Moon M R, Ingels N B, Daughters G T, Stinson E B, Hansen D E, Miller D C
Department of Cardiovascular and Thoracic Surgery, Stanford University School of Medicine, Calif. 94305.
Circulation. 1994 Jan;89(1):142-50. doi: 10.1161/01.cir.89.1.142.
Left ventricular (LV) twist, the longitudinal gradient of circumferential rotation about the LV long axis, may play an important role in the storage of potential energy at end systole and its subsequent release as elastic recoil during early diastole; however, the effects of load and inotropic state on LV systolic twist and diastolic untwist in human subjects have not previously been characterized.
Six cardiac transplant recipients with 12 implanted radiopaque midwall LV myocardial markers were studied 1 year after transplantation. Biplane cinefluoroscopic marker images and LV pressure were recorded during control conditions and after afterload augmentation (methoxamine, 5 to 10 micrograms.kg-1 x min-1), inotropic stimulation (dobutamine, 5 micrograms.kg-1 x min-1), and preload augmentation (volume loading with normal saline). Systolic twist dynamics were assessed by maximum twist (Tmax[rad/cm]), peak negative twist rate (-dT/dtmin[rad.cm-1 x s-1]), and the slope of the twist normalized-ejection fraction relation (T-nEFR, Msys[rad/cm]) during systole. Diastolic untwist was assessed by the peak positive untwist rate (+dT/dtmax [rad.cm-1 x s-1]) and the slopes (rad/cm) of the T-nEFR during early diastole (Mear-dia) and mid diastole (Mmid-dia). Compared with control values, LV pressure and volume loading had no significant effect on Tmax, -dT/dtmin, or Msys; however, inotropic stimulation significantly increased all parameters describing systolic twist (Tmax: -0.10 +/- 0.03 versus -0.06 +/- 0.02 rad/cm, P < .001; -dT/dtmin: -0.72 +/- 0.19 versus -0.44 +/- 0.22 rad.cm-1 x s-1, P < .001; Msys: -0.10 +/- 0.03 versus -0.06 +/- 0.01 rad/cm, P < .001). Pressure loading had no effect on early diastolic untwisting; however, dobutamine significantly increased M(ear)-dia (-0.24 +/- 0.06 versus -0.13 +/- 0.04 rad/cm, P < .0001) and +dT/dtmax (0.78 +/- 0.24 versus 0.45 +/- 0.16 rad.cm-1 x s-1, P < .001). Conversely, volume loading significantly decreased M(ear)-dia (-0.08 +/- 0.04 versus -0.13 +/- 0.04 rad/cm, P < .05). M(ear)-dia correlated directly with LV contractile state (as assessed as maximum dP/dt, r = .60, P < .0001) and inversely with end-systolic volume (r = -.87, P < .0001) but was unrelated to stroke volume (r = .08, P = .30) or LV afterload (estimated as effective arterial elastance, r = .08, P = .29). Mmid-dia did not change during any intervention.
In conscious human transplant patients, (1) pressure and volume loading do not affect systolic LV twist; (2) dobutamine augments systolic twist and early diastolic untwisting, suggesting more end-systolic potential energy storage and early diastolic elastic recoil with enhanced inotropic state; (3) volume loading decreases early diastolic untwisting, possibly reflecting diminished recoil forces after preload augmentation associated with larger end-systolic volumes (ESV); and (4) M(ear)-dia correlates strongly with ESV (in an inverse fashion), and less strongly, but directly, with LV dP/dtmax.
左心室（LV）扭转，即围绕左心室长轴的圆周旋转的纵向梯度，可能在收缩末期势能的储存及其在舒张早期作为弹性回缩的后续释放中起重要作用；然而，负荷和心肌收缩状态对人体左心室收缩期扭转和舒张期解旋的影响此前尚未得到明确描述。
对6名心脏移植受者进行研究，这些受者在移植后1年植入了12个不透X线的左心室中层心肌标记物。在对照条件下以及后负荷增加（甲氧明，5至10微克·千克⁻¹·分钟⁻¹）、心肌收缩刺激（多巴酚丁胺，5微克·千克⁻¹·分钟⁻¹）和前负荷增加（用生理盐水扩容）后，记录双平面荧光透视标记物图像和左心室压力。通过收缩期最大扭转（Tmax[弧度/厘米]）、最大负扭转率（-dT/dtmin[弧度·厘米⁻¹·秒⁻¹]）以及扭转归一化射血分数关系的斜率（T-nEFR，Msys[弧度/厘米]）评估收缩期扭转动力学。通过舒张早期最大正解旋率（+dT/dtmax [弧度·厘米⁻¹·秒⁻¹]）以及舒张早期（Mear-dia）和舒张中期（Mmid-dia）的T-nEFR斜率（弧度/厘米）评估舒张期解旋。与对照值相比，左心室压力和容量负荷对Tmax、-dT/dtmin或Msys无显著影响；然而，心肌收缩刺激显著增加了所有描述收缩期扭转的参数（Tmax：-0.10±0.03对-0.06±0.02弧度/厘米，P<.001；-dT/dtmin：-0.72±0.19对-0.44±0.22弧度·厘米⁻¹·秒⁻¹，P<.001；Msys：-0.10±0.03对-0.06±0.01弧度/厘米，P<.001）。压力负荷对舒张早期解旋无影响；然而，多巴酚丁胺显著增加了M(ear)-dia（-0.24±0.06对-0.13±0.04弧度/厘米，P<.0001）和+dT/dtmax（0.78±0.24对0.45±0.16弧度·厘米⁻¹·秒⁻¹，P<.001）。相反，容量负荷显著降低了M(ear)-dia（-0.08±
