Myocardial contractility and contraction duration are unrelated in the left ventricle with moderate pressure-overload hypertrophy
| Autor: | Tsuneaki Sugimoto, Takashi Serizawa, Yasunobu Hirata, Israel Mirsky, Masahiko Iizuka, Shin-ichi Momomura, Teruhiko Aoyagi, Hiroshi Matsui |
|---|---|
| Rok vydání: | 1991 |
| Předmět: |
medicine.medical_specialty
Time Factors Contraction (grammar) Diastole Hemodynamics Blood Pressure Cardiomegaly Ventricular Function Left Muscle hypertrophy Contractility Internal medicine medicine Animals cardiovascular diseases Pressure overload Ejection fraction business.industry Models Cardiovascular Rats Inbred Strains Stroke Volume Myocardial Contraction Rats medicine.anatomical_structure Ventricle Cardiology Female Cardiology and Cardiovascular Medicine business Mathematics |
| Zdroj: | Japanese Heart Journal. 32:111-130 |
| ISSN: | 1348-673X 0021-4868 |
| DOI: | 10.1536/ihj.32.111 |
| Popis: | Both myocardial contractility and contraction duration were assessed load-independently in isolated hypertrophic and control rat hearts. Hemodynamic parameters for isolated isovolumically contracting hearts were compared for 7 Wistar rats with DOCA-salt induced hypertrophy (LVH) and 7 controls. Loads were altered by changing the volume of an intraventricular balloon. Myocardial contractility was assessed in terms of the shortening-afterload (Sm-sigma aft), and the ejection fraction-afterload (EF-sigma aft) relations at common preloads, based upon the systolic myocardial stiffness concept. Indices of contraction duration (time to maximum stiffness, pressure time integral divided by peak pressure and the time required for left ventricular (LV) peak pressure to be reduced by a half) were prolonged in LVH. Multiple regression analyses indicated that the degree of hypertrophy was an independent determinant of the contraction duration. The Sm-sigma aft and EF-sigma aft relations at common preloads demonstrated normal contractility in the LVH group. The time constant of the fall in LV pressure and the diastolic myocardial stiffness remained normal in the LVH group. Thus, we introduced the new approach to load-independently assess both the myocardial contractility and the contraction duration in a whole ventricle. A prolonged contraction duration in the presence of normal myocardial contractility was observed in a ventricle with moderate pressure-overload hypertrophy. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|