Assist effect of stimulated right latissimus dorsi muscle flap on right atrial function and preventive effect of regurgitation from right atrium to SVC,IVC in atrial systole using synchronously stimulated latissimus dorsi muscle flap wrapped around SVC an

本实验的目的是探讨右功能背阔肌瓣对右房功能的辅助作用，以及对房缩期双腔静脉返流的预防作用。背阔肌肌皮瓣分为三个节段，位于背阔肌肌皮瓣上方。上腔静脉(SVC)和下腔静脉(IVC)分别被包裹。Carimyostimator(MyoStim7220型，Telektronics Inc.澳大利亚公司)用作突发刺激器，其产生5个脉冲串(脉冲宽度0.4毫秒，间隔30 ns，5V)。用多普勒血流探头(DimensionSystem VF-1)测量主动脉血流速度，用Statham P23b探头测量平均主动脉压(AOP)和右房压(RAP)。在肌肉包裹SVC和IVC和不包裹肌肉的情况下，获得稳态数据和爆发式刺激时的数据。与无刺激条件下相比，肌肉包裹条件下爆发刺激可显著增加最大RAP，降低平均RAP、平均AOP和平均主动脉血流速度。与无刺激条件下相比，不包裹的爆发式刺激显著增加最大RAP和平均RAP，但降低AOP。刺激时平均动脉血流速度大于无肌肉收缩时的平均血流速度(P<0.05)。这些数据表明，刺激性肌肉包裹的作用主要是流入阻塞，但只有右功能的背阔肌瓣才能改善右房功能，可能会增加主动脉血流速度。

The purpose of this experiment is to investigate whether the right functioning latissimus dorsi muscle flap has not only the assist effect on right atrial function but also the preventive effect on bicaval regurgitant flow in atrial systole. The latissimus dorsi muscle flap is divided into three segments which are over the rt. atrium (RA) and wrapped round SVC and IVC,respectively. Cariomyostimulator (Myostim Model 7220, Telektronics Inc. Austrlia) is used as a burst stimulator that makes 5 pulse trains (pulse width 0.4 msec, interval 30 ns, 5V). Aortic flow velocity is measured with Doppler flow probe (Dimension system VF-1) and mean aortic pressure (AoP), right atrial pressure (RAP) are measured with Statham P23b transducer (Gould Inc. Cardiovascular Products, Oxnard, Calif.). Steady-state data and data during burst stimulation were obtained under muscle wrapping around SVC and IVC and without wrapping. Burst stimulation under muscle wrapping significantly increased maximal RAP but decreased mean RAP,mean AoP and mean aortic flow velocity in comparison with these parameters under no stimulation. Burst stimulation without wrapping significantly increased maximal RAP and mean RAP but decreased AoP compared with these parameters under no stimulation. Mean aortic flow velocity on stimulation was greater than that without muscle contraction (no significance). These data indicates stimulated muscle wrapping has mainly the effect of inflow obstruction but only right functioning latissmus dorsi muscle flap over RA improves right atrial function may increase aortic flow velocity.