Instituto Dante Pazzanese de Cardiologia,São Paulo, SP - Brasil.
Arq Bras Cardiol. 2022 May;118(5):861-872. doi: 10.36660/abc.20200732.
Hypertrophic cardiomyopathy (HCM) can cause obstruction in the left ventricular outflow tract (LVOT), and be responsible for the onset of limiting symptoms, such as tiredness. When such symptoms are refractory to pharmacological treatment, interventionist alternative therapies can be useful, such as septal ablation through the infusion of alcohol in the coronary artery or through myectomy. Recently, the use of a radiofrequency (RF) catheter for endocardial septal ablation guided by electroanatomic mapping has proven to be efficient, despite the high incidence of complete atrioventricular block. An alternative would be the application of RF at the beginning point of the septal gradient guided by the transesophageal echocardiography (TEE). The echocardiography is an imaging method with high accuracy to determine septal anatomy.
To assess the long term effect of septal ablation for the relief of ventricular-arterial gradient, using TEE to help place the catheter in the area of larger septal obstruction. Besides, to assess the effects of ablation on the functional class and echocardiographic parameters.
Twelve asymptomatic patients, with LVOT obstruction, refractory to pharmacological therapy, underwent endocardial septal ablation with 8mm-tip catheters, whose placement was oriented in the region of larger obstruction, assisted by the TEE. Temperature-controlled and staggered RF applications were performed. After each application, the gradient was reassessed and a new application was performed according to the clinical criterion. The effects of RF applications were assessed both for the gradient at rest and for that provoked by the Valsalva maneuver, and considering the gradient. The differences were significant when p-value was lower than or equal to 0.05.
It was possible to observe that the mean reduction of the maximum gradients was from 96.8±34.7 mmHg to 62.7±25.4 mmHg three months after the procedure (p=0.0036). After one year, the mean of maximum gradient was 36.1±23.8 mmHg (p=0.0001). The procedure was well tolerated, without records of complete atrioventricular block nor severe complications.
The TEE-guided septal ablation was efficient and safe, and the results were maintained during the clinical follow-up period. It is a reasonable option for the interventionist treatment of LVOT obstruction in HCM.
肥厚型心肌病（HCM）可导致左心室流出道（LVOT）阻塞，并引发疲劳等限制症状。当这些症状对药物治疗无反应时，介入性替代疗法可能会有所帮助，例如通过冠状动脉内输注酒精或通过心肌切除术进行间隔消融。最近，使用射频（RF）导管在电解剖标测引导下进行心内膜间隔消融已被证明是有效的，尽管完全性房室传导阻滞的发生率较高。另一种方法是在经食管超声心动图（TEE）引导下，在间隔梯度的起始点应用 RF。超声心动图是一种具有高准确性的成像方法，可用于确定间隔解剖结构。
评估 TEE 辅助下心内膜间隔消融治疗缓解心室-动脉梯度的长期效果，在 TEE 引导下帮助将导管放置在间隔较大阻塞部位。此外，评估消融对功能分级和超声心动图参数的影响。
12 名无症状患者，LVOT 阻塞，对药物治疗无反应，接受 8mm 尖端导管的心内膜间隔消融治疗，其放置方向为较大阻塞区域，由 TEE 辅助。进行温度控制和交错的 RF 应用。每次应用后，重新评估梯度，并根据临床标准进行新的应用。评估 RF 应用对静息时梯度和瓦尔萨尔瓦动作引起的梯度的影响，并考虑梯度。当 p 值低于或等于 0.05 时，差异具有统计学意义。
可以观察到，在术后 3 个月时，最大梯度的平均降低幅度从 96.8±34.7mmHg 降至 62.7±25.4mmHg（p=0.0036）。术后 1 年，最大梯度平均值为 36.1±23.8mmHg（p=0.0001）。该手术耐受性良好，无完全性房室传导阻滞或严重并发症记录。
TEE 引导下的间隔消融是有效且安全的，在临床随访期间结果得以维持。它是肥厚型心肌病 LVOT 阻塞介入治疗的合理选择。
