Lançon J P, Pillet M, Gabrielle F, Fayolle J L, Tatou E
Department of Anesthesiology, Hôpital Universitaire du Bocage, Dijon, France.
J Cardiothorac Vasc Anesth. 1994 Oct;8(5):536-40.
Increasing heart rate enhances the strength of contraction of cardiac fibers. This has been demonstrated in vitro and recently for the left ventricle. To study this phenomenon on the right ventricle, the effects of increasing heart rate by atrial pacing on right ventricular (RV) contractility were observed after coronary artery surgery in 20 patients. Right ventricular ejection fraction (EF) and stroke volume (SV) were measured by use of a rapid-response thermistor pulmonary artery catheter. Right ventricular volumes were calculated from EF and SV. Right ventricular contractility was assessed by the slope of the end-systolic pressure-volume relationship (ESPVR) before and after increasing RV preload by means of military antishock trousers (MAST) inflation. The dP/dtmax/end-diastolic volume index (EDVI) ratio, which is independent of ventricular preload, was also used as an inotropic index. Results are expressed as mean +/- SEM. Right ventricular preload, as reflected by RVEDVI, was increased by MAST inflation (99 +/- 6 mL/m2 v 106 +/- 7 mL/m2, P < 0.01), but returned to control values when inflation of MAST was combined with pacing (100 +/- 6 mL/m2). The slope of the RV ESPVR significantly increased when heart rate was increased (0.22 +/- 0.03 mmHg/mL/m2 before pacing v 0.77 +/- 0.07 mmHg/mL/m2 during pacing, P < 0.05). The dP/dtmax/EDVI ratio was also increased by pacing (2.32 +/- 0.4 mmHg/min/mL/m2 before pacing v 3.15 +/- 0.5 mmHg/min/mL/m2 during pacing, P < 0.01). Moreover, cardiac index was increased by pacing alone (2.45 +/- 0.2 L/min/m2 v 2.78 +/- 0.2 L/min/m2, P < 0.01), and significantly more when MAST were inflated (2.94 +/- 0.2 mL/m2, P < 0.05 v pacing alone). It is concluded that increasing heart rate by atrial pacing increases RV inotropic status after coronary artery surgery.
心率增加可增强心肌纤维的收缩力。这已在体外得到证实，最近在左心室也得到了验证。为了研究右心室的这一现象，观察了20例冠状动脉手术后通过心房起搏增加心率对右心室（RV）收缩力的影响。使用快速响应热敏电阻肺动脉导管测量右心室射血分数（EF）和每搏量（SV）。根据EF和SV计算右心室容积。通过使用抗休克裤（MAST）充气增加右心室前负荷前后的收缩末期压力-容积关系（ESPVR）斜率来评估右心室收缩力。dP/dtmax/舒张末期容积指数（EDVI）比值，其独立于心室前负荷，也被用作心肌收缩力指数。结果以平均值±标准误表示。MAST充气使反映右心室前负荷的右心室舒张末期容积指数（RVEDVI）增加（99±6 mL/m²对106±7 mL/m²，P<0.01），但当MAST充气与起搏联合时恢复到对照值（100±6 mL/m²）。当心率增加时，右心室ESPVR斜率显著增加（起搏前0.22±0.03 mmHg/mL/m²对起搏期间0.77±0.07 mmHg/mL/m²，P<0.05）。起搏也使dP/dtmax/EDVI比值增加（起搏前2.32±0.4 mmHg/min/mL/m²对起搏期间3.15±0.5 mmHg/min/mL/m²，P<0.01）。此外，单独起搏使心脏指数增加（2.45±0.2 L/min/m²对2.78±0.2 L/min/m²，P<0.01），当MAST充气时增加更显著（2.94±0.2 mL/m²，与单独起搏相比P<0.05）。结论是冠状动脉手术后通过心房起搏增加心率可增加右心室心肌收缩力状态。
