**Blood Flow in LDM under Work and Rest**

**Figure 18.** Blood flow within the Arteria thoraco-dorsalis of a non pre-stimulated LDM in a goat in-situ (left) in com‐ parison to the same setting 14 days after electrically pre-stimulation of LDM in-situ (right) The pre-stimulated LDM (right) showed a higher blood flow under work conditions during a 10 minutes burst stimulation (work).

**Figure 19.** Change of blood flow [%] in arteria thoracodorsalis of non- (white spots)- and pre-stimulated (black spots) LDM (p≤0.05\*) under rest, exercise (stimulation) and recovery. The two weeks stimulated muscle (n=5) shows a signifi‐ cant higher blood flow under exercise and recovery (\*).

In group I, the pre-stimulated muscle (black spotted curve) shows an increased mean blood flow from 5.0±2.4 ml/min at rest to 30.2±2.7 ml/min under exercise. In group II, blood flow was 5.1±2.8 ml/min at rest and 19.9±0.9 ml/min under exercise. Therefore flow under exercise increased to 51.8% (p ≤ 0.01).

#### **5.1. Collaterals**

Within latissimus dorsi muscle there exist two arterial territories. A proximal one supported by the thoracodorsal artery and a distal territory supplied by perforating arteries deriving from intercostal arteries. Mobilization of the latissimus dorsi muscle as a functional graft necessarily involves division of perforating arteries that enter the distal portion of the muscle causing an ischemic tissue with a loss in function.

Between the two arterial territories anastomotic connections are well described by Salmons et.al 1998 [9]. In clinical applications, the existence of anastomotic connections offers the prospect of maintaining flow to the distal part of the grafted muscle. Electrical stimulation enhances blood flow through these anastomoses (Tang et al, 1998 [10]) demonstrated in a sheep model that a pre-stimulation of LDM in situ over two weeks increases blood flow in the distal part of LDM to a normal range while a reduction of flow by 50% was found in the untreated muscle. Own experience with pre-stimulated LDM in situ in goats confirm these findings. Prestimulated LDM's distal part looked well perfused after dissection but ischemic without prestimulation. We conclude, electrical pre-stimulation of the latissimus dorsi muscle in situ reduces the acute distal ischemia of LDM caused by surgical manipulations, and promotes subsequent recovery of blood flow.

In conclusion, applying pre-stimulation in-situ before a DCMP procedure might result in a relevant functional advantage and might prevent muscle damage in the distal muscle tissue of the LDM.

#### **5.2. Capillary density**

**Figure 19.** Change of blood flow [%] in arteria thoracodorsalis of non- (white spots)- and pre-stimulated (black spots) LDM (p≤0.05\*) under rest, exercise (stimulation) and recovery. The two weeks stimulated muscle (n=5) shows a signifi‐

In group I, the pre-stimulated muscle (black spotted curve) shows an increased mean blood flow from 5.0±2.4 ml/min at rest to 30.2±2.7 ml/min under exercise. In group II, blood flow was 5.1±2.8 ml/min at rest and 19.9±0.9 ml/min under exercise. Therefore flow under exercise

Within latissimus dorsi muscle there exist two arterial territories. A proximal one supported by the thoracodorsal artery and a distal territory supplied by perforating arteries deriving from intercostal arteries. Mobilization of the latissimus dorsi muscle as a functional graft necessarily involves division of perforating arteries that enter the distal portion of the muscle causing an

Between the two arterial territories anastomotic connections are well described by Salmons et.al 1998 [9]. In clinical applications, the existence of anastomotic connections offers the prospect of maintaining flow to the distal part of the grafted muscle. Electrical stimulation enhances blood flow through these anastomoses (Tang et al, 1998 [10]) demonstrated in a sheep model that a pre-stimulation of LDM in situ over two weeks increases blood flow in the distal part of LDM to a normal range while a reduction of flow by 50% was found in the untreated muscle. Own experience with pre-stimulated LDM in situ in goats confirm these findings. Prestimulated LDM's distal part looked well perfused after dissection but ischemic without prestimulation. We conclude, electrical pre-stimulation of the latissimus dorsi muscle in situ

cant higher blood flow under exercise and recovery (\*).

increased to 51.8% (p ≤ 0.01).

810 Regenerative Medicine and Tissue Engineering

ischemic tissue with a loss in function.

**5.1. Collaterals**

Experimental own data from big animal experiments in Fig.20 and Fig.21 and experimental papers of others dealing with muscle powered cardiac assist show that a pre-stimulation of the LDM in-situ enhances LDM's capillarization.

**Capillaries**

**Figure 20.** Histologic visualization of cross-section areas from LDMs muscle fibers surrounded by capillaries (black dots), in the stimulated muscle (right) exists a higher number of capillaries than in the non-stimulated LDM (left).

(n=6)

C/F ratio in muscular tissue in five boore goats of non (white block)- and pre-stimulated (black block) LDM ( p≤0.05\*; p≤0.01\*\*,n.s. = not significant;).

**Figure 21.** 14 days of electrical stimulation increased the capillary to fiber ratio in goat's LDM (n=5) to 38% (black columns) in comparison to the non-stimulated contra- lateral LDM control (white columns). (\* p < 0.05; \*\* p < 0.01; n.s. not significant)

Ischemic damage in the latissimus dorsi muscle may limit the success of cardiomyoplasty. Electrical pre-stimulation of the muscle in situ is known to enhance capillarization and thoracodorsal perfusion to the distal latissimus dorsi muscle immediately after grafting. Use of a pre-stimulated graft may therefore improve the outcome of skeletal muscle cardiac assistance (Tang et. al,1998, [10])
