tailieunhanh - Essential Cardiac Electrophysiology Self Assessment - Part 3

• thành công tần số vô tuyến (RF) cắt bỏ của Nhóm hoặc sửa đổi nút xoang vẫn còn khó khăn. Mặc dù tỷ lệ thành công ngắn hạn có thể được thuận lợi (từ 76-100%), kết quả dài hạn là đáng thất vọng. • Các thiết bị đầu cuối của nút xoang cắt bỏ thành công vẫn còn chưa rõ ràng | Sinus Node Dysfunction and AV Blocks 47 Successful radiofrequency RF ablation of 1ST or sinus node modification remains difficult. Although short-term success rates may be favorable range 76-100 long-term outcomes are disappointing. The endpoint of successful sinus node ablation remains unclear. Heart rate below 80-90 bpm with or without isoproterenol infusion usually 1-2 g min at the conclusion of the procedure is considered a reasonable end point. Most of the cardiac and extra-cardiac symptoms persist despite documented slower heart rates suggesting that sinus tachycardia and symptoms of palpitations are likely secondary manifestations of autonomic dysregulation. In the absence of atrial or other supraventricular tachycardia and autonomic and other multisystem symptoms RF ablation can be considered. Three-dimensional mapping or intracardiac echocardiography in localizing the crista may improve the outcome of the ablation. Surgical or RF ablation of the SAN and insertion of a permanent pacemaker may be considered. Fatigue awareness of the paced rhythm and other symptoms may persist in spite of rate reduction. To avoid diaphragmatic paralysis high output pacing should be performed with an ablation catheter along the crista terminalis before delivering RF current. The clinical features of 1ST significantly overlap with postural orthostatic tachycardia syndrome POTS . A multidisciplinary approach involving neurologist cardiovascular rehabilitation and psychiatrist may be necessary in managing patients with 1ST. Sinus node dysfunction SND Causes of sinus node dysfunction Intrinsic primary SND may result from fibrosis and ageing-related loss of pacemaker cells. Extrinsic secondary causes of SND are listed in Box . Pathophysiology The sinus node is located near the superior anterolateral portion of RA near the SVC junction and the superior end of the crista terminalis. Cells in the SAN demonstrate diastolic depolarization and its AP is calcium channel dependent. .