Skeletal muscle ventricles with a single-limb conduit: the importance of hemodynamic design

Skeletal muscle ventricles (SMVs) connected to the descending thoracic aorta have the potential for providing long-term diastolic augmentation. A successful existing design employs a bifurcated conduit, but aortic constriction between the limbs of the conduit is required to ensure obligatory flow-through. Here we evaluate an alternative approach in which connection to the aorta is made by a single-limb conduit.

In two groups of dogs SMVs were constructed from the left latissimus dorsi muscle and connected to the circulation via a single-limb conduit of length 110-120 mm (Group 1, n = 5) or 70 mm (Group 2, n = 5). The animals were followed over 10 weeks.

Although all animals showed significant augmentation of diastolic aortic pressure at the outset, substantial thrombus developed in the SMVs of both groups. The results were analyzed by reference to design criteria for a single-limb conduit SMV, developed from empirical, in-vitro flow studies and formulated mathematically.

The SMVs constructed in this experiment appeared to meet the criteria for adequate mixing of blood within the ventricle. They did not, however, achieve adequate exchange of blood with the circulation. Thrombosis was therefore attributable to excessive residence time of blood in the SMV and conduit. Both the experimental study and the mathematical analysis point to the need for SMVs of this configuration to be constructed closer to the aorta. Preliminary results are reported for such an experiment in the pig, in which the SMV was thrombus-free when terminated electively after 1 week.