患者,男,29岁。无明显诱因,出现头昏、心悸、四肢乏力、平卧时症状好转,坐位及活动后症状出现。平素健康。体查:心率65次,血压12.0/8.0kPa。双肺呼吸音清晰,心界不大,心音正常,卧位时心律匀齐,心率相对较慢;坐位可闻及频发早搏(8～10次),心率相对较快。各瓣膜区无杂音。血钾5.9mmol/L,血沉2mm/h,抗“O”500u。胸片:心肺正常。 入院常规心电图检查:窦P清晰,P-P匀齐,约100cs,P-P=12cs,心率约60次,为正常窦性心率(图1)。因坐位听诊发现有频发早搏,故取坐位Ⅱ导联连续纪录(实际描录4500cs),发现心率增快至 Patient, male, 29 years old. No obvious incentive, there dizziness, palpitations, limb weakness, supine symptoms improved, sitting and activities after the symptoms appear. Usually healthy. Physical examination: heart rate 65 times, blood pressure 12.0 / 8.0kPa. Breath sounds clear lungs, heart is not big, normal heart sound, lying heart rate rhythm homogeneous, relatively slow heart rate; seat can be heard and frequent premature beats (8 to 10 times), the heart rate is relatively fast. The valve area without noise. Blood potassium 5.9mmol / L, ESR 2mm / h, anti “O” 500u. Chest radiograph: normal heart and lungs. Admission routine ECG: Sinus P clear, P-P uniform, about 100cs, P-P = 12cs, heart rate of about 60 times for the normal sinus heart rate (Figure 1). Due to sitting auscultation found to have frequent premature beats, so taking seat Ⅱ lead continuous record (actual profile 4500cs), found that heart rate increased to