Niinami H, Hooper T L, Ruggiero R, Suga H, Stephenson L W
Department of Surgery, Wayne State University School of Medicine, Detroit, Michigan, USA.
J Card Surg. 1995 Nov;10(6):677-89. doi: 10.1111/j.1540-8191.1995.tb00658.x.
In five dogs, skeletal muscle ventricles (SMVs) were constructed from the latissimus dorsi muscle, and placed within the thoracic cavity. After a 3-week delay period, SMVs were electrically preconditioned with 2-Hz continuous stimulation for 6 weeks. At a second procedure, SMVs were connected to a mock-circulation system, and performance was evaluated according to pressure-volume relationships at three different SMV contraction rates (33, 54, and 97 per min) and three stimulation protocols (25, 43, and 85 Hz) under varying loading conditions. Under appropriate conditions of afterload, the end-diastolic pressure-volume relation of SMVs was comparable with that of the cardiac ventricles, although SMVs were less compliant. At higher burst stimulation frequencies, SMV compliance was increased. Compliance was not affected by varying the rate of SMV contraction. End-systolic elastance, a reflection of contractility, appeared to be constant for each SMV, in contrast to cardiac ventricles, and was not influenced by changes in burst stimulation frequency or contraction rate. In this study, SMVs were capable of a level of stroke work 180% of that of the native right ventricle (RV) at rest (0.397 +/- 0.047 x 10(6) ergs) and 37% of that of the left ventricle (LV) at rest (0.298 +/- 0.61 x 10(6) ergs), at 33 contractions per minute (CPM), 25-Hz burst frequency, and physiological preload, but this level could not be sustained at higher contraction rates. Nevertheless, power output (SMV stroke work x contraction rate) was maximal at 97 CPM. These findings demonstrate important function differences between pumping chambers constructed from conditioned skeletal muscle, and those composed of cardiac muscle, which must be considered when using skeletal muscle ventricles for cardiac support or replacement.
在五只犬中，利用背阔肌构建骨骼肌心室（SMV），并将其置于胸腔内。经过3周的延迟期后，对SMV进行2赫兹连续刺激电预处理6周。在第二次手术中，将SMV连接到模拟循环系统，并根据三种不同的SMV收缩率（每分钟33次、54次和97次）和三种刺激方案（25赫兹、43赫兹和85赫兹）在不同负荷条件下的压力-容积关系评估其性能。在适当的后负荷条件下，尽管SMV的顺应性较低，但其舒张末期压力-容积关系与心脏心室相当。在较高的爆发刺激频率下，SMV的顺应性增加。顺应性不受SMV收缩率变化的影响。与心脏心室不同，反映收缩性的收缩末期弹性对于每个SMV似乎是恒定的，并且不受爆发刺激频率或收缩率变化的影响。在本研究中，在每分钟33次收缩（CPM）、25赫兹爆发频率和生理预负荷下，SMV的每搏功水平在静息时是天然右心室（RV）的180%（0.397±0.047×10⁶尔格），是左心室（LV）静息时的37%（0.298±0.61×10⁶尔格），但在较高的收缩率下无法维持这一水平。然而，功率输出（SMV每搏功×收缩率）在97 CPM时最大。这些发现表明，由条件性骨骼肌构建的泵血腔室与由心肌组成的泵血腔室之间存在重要的功能差异，在使用骨骼肌心室进行心脏支持或替代时必须考虑这些差异。
