【Introduction】We measured the cerebral blood flow velocity and waveforms before and after balloon deflation（B-def）during cryoballoon-based pulmonary vein isolation（CBPVI）. 【Subjects and Methods】 Thirty patients undergoing CBPVI were included in the study. Intraoperative monitoring of the unilateral middle cerebral artery（MCA）was performed using transcranial doppler（TCD）ultrasound. 【Results】At 19（12-28）seconds after B-def, blood flow velocity exhibited a maximal change. Pulsatility index（PI）and peak systolic velocity, which evaluate cerebrovascular hypoperfusion, increased. There was no change in heart rate at that time, and mean velocity and end diastolic velocity decreased. The waveform of blood velocity also changed to a decreasing diastolic pattern. After that, PI recovered to the pre-B-def level 32（19-48）seconds after the B-def.【Discussion】Peripheral vasoconstriction by freezing blood and peripheral vasoconstriction by circulatory reflex were considered the causes of the increase in PI. 【Conclusion】After the B-def, transient contraction occurred in the peripheral MCA, suggesting the possibility of rapid vasoconstriction.

A 54-year-old woman who had been diagnosed with cardiac implantable electronic devices（CIEDs）infection had been receiving conservative management but then suffered septic shock. She was diagnosed with prosthetic aortic valve endocarditis with aorto-right atrium fistula. She was referred to our hospital. Her pacemaker system was removed using an excimer laser sheath, the prosthetic valve was removed and replaced with a 25mm bioprosthetic valve, and the aorto-right atrium fistula was closed with a rifampicin-soaked bovine pericardial patch. Residural aorto-right atrium shunt was not detected after the operation, and her post operative course was uneventful without congestive heart failure or signs of infection.