Objectives.
The main limitation for indication to a Fontan procedure is the presence of elevated Pulmonary Vascular Resistance (PVR).
A skeletal muscle (Latissimus Dorsi = LD) intermittently stimulated with a pulse-generator has been proven to become a powerful fatigue-resistant muscle.
We tested the hypothesis that an extra-cardiac Fontan connection including a uni-directional valve with the LD wrapped around, intermittently compressing the conduit, would: a) increase the baseline flow; b) overcome increased P.V.R.
Methods.
The LD was prepared in 4 pigs by three weeks of activation via the thoraco-dorsal nerve (210 μs pulses at 30 Hz frequency, amplitude 1.5-2.5 V, on 0.19 seconds and off 6 seconds, 24 hrs/day).
The pigs (mean body weight 63 kg, range 57-68 kg) then underwent connection of the inferior vena cava to the pulmonary artery (PA) by implantation of combined valved conduit (Contegra and Dacron prosthesis).
After weaning from cardiopulmonary bypass (mean duration = 136’, range 132-143’) the prepared distal LD was wrapped around the extracardiac cavo-pulmonary valved conduit.
Results.
The extrinsic conduit compression by intermittent stimulation of the LD provided a mean 7% (range 3.7-10.0%) decrease of the baseline PA pressure, with simultaneous increase of the flow through the conduit of 2% (range -6 to +12.5%).
Conclusions.
The preliminary results confirmed the feasibility of the technique. More studies are required to further test our hypothesis and to overcome technical problems related to the poor perfusion of the mobilized LD, the timing of LD transfer, and the low “pre-load” within the wrapped conduit.