1. Mechanical alternans in human idiopathic dilated cardiomyopathy is caused with impaired force-frequency relationship and enhanced poststimulation potentiation.
- Author
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Kashimura, Takeshi, Kodama, Makoto, Tanaka, Komei, Sonoda, Keiko, Watanabe, Satoru, Ohno, Yukako, Tomita, Makoto, Obata, Hiroaki, Mitsuma, Wataru, Ito, Masahiro, Hirono, Satoru, Hanawa, Haruo, and Aizawa, Yoshifusa
- Subjects
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IDIOPATHIC dilated cardiomyopathy , *HEART failure , *CARDIAC pacing , *CARDIAC contraction , *LEFT heart ventricle , *TACHYCARDIA , *HEART beat - Abstract
Mechanical alternans (MA) is frequently observed in patients with heart failure, and is a predictor of cardiac events. However, there have been controversies regarding the conditions and mechanisms of MA. To clarify heart rate-dependent contractile properties related to MA, we performed incremental right atrial pacing in 17 idiopathic dilated cardiomyopathy (DCM) patients and in six control patients. The maximal increase in left ventricular d P/d t during pacing-induced tachycardia was assessed as the force gain in the force-frequency relationship (FG-FFR), and the maximal increase in left ventricular d P/d t of the first post-pacing beats was examined as the force gain in poststimulation potentiation (FG-PSP). As a result, MA was induced in 9 DCM patients (DCM MA(+)) but not in the other 8 DCM patients (DCM MA(−)), and not in any of the control patients. DCM MA(+) had significantly lower FG-FFR (34.7 ± 40.9 vs 159.4 ± 103.9 mmHg/s, P = 0.0091) and higher FG-PSP (500.0 ± 96.8 vs 321.9 ± 94.9 mmHg/s, P = 0.0017), and accordingly a wider gap between FG-PSP and FG-FFR (465.3 ± 119.4 vs 162.5 ± 123.6 mmHg/s, P = 0.0001) than DCM MA(−) patients. These characteristics of DCM MA(+) showed clear contrasts to those of the control patients. In conclusion, MA is caused with an impaired force-frequency relationship despite significant poststimulation potentiation, suggesting that MA reflects ineffective utilization of the potentiated intrinsic force during tachycardia. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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