Research Project
Grant-in-Aid for Scientific Research (C)
Mechanical alternans is a poorly-understood phenomenon of alternating strong and weak beats with a constant beat-to-beat interval. It is a possible linker between failing myocardium and ventricular fibrillation in patients with chronic heart failure. Interval-force relationship, so-called mechanical restitution, is an intrinsic regulatory principle of myocardial contractility depending on sarcoplasmic reticulum (SR)Ca^(2+) cycling. Force-frequency relationship is also considered to reflect Ca^(++) handling of SR. We analyzed interval-force relationship and force frequency relationship in patients with chronic heart failure. In patients with atrial fibrillation, mechanical restitution curves were able to be obtained from beat by beat variance of left ventricular contractility adjusted by pre-preceding coupling intervals. We estimated mechanical restitution curves by fitting to monoexponential curves. Tau of the mechanical restitution curve increased in accord with the decrease of ejection fraction. We analyzed force-frequency relationship. In patients with chronic heart failure, peak force rate shifted to lower heart rate. The force gain of patients was little. A force gain was correlated to the left ventricular ejection fraction. We were able to obtain adequate mechanical restitution curves after both strong beats and weak beats from some patients. Mechanical restitution curves after weak beats steeply rose compared with those after strong beats. The time constant after weak beats were shorter than those after strong beats. Thus mechanical restitution properties were different after strong beats and weak beats during mechanical alternans. This implies that mechanical alternans originates from alternating changes of myocardial Ca^(2+) cycling property.
All 2008 2007 2006
All Journal Article (21 results) (of which Peer Reviewed: 8 results) Presentation (9 results) Book (2 results)
Annual Review 2008
Pages: 144-150
Intern Heart J 49
Pages: 39-47
呼吸と循環 55
Pages: 329-336
Circ J 71
Pages: 343-347
Am J Cardiol 99
Pages: 494-498
Am J Physiol Heart Circ Physiol 292
Heart 93
Pages: 151-151
Am J Cardiol 100
Pages: 106-109
Kokyuu to Junkan 55
110006224201
Pages: 1267-1277
Am J Cardiol 2007 100
心臓 39
Pages: 100-103
Am J Cardiol 98
Pages: 915-917
