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Objective To compare the acute hemodynamic effects of five different pacing modes in patients with cardiac function NYHA class to Ⅱ without bundle branch block (BBB). Methods This study included 12 patients (SSS 7, Ⅲ°AVB 5) undergoing pacemaker implantation. Right ventricular apex (RVA), right ventricular outflow tract (RVOT),right ventricular bifocal (RV-Bi), left ventricular base (LVB) and bi - ventricular (Bi - V) pacing at 60～ 80 ppm were done in VVI mode prior to implantation of DDD pacemaker. The cardiac index (CI), mean pulmonary artery pressure (mPAP) and pulmonary capillary wedge pressure (PCWP) were measured with Swan - Ganz thermodilution catheter after 5 minutes of each pacing mode. Results ( 1 ) Comparing to pacing at RVA (CI: 2. 41 ±0. 38 L/min per m2, PCWP: 16. 7± 3.3 mmHg), the CI increased and the PCWP decreased significantly in pacing at RVOT(CI: 2.63 ±0.46, PCWP: 13.8±2.3), LVB(CI: 2.78±0.52,PCWP: 14.4±3.1), RV-Bi(CI: 2.83±0.57,PCWP: 12.8±2.5) and Bi-Vpacing(CI: 2.94±0. 60, PCWP: 12. 7 ±2.5), P ＜ 0. 01, respectively.(2) The CI of RV- Bi and Bi- V pacing was higher than that of RVOT and LVB pacing, the PCWP was lower, P ＜ 0.05, respectively. (3) There was no significant difference between RV- Bi pacing and Bi- V pacing in CI and PCWP. Conclusion There is no significant difference between RV - Bi pacing and Bi V pacing in the acute hemodynamic effects; however,dual - site pacing is much better than single site pacing in that aspect for patients with cardiac function NYHA class Ⅰ to Ⅱ without BBB. Among single site pacing, the RVOT and LVB pacing is better than RVA pacing in cardiac function.