title: Electromechanical concordance in alternans during sustained tachycardias.
abstract: Electrical alternans and mechanical alternans are intriguing phenomena that have been reported to occur during tachycardias. Their precise pathophysiologic mechanism and in particular their interrelation have not been well defined. This report documents an unusual electromechanical concordance in alternans during sustained supraventricular tachycardia and ventricular tachycardia in two patients, raising interesting possibilities on the underlying mechanism of the concordant phenomena. The findings highlight the principle of excitation--contraction coupling of the heart.
authors.affiliation: Department of Medicine, University of Hong Kong.
authors.forename: Y T
authors.initials: YT
authors.lastname: Tai
authors.forename: C P
authors.initials: CP
authors.lastname: Lau
authors.forename: W H
authors.initials: WH
authors.lastname: Chow
authors.forename: W H
authors.initials: WH
authors.lastname: Leung
mesh_terms: D000328:Adult; D001283:Atrioventricular Node / Q000503:physiopathology; D002036:Bundle of His / Q000503:physiopathology; D002037:Bundle-Branch Block / Q000503:physiopathology; D004452:Echocardiography; D004562:Electrocardiography; D004719:Endomyocardial Fibrosis / Q000503:physiopathology; D005260:Female; D006346:Heart Septum / Q000503:physiopathology; D006801:Humans; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology*; D011674:Pulse / Q000502:physiology*; D012595:Scleroderma, Systemic / Q000503:physiopathology; D013318:Stroke Volume / Q000502:physiology; D013599:Systole / Q000502:physiology; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology; D013617:Tachycardia, Supraventricular / Q000503:physiopathology*; D017180:Tachycardia, Ventricular / Q000503:physiopathology*