Skeletal muscle powered pumps can work under low preload. Design considerations

Characteristics of a dual chambered, single layered skeletal muscle powered pump (DCSLP) and a single chamber, multilayered pump (SCMLP) made from similar masses of untrained latissimus dorsi muscle (LD) were compared. For the DCSLP, 16 canine LDs (51.5 +/- 1.6 g) were wrapped in a "figure eight" around two parallel mandrels, whereas for the SCMLP, LDs were made in 10 by wrapping the LD (54 +/- 8.5 g) twice around one mandrel. Chamber compliance and pump isovolumic peak developed pressure (PDP), stroke volume (SV), stroke work (SW), and ejection fraction (EF) of single contractions were measured. In six of the DCSLP dogs (LV), heart left ventricular stroke volume (LVSV) and left ventricular stroke work (LVSW) were determined. Stimulation parameters were the same for all. Student's t-test (* = p < 0.05) was used for statistical analysis. Dual chambered, single layered skeletal muscle powered pumps with a diastolic volume/mass ratio of 0.63 were more compliant than SCMLPs with a ratio of 0.37. Single chamber, multilayered pumps generated slightly higher PDP, but this was significant only at 60 mmHg preload. At a preload of 15 and an afterload of 120 mmHg, DCSLPs had higher SV (10.7 +/- 1.1 ml) and SW (0.98 +/- 0.14 x 10(6) ergs) than SCMLPs (6.8 +/- 0.7 ml* and 0.58 +/- 0.08 x 10(6) ergs*), or their LV counterparts (5.3 +/- 0.9 ml and 0.84 +/- 0.22 x 10(6) ergs).(ABSTRACT TRUNCATED AT 250 WORDS)