Cryoballoon ablation using the sheath‐in‐sheath technique in a patient with a tortuous common iliac vein oleh Yuhei Kasai, Takayuki Kitai, Junji Morita, Kizuku Iitsuka, Takuya Haraguchi, Masanaga Tsujimoto, Takuya Okada, Yumetsugu Munakata, Jungo Kasai, Tsutomu Fujita