SHIRATO, K., ISHIKAWA, K., KANAZAWA, M., NAKAJIMA, T., MUNAKATA, K., SAKUMA, M., HANEDA, T. and TAKISHIMA, T.
Effect of Pericardium of Regional Myocardial Systolic Function in Acute Ischemia. Tohoku J. Exp. Med., 1991,
165 (4), 271-282-To know whether or not the pericardium affects regional myocardial systolic function in acute ischemia, we measured ischemic and non-ischemic segment lengths of the left ventricle using ultrasonic crystals in 10 open-chest dogs with the pericardium preserved. When the left ventricular pressure and segment lengths were stable after left circumflex coronary occlusion, we opened the pericardium widely. After coronary occlusion, end-diastolic length (EDL) in ischemic and non-ischemic segments increased, and the ischemic segment showed paradoxical systolic expansion while the non-ischemic segment increased its active shortening. After pericardiectomy, heart rate, left ventricular systolic pressure, and peak positive and negative dP/dt did not change. EDL in ischemic and non-ischemic segments further increased from 12.02±0.18 to 12.50±0.16mm (mean±S.E.,
p< 0.01) and from 11.12±0.20 to 11.45±0.18mm (
p<0.05), respectively, despite the concomitant fall in left ventricular end-diastolic pressure (LVEDP) from 12.4±0.6 to 10.6±0.8mmHg (
p<0.01). End-systolic length in ischemic and non-ischemic segments also increased from 12.37±0.25 to 12.70±0.20mm (
p<0.05) and from 8.50±0.13 to 8.74±0.13mm (
p<0.01), respectively, although the left ventricular end-systolic pressure did not change. Maximum expanded systolic length of the ischemic segment also increased from 12.99±0.20 to 13.42±0.16mm (
p<0.01). These results indicate that, in acute ischemia, the pericardium inhibits paradoxical systolic expansion of the ischemic region and increase in end-systolic length of non-ischemic segment. Thus, it is concluded that the pericardium modifies the regional myocardial systolic function in acute ischemia, perhaps through the mechanical restraint of the pericardium.
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