To study the regional effects of the assisted left ventricle, different areas in the heart were evaluated by means of mean movement direction of points in the apex, mid, and base of the heart. There was a difference in the number of point movements during assisted systole as compared to unassisted systole in the three regions: base (7.9 ± 1.9 mm vs 3.6 ± 1.7 mm, p < 0.01), middle (13.8 ± 4.0 mm vs 7.3 ± 1.8 mm, p < 0.005), and apex of the heart (28.1 ± 4.5 mm vs 5.3 ± 2.3 mm, p < 0.001). The other difference between the regions was in the direction of the movements of the point during the assisted beats: the apex moved upward 71 ± 7.5° and θ − 30 ± 13°, the mid part of the heart moved upward 64 ± 16° and θ − 14 ± 25°, and the base moved upward 11 ± 21° and θ − 32 ± 26°. Although the SD was found to be relatively high, the difference in point movement direction was statistically significant between the three areas of the heart (p < 0.001). These relatively complex regional changes can be observed in Figure 4
, where the direction of each point movement is indicated. The ejection fraction of the assisted beats was statistically higher (39 ± 7% vs 28 ± 7% in the unassisted beats, p < 0.01), and the main change was found to be in the left ventricular end-systolic volumes (40 ± 6 mL vs 46 ± 8 mL in the unassisted beats, p < 0.05), while no significant difference was found in the left ventricular end-diastolic volumes (66 ± 9 mL vs 64 ± 10 mL in the unassisted beats, p = 0.11). To evaluate the relative contribution of the different heart segments during the assisted systole, the area of three inner cross-sections around the apex, mid, and base of the heart was studied during normal and assisted systole. It was found that only the mid part of the heart contributes to the higher ejection fraction in the assisted beats (cross-section area of 412 ± 123 mm2 vs 471 ± 129 mm2 in the previous unassisted beats, p = 0.0004). An example of changes in the cross-section area at the mid part of the heart is presented in Figure 5
. While the cross-section area of the base did not change, the cross-section area of the apex was paradoxically higher in the assisted beats (276 ± 104 mm2 vs 249 ± 85 mm2 in the previous unassisted beats, p = 0.047). In contrast, the postassisted diastole cross-section area was not significantly changed in the mid part of the heart, while end-diastolic cross-section areas were found to be high in the postassisted diastole, both in the apex (cross-section area of 439 ± 87 mm2 vs 389 ± 113 mm2 in the preassisted diastole, p = 0.0053), and base (cross-section area of 1,026 ± 232 mm2 vs 991 ± 214 mm2 in the previous unassisted beats, p = 0.017).