[Recording of monophasic action potentials of the right ventricle in a case of long QT and isolated alternation of the U wave].
Monophasic action potentials (MAP) of the right ventricle were recorded with suction electrodes in a case of long QTU, electrical alternans of the U wave and "torsades de pointe" by hypocalcaemia. Two electrophysiological features were observed:--a notable difference in the duration of MAPs of different zones of the right ventricle;--a change in the length and appearances of phase 3 of the longest MAPs with an inconstant bulge (delayed repolarisation) in the terminal portion of these same MAPs. These changes, which favourise focal reentry phenomena and/or reciprocal conduction are the probable explanation of the pathogenesis of episodes of "torsades de pointe". A reduction in the conductance of potassium associated or related to hypocalcaemia probably explains the second of the two changes.
D000368:Aged; D001145:Arrhythmias, Cardiac / Q000150:complications* / Q000503:physiopathology; D005117:Cardiac Complexes, Premature / Q000175:diagnosis; D004562:Electrocardiography; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D006996:Hypocalcemia / Q000175:diagnosis*; D013575:Syncope / Q000209:etiology*
Enregistrement des potentiels d'action monophasiques du ventricule droit dans un cas de QT long et alternance isolée de l'onde U.