Pacemakers are widely used in postcardiotomy patients to avoid severe arrhythmia. The peripheral perfusion index (PI) has been considered as an effective parameter evaluating the circulation. In this study, investigators aim to avaluate the ability of peripheral perfusion index to detect changes of hemodynamics in postcardiotomy patients with pacemakers.

Pacemakers are widely used in postcardiotomy patients to avoid severe arrhythmia. The peripheral perfusion index (PI) has been considered as an effective parameter evaluating the circulation. In this study, investigators aim to evaluate the ability of peripheral perfusion index to detect changes of hemodynamics (cardiac output or storke volume,et al) in postcardiotomy patients with pacemakers.

Inclusion Criteria:

• age >=18 years old;
• postcardiotomy
• placement of temportary pacemaker during the surgery
• dependence of pacemaker (abscence of autonomic cardiac rhythm）

Exclusion Criteria:

• hemodynamic unstable （high dose of vasoactive drugs）
• fingers ischemia, cannot monitor the peripheral perfusion index

Pacemakers are widely used in post-cardiotomy patients, while it's common that some patients may be pacemaker dependent. We choose these patients who has been placed with temportary pacemaker during the cardic surgery