The effect of pericardium on the end-systolic pressure-segment length relationship in canine left ventricle in acute volume overload.

The effect of the pericardium on the end-systolic pressure-segment length relationship in the left ventricle was examined with an ultrasonic miniature gauge in open-chest dogs. In 12 dogs, blood was infused until left ventricular (LV) end-diastolic pressure reached about 20 mm Hg, and then the pericardium was opened widely. In the other 12 dogs a pericardiectomy was performed without blood infusion. Stroke volume was measured in six dogs in the former group and in seven dogs in the latter group. After blood infusion, LV systolic, end-systolic, and end-diastolic pressures increased from 120 +/- 14 to 162 +/- 16 mm Hg (mean +/- SD), from 106 +/- 13 to 146 +/- 17 mm Hg, and from 8 +/- 2 to 19 +/- 2 mm Hg, respectively (all p less than .01). End-systolic and end-diastolic segment lengths increased from 8.9 +/- 2.1 to 10.6 +/- 2.2 mm and from 11.6 +/- 2.5 to 14.9 +/- 2.7 mm, respectively (both p less than .01). After pericardiectomy, the segments were further lengthened by 8.9 +/- 4.4% and by 10.0 +/- 6.2%, respectively (both p less than .01). Heart rate, LV systolic and end-systolic pressures, and peak positive dp/dt did not change, although end-diastolic pressure fell from 19 +/- 2 to 18 +/- 2 mm Hg (p less than .01). Stroke volume rose from 13.1 +/- 3.7 to 23.9 +/- 5.0 ml due to volume loading and further increased by 26.7 +/- 9.0% after pericardiectomy.(ABSTRACT TRUNCATED AT 250 WORDS)