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The aim of this study was to define normal left ventricular performance at rest and during supine bicycle exercise with equilibrium radionuclide ventriculography in a normal population other than young healthy volunteers. Thirty-one patients (mean age 45 years +/- 9 SD) with chest pain of varying origin and no evidence of heart disease proven by means of noninvasive and invasive techniques were studied. Left ventricular ejection fraction (LVEF) at rest averaged 0.64 +/- 0.07 SD and increased with peak exercise to 0.73 +/- 0.08 SD (P less than 0.005). Change in LVEF from rest to maximum exercise ranged within 0-0.19. Six patients (19%) failed to augment LVEF with exercise to more than 0.05; none of the patients dropped LVEF during exercise. Multivariate analysis revealed no significant predictors of LVEF response to exercise. However, there was a tendency that resting LVEF and enddiastolic volume index with exercise might influence LVEF response to exercise. Peak left ventricular ejection rate (LVER) at rest averaged 3.3 s-1 +/- 0.6 SD and increased to 5.1 s-1 +/- 1.1 SD (P less than 0.005) with exercise. Peak left ventricular early filling rate (LVFR) was 2.8 s-1 +/- 0.6 SD at rest and was measured 5.5 s-1 +/- 1.3 SD at maximum exercise (P less than 0.005). Left ventricular enddiastolic volume (EDV) did not change significantly from rest to maximum exercise, whereas left ventricular endsystolic volume (ESV) decreased to 79% +/- 19 SD (P less than 0.01) of the value at rest.(ABSTRACT TRUNCATED AT 250 WORDS)

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Dobutamine, a new catecholamine with a positive inotropic action, was given by infusion to 9 patients with cardiac failure in a dosage of 5 and 7.5 mug/kg-min over a period of 15 minutes. An improvement of left ventricular function was proven by an increase of cardiac output by 33%, a reduction of end-diastolic pressure from 21 to 14 mm Hg, an improvement of left ventricular ejection fraction from 29 to 39% and of the mean circumferential fibre contraction velocity from 0.4 to 0.8 circ/s. The systolic aortic pressure increased by a mean of 14% (5 mug/kg-min) and 23% (7.5 mug/kg-min). However, the resistance of the systemic circulation decreased from 1858 to 1439 and 1444 dyn-s-cm-5. Cardiac frequency remained unchanged with a dosage of 5 mug/kg-min and increased by a mere 7 beats/min with a dosage of 7.5 mug/kg-min. There was no increased tendency for arrhythmia. Dobutamine thus appears to act relatively selectively on myocardial beta-1 receptors. Results so far indicate therapeutic success in patients with severe cardiac failure, particularly in the low-output syndrome.

68 patients with clinical and hemodynamical diagnosis of idiopathic cardiomyopathy (CM) were analysed for antibody in their sera using an immunofluorescence sandwich technique after titration of the sera in tissue sections. 60 of these patients had antibodies against heart muscle sarcolemma with titers up to 1:64. Out of these, the antibodies in 9 sera could be absorbed with group A streptococci. The antibodies reacted in no case with striated or smooth muscle sarcolemma. The 25 patients with an obstructive type of CM showed the highest titers and 12 of them, in addition, had antinuclear factors in their sera. These findings suggested an auto-allergic etiology for most cases of idiopathic CM.

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