超音波検査技術

A man in his 40s was admitted with acute heart failure due to atrial flutter and fibrillation. He underwent pulmonary vein isolation and linear ablation of the tricuspid valve isthmus. Three months after discharge, transthoracic echocardiography (TTE) revealed accelerated color Doppler flow within the left atrium (LA) and elevated blood flow velocity in the left inferior pulmonary vein (PV) (peak V＝1.7 m/s). Although asymptomatic, a ventilation–perfusion mismatch in the left lung was detected, leading to a diagnosis of PV stenosis and subsequent balloon angioplasty. Following the procedure, flow velocity in the left inferior PV remained elevated (1.6 m/s), and contrast-enhanced CT showed poor enhancement. Additional dilation was considered, but the patient was discharged as blood flow was preserved in the left superior PV. Two months later, however, he developed cough and hemoptysis. Three months post-angioplasty, chest X-ray demonstrated abnormal shadows in the left inferior lung field, and TTE showed absent blood flow in the left inferior PV. CT imaging confirmed obstruction of both the left superior and inferior PVs, along with ground-glass opacity and nodular infiltrative changes. A second angioplasty with stent implantation was performed in both the left superior and inferior PVs. Postoperatively, TTE confirmed restored blood flow. This case underscores the value of systematic TTE assessment—including detection of color Doppler flow in the LA from the parasternal long-axis view—in diagnosing PV stenosis following ablation procedures.