Right and left ventricular compliance in the hereditary cardiomyopathy of the Syrian hamster

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Abstract
Ventricular pressure-volume curves were examined in 10 pre-oedematous cardiomyopathic Syrian hamsters, aged 120 d, and 10 oedematous cardiomyopathic hamsters, aged 210 d, and compared with 10 and 8 age-matched controls, respectively. Previous studies had shown filling pressures and cardiac output to be normal in the pre-oedematous stage. In contrast, the oedematous stage was characterised by elevated filling pressures and increased cardiac output, raising the question whether this stage represents true myocardial failure or circulatory congestion associated with decreased ventricular compliance. Compliance, defined as dV/dP, was derived simultaneously for both ventricles from post-mortem pressure-volume curves from 0 to 2.66 kPa (0 to 20 mmHg). Left ventricular tissue elastic modulus, E, defined as dσ/d∊ or the incremental stress (σ) for an increment of strain (∊), was derived from the compliance curves and certain linear dimensions of the heart. At isobaric intervals, compliance did not differ between control and myopathic ventricles. At pressures corresponding to previously measured, naturally prevailing end-diastolic pressures, the myopathic ventricles were significantly dilated in both stages; end-diastolic compliance was normal in pre-oedematous hamsters, but was significantly decreased in the oedematous animals. Left ventricular elastic modulus was elevated at all values of σ, in both groups of myopathic animals.