Q-TC) due to a coexisting subepicardial or
transmural ischemia. From these considerations, the usefulness of
the thoracic circle and high abdominal unipolar leads is inferred.
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