## Introduction

## Subjects

## Methods

### Surgical techniques to dissect and ligate pulmonary vein

### Blood flow analysis in the pulmonary vein stump

^{3}, viscosity coefficient 0.004 Pa*s).

### Statistical analysis

## Results

Patients with thrombus (n = 6) | Patients without thrombus (n = 9) | p-value | |
---|---|---|---|

Age (years, mean) | 69.7 | 69.0 | 0.90 |

Sex, (male/female) | 5/1 | 5/4 | 0.58 |

Previous episode of CI (yes/no) | 0/6 | 1/8 | > .99 |

Preoperative haematological parameters | |||

HTC (%, mean) | 41.6 | 39.3 | 0.18 |

WBC count (10 ^{4}/mm^{3}, mean) | 73.8 | 65.6 | 0.33 |

Platelet count (10 ^{4}/mm^{3}, mean) | 23.9 | 25.9 | 0.60 |

PT-INR (mean) | 1.02 | 1.03 | 0.81 |

APTT (mean) | 31.6 | 29.2 | 0.30 |

Surgical procedure | |||

VATS/Open (n) | 1/5 | 2/7 | 1.0 |

PV ligation (yes/no) | 2/4 | 9/0 | 0.011 |

PV stump length (mm, mean) | 18.5 | 5.4 | < .001 |

Postoperative day 1 haematological parameters | |||

HTC (%, mean) | 35.5 | 32.6 | 0.27 |

WBC count (10 ^{4}/mm^{3}, mean) | 113.2 | 98.3 | 0.26 |

Platelet count (10 ^{4}/mm^{3}, mean) | 23.0 | 21.7 | 0.71 |

Postoperative CI within 3 months (n) | 1 | 0 | 0.40 |

Case No | 1 | 2 | 3 | 4 | 5 | 6 |
---|---|---|---|---|---|---|

Sex (M/F) | 77 | 81 | 66 | 69 | 50 | 75 |

VATS/Open | Open | VATS | VATS | VATS | VATS | VATS |

PV ligation (yes/no) | No | No | No | No | Yes | Yes |

Stump length (mm) | 13.5 | 17.2 | 18.0 | 27.6 | 14.6 | 20.1 |

Postoperative CI within 3 months (yes/no) | Yes | No | No | No | No | No |

Area of average blood flow velocity (cm ^{3}) | ||||||

< 10 mm/s | 2.1 | 1.1 | 1.9 | 2.9 | 0.8 | 2.4 |

< 5 mm/s | 1.4 | 0.7 | 1.6 | 2.5 | 0.7 | 2.2 |

< 3 mm/s | 1.0 | 0.5 | 1.2 | 2.2 | 0.6 | 2.0 |

Area of all time blood flow velocity (cm ^{3}) | ||||||

< 10 mm/s | 1.3 | 0.1 | 0.4 | 2.5 | 0.5 | 2.2 |

< 5 mm/s | 0.7 | 0.1 | 0.2 | 2.0 | 0.4 | 1.9 |

< 3 mm/s | 0.4 | 0.0 | 0.2 | 1.7 | 0.3 | 1.6 |

Area of average WSS (cm ^{2}) | ||||||

< 0.1 Pa | 8.2 | 6.0 | 7.5 | 9.4 | 4.7 | 8.6 |

< 0.03 Pa | 5.8 | 3.3 | 5.7 | 8.7 | 4.1 | 7.9 |

< 0.01 Pa | 2.7 | 1.7 | 3.7 | 7.3 | 3.2 | 6.7 |

Area of all time WSS (cm ^{2}) | ||||||

< 0.1 Pa | 6.9 | 0.9 | 3.7 | 9.1 | 3.1 | 8.2 |

< 0.03 Pa | 3.1 | 0.3 | 1.1 | 7.0 | 2.3 | 7.1 |

< 0.01 Pa | 1.2 | 0.1 | 0.5 | 5.5 | 1.1 | 5.3 |

^{3}and 0.84 cm

^{3}in the thrombus and non-thrombus groups, respectively (Fig. 2A). The mean volumes of an average blood flow velocity < 5 mm/s were 1.51 cm

^{3}and 0.44 cm

^{3}in the thrombus and non-thrombus groups, respectively (Fig. 2B). The mean volumes of an average blood flow velocity < 3 mm/s were 1.25 cm

^{3}and 0.26 cm

^{3}in the thrombus and non-thrombus groups, respectively (Fig. 2C). For the three cut-off values of 10 mm/s, 5 mm/s, and 3 mm/s, statistically significant differences were noted between the two groups in the volumes where the average blood flow velocity per heartbeat was less than the cut-off value (p-values 0.0096, 0.0016, 0.0014, respectively). The mean volume where the blood flow velocity was consistently < 10 mm/s was 1.17 cm

^{3}and 0.27 cm

^{3}in the thrombus and non-thrombus groups, respectively (Fig. 2D). The mean volume where the blood flow velocity was always < 5 mm/s was 0.86 cm

^{3}and 0.09 cm

^{3}in the thrombus and non-thrombus groups, respectively (Fig. 3E). The mean volume where the blood flow velocity was always < 3 mm/s was 0.69 cm

^{3}and 0.05 cm

^{3}in the thrombus and non-thrombus groups, respectively (Fig. 3F). For the three cut-off values of 10 mm/s, 5 mm/s, and 3 mm/s, statistically significant differences were noted between the two groups in the volume of the region where the blood flow velocity was always below the cut-off value (p-values 0.019, 0.015, 0.017, respectively).

^{2}and 3.24 cm

^{2}in the thrombus and non-thrombus groups, respectively (Fig. 3A). The mean areas of an average WSS < 0.03 Pa were 5.03 cm

^{2}and 1.51 cm

^{2}in the thrombus and non-thrombus groups, respectively (Fig. 3B). The mean areas of an average WSS < 0.01 Pa were 4.21 cm

^{2}and 0.39 cm

^{2}in the thrombus and non-thrombus groups, respectively (Fig. 3C). For the three cut-off values of 0.1 Pa, 0.03 Pa, and 0.01 Pa, statistically significant differences were noted between the two groups in the area where an average WSS per heartbeat was less than the cut-off value (p-values 0.0002, < 0.0001, 0.0002, respectively). The mean areas where the WSS was always < 0.1 Pa were 5.33 cm

^{2}and 1.64 cm

^{2}in the thrombus and non-thrombus groups, respectively (Fig. 3D). The mean areas where the WSS was always < 0.03 Pa were 3.49 cm

^{2}and 0.13 cm

^{2}in the thrombus and non-thrombus groups, respectively (Fig. 3E). The mean areas where the WSS was always < 0.01 Pa were 2.29 cm

^{2}and 0.004 cm

^{2}in the thrombus and non-thrombus groups, respectively (Fig. 3F). For the three cut-off values of 0.1 Pa, 0.03 Pa, and 0.01 Pa, statistically significant differences were noted between the two groups in the area where WSS was always below the cut-off value (p-values 0.0088, 0.0041, 0.0014, respectively).

## Discussion

^{8}However, there is insufficient evidence regarding the optimal timing of anticoagulant therapy. We also observed recurrent stroke after administering anticoagulant therapy for pulmonary vein thrombosis [8]. Overall, the incidence of embolism is rarer than the incidence of thrombi detected in the pulmonary vein stump; therefore, whether early postoperative anticoagulant therapy outweighs the risks of complications such as postoperative bleeding is questionable. Considering these factors, we did not examine ROC with the CFD data to predict thrombus in the pulmonary vein stump.