[Left ventricular contraction and relaxation in patients with congestive cardiomyopathy during exercise].

UNLABELLED

Left ventricular (LV) contraction and relaxation were analysed in 16 patients with congestive cardiomyopathy (COCM) at rest (R) and during supine bicycle ergometer exercise (E), and were compared with 10 normals (N). In patients with COCM, left ventricular ejection fraction (EF) was significantly reduced at rest, but during exercise like in the normal patients there were no significant changes (EFCOCM: 34 +/- 12% (R) and 35 +/- 10% (E);EFN: 72 +/- 5% (R) and 74 +/- 5% (E). LV-enddiastolic volume in COCM was more than 100% larger than in N. Left ventricular filling pressures (PLVed) were elevated already at rest, the increase during exercise was very similar to that of the normal group (COCM: 20.5 +/- 9.0 (R), 33.3 +/- 7.6 (E) mm Hg, p less than 0.001; normal group: 11.1 +/- 2.2 (R), 18.7 +/- 5.9 (E) mm Hg, p less than 0.001). The increase of maximum dP/dt during exercise as an index of contractility reserve was distinctly lower in COCM (delta means COCM: + 51%; delta means N: + 105%). Left ventricular relaxation as measured from minimal dP/dt was significantly impaired already at rest in COCM (COCM: -1109 +/- 329; N: -1832 +/- 468 mm Hg X s-1, p less than 0.001), the increase of dP/dtmin during exercise (COCM + 37%) was similar to that of normal patients (+ 35%). The time constant T of isovolumic pressure fall was significantly prolonged at rest in COCM, and there were no changes during exercise. After correction for the right atrial pressure rise during exercise, the time contant T' was significantly shortened to the same extent in the normal group (COCM: (R) 44 +/- 9, (E) 36 +/- 10 ms; N: (R) 33 +/- 5, (E) 25 +/- 5 ms, p less than 0.001).

CONCLUSIONS

In patients with COCM, changes of left ventricular ejection fraction during exercise are inconsistent; in the individual patient, changes in global LV function during exercise cannot be predicted from EF at rest. At rest, LV relaxation is prolonged, the lack of shortening of the time constant T during exercise is thought to be mainly due to the pressure rise in the pericardial space.