[Contractile and relaxation reserve of the left ventricle. I. Normal left ventricle (author's transl)].

The validation of parameters of left ventricular contractility at rest is pure. Therefore, the contractile function of the left ventricle was measured during exercise. The reserve in contractility and relaxation was obtained in a group of 13 patients with normal left ventricle (ergometer). The maximal rate of left ventricular pressure rise (max dP/dt) increased from 1721 +-378 to 4954 +- 1246 mmHg/s and the peak measured velocity of contractile elements (dP/dt/P) from 38 +- 9 to 76 +- 11 s-1 at a mean load of 112 +- 43 (+-SD) watts. The parameter of the isovolumic relaxation phase, the maximal rate of left ventricular pressure fall (min dP/dt) increased from 1862 +- 343 to 3128 +- 445 mmHg/s. Left ventricular enddiastolic pressure was unchanged. All patients reached at least 3200 mmHg/s (max dP/dt) 60 s-1 (dP/dt/P) and 2400 mmHg/s (min dP/dt). The difference between rest- and exercise values was at least 1800 mmHg/s (max dP/dt), 22 s-1 (dP/dt/P) and 1000 mmHg/s (min dP/dt).